Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] $400 million senior unsecured term loan facility due November 25, 2019 (average interest rate of 3.48% for the period January 1, 2018 through December 31, 2018)(2) Four Hundred Million Term Loan Facility [Member] Four Hundred Million Term Loan Facility [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Remaining amount outstanding Long-term Line of Credit Income Tax Disclosure [Abstract] Current income tax provision: Current Federal, State and Local, Tax Expense (Benefit) [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Foreign Current Foreign Tax Expense (Benefit) Total current income taxes Current Income Tax Expense (Benefit) Deferred income tax provision (benefit): Deferred Federal, State and Local, Tax Expense (Benefit) [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Foreign Deferred Foreign Income Tax Expense (Benefit) Total deferred income provision (benefit) Deferred Income Tax Expense (Benefit) Total income tax provision Income Tax Expense (Benefit) Restructuring and Related Activities [Abstract] Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Severance and other termination benefits Employee Severance [Member] Asset impairments Asset Impairment [Member] Asset Impairment Member Other Other Restructuring [Member] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Restructuring charges Restructuring Charges Number of positions eliminated Restructuring and Related Cost, Number of Positions Eliminated Restructuring reserve Restructuring Reserve Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Foreign Tax Authority Foreign Tax Authority [Member] State and local jurisdiction State and Local Jurisdiction [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Net operating loss carryforwards, subject to expiration Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration Net operating loss carryforwards, not subject to expiration Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration Earnings Per Share [Abstract] Antidilutive securities Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Fair Value Disclosures [Abstract] Schedule of Financial Assets Measured at Fair Value on Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Senior Notes Senior Notes [Member] 3.85% senior unsecured notes due June 30, 2026 Three Point Eight Five Senior Secured Notes Due June302026 [Member] Three Point Eight Five Senior Secured Notes Due June302026 [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Stated rate Debt Instrument, Interest Rate, Stated Percentage Maximum interest rate on debt instrument Debt Instrument, Interest Rate, Effective Percentage Property, Plant and Equipment [Abstract] Depreciation and amortization expense Depreciation, Depletion and Amortization Asset impairment charges Tangible Asset Impairment Charges Due to and from Broker-Dealers and Clearing Organizations [Abstract] Clearing Operations [Table] Clearing Operations [Table] Clearing Operations [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] Cash Contributions Nordic Clearing Members Cash Contributions [Member] Nordic Clearing Members Cash Contributions [Member] Non-Cash Contributions Nordic Clearing Members Non Cash Contributions [Member] Nordic Clearing Members Non Cash Contributions [Member] Clearing Operations [Line Items] Clearing Operations [Line Items] Clearing Operations [Line Items] Default fund contributions Default Fund Contributions Default fund Contributions. Margin deposits Margin deposits Margin deposits Total Default fund contributions and margin deposits Default fund contributions and margin deposits Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss) Attributable to Parent Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Share-based compensation Share-based Compensation Deferred income taxes Reversal of certain Swedish tax benefits Income Tax Credits and Adjustments Net gain on divestiture of businesses Gain (Loss) on Disposition of Business Gain on sale of investment security Gain on Sale of Investments Asset impairment charge Asset Impairment Charges Net income from unconsolidated investees Income (Loss) from Equity Method Investments Other reconciling items included in net income Other Noncash Income (Expense) Net change in operating assets and liabilities, net of effects of divestiture and acquisitions: Increase (Decrease) in Operating Capital [Abstract] Receivables, net Increase (Decrease) in Receivables Other assets Increase (Decrease) in Other Operating Assets Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Section 31 fees payable to SEC Increase (Decrease) in Other Accounts Payable Accrued personnel costs Increase (Decrease) in Employee Related Liabilities Deferred revenue Increase (Decrease) in Contract with Customer, Liability Other liabilities Increase (Decrease) in Other Operating Liabilities Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of securities Payments to Acquire Short-term Investments Proceeds from sales and redemptions of securities Proceeds from Sale, Maturity and Collection of Short-term Investments Proceeds from divestiture of businesses, net Proceeds from Divestiture of Businesses, Net of Cash Divested Proceeds from sale of investment security Proceeds from Sale and Maturity of Debt and Equity Securities, FV-NI, Held-for-investment Acquisition of businesses, net of cash and cash equivalents acquired and other investment activities Payments to Acquire Businesses, Net of Cash Acquired Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from (repayments of) commercial paper, net Proceeds from (Repayments of) Commercial Paper Repayments of long-term debt Repayments of Long-term Debt Payment of debt extinguishment cost Payment for Debt Extinguishment or Debt Prepayment Cost Proceeds from long-term debt issuances, net of debt issuance costs Proceeds from Lines of Credit Repurchases of common stock Payments for Repurchase of Common Stock Dividends paid Payments of Dividends Proceeds received from employee stock activity Proceeds from Issuance of Common Stock Payments related to employee shares withheld for taxes Payments related to employee shares withheld for taxes Payments related to employee shares withheld for taxes Proceeds of customer funds Proceeds from (Disbursements of) Customer Funds Proceeds from (Disbursements of) Customer Funds Other financing activities Proceeds from (Payments for) Other Financing Activities Net cash (used in) provided by financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash and cash equivalents and restricted cash Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Net increase (decrease) in cash and cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash and cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents and restricted cash at end of period Supplemental Disclosure Cash Flow Information Supplemental Cash Flow Information [Abstract] Cash paid for: Supplemental Cash Flow Information Cash Paid The amount of cash paid during the period. Interest Interest Paid, Excluding Capitalized Interest, Operating Activities Income taxes, net of refund Income Taxes Paid, Net Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization And Basis Of Presentation [Table] Organization And Basis Of Presentation [Table] Organization And Basis Of Presentation [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Market Services Market Services [Member] Market Services [Member] Corporate Services Corporate Services [Member] Corporate Services [Member] Information Services Global Information [Member] Global Information [Member] Market Technology Market Technology [Member] Market Technology [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] United States UNITED STATES Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Options Markets Options Markets [Member] Options Markets [Member] Cash Equities Trading Markets Cash Equities Trading Markets [Member] Cash Equities Trading Markets [Member] Organization And Basis Of Presentation [Line Items] Organization And Basis Of Presentation [Line Items] Organization And Basis Of Presentation [Line Items] Number of operating segments Number of Operating Segments Number of exchanges Services Provided Over Number Of MarketPlaces Number of marketplaces Number of derivative exchanges listing commodities offerings Number of Derivative Exchanges Listing Commodities Offerings Number of Derivative Exchanges Listing Commodities Offerings Total number of listings on The Nasdaq Stock Market Total Number Of U S Listed Companies Total Number Of U.S. Companies Listed On The Nasdaq Stock Market. ETPs and other listings listed on Nasdaq Stock Market Number Of Exchange Traded Products and Other Listings Companies Number Of Exchange Traded Products and Other Listings Companies Approximate combined market capitalization, U.S. Approximate Combined Market Capitalization United States Approximate Combined Market Capitalization United States. Total number of listed companies within Nordic and Baltic exchanges Total Number Of Listed Companies Within Nordic And Baltic Exchanges Total Number of Listed Companies within Nordic and Baltic Exchanges Approximate combined market capitalization within Nordic and Baltic exchanges Approximate combined market capitalization within Nordic and Baltic exchanges Approximate Combined Market Capitalization within Nordic and Baltic exchanges Number of exchange traded products licensed to Nasdaq's Indexes Number Of Exchange Traded Products Licensed Number Of ETPs Licensed Assets management value Assets management value Assets under management value of ETPs licensed to Nasdaq's indexes. Number of funds and other investment vehicles Number Of Funds And Other Investment Vehicles Number Of Funds And Other Investment Vehicles Number of countries services are provided Services Provided Over Number Of Countries Services Provided Over Number Of Countries Accounting Policies [Abstract] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2014-09 Accounting Standards Update 2014-09 [Member] Restatement [Axis] Restatement [Axis] Restatement [Domain] Restatement [Domain] Restatement Adjustment Restatement Adjustment [Member] Market Services Corporate Services Information Services Information Services [Member] Information Services [Member] Market Technology Technology Service [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Revenues: Revenues [Abstract] Total revenues Revenue from Contract with Customer, Excluding Assessed Tax Total operating expenses Operating Expenses Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax provision Net income attributable to Nasdaq Diluted earnings per share (in dollars per share) Earnings Per Share, Diluted Assets Assets [Abstract] Other current assets Other Assets, Current Other non-current assets Other Assets, Noncurrent Deferred tax assets Deferred Tax Assets, Gross Total assets Assets Liabilities Liabilities [Abstract] Deferred revenue Contract with Customer, Liability, Current Non-current deferred revenue Contract with Customer, Liability, Noncurrent Total liabilities Liabilities Nasdaq stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Retained earnings Retained Earnings (Accumulated Deficit) Total Nasdaq stockholders' equity Stockholders' Equity Attributable to Parent Total liabilities and equity Liabilities and Equity Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Equity [Abstract] Stockholders' Equity [Table] Stockholders Equity [Table] Stockholders' Equity [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Other Repurchases of Common Stock Other Repurchases Of Common Stock [Member] Other Repurchases of Common Stock [Member] Series A Preferred Stock Series A Preferred Stock [Member] Stockholders Equity [Line Items] Stockholders Equity [Line Items] Stockholders Equity [Line Items] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Common stock (in votes per share) Stockholders' Equity, Number Of Votes Stockholders' Equity, Number Of Votes Common stock holder voting rights, maximum percentage of the then-outstanding shares of Nasdaq common stock Common Stock Holder Voting Rights Common Stock Holder Voting Rights Common stock in treasury (in shares) Treasury Stock, Shares Share repurchase program additional amount authorized Share Repurchase Program, Additional Amount Authorized Share Repurchase Program, Additional Amount Authorized Share repurchase program, authorized amount Stock Repurchase Program, Authorized Amount Remaining authorized share repurchase amounts under repurchase program Stock Repurchase Program, Remaining Authorized Repurchase Amount Number of shares of common stock repurchased (in shares) Treasury Stock, Shares, Acquired Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred stock par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, series A convertible preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Preferred stock, series A convertible preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Payments of dividends Payments of Ordinary Dividends, Common Stock Cash dividends declared per common share (in dollars per share) Common Stock, Dividends, Per Share, Declared Percent increase over prior quarter dividend Common Stock, Dividends, Percent Increase Over Prior Quarter Common Stock, Dividends, Percent Increase Over Prior Quarter Dividends declared Dividends, Common Stock, Cash Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Commercial paper Commercial Paper [Member] Minimum Minimum [Member] Weighted Average Weighted Average [Member] Short-term Debt [Line Items] Short-term Debt [Line Items] Maturity period Debt Instrument, Term Weighted average interest rate Debt, Weighted Average Interest Rate Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Commodity and seafood options, futures and forwards Commodity Forwards And Options [Member] Commodity Forwards And Options [Member]. Fixed-income options and futures Fixed Income Options And Futures [Member] Fixed-Income Options And Futures [Member]. Stock options and futures Stock Options And Futures [Member] Stock Options And Futures [Member]. Index options and futures Index Options And Futures [Member] Index Options And Futures [Member]. Market value of derivative contracts Derivative Contracts Market Value Derivative contracts market value Total number of cleared contracts Derivative, Number of Instruments Held Total volume in cleared power, in Terawatt hours (TWh) Total Volume In Cleared Power Total volume in cleared power. Discontinued Operations and Disposal Groups [Abstract] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] Public Relations Solutions and Digital Media Services Public Relations Solutions and Digital Media Services [Member] Public Relations Solutions and Digital Media Services [Member] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Disposal Group Classification [Domain] Disposal Group Classification [Domain] Disposal Group, Not Discontinued Operations Disposal Group, Not Discontinued Operations [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Impairment charge Impairment of Long-Lived Assets to be Disposed of Carrying Amount of Assets and Liabilities Held for Sale [Abstract] Carrying Amount of Assets and Liabilities Held for Sale [Abstract] Carrying Amount of Assets and Liabilities Held for Sale [Abstract] Receivables, net Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net Property and equipment, net Disposal Group, Including Discontinued Operation, Property, Plant and Equipment, Current Goodwill Disposal Group, Including Discontinued Operation, Goodwill, Current Intangible assets, net Disposal Group, Including Discontinued Operation, Intangible Assets, Current Other assets Disposal Group, Including Discontinued Operation, Other Assets, Current Total assets held for sale Disposal Group, Including Discontinued Operation, Assets, Current Deferred tax liabilities Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities Other current liabilities Disposal Group, Including Discontinued Operation, Other Liabilities, Current Total liabilities held for sale Disposal Group, Including Discontinued Operation, Liabilities, Current Domestic and Foreign Components of Income Before Income Tax Provision Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Schedule of Components of Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Reconciliation of Provision of Income Taxes Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Summary of Net Operating Losses and Credits Summary of Operating Loss Carryforwards [Table Text Block] Summary of Tax Credit Carryforwards Summary of Tax Credit Carryforwards [Table Text Block] Reconciliation of Unrecognized Tax Benefits Summary of Income Tax Contingencies [Table Text Block] Earnings Per Share Earnings Per Share [Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Employee Stock Purchase Plan Employee Stock [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Number of shares purchased by employees Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Weighted-average price of shares purchased (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Per Share Weighted Average Price of Shares Purchased Compensation expenses Allocated Share-based Compensation Expense Segment Reporting [Abstract] Business Segments Segment Reporting Disclosure [Text Block] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Exercise Price Range [Axis] Exercise Price Range [Axis] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] Exercise Price Range One Exercise Price Range One [Member] Exercise Price Range One [Member] Exercise Price Range Two Exercise Price Range Two [Member] Exercise Price Range Two [Member] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Stock Options Employee Service Share-based Compensation, Aggregate Disclosures [Abstract] Range of exercise price, lower range limit (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit Range of exercise price, lower range limit (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit Outstanding, number of stock options (in shares) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options Outstanding, weighted-average remaining contractual term Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term Outstanding, weighted-average exercise price (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price Outstanding, aggregate intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Exercisable, number of exercisable (in shares) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options Exercisable, weighted-average remaining contractual term Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term Exercisable, weighted-average exercise price (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price Exercisable, aggregate intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Deferred tax assets: Components of Deferred Tax Assets [Abstract] Deferred revenues Deferred Tax Assets, Deferred Income U.S. federal net operating loss Deferred Tax Assets, Operating Loss Carryforwards, Domestic Foreign net operating loss Deferred Tax Assets, Operating Loss Carryforwards, Foreign State net operating loss Deferred Tax Assets, Operating Loss Carryforwards, State and Local Compensation and benefits Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Foreign currency translation Deferred Tax Assets, Unrealized Currency Losses Tax credits Deferred Tax Assets, Tax Credit Carryforwards Federal benefit of uncertain tax positions Deferred Tax Assets, Federal Benefit Of Uncertain Tax Positions Deferred Tax Assets, Federal Benefit Of Uncertain Tax Positions Other Deferred Tax Assets, Other Gross deferred tax assets Less: valuation allowance Deferred Tax Assets, Valuation Allowance Total deferred tax assets, net of valuation allowance Deferred Tax Assets, Net of Valuation Allowance Deferred tax liabilities: Components of Deferred Tax Liabilities [Abstract] Amortization of software development costs and depreciation Deferred Tax Liabilities, Deferred Expense, Capitalized Software Amortization of acquired intangible assets Deferred Tax Liabilities, Intangible Assets Investments Deferred Tax Liabilities, Investments Other Deferred Tax Liabilities, Other Gross deferred tax liabilities Deferred Tax Liabilities, Gross Net deferred tax liabilities Deferred Tax Liabilities, Net Non-current deferred tax assets Deferred Income Tax Assets, Net Deferred tax liabilities, net Deferred Income Tax Liabilities, Net Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Acquired Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Income Taxes Income Tax Disclosure [Text Block] PSUs Performance Shares [Member] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Three-Year Program Three Year Performance Share Unit Program [Member] Three Year Performance Share Unit Program Weighted-average risk free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Expected volatility Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate Weighted-average grant date share price (in dollars per share) Share Price Weighted-average fair value at grant date (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Facilities-related Facility Closing [Member] Total restructuring charges Dividends Payable [Table] Dividends Payable [Table] Dividends [Axis] Dividends [Axis] Dividends [Domain] Dividends [Domain] Dividend Declaration Date Fourth Quarter Dividend Declaration Date Fourth Quarter [Member] Dividend Declaration Date Fourth Quarter [Member] Dividends Payable [Line Items] Dividends Payable [Line Items] Dividend per common share (in dollars per share) Total Amount Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Technology Developed Technology Rights [Member] Customer relationships Customer Relationships [Member] Other Other Intangible Assets [Member] Foreign currency translation adjustment Foreign Currency Translation Adjustment [Member] Foreign currency translation adjustment [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Gross Amount Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Net Amount Finite-Lived Intangible Assets, Net Weighted-Average Useful Life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Schedule of Indefinite-Lived Intangible Assets [Table] Schedule of Indefinite-Lived Intangible Assets [Table] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Exchange and clearing registrations Exchange And Clearing Registrations [Member] Exchange and clearing registrations [Member] Trade name Trade Names [Member] Licenses Licensing Agreements [Member] Indefinite-lived Intangible Assets [Line Items] Indefinite-lived Intangible Assets [Line Items] Indefinite-Lived Intangible Assets Indefinite-lived Intangible Assets (Excluding Goodwill) Total intangible assets Intangible Assets, Gross (Excluding Goodwill) Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Leases [Abstract] Leases Leases of Lessee Disclosure [Text Block] Average price paid per share (in dollars per share) Treasury Stock Acquired, Average Cost Per Share Total purchase price Treasury Stock, Value, Acquired, Par Value Method Revenue from Contract with Customer [Abstract] Deferred Revenue Revenue from Contract with Customer [Text Block] Schedule of Debt [Table] Schedule of Debt [Table] Schedule of Debt [Table] Senior unsecured floating rate notes due March 22, 2019 Senior Unsecured Floating Rate Notes Due March 2019 [Member] Senior Unsecured Floating Rate notes Due March 2019 [Member] Revolving Credit Facility Revolving Credit Facility [Member] 5.55% senior unsecured notes due January 15, 2020 Five Point Five Five Percent Senior Unsecured Notes Due January Fifteen Two Thousand Twenty [Member] Five Point Five Five Percent Senior Unsecured Notes Due January Fifteen Two Thousand Twenty [Member] 3.875% senior unsecured notes due June 7, 2021 Three Point Eight Seven Five Percent Senior Unsecured Notes Due June72021 [Member] 3.875% senior unsecured notes due June 7, 2021 [Member] 4.25% senior unsecured notes due June 1, 2024 Four Point Two Five Percent Senior Unsecured Notes Due June12024 [Member] Four Point Two Five Percent Senior Unsecured Notes Due June 1 2024 [Member] 1.75% senior unsecured notes due May 19, 2023 One Point Seven Five Senior Unsecured Notes Due May192023 [Member] One Point Seven Five Senior Unsecured Notes Due May192023 [Member] $1 billion revolving credit commitment due April 25, 2022 (average interest rate of 2.74% for the period January 1, 2018 through December 31, 2018) One Billion, Five-Year Revolving Credit Facility [Member] One Billion, Five-Year Revolving Credit Facility [Member] Schedule of Debt [Line Items] Schedule of Debt [Line Items] [Line Items] for Schedule of Debt [Table] Facility borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Interest rate Debt Instrument, Interest Rate During Period Changes In Short-Term Debt Obligations [Roll Forward] Changes In Short-Term Debt Obligations [Roll Forward] Changes In Short-Term Debt Obligations [Roll Forward] Short-term debt - commercial paper beginning balance Short-term Debt Additions Proceeds from Short-term Debt Payments, Accretion and Other Proceeds from (Repayments of) Short-term Debt Short-term debt - commercial paper ending balance Changes in Long-Term Debt Obligations [Roll Forward] Changes in Long-Term Debt Obligations [Roll Forward] Changes in Long-Term Debt Obligations [Roll Forward] Long-term debt obligations at beginning of period Long-term Debt Additions Proceeds from Issuance of Long-term Debt Payments, Accretion and Other Payments (Accretions) And Other of Long-term Debt Payments (Accretions) And Other of Long-term Debt Long-term debt obligations at end of period Changes In Debt Obligations [Roll Forward] Changes In Debt Obligations [Roll Forward] Changes In Debt Obligations [Roll Forward] Total debt obligations at beginning of period Debt, Long-term and Short-term, Combined Amount Additions Proceeds from Issuance of Debt Payments, Accretion and Other Payments (Accretions) And Other Of Long-Term And Short-Term Debt Payments (Accretions) And Other Of Long-Term And Short-Term Debt Total debt obligations at end of period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Accounting Standards Update 2016-02 Accounting Standards Update 2016-02 [Member] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Building and Building Improvements Building and Building Improvements [Member] Data processing equipment and software Data Processing Equipment And Software [Member] Data processing equipment and software [Member] Furniture And Equipment Furniture And Equipment [Member] Furniture And Equipment [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Order Machine Order Machine [Member] Order Machine [Member] Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Cash Equivalents Cash Equivalents [Member] Computer Software, Intangible Asset Computer Software, Intangible Asset [Member] Rebranding of trade name Rebranding Of Trade Name [Member] Rebranding of trade name [Member] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Axis] Timing of Transfer of Good or Service [Domain] Timing of Transfer of Good or Service [Domain] Services transferred at a point in time Transferred at Point in Time [Member] Services transferred over time Transferred over Time [Member] Europe Europe [Member] Trade management services Trade Management Services [Member] Trade Management Services [Member] Listing services Listing Services [Member] Listing Services [Member] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash and cash equivalents, current Restricted Cash and Cash Equivalents, Current Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable Equity security impairment loss Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount Impairment charge Equity Method Investment, Other than Temporary Impairment Estimated useful life of property and equipment Property, Plant and Equipment, Useful Life Estimated useful life of intangible assets Finite-Lived Intangible Asset, Useful Life Goodwill, impairment loss Goodwill, Impairment Loss Non-cash write-off related to indefinite-lived intangible asset Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) Revenue, remaining performance obligation, expected timing of satisfaction Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Number of types of license agreements Number of types of license agreements Number of types of license agreements Revenue recognized (percentage) Revenue From Contract With Customer, Percentage Revenue From Contract With Customer, Percentage Percentage of fair market value of common stock Percentage Of Fair Market Value Of Common Stock Our ESPP allows eligible U.S. and non-U.S. employees to purchase a limited number of shares of our common stock at six-month intervals, called offering periods, at 85.0% of the lower of the fair market value on the first or the last day of each offering period. The 15.0% discount given to our employees is included in compensation and benefits expense in the Condensed Consolidated Statements of Income. Percentage of discount to employees on purchase of common stock under employee stock purchase plant Percentage Of Discount To Employees On Purchase Of Common Stock Under Employee Stock Purchase Plan Our ESPP allows eligible U.S. and non-U.S. employees to purchase a limited number of shares of our common stock at six-month intervals, called offering periods, at 85.0% of the lower of the fair market value on the first or the last day of each offering period. The 15.0% discount given to our employees is included in compensation and benefits expense in the Condensed Consolidated Statements of Income. Net lease assets Operating Lease, Right-of-Use Asset Lease liabilities Operating Lease, Liability Elimination of operating sublease income Operating Leases, Rent Expense, Sublease Rentals Retirement Benefits [Abstract] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension Pension Plan [Member] SERP Supplemental Employee Retirement Plan [Member] Post-retirement Other Postretirement Benefits Plan [Member] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] 2019 Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months 2020 Defined Benefit Plan, Expected Future Benefit Payment, Year Two 2021 Defined Benefit Plan, Expected Future Benefit Payment, Year Three 2022 Defined Benefit Plan, Expected Future Benefit Payment, Year Four 2023 Defined Benefit Plan, Expected Future Benefit Payment, Year Five 2024 through 2028 Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter Total future benefit payments Defined Benefit Plan Expected Future Benefit Payments Defined Benefit Plan Expected Future Benefit Payments. Income Tax Disclosure [Table] Income Tax Disclosure [Table] Income Tax Disclosure [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Retained Earnings Retained Earnings [Member] Accounting Standards Update 2018-02 Accounting Standards Update 2018-02 [Member] Accounting Standards Update 2018-02 [Member] Sweden SWEDEN Income Tax Disclosure [Line Items] Income Tax Disclosure [Line Items] Income Tax Disclosure [Line Items] Undistributed earnings Undistributed Earnings, Basic Income tax benefits primarily related to share-based compensation Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Unrecognized tax benefits that would impact effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate decrease in unrecognized tax benefits, reasonably possible Decrease in Unrecognized Tax Benefits is Reasonably Possible Penalties and interest expense Income Tax Examination, Penalties and Interest Expense Interest and penalties related to income tax Income Tax Examination, Penalties and Interest Accrued Tax expense (benefits) associated with foreign tax agency Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority Payments for tax settlements Payments For Tax Settlements Payments For Tax Settlements Tax expense (benefits), per diluted share (in dollars per share) Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority Per Diluted Share Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority Per Diluted Share Quarterly recurring tax expense Recurring Tax Expense (Benefits) Recurring Tax Expense (Benefits) Provisional tax benefit, due to Tax Cuts and Jobs Act Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit) Reduction to deferred tax assets relating to foreign currency translation Tax Cuts and Jobs Act of 2017,Measurement Period Adjustment,Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017,Measurement Period Adjustment,Income Tax Expense (Benefit) Reclassification from AOCI, tax amount Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect Changes in Deferred Revenue Contract with Customer, Asset and Liability [Table Text Block] Estimated Deferred Revenue Estimated Deferred Revenue [Table Text Block] The year in which deferred revenue is expected to be recognized. Investments, Debt and Equity Securities [Abstract] Schedule of Investments Schedule of Investments [Table Text Block] Schedule of Investments Schedule of Operating Segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of Corporate Items Schedule of Corporate Items and Elimination [Table Text Block] Schedule of Corporate Items and Elimination [Table Text Block] Revenue from External Customers by Geographic Areas Revenue from External Customers by Geographic Areas [Table Text Block] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Corporate Items Corporate, Non-Segment [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Revenues - divested businesses Expenses: Operating Expenses [Abstract] Amortization expense of acquired intangible assets Amortization of Intangible Assets Merger and strategic initiatives expense Business Combination, Acquisition Related Costs Clearing default Loss Due To Commodities Market Default Allocated To Junior Capital Loss Due To Commodities Market Default Allocated To Junior Capital Extinguishment of debt Regulatory matter Regulatory Operating Expense Regulatory expense includes cost incurred during the period associated with regulation of trading activity and the surveillance and investigation functions of Nasdaq. Expenses - divested businesses Executive compensation Labor and Related Expense Other Other General Expense Total expenses Costs and Expenses Operating income Operating Income (Loss) Clearing Operations Due to and from Broker-Dealers and Clearing Organizations Disclosure [Text Block] Statement of Financial Position [Abstract] Current assets: Assets, Current [Abstract] Restricted cash Restricted Cash, Current Financial investments, at fair value Marketable Securities, Current Receivables, net Receivables, Net, Current Default funds and margin deposits Default Funds And Margin Deposits Assets Nasdaq Clearing members cash contributions for regulatory capital requirements associated with default fund contributions and margin deposits. Total current assets Assets, Current Property and equipment, net Property, Plant and Equipment, Net Goodwill Goodwill Current liabilities: Liabilities, Current [Abstract] Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities, Current Section 31 fees payable to SEC Section Thirty One Fees Payable Section Thirty One Fees Payable Accrued personnel costs Employee-related Liabilities, Current Other current liabilities Other Liabilities, Current Default funds and margin deposits Default Funds And Margin Deposits Liabilities Nasdaq Clearing members cash contributions for regulatory capital requirements associated with default fund contributions and margin deposits. Short-term debt Debt, Current Total current liabilities Liabilities, Current Long-term debt Long-term Debt, Excluding Current Maturities Deferred tax liabilities, net Other non-current liabilities Other Liabilities, Noncurrent Total liabilities Commitments and contingencies Commitments and Contingencies Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common stock, $0.01 par value, 300,000,000 shares authorized, shares issued: 170,709,425 at December 31, 2018 and 172,373,432 at December 31, 2017; shares outstanding: 165,165,104 at December 31, 2018 and 167,441,030 at December 31, 2017 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Common stock in treasury, at cost: 5,544,321 shares at December 31, 2018 and 4,932,402 shares at December 31, 2017 Treasury Stock, Value Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total Nasdaq stockholders’ equity Property and Equipment, net Property, Plant and Equipment Disclosure [Text Block] Liability Waterfall Liability Waterfall [Member] Liability Waterfall [Member] Expenses related to clearing default Expense Related To Clearing Default Expense Related To Clearing Default Loss due to commodities market default allocated to junior capital Increase decrease in total assets Increase (Decrease) In Assets Increase (Decrease) in Assets Capital relief program expense Capital Relief Program Expense Capital Relief Program Expense Retirement Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Nasdaq Clearing Nasdaq Clearing Operations [Member] Nasdaq Clearing Operations [Member] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Reverse Repurchase Agreements Repurchase Agreements [Member] Utilize as capital resources Default fund contribution capital resources available [Member] Default fund contribution capital resources available [Member] Utilize as member posted surplus balance Default fund contribution member posted surplus balance [Member] Default fund contribution member posted surplus balance [Member] Number of member sponsored default funds Number of member sponsored default funds Number of member sponsored default funds Loss due to commodities market default Gain (Loss) Due To Commodities Market Default Gain (Loss) Due To Commodities Market Default Increase to commodities market to junior capital Increase (Decrease) To Commodities Market To Junior Capital Increase (Decrease) To Commodities Market To Junior Capital Collateral due to market default Collateral Due To Market Default Collateral Due To Market Default Default fund cash contributions invested in highly rated government debt securities Highly Rated Government Debt Securities Highly Rated Government Debt Securities Maturity period of time deposits Maturity of Time Deposits Reverse purchase agreements, maturity range Reverse Purchase Agreements, Maturity Date Range Reverse Purchase Agreements, Maturity Date Range Committed capital Liability due to market default Liability Due To Market Default Liability Due To Market Default Power of assessment of the clearing member's contribution to the financial markets and commodities markets default funds Contribution To Financial Markets Contribution to the financial markets. Junior capital, cash deposits and pledged assets Junior Capital Cash Deposits And Pledged Assets Junior capital, cash deposits and pledged assets. Senior capital, cash deposits and pledged assets Senior Capital Cash Deposits And Pledged Assets Senior capital, cash deposits and pledged assets. Committed capital Committed Capital Committed Capital Contract value of resale and repurchase agreements Contract Value Of Resale And Repurchase Agreements Contract value of resale and repurchase agreements. Total number of derivative contracts cleared Total Number Of Derivative Contracts Cleared Total number of derivative contracts cleared All other countries All Other Countries [Member] All Other Countries [Member] Revenues Revenues Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Commercial Paper And Letter Of Credit Commercial Paper And Letter Of Credit [Member] Commercial Paper And Letter Of Credit [Member] Credit facility, borrowing capacity Credit facility term Line of Credit Facility, Fair Value of Amount Outstanding Line of Credit Facility, Fair Value of Amount Outstanding Unamortized debt issuance expense Unamortized Debt Issuance Expense Remaining amount available Line of Credit Facility, Remaining Borrowing Capacity Credit facility, remaining residual borrowing capacity Line Of Credit Facility, Used For Liquidity Support Line Of Credit Facility used for Liquidity Support Line of Credit Facility, Commitment Fee Percentage Line of Credit Facility, Commitment Fee Percentage Option to increase available aggregate amount Line Of Credit Facility, Optional Increase In Maximum Borrowing Capacity Line Of Credit Facility, Optional Increase In Maximum Borrowing Capacity Business Combinations [Abstract] Acquisitions and Divestiture Mergers, Acquisitions and Dispositions Disclosures [Text Block] Decrease in carrying amount Share-based compensation expense before income taxes Income tax benefit Other Tax Expense (Benefit) Share-based compensation expense after income taxes Allocated Share-based Compensation Expense, Net of Tax Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Furniture, equipment and leasehold improvements Furniture Equipment And Leasehold Improvements [Member] Furniture, equipment and leasehold improvements [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Total property and equipment Property, Plant and Equipment, Gross Less: accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total property and equipment, net Schedule Of Finite Lived And Indefinite Lived Intangible Assets [Table] Schedule Of Finite Lived And Indefinite Lived Intangible Assets [Table] Schedule Of Finite Lived And Indefinite Lived Intangible Assets [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] eVestment eVestment [Member] eVestment [Member] ISE ISE [Member] ISE [Member] Boardvantage Boardvantage [Member] Boardvantage [Member] Marketwired Marketwired [Member] Marketwired [Member] Nasdaq Canada Chi X Canada [Member] Chi-X Canada [Member] Measurement Input Type [Axis] Measurement Input Type [Axis] Measurement Input Type [Domain] Measurement Input Type [Domain] Discount rate used Measurement Input, Discount Rate [Member] Finite Lived And Indefinite Lived Intangible Assets [Line Items] Finite Lived And Indefinite Lived Intangible Assets [Line Items] Finite Lived And Indefinite Lived Intangible Assets [Line Items] Intangible assets, indefinite-lived Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets Intangible assets, finite-lived Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles Identifiable assets acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Discount rate used Business Combination, Contingent Consideration, Liability, Measurement Input Estimated average useful life Finite-Lived Intangible Assets, Remaining Amortization Period Amortization period of intangible assets for tax purposes Amortization period of intangible assets for tax purposes Amortization period of intangible assets for tax purposes. Operating Segments Operating Segments [Member] Market Technology Total revenues Transaction-based expenses Cost of Revenue Revenues less transaction-based expenses Gross Profit Operating income (loss) Purchase of property and equipment Letter of Credit Letter of Credit [Member] Clearinghouse Credit Facilities Clearinghouse Credit Facilities [Member] Clearinghouse Credit Facilities [Member] Common Stock in Treasury, at Cost Class of Treasury Stock [Table Text Block] Schedule of Dividends Declared Dividends Declared [Table Text Block] Employer contribution match, percent match Defined Contribution Plan, Employer Matching Contribution, Percent of Match Employer contribution match, percentage of employee contribution Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Defined contributions plan expense Defined Contribution Plan, Cost Cost or expenses included in compensation and benefit expense Pension and Other Postretirement Benefits Cost (Reversal of Cost) Employer contribution amount Defined Contribution Plan, Employer Discretionary Contribution Amount Plan funded percentage Defined Contribution Plan, Funded Percentage Defined Contribution Plan, Funded Percentage Funded status, underfunded amount Defined Benefit Plan, Funded (Unfunded) Status of Plan Fair value of plan assets Defined Benefit Plan, Plan Assets, Amount Benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Accumulated other comprehensive loss for benefit plan Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax Unrecognized net loss Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Income tax benefit Other Comprehensive Income Accumulated Defined Benefit Plans Tax Accumulated tax amount included in other comprehensive income that has not yet been recognized in net periodic benefit costs. Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Table] Commitments and Contingencies Disclosure [Table] Commitments and Contingencies Disclosure [Table] OCC Options Clearing Corporation [Member] Options Clearing Corporation [Member] Other Commitments [Axis] Other Commitments [Axis] Other Commitments [Domain] Other Commitments [Domain] Contribution of Equity Capital Contribution Of Equity Capital [Member] Contribution Of Equity Capital [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] ICBC ICBC [Member] ICBC [Member] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Escrow Agreement Escrow Agreement [Member] Escrow Agreement [Member] eSpeed Espeed [Member] eSpeed [Member] OCC Options Clearing Corporation (OCC) [Member] Options Clearing Corporation (OCC) [Member] Commitments and Contingencies Disclosure [Line Items] Commitments and Contingencies Disclosure [Line Items] Commitments and Contingencies Disclosure [Line Items] Financial guarantees obtained Financial guarantees obtained to provide further liquidity and default protection related to clearing businesses Financial guarantees obtained to provide further liquidity and default protection related to clearing businesses Credit facility, available liquidity Credit Facility Available Liquidity Credit Facility Available Liquidity Margin deposits contributed to brokers Receivables from Brokers-Dealers and Clearing Organizations Contingent future issuance of common stock (in shares) Stock Issued During Period, Shares, Acquisitions Revenue required to trigger annual issuance of Nasdaq common stock Consolidated Amount of Revenue required to trigger annual issuance of Nasdaq common stock Minimum amount of revenue required to trigger annual issuance of stock Contingency, accrual Loss Contingency Accrual Ownership percentage Equity Method Investment, Ownership Percentage Commitment contributions Other Commitment National exchanges named as defendants Number Of National Exchanges Named As Defendants Number Of National Exchanges Named As Defendants Estimate of possible legal fees Loss Contingency, Estimate of Possible Loss Schedule of Changes in Goodwill Schedule of Goodwill [Table Text Block] Schedule of Acquired Finite-Lived Intangible Assets Schedule of Acquired Finite-Lived Intangible Assets by Major Class [Table Text Block] Schedule of Acquired Indefinite-lived Intangible Assets Schedule of Acquired Indefinite-lived Intangible Assets by Major Class [Table Text Block] Estimated Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of Finite-Lived Intangible Assets [Table Text Block] Schedule of Indefinite-Lived Intangible Assets [Table Text Block] Schedule of Indefinite-Lived Intangible Assets [Table Text Block] 2019 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Five 2024 and thereafter Finite-Lived Intangible Assets, Amortization Expense, after Year Five Total Finite Lived Intangible Assets Net Excluding Foreign Currency Translation Adjustment Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. Excluding the impact of foreign currency translation adjustment. Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Beginning balance Unrecognized Tax Benefits Additions as a result of tax positions taken in prior periods Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Additions as a result of tax positions taken in the current period Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Reductions related to settlements with taxing authorities Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Reductions as a result of lapses of the applicable statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Ending balance Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Balance at beginning of period Goodwill acquired Goodwill, Acquired During Period Measurement period adjustment Goodwill, Purchase Accounting Adjustments Reclassification of goodwill Goodwill, Transfers Goodwill reclassified to held for sale Goodwill, Written off Related to Sale of Business Unit Foreign currency translation adjustment Goodwill, Foreign Currency Translation Gain (Loss) Balance at end of period Summary of Computation of Basic and Diluted Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Foreign Government Debt Securities Debt Security, Government, Non-US [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Nonrecurring Fair Value, Measurements, Nonrecurring [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Level 2 Fair Value, Inputs, Level 2 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Trading securities Debt Securities, Trading, and Equity Securities, FV-NI Other financial instruments Other Financial Liabilities, Fair Value Disclosure Other Financial Liabilities, Fair Value Disclosure Fair value of debt utilizing discounted cash flow analyses Long-term Debt, Fair Value Schedule of carrying amounts of assets and liabilities classified as held for sale Disposal Groups, Including Discontinued Operations [Table Text Block] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Initial Listing Revenues Initial Listing Fees [Member] Initial Listing Fees [Member] Annual Listings Revenues Annual Renewal Fees And Other [Member] Annual Renewal Fees And Other [Member] Market Technology Revenues Market Technology Revenues [Member] Market Technology Revenues [Member] Corporate Solutions and Other Revenues Corporate Solutions And Other Revenue [Member] Corporate Solutions And Other Revenue [Member] Information Services Revenues Information Services Revenue [Member] Information Services Revenue [Member] Other Listing Of Additional Shares Fees [Member] Listing Of Additional Shares Fees [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Change in Contract with Customer Liability [Roll Forward] Change In Contract With Customer Liability [Roll Forward] Change In Contract With Customer Liability [Roll Forward] Beginning balance Contract with Customer, Liability Additions Contract With Customer, Liability, New Contract Additions Contract With Customer, Liability, New Contract Additions Revenue recognized Contract with Customer, Liability, Revenue Recognized Reclassification of deferred revenue Contract With Customer, Liability, Segment Reclassification Contract With Customer, Liability, Segment Reclassification Deferred revenue reclassified to held for sale(2) Contract With Customer, Liability, Revenue Recognized, Other Contract With Customer, Liability, Revenue Recognized, Other Translation adjustment Contract With Customer, Liability, Revenue Translation Adjustment Contract With Customer, Liability, Revenue Translation Adjustment Ending balance Domestic Income (Loss) from Continuing Operations before Income Taxes, Domestic Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Statement of Comprehensive Income [Abstract] Statement [Table] Statement [Table] Statement [Line Items] Statement [Line Items] Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Foreign currency translation gains (losses) Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Income tax benefit (expense) Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Foreign currency translation, net Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Employee benefit plan adjustment gains (losses) Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Employee benefit plan income tax (benefit) expense Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax Employee benefit plan, net Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Total other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Comprehensive income (loss) attributable to Nasdaq Comprehensive Income (Loss), Net of Tax, Attributable to Parent Summary of Share-Based Compensation Expense Schedule Of Share Based Compensation Expense Resulting From Equity Awards [Table Text Block] Schedule of Share-Based Compensation Expense Resulting From Equity Awards [Text Block] Summary of Restricted Stock Activity Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Schedule of Weighted-Average Assumptions Used to Determine the Weighted-Average Fair Values Schedule of Weighted-Average Assumptions Used to Determine the Weighted- Average Fair Values [Table Text Block] Weighted Average Estimated Fair Value Table Summary of PSU Activity Share-based Compensation, Performance Shares Award Nonvested Activity [Table Text Block] Summary of Stock Options, Valuation Assumptions Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Summary of Stock Option Activity Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of Significant Ranges of Outstanding and Exercisable Stock Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block] Summary of ESPP Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity [Table Text Block] Schedule of Clearing Member Default Fund Contributions Schedule Of Default Fund Contributions Table [Table Text Block] Schedule Of Default Fund Contributions Table Schedule of Derivative Contracts Outstanding Schedule of Derivative Instruments [Table Text Block] Schedule of Derivative Contracts Cleared Schedule of Derivative Contracts Cleared [Table Text Block] Schedule of Derivative Contracts Cleared. Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, remaining performance obligation Revenue, Remaining Performance Obligation, Amount Schedule of Expected Benefit Payments Schedule of Expected Benefit Payments [Table Text Block] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast Scenario, Forecast [Member] Cinnober Cinnober [Member] Cinnober [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] SEK per share offering (in SEK per share) Business Acquisition, Share Price SEK per warrant offering (in SEK per warrant) Warrants Issued Common Stock Exercise Price Per Share Warrants Issued Common Stock Exercise Price Per Share Payments to acquire businesses Payments to Acquire Businesses, Gross Ownership percentage before transaction Sale of Stock, Percentage of Ownership before Transaction Ownership percentage after transaction Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions Investments, Debt, and Equity Securities [Table] Investments, Debt, and Equity Securities [Table] Investments, Debt, and Equity Securities [Table] Ownership [Axis] Ownership [Axis] Ownership [Domain] Ownership [Domain] LCH Lch [Member] LCH [Member] Borsa Istanbul Cost Method Investment Borsa Istanbul Cost Method Investment [Member] Cost Method Investment in Borsa Istanbul Investments, Debt and Securities [Line Items] Investments, Debt and Securities [Line Items] Investments, Debt and Securities [Line Items] Gains and losses on available-for-sale investment securities Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax Net income from unconsolidated investees Additional ownership percentage Equity Method Investment, Additional Ownership Percentage Equity Method Investment, Additional Ownership Percentage Committed equity contribution Contribution In Equity Capital OCC's new capital plan – each existing exchange stockholder agrees to contribute a pro-rata share of the total commitment if certain thresholds are breached Capital contribution Payments to Acquire Equity Method Investments Annual dividend from shareholders percentage Annual Dividend From Shareholders Percentage Commitment to pay annual dividend, in excess of the amount required to maintain its target capital requirement and satisfy other capital requirements, and after refunds, the percentage of distributable earnings before tax Shares owned (in shares) Investment Owned, Balance, Shares Annual dividend received Proceeds from Equity Method Investment, Distribution Ownership percentage Equity Securities without Readily Determinable Fair Value, Ownership Percentage Equity Securities without Readily Determinable Fair Value, Ownership Percentage Gain on sale of equity investment, pre-tax Equity Securities, FV-NI, Realized Gain (Loss) Gain on sale of equity investment, after tax Equity Securities, FV-NI, Realized Gain (Loss), After Tax Equity Securities, FV-NI, Realized Gain (Loss), After Tax Equity securities Equity Securities without Readily Determinable Fair Value, Amount Consideration received for put option exercised Consideration Received For Put Option Exercised Consideration Received For Put Option Exercised Statement of Stockholders' Equity [Abstract] Common stock Common Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Common Stock In Treasury, at Cost Treasury Stock [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Common stock, shares outstanding (in shares) Shares, Outstanding Balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other comprehensive (loss) income Other Comprehensive Income (Loss), Net of Tax Reclassification impact of Tax Reform Tax Cuts And Jobs Act Of 2017, Reclassification From AOCI To Retained Earnings Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings Cash dividends declared per common share Share repurchase program (in shares) Share repurchase program Share-based compensation (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Share-based compensation Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Stock option exercises, net (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Stock option exercises, net Stock Issued During Period, Value, Stock Options Exercised Other issuances of common stock, net (in shares) Stockholders' Equity, Other Shares Other issuances of common stock, net Stockholders' Equity, Other Issuance of Nasdaq common stock related to a prior acquisition (in shares) Common stock, shares outstanding (in shares) Balance Summary of Restructuring Charges Restructuring and Related Costs [Table Text Block] Disposal Group, Disposed of by Sale, Not Discontinued Operations Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Net gain on divestiture of businesses Gain on divestiture of business, after tax Gain (Loss) On Disposition Of Business, Net Of Tax Gain (Loss) On Disposition Of Business, Net Of Tax Working capital adjustment Disposal Group, Working Capital Adjustment Disposal Group, Working Capital Adjustment Working capital adjustment, after tax Disposal Group, Working Capital Adjustment, Net of Tax Disposal Group, Working Capital Adjustment, Net of Tax Income Statement [Abstract] Other revenues Service, Other [Member] Transaction-based expenses: Cost of Revenue [Abstract] Transaction rebates Transaction Rebate We credit a portion of the per share execution charge to market participants and record the transaction rebate as a cost of revenues in the Consolidated Statements of Income. Brokerage, clearance and exchange fees Floor Brokerage, Exchange and Clearance Fees Operating expenses: Compensation and benefits Professional and contract services Professional Fees Computer operations and data communications Communications and Information Technology Occupancy Occupancy, Net General, administrative and other General and Administrative Expense Marketing and advertising Marketing and Advertising Expense Regulatory Merger and strategic initiatives Total operating expenses Interest income Investment Income, Interest Interest expense Interest Expense Gain on sale of investment security Gain (Loss) on Sale of Investments Net gain on divestiture of businesses Asset impairment charge Other investment income Investment Income, Nonoperating Income tax provision Per share information: Basic earnings per share (in dollars per share) Earnings Per Share, Basic Level 1 Fair Value, Inputs, Level 1 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Assets at Fair Value Assets, Fair Value Disclosure [Abstract] Default fund and margin deposit investments Default Fund Investments Clearing member cash contribution invested in highly rated government debt securities. Total Assets at Fair Value Assets, Fair Value Disclosure Liabilities at Fair Value Liabilities, Fair Value Disclosure [Abstract] Total Liabilities at Fair Value Financial Liabilities Fair Value Disclosure Employee Stock Option Employee Stock Option [Member] Expected life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Dividend yield Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Payments Share-Based Compensation Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block] Nasdaq Canada Cash consideration Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net Total Net Liabilities Acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Total Net Deferred Tax Liability Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Acquired Intangible Assets, Indefinite-lived Measurement period adjustment related to acquisition Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period Measurement period adjustment, financial liabilities Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities Purchase price allocation deferred tax liabilities Business Acquisition Purchase Price Allocation Deferred Tax Liabilities Business Acquisition Purchase Price Allocation Deferred Tax Liabilities Purchase price allocation deferred tax assets Acquisition Recorded As Deferred Tax Asset Acquisition Recorded As Deferred Tax Asset Cost of acquired entity working capital adjustments Business acquisition cost of acquired entity working capital adjustments Business acquisition cost of acquired entity working capital adjustments Subsequent Event [Table] Subsequent Event [Table] OSLO BORS ASA OSLO BORS ASA [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] NOK per share offering (in NOK per share) Interest rate on offer price Business Combinations, Interest Rate On Offer Price Payments Business Combinations, Interest Rate On Offer Price Payments Purchase Consideration Business Combination, Consideration Transferred Required percentage of votes for approval, minimum Business Acquisitions, Required Votes For Approval, Percentage, Minimum Business Acquisitions, Required Votes For Approval, Percentage. Minimum Changes in Debt Obligations Schedule of Debt [Table Text Block] Corporate Solutions Revenues Corporate Solutions Revenue [Member] Corporate Solutions Revenue [Member] Fiscal year ended: Fiscal Year Ended [Abstract] Fiscal Year Ended [Abstract] 2019 Contract With Customer, Liability, Expected To Be Recognized In Next Twelve Months Contract With Customer, Liability, Expected To Be Recognized In Next Twelve Months 2020 Contract With Customer, Liability, Expected To Be Recognized In Year Two Contract With Customer, Liability, Expected To Be Recognized In Year Two 2021 Contract With Customer, Liability, Expected To Be Recognized In Year Three Contract With Customer, Liability, Expected To Be Recognized In Year Three 2022 Contract With Customer, Liability, Expected To Be Recognized In Year Four Contract With Customer, Liability, Expected To Be Recognized In Year Four 2023 Contract With Customer, Liability, Expected To Be Recognized In Year Five Contract With Customer, Liability, Expected To Be Recognized In Year Five 2024 and thereafter Contract With Customer, Liability, Expected To Be Recognized After Year Five Contract With Customer, Liability, Expected To Be Recognized After Year Five Total Commitments, Contingencies and Guarantees Commitments Contingencies and Guarantees [Text Block] Assets and Liabilities Held For Sale Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Future Minimum Lease Payments Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Second Anniversary Share-based Compensation Award, Tranche One [Member] Third Anniversary Share-based Compensation Award, Tranche Two [Member] Fourth Anniversary Share-based Compensation Award, Tranche Three [Member] Restricted stock Restricted Stock [Member] PSUs, Negative TSR Performance Shares, Negative Shareholder Return [Member] Performance Shares, Negative Shareholder Return [Member] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Officer Officer [Member] CEO Chief Executive Officer [Member] One-Year Program One-Year Performance Share Unit Program [Member] One-Year Performance Share Unit Program Discount from market price Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date Common stock shares reserved for future issuance (in shares) Common Stock, Capital Shares Reserved for Future Issuance Vesting percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Total unrecognized compensation cost Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted-average period unrecognized compensation cost is expected to be recognized, in years Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Number of performance-based programs Number of Performance-Based Programs Number of Performance-Based Programs Performance period Share-based Compensation Arrangement by Share-based Payment Award, Performance Period Share-based Compensation Arrangement by Share-based Payment Award, Performance Period Percentage of target amount granted, minimum Percentage Of Target Amount Granted Minimum Percentage Of Target Amount Granted Minimum Percentage of target amount granted, maximum Percentage Of Target Amount Granted Maximum Percentage Of Target Amount Granted Maximum Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Additional units granted above target (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Grants in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Grants in Period Number of peer groups Number Of Peer Groups Number of peer groups. 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Discount given to employees Rate Of Discount Given To Employees Rate of Discount given to Employees. Schedule of Property and Equipment, Net Property, Plant and Equipment [Table Text Block] Finite-lived intangible assets reclassified as held for sale - customer relationships, Gross Amount Finite-lived intangible assets reclassified as held for sale - customer relationships, Accumulated Amortization Finite-lived intangible assets reclassified as held for sale - customer relationships, Net Amount Indefinite-lived intangible assets reclassified as held for sale - trade name, Gross Amount Indefinite-lived intangible assets reclassified as held for sale - trade name, Net Amount Indefinite-Lived Intangible Assets, Net Indefinite-Lived Intangible Assets, Net Intangible Assets, Gross (Excluding Goodwill) Total intangible assets held for sale, Net Amount Federal income tax provision at the statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent State income tax provision, net of federal effect Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Change in deferred taxes due to change in law Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent Excess tax benefits related to employee share-based compensation Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Percent Non-U.S. subsidiary earnings Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent Tax credits and deductions Effective Income Tax Rate Reconciliation, Tax Credit, Percent Change in unrecognized tax benefits Effective Income Tax Rate Reconciliation Change In Unrecognized Tax Benefits, Percent Effective Income Tax Rate Reconciliation Change In Unrecognized Tax Benefits, Percent Other, net Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Actual income tax provision Effective Income Tax Rate Reconciliation, Percent Operating sublease income Rent expense for operating leases Operating Leases, Rent Expense, Net Available-for-sale investment securities Debt Securities, Available-for-sale Financial investments, at fair value Investments, Fair Value Disclosure Equity method investments Equity Method Investments Remaining Performance Obligation, Expected Timing of Satisfaction Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Schedule of the Recent Accounting Pronouncements Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Number of Stock Options Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Outstanding at Beginning of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Granted (in shares) Exercised (in shares) Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Outstanding at End of period (in shares) Weighted-Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Outstanding at Beginning of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Granted (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Exercised (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Forfeited (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Outstanding at End of period (in dollars per share) Number of Awards Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Unvested balances at beginning of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Unvested balances at end of period (in shares) Weighted-Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Unvested balances at beginning of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Forfeited (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Unvested balances at end of period (in dollars per share) Numerator: Numerator [Abstract] Numerator [Abstract] Net income attributable to common shareholders Denominator: Denominator [Abstract] Denominator [Abstract] Weighted-average common shares outstanding for basic earnings per share (in shares) Weighted Average Number of Shares Outstanding, Basic Weighted-average effect of dilutive securities: Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract] Employee equity awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Contingent issuance of common stock Incremental Common Shares Attributable to Dilutive Effect of Contingently Issuable Shares Weighted-average common shares outstanding for diluted earnings per share (in shares) Weighted Average Number of Shares Outstanding, Diluted Basic and diluted earnings per share: Earnings Per Share, Basic and Diluted [Abstract] Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock in treasury (in shares) Debt Obligations Debt Disclosure [Text Block] Purchase Consideration Acquired Intangible Assets Purchase price Acquisition of businesses, net of cash and cash equivalents acquired Cash Acquired from Acquisition Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Consolidation Consolidation, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Foreign Currency Foreign Currency Transactions and Translations Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Restricted Cash Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Receivables, net Receivables, Policy [Policy Text Block] Investments Investment, Policy [Policy Text Block] Property and Equipment, net Property, Plant and Equipment, Policy [Policy Text Block] Goodwill and Indefinite-Lived Intangible Assets Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Valuation of Other Long-Lived Assets Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] Revenue From Contracts With Customers Revenue from Contract with Customer [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Pension and Post-Retirement Benefits Pension and Other Postretirement Plans, Policy [Policy Text Block] Share-Based Compensation Compensation Related Costs, Policy [Policy Text Block] Merger and Strategic Initiatives Business Combinations and Other Purchase of Business Transactions, Policy [Policy Text Block] Leases Lessee, Leases [Policy Text Block] Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Tax Matters Income Tax, Policy [Policy Text Block] Assets Held for Sale Finance, Loan and Lease Receivables, Held-for-sale, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Segment Reconciling Items Segment Reconciling Items [Member] Transaction-based trading and clearing, net Transaction-based Trading and Clearing, Net [Member] Transaction-based Trading and Clearing, Net [Member] Corporate solutions Corporate Solutions [Member] Corporate Solutions [Member] Market data products Market Data Products [Member] Market Data Products [Member] Index Index Licensing and Services [Member] Index Licensing and Services [Member] Investment data & analytics Investment Data and Analytics [Member] Investment Data and Analytics [Member] Market technology Market Technology Services [Member] Market Technology Services [Member] Revenues less transaction-based expenses Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] LIBOR London Interbank Offered Rate (LIBOR) [Member] Spread on variable rate Debt Instrument, Basis Spread on Variable Rate Short-term Debt Document And Entity Information [Abstract] Document And Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Public Float Entity Public Float Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Entity Shell Company Entity Shell Company Restructuring Charges Restructuring and Related Activities Disclosure [Text Block] Foreign currency translation adjustment Amount of goodwill expected to be deductible for tax purposes Business Acquisition, Goodwill, Expected Tax Deductible Amount Goodwill, impairment loss Foreign currency translation amortization expense Schedule of Business Acquisitions, by Acquisition Schedule of Business Acquisitions, by Acquisition [Table Text Block] Acquired Finite Lived Intangible Assets in Acquisition Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block] Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Nasdaq Stockholders' Equity Stockholders' Equity Note Disclosure [Text Block] Senior Notes Excluding 2020 Notes Senior Notes Excluding 2020 Notes [Member] Senior Notes Excluding 2020 Notes [Member] Aggregate principal amount purchased plus accrued and unpaid interest Aggregate Principal Amount Purchased Plus Accrued And Unpaid Interest Aggregate Principal Amount Purchased Plus Accrued And Unpaid Interest Organization and Nature of Operations Nature of Operations [Text Block] Schedule of Operating Leased Assets [Table] Schedule of Operating Leased Assets [Table] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Axis] Lease Arrangement, Type [Domain] Lease Arrangement, Type [Domain] Gross Lease Commitments Gross Lease Commitments [Member] Gross Lease Commitments [Member] Sublease Income Sublease Income [Member] Sublease Income [Member] Net Lease Commitments Net Lease Commitments [Member] Net Lease Commitments [Member] Operating Leased Assets [Line Items] Operating Leased Assets [Line Items] 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2020 Operating Leases, Future Minimum Payments, Due in Two Years 2021 Operating Leases, Future Minimum Payments, Due in Three Years 2022 Operating Leases, Future Minimum Payments, Due in Four Years 2023 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total future minimum lease payments Operating Leases, Future Minimum Payments Due