Nasdaq (NDAQ) 10-Q 6 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 30, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	Nasdaq, Inc.
Entity Central Index Key	1,120,193
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	ndaq
Amendment Flag	false
Entity Common Stock, Shares Outstanding		163,957,026
Entity Emerging Growth Company	false
Entity Small Business	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 324	$ 377
Restricted cash	52	22
Financial investments, at fair value	202	235
Receivables, net	356	356
Default funds and margin deposits	4,219	3,988
Other current assets	304	235
Assets held for sale	0	297
Total current assets	5,457	5,510
Property and equipment, net	371	400
Goodwill	6,369	6,586
Intangible assets, net	2,328	2,468
Other non-current assets	330	390
Total assets	14,855	15,354
Current liabilities:
Accounts payable and accrued expenses	176	177
Section 31 fees payable to SEC	21	128
Accrued personnel costs	145	170
Deferred revenue	257	161
Other current liabilities	173	85
Default funds and margin deposits	4,219	3,988
Short-term debt	808	480
Liabilities held for sale	0	45
Total current liabilities	5,799	5,234
Long-term debt	3,072	3,727
Deferred tax liabilities, net	137	225
Non-current deferred revenue	91	126
Other non-current liabilities	154	162
Total liabilities	9,253	9,474
Commitments and contingencies
Nasdaq stockholders’ equity:
Common stock, $0.01 par value, 300,000,000 shares authorized, shares issued: 169,423,805 at September 30, 2018 and 172,373,432 at December 31, 2017; shares outstanding: 163,949,047 at September 30, 2018 and 167,441,030 at December 31, 2017	2	2
Additional paid-in capital	2,676	3,024
Common stock in treasury, at cost: 5,474,758 shares at September 30, 2018 and 4,932,402 shares at December 31, 2017	(291)	(247)
Accumulated other comprehensive loss	(1,184)	(862)
Retained earnings	4,399	3,963
Total Nasdaq stockholders’ equity	5,602	5,880
Total liabilities and equity	$ 14,855	$ 15,354

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	169,423,805	172,373,432
Common stock, shares outstanding (in shares)	163,949,047	167,441,030
Common stock in treasury (in shares)	5,474,758	4,932,402

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Revenues	$ 964	$ 965	$ 3,141	$ 2,929
Transaction-based expenses:
Transaction rebates	(293)	(266)	(947)	(874)
Brokerage, clearance and exchange fees	(71)	(96)	(312)	(275)
Revenues less transaction-based expenses	600	603	1,882	1,780
Operating expenses:
Compensation and benefits	164	167	534	489
Professional and contract services	33	38	105	110
Computer operations and data communications	32	32	94	91
Occupancy	23	23	72	69
General, administrative and other	28	15	73	64
Marketing and advertising	7	7	27	22
Depreciation and amortization	53	47	159	140
Regulatory	8	9	24	25
Merger and strategic initiatives	6	3	7	20
Total operating expenses	354	341	1,095	1,030
Operating income	246	262	787	750
Interest income	3	2	8	6
Interest expense	(38)	(34)	(112)	(107)
Net gain on divestiture of businesses	(8)	0	33	0
Other investment income	0	0	7	2
Net income from unconsolidated investees	6	4	13	10
Income before income taxes	209	234	736	661
Income tax provision	46	64	234	178
Net income attributable to Nasdaq	$ 163	$ 170	$ 502	$ 483
Per share information:
Basic earnings per share (in dollars per share)	$ 0.99	$ 1.02	$ 3.03	$ 2.91
Diluted earnings per share (in dollars per share)	0.97	1	2.99	2.85
Cash dividends declared per common share (in dollars per share)	$ 0.44	$ 0.38	$ 1.26	$ 1.08
Market Services
Revenues:
Revenues	$ 586	$ 581	$ 1,968	$ 1,808
Corporate Services
Revenues:
Revenues	131	126	395	370
Information Services
Revenues:
Revenues	179	150	528	432
Market Technology
Revenues:
Revenues	68	62	194	176
Other revenues
Revenues:
Revenues	0	46	56	143
Transaction-based expenses:
Revenues less transaction-based expenses	$ 0	$ 46	$ 56	$ 143

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income		$ 163	$ 170	$ 502	$ 483
Foreign currency translation gains (losses):
Net foreign currency translation gains (losses)		22	92	(239)	258
Income tax (expense)	[1]	(15)	(25)	(76)	(104)
Total		7	67	(315)	154
Employee benefit plan income tax (expense)	[1]	0	0	(7)	0
Total other comprehensive income (loss), net of tax		7	67	(322)	154
Comprehensive income attributable to Nasdaq		$ 170	$ 237	$ 180	$ 637
[1]	For the nine months ended September 30, 2018, includes the reclassification of the stranded tax effects related to the Tax Cuts and Jobs Act. See Note 17, “Income Taxes,” for further discussion.

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 502	$ 483
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	159	140
Share-based compensation	51	52
Deferred income taxes	(12)	(4)
Reversal of certain Swedish tax benefits	41	0
Net gain on divestiture of businesses	(33)	0
Net income from unconsolidated investees	(13)	(10)
Other reconciling items included in net income	10	18
Net change in operating assets and liabilities, net of effects of divestiture and acquisitions:
Receivables, net	(11)	30
Other assets	(23)	376
Accounts payable and accrued expenses	6	(18)
Section 31 fees payable to SEC	(107)	(77)
Accrued personnel costs	(22)	(82)
Deferred revenue	74	18
Other liabilities	46	(66)
Net assets held for sale	0	(251)
Net cash provided by operating activities	668	609
Cash flows from investing activities:
Purchases of trading securities	(294)	(291)
Proceeds from sales and redemptions of trading securities	299	334
Purchases of available-for-sale investment securities	(18)	(12)
Proceeds from maturities of available-for-sale investment securities	32	30
Proceeds from divestiture of businesses, net	286	0
Purchases of property and equipment	(72)	(102)
Other investment activities	(6)	(32)
Net cash provided by (used in) investing activities	227	(73)
Cash flows from financing activities:
Proceeds from (repayments of) commercial paper, net	(170)	154
Repayments of long-term debt	(115)	(683)
Payment of debt extinguishment cost	0	(9)
Proceeds from utilization of credit commitment, net of debt issuance costs	0	10
Proceeds from issuances of senior unsecured notes, net of debt issuance costs	0	498
Cash paid for repurchase of common stock	(394)	(175)
Cash dividends paid	(208)	(180)
Proceeds received from employee stock activity	10	32
Payments related to employee shares withheld for taxes	(44)	(65)
Proceeds of customer funds	15	0
Net cash used in financing activities	(906)	(418)
Effect of exchange rate changes on cash and cash equivalents and restricted cash	(12)	15
Net increase (decrease) in cash and cash equivalents and restricted cash	(23)	133
Cash and cash equivalents and restricted cash at beginning of period	399	418
Cash and cash equivalents and restricted cash at end of period	376	551
Cash paid for:
Interest	121	114
Income taxes, net of refund	$ 195	$ 126

Organization and Nature of Oper

Organization and Nature of Operations	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Nature of Operations	Organization and Nature of Operations Nasdaq, Inc. is a leading provider of trading, clearing, marketplace technology, regulatory, securities listing, information and public and private company services. Our global offerings are diverse and include trading and clearing across multiple asset classes, trade management services, market data products, financial indexes, investment data and analytics, capital formation solutions, corporate solutions, and market technology products and services. Our technology powers markets across the globe, supporting equity derivative trading, clearing and settlement, cash equity trading, fixed income trading, trading surveillance and many other functions. We manage, operate and provide our products and services in four business segments: Market Services, Corporate Services, Information Services and Market Technology. Market Services Our Market Services segment includes our Equity Derivative Trading and Clearing, Cash Equity Trading, FICC and Trade Management Services businesses. We operate multiple exchanges and other marketplace facilities across several asset classes, including derivatives, commodities, cash equity, debt, structured products and ETPs. In addition, in some countries where we operate exchanges, we also provide broker services, clearing, settlement and central depository services. Our transaction-based platforms provide market participants with the ability to access, process, display and integrate orders and quotes. The platforms allow the routing and execution of buy and sell orders as well as the reporting of transactions, providing fee-based revenues. In the U.S., we operate six electronic options exchanges and three cash equity exchanges. The Nasdaq Stock Market, the largest of our cash equities exchanges, is the largest single venue of liquidity for trading U.S.-listed cash equities. We also operate an electronic platform for trading of U.S. Treasuries and NFX, a U.S. based designated contract market which lists cash-settled energy derivatives based on key energy benchmarks including oil, natural gas and U.S. power. In addition, we also operate a Canadian exchange for the trading of Canadian-listed securities. In Europe, we operate exchanges in Stockholm (Sweden), Copenhagen (Denmark), Helsinki (Finland), and Reykjavik (Iceland), as well as the clearing operations of Nasdaq Clearing, as Nasdaq Nordic. We also operate exchanges in Tallinn (Estonia), Riga (Latvia) and Vilnius (Lithuania) as Nasdaq Baltic. Collectively, Nasdaq Nordic and Nasdaq Baltic offer trading in cash equities, depository receipts, warrants, convertibles, rights, fund units and ETFs, as well as trading and clearing of derivatives and clearing of resale and repurchase agreements. Nasdaq Commodities is the brand name for Nasdaq’s worldwide suite of commodity-related products and services. Nasdaq Commodities’ offerings include oil, power, natural gas and carbon emission markets, tanker and dry cargo freight, seafood derivatives, iron ore, electricity certificates and clearing services. These products are listed on two of Nasdaq’s derivatives exchanges, Nasdaq Oslo ASA and NFX. Through our Trade Management Services business, we provide market participants with a wide variety of alternatives for connecting to and accessing our markets via a number of different protocols used for quoting, order entry, trade reporting, DROP functionality and connectivity to various data feeds. We also provide data center services, including co-location to market participants, whereby firms may lease cabinet space and power to house their own equipment and servers within our data centers. Our broker services operations offer technology and customized securities administration solutions to financial participants in the Nordic market. Corporate Services Our Corporate Services segment includes our Corporate Solutions and Listing Services businesses. Our Corporate Solutions business serves corporate clients, including companies listed on our exchanges and private companies. We help organizations manage the two-way flow of information with their key constituents, including their board members and investors, and with clients and the public through our suite of advanced technology, analytics, and consultative services. In April 2018, we sold our Public Relations Solutions and Digital Media Services businesses. See “2018 Divestiture,” of Note 4, “Acquisitions and Divestiture,” for further discussion. As of September 30, 2018 , our Corporate Solutions business includes our investor relations, board & leadership, and governance, risk and compliance products and services. For segment reporting purposes, we have included in corporate items the revenues and expenses of the Public Relations Solutions and Digital Media Services businesses, which were part of the Corporate Solutions business, within our Corporate Services segment, prior to the date of sale. See Note 18, “Business Segments,” for further discussion. Earlier this year, we realigned our businesses to better serve the needs of our corporate clients. As a result, beginning in the second quarter of 2018, our BWise corporate enterprise risk management solutions are now offered as part of governance, risk and compliance products and services within our Corporate Solutions business. BWise was previously part of our Market Technology segment. Our Listing Services business includes our U.S. and European Listing Services businesses. We operate a variety of listing platforms around the world to provide multiple global capital raising solutions for private and public companies. Our main listing markets are The Nasdaq Stock Market and the Nasdaq Nordic and Nasdaq Baltic exchanges. Through Nasdaq First North, our Nordic and Baltic operations also offer alternative marketplaces for smaller companies and growth companies. Our Listing Services business also includes NPM, which provides liquidity solutions for private companies. As of September 30, 2018 , there were 3,049 total listings on The Nasdaq Stock Market, including 390 ETPs. The combined market capitalization was approximately $13.4 trillion . In Europe, the Nasdaq Nordic and Nasdaq Baltic exchanges, together with Nasdaq First North, were home to 1,010 listed companies with a combined market capitalization of approximately $1.5 trillion . Information Services Beginning in the second quarter of 2018, our Information Services segment was recategorized into the following businesses: • Market Data; • Index; and • Investment Data & Analytics. Prior to the second quarter, our Information Services segment was comprised of our Data Products and our Index Licensing and Services businesses. Our Market Data business sells and distributes historical and real-time quote and trade information to the sell-side, the buy-side, retail online brokers, proprietary trading shops, other venues, internet portals and data distributors. Our market data products enhance transparency of market activity within our exchanges and provide critical information to professional and non-professional investors globally. Our Index business develops and licenses Nasdaq-branded indexes, associated derivatives, and financial products and also provides custom calculation services for third-party clients. As of September 30, 2018 , we had 358 ETPs licensed to Nasdaq’s indexes which had $206 billion in assets under management. Our Investment Data & Analytics business is a leading content and analytics cloud-based solutions provider used by asset managers, investment consultants and asset owners to help facilitate better investment decisions. Market Technology Our Market Technology segment is a leading global technology solutions provider and partner to exchanges, clearing organizations, central securities depositories, regulators, banks, brokers and corporate businesses. Our Market Technology business is the sales channel for our complete global offering to other marketplaces. Market Technology provides technology solutions for trading, clearing, settlement, surveillance and information dissemination to markets with wide-ranging requirements, from the leading markets in the U.S., Europe and Asia to emerging markets in the Middle East, Latin America, and Africa. Our marketplace solutions can handle a wide array of assets, including cash equities, equity derivatives, currencies, various interest-bearing securities, commodities and energy products, and are currently powering more than 100 marketplaces in 50 countries. Market Technology also provides market surveillance services to broker-dealer firms worldwide, as well as risk management solutions. As discussed above under “Corporate Services,” as of the second quarter of 2018, our BWise business, which was previously part of our Market Technology segment, is now offered as part of our Corporate Solutions business.

Basis of Presentation and Princ

Basis of Presentation and Principles of Consolidation	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The condensed consolidated financial statements are prepared in accordance with U.S. GAAP and include the accounts of Nasdaq, its wholly-owned subsidiaries and other entities in which Nasdaq has a controlling financial interest. When we do not have a controlling interest in an entity but exercise significant influence over the entity’s operating and financial policies, such investment is accounted for under the equity method of accounting. We recognize our share of earnings or losses of an equity method investee based on our ownership percentage. See “Equity Method Investments,” of Note 7, “Investments,” for further discussion of our equity method investments. The accompanying condensed consolidated financial statements reflect all adjustments which are, in the opinion of management, necessary for a fair statement of the results for the interim periods presented. These adjustments are of a normal recurring nature. All significant intercompany accounts and transactions have been eliminated in consolidation. As permitted under U.S. GAAP, certain footnotes or other financial information can be condensed or omitted in the interim condensed consolidated financial statements. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the consolidated financial statements and accompanying notes included in Nasdaq’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017 that was filed with the SEC on February 28, 2018. Certain prior year amounts have been reclassified to conform to the current year presentation primarily due to the adoption of ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” on January 1, 2018. See Note 3, “Significant Accounting Policies Update,” for further discussion. The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts and the disclosure of contingent amounts in the condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates. Subsequent Events We have evaluated subsequent events through the issuance date of this Quarterly Report on Form 10-Q. See Note 19, “Subsequent Events,” for further discussion. Recent Accounting Pronouncements Accounting Standard Description Effective Date Effect on the Financial Statements or Other Significant Matters Intangibles - Goodwill and Other - Internal-Use Software In August 2018, the FASB issued ASU 2018-15, “Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract.” This ASU clarifies the accounting for implementation costs of a hosting arrangement and aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). Capitalized implementation costs should be expensed over the term of the hosting arrangement and recognized in the same line item in the statement of income as the hosted service costs. Payments for capitalized implementation costs should be classified in the statement of cash flows in the same manner as payments made for fees associated with the hosting element. Capitalized implementation costs should be presented in the balance sheet in the same line item as a prepayment for the fees of the associated hosting arrangement. January 1, 2020, with early adoption permitted. We early adopted this standard as of July 1, 2018. There was no impact to the financial statements as a result of the adoption of this standard, as we are currently accounting for costs incurred in a cloud computing arrangement in accordance with the guidance provided in this standard. Fair Value Measurements In August 2018, the FASB issued ASU 2018-13 “Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement.” This ASU modifies the disclosure requirements on fair value measurements by removing certain disclosure requirements related to the fair value hierarchy, modifying existing disclosure requirements related to measurement uncertainty, and adding new requirements, mainly for Level 3 fair value measurements. January 1, 2020, with early adoption permitted. We early adopted this standard as of July 1, 2018 on a prospective basis. There was no impact to the financial statements or our disclosures as a result of the adoption of this standard. Accounting Standard Description Effective Date Effect on the Financial Statements or Other Significant Matters Income Statement - Reporting Comprehensive Income In February 2018, the FASB issued ASU 2018-02, “Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (Topic 220).” This ASU provides an election to reclassify tax effects that are stranded in accumulated other comprehensive income as a result of tax reform to retained earnings. An election is also available to reclassify other stranded tax effects that relate to the Tax Cuts and Jobs Act but do not directly relate to the change in the federal rate. Tax effects that are stranded in accumulated other comprehensive income for other reasons (e.g., prior changes in tax law, a change in valuation allowance) may not be reclassified. Previously, the effects of changes in tax rates and laws on deferred tax balances were required to be recorded as a component of tax expense related to continuing operations for the period in which the law was enacted, even if the assets and liabilities related to items of accumulated other comprehensive income. In other words, backward tracing of the income tax effects of items originally recognized through accumulated other comprehensive income was prohibited. January 1, 2019, with early adoption permitted. We early adopted this standard as of January 1, 2018. As a result of the adoption of this standard, in the first quarter of 2018, we recorded a reclassification of $142 million for stranded tax effects related to the Tax Cuts and Jobs Act from accumulated other comprehensive loss to retained earnings within stockholders’ equity in the Condensed Consolidated Balance Sheets. See Note 17, “Income Taxes,” for further discussion. Goodwill In January 2017, the FASB issued ASU 2017-04, “Simplifying the Test for Goodwill Impairment.” This ASU simplifies how an entity is required to test goodwill for impairment and removes the second step of the goodwill impairment test, which required a hypothetical purchase price allocation if the fair value of a reporting unit is less than its carrying amount. Goodwill impairment will now be measured using the difference between the carrying amount and the fair value of the reporting unit and the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The amendments in this ASU should be applied on a prospective basis. January 1, 2020, with early adoption permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We do not anticipate a material impact on our consolidated financial statements at the time of adoption of this new standard as the carrying amounts of our reporting units have been less than their corresponding fair values in recent years. Therefore, the second step of the goodwill impairment test was not required. However, changes in future projections, market conditions and other factors may cause a change in the excess of fair value of our reporting units over their corresponding carrying amounts. We do not anticipate early adoption of this standard. Financial Instruments - Credit Losses In June 2016, the FASB issued ASU 2016-13, “Measurement of Credit Losses on Financial Instruments.” This ASU changes the impairment model for certain financial instruments. The new model is a forward looking expected loss model and will apply to financial assets subject to credit losses and measured at amortized cost and certain off-balance sheet credit exposures. This includes loans, held-to-maturity debt securities, loan commitments, financial guarantees and net investments in leases, as well as trade receivables. For available-for-sale debt securities with unrealized losses, credit losses will be measured in a manner similar to today, except that the losses will be recognized as allowances rather than reductions in the amortized cost of the securities. January 1, 2020, with early adoption permitted as of January 1, 2019. We expect to adopt this standard on January 1, 2020. We are currently assessing the impact that this standard will have on our consolidated financial statements. We do not anticipate early adoption of this standard. Accounting Standard Description Effective Date Effect on the Financial Statements or Other Significant Matters Leases In February 2016, the FASB issued ASU 2016-02, “Leases.” Under this ASU, at the commencement date, lessees will be required to recognize a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. This guidance is not applicable for leases with a term of 12 months or less. Recognition, measurement and presentation of expenses will depend on classification as a finance or operating lease. The guidance also requires certain quantitative and qualitative disclosures about leasing arrangements. Lessor accounting is largely unchanged. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. January 1, 2019. See discussion below. Leases We will adopt ASU 2016-02 on January 1, 2019. When adopted, this new standard will result in an increase in the assets and liabilities reflected on our consolidated balance sheets. In addition, we will be required to disclose key information about our leases. Nasdaq’s current operating lease portfolio is primarily comprised of real estate and data center leases. As of September 30, 2018, we had future contractual lease payment obligations of $636 million . We expect that we will elect the alternative transition approach allowed under the guidance and expect to implement new accounting policies as well as to elect certain practical expedients available under the guidance, including those related to leases with a term of 12 months or less and our application of discount rates. We do not expect the adoption of this new standard to have a material impact on our consolidated balance sheets or statements of income and it will not impact our cash flows.

Significant Accounting Policies

Significant Accounting Policies Updates	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Significant Accounting Policies Update	Significant Accounting Policies Update Our significant accounting policies are detailed in Note 2, “Summary of Significant Accounting Policies,” in our Annual Report on Form 10-K for the year ended December 31, 2017 that was filed with the SEC on February 28, 2018. Significant changes to our accounting policies as a result of adopting Topic 606 and ASU 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities,” or ASU 2016-01, are discussed below. Revenue From Contracts With Customers On January 1, 2018, we adopted Topic 606 using the full retrospective method. The adoption of Topic 606 impacted the revenue and expense recognition for our Market Technology business and revenue recognition for our Listing Services business. However, the adoption of Topic 606 did not have a material impact on our consolidated financial statements at the time of adoption or in any prior reporting periods. There was no impact to revenue and expense recognition for our other businesses. Additional disclosures required by Topic 606 are provided below. Contract Balances Substantially all of our revenues are considered to be revenues from contracts with customers. The related accounts receivable balances are recorded in our Condensed Consolidated Balance Sheets as receivables which is net of allowance for doubtful accounts of $13 million as of September 30, 2018 and $9 million as of December 31, 2017 . The changes in the balance between periods were immaterial. We do not have obligations for warranties, returns or refunds to customers. For the majority of our contracts with customers, except for our market technology and listings services contracts, our performance obligations are short-term in nature and there is no significant variable consideration. We do not have revenues recognized from performance obligations that were satisfied in prior periods. We have elected not to provide disclosures about transaction price allocated to unsatisfied performance obligations if contract durations are less than one year. For contract durations that are one-year or greater, we do not have a material portion of transaction price allocated to unsatisfied performance obligations that are not included in deferred revenue other than for our market technology contracts which are discussed below under “Market Technology.” Deferred revenue primarily represents our contract liabilities related to our fees for annual and initial listings, market technology, corporate solutions and information services contracts. Deferred revenue is the only significant contract asset or liability impacted by our adoption of Topic 606. See Note 8, “Deferred Revenue,” for our discussion on deferred revenue balances, activity, and expected timing of recognition. See “Revenue Recognition” below for further descriptions of our revenue contracts. Sales commissions earned by our sales force are considered incremental and recoverable costs of obtaining a contract with a customer. These costs are deferred and amortized on a straight-line basis over the period of benefit that we have determined to be the contract term or estimated service periods. Sales commissions for renewal contracts are deferred and amortized on a straight-line basis over the related contractual renewal period. Amortization expense is included in compensation and benefits expense in the Condensed Consolidated Statements of Income. The balance of deferred costs and related amortization expense are not material to our consolidated financial statements. We elected the practical expedient of recognizing sales commissions as an expense when incurred if contract durations are one year or less. We also have elected the practical expedient of excluding sales taxes from transaction prices. Certain judgments and estimates were used in the identification and timing of satisfaction of performance obligations and the related allocation of transaction price and are discussed below. We believe that these represent a faithful depiction of the transfer of services to our customers. Revenue Recognition Our primary revenue contract classifications are described below. Though we discuss additional revenue details in our “Management's Discussion and Analysis of Financial Condition and Results of Operations,” the categories below best represent those that depict similar economic characteristics of the nature, amount, timing and uncertainty of our revenues and cash flows. Market Services Transaction-Based Trading and Clearing Transaction-based trading and clearing includes equity derivative trading and clearing revenues, cash equity trading revenues and FICC revenues. Nasdaq charges transaction fees for trades executed on our exchanges, as well as on orders that are routed to and executed on other market venues. Nasdaq charges clearing fees for contracts cleared with Nasdaq Clearing. In the U.S., transaction fees are based on trading volumes for trades executed on our U.S. exchanges and in Europe, transaction fees are based on the volume and value of traded and cleared contracts. In Canada, transaction fees are based on trading volumes for trades executed on our Canadian exchange. Nasdaq satisfies its performance obligation for trading services upon the execution of a customer trade and clearing services when a contract is cleared, as trading and clearing transactions are substantially complete when they are executed and we have no further obligation to the customer at that time. Transaction-based trading and clearing fees can be variable and are based on trade volume tiered discounts. Transaction revenues, as well as any tiered volume discounts, are calculated and billed monthly in accordance with our published fee schedules. In the U.S., we also pay liquidity payments to customers based on our published fee schedules. We use these payments to improve the liquidity on our markets and therefore recognize those payments as a cost of revenue. The majority of our FICC trading and clearing customers are charged transaction fees, as discussed above, which are based on the volume and value of traded and cleared contracts. We also enter into annual fixed contracts with customers trading U.S. Treasury securities. The customers are charged an annual fixed fee which is billed per the agreement, on a monthly or quarterly basis. Revenues earned on fixed contracts are recognized over time on a ratable basis over the contract period beginning on the date that our service is made available to the customer since the customer receives and consumes the benefit as Nasdaq provides the service. For U.S. equity derivative trading, we credit a portion of the per share execution charge to the market participant that provides the liquidity. For U.S. cash equity trading, for Nasdaq and Nasdaq PSX, we credit a portion of the per share execution charge to the market participant that provides the liquidity and for Nasdaq BX, we credit a portion of the per share execution charge to the market participant that takes the liquidity. We record these credits as transaction rebates that are included in transaction-based expense in the Condensed Consolidated Statements of Income. These transaction rebates are paid on a monthly basis and the amounts due are included in accounts payable and accrued expenses in the Condensed Consolidated Balance Sheets. In the U.S., we pay Section 31 fees to the SEC for supervision and regulation of securities markets. We pass these costs along to our customers through our equity derivative trading and clearing fees and our cash equity trading fees. We collect the fees as a pass-through charge from organizations executing eligible trades on our options exchanges and our cash equity platforms and we recognize these amounts in transaction-based expenses when incurred. Section 31 fees received are included in cash and cash equivalents in the Condensed Consolidated Balance Sheets at the time of receipt and, as required by law, the amount due to the SEC is remitted semiannually and recorded as Section 31 fees payable to the SEC in the Condensed Consolidated Balance Sheets until paid. Since the amount recorded as revenues is equal to the amount recorded as transaction-based expenses, there is no impact on our revenues less transaction-based expenses. As we hold the cash received until payment to the SEC, we earn interest income on the related cash balances. Under our Limitation of Liability Rule and procedures, we may, subject to certain caps, provide compensation for losses directly resulting from the systems’ actual failure to correctly process an order, quote, message or other data into our platform. We do not record a liability for any potential claims that may be submitted under the Limitation of Liability Rule unless they meet the provisions required in accordance with U.S. GAAP. As such, losses arising as a result of the rule are accrued and charged to expense only if the loss is probable and estimable. Trade Management Services We provide market participants with a wide variety of alternatives for connecting to and accessing our markets for a fee. We also offer market participants co-location services, whereby firms may lease cabinet space and power to house their own equipment and servers within our data centers. These participants are charged monthly fees for cabinet space, connectivity and support in accordance with our published fee schedules. These fees are recognized on a monthly basis when the performance obligation is met. We also earn revenues from annual and monthly exchange membership and registration fees. Revenues for providing access to our markets, co-location services and monthly exchange membership and registration fees are recognized on a monthly basis as the service is provided. Revenues from annual fees for exchange membership and registration fees are recognized ratably over the following 12 -month period since the customer receives and consumes the benefit as Nasdaq provides the service. We also offer broker services to financial participants in the Nordic market primarily providing flexible back-office systems, which allow customers to entirely or partly outsource their company’s back-office functions. Revenues from broker services are based on a fixed basic fee for administration or licensing, maintenance and operations, and an incremental fee depending on the number of transactions completed. Broker services revenues are generally billed and recognized monthly. Corporate Solutions As of September 30, 2018 , corporate solutions revenues primarily include subscription and transaction-based income from our investor relations, board & leadership, and governance, risk and compliance products and services. In April 2018, we completed the sale of our Public Relations Solutions and Digital Media Services businesses. See “2018 Divestiture,” of Note 4, “Acquisitions and Divestiture,” for further discussion. Subscription-based revenues earned are recognized over time on a ratable basis over the contract period beginning on the date that our service is made available to the customer since the customer receives and consumes the benefit as Nasdaq provides the service. Generally, fees are billed quarterly in advance and the contract provides for automatic renewal. As part of the subscription agreements, customers can also be charged usage fees based upon actual usage of the services provided. Revenues from usage fees are recognized at a point in time upon completion of the service. Listing Services Listing services revenues primarily include initial listing fees and annual renewal fees. Under Topic 606, the initial listing fee is allocated to multiple performance obligations including initial and subsequent listing services and corporate solutions services (when a company qualifies to receive these services under the applicable Nasdaq rule), as well as a customer's material right to renew the option to list on our exchanges. In performing this allocation, the standalone selling price of the performance obligations is based on the initial and annual listing fees and the standalone selling price of the corporate solutions services is based on its market value. All listing fees are billed upfront and the identified performance obligations are satisfied over time since the customer receives and consumes the benefit as Nasdaq provides the listing service. Upon adoption of Topic 606, the amount of revenue related to the corporate solutions services performance obligation is recognized ratably over a two -year period, which is based on contract terms, with the remaining revenue recognized ratably over time as customers continue to list on our exchanges, which is estimated to be over a period of six years based on our historical listing experience and projected future listing duration. In the U.S., annual renewal fees are charged based on the number of outstanding shares of companies listed in the U.S. at the end of the prior year and are recognized ratably over the following 12 -month period since the customer receives and consumes the benefit as Nasdaq provides the service. European annual renewal fees, which are received from companies listed on our Nasdaq Nordic and Nasdaq Baltic exchanges and Nasdaq First North, are directly related to the listed companies’ market capitalization on a trailing 12 -month basis and are recognized ratably over the following 12 -month period since the customer receives and consumes the benefit as Nasdaq provides the service. Market Data Products Market data products revenues are earned from U.S. and European proprietary market data products. In the U.S., we also earn revenues from U.S. shared tape plans. We earn revenues primarily based on the number of data subscribers and distributors of our data. Market data products revenues are subscription-based and are recognized on a monthly basis net of amounts due under revenue sharing arrangements with market participants. For U.S. tape plans, revenues are collected monthly based on published fee schedules and distributed quarterly to the U.S. exchanges based on a formula required by Regulation NMS that takes into account both trading and quoting activity. Revenues are presented on a net basis as we are acting as an agent in this arrangement. Market Data Products Revenue Sharing The most significant component of market data products revenues recorded on a net basis is the UTP Plan revenue sharing in the U.S. All indicators of principal versus agent reporting under U.S. GAAP have been considered in analyzing the appropriate presentation of UTP Plan revenue sharing. However, the following are the primary indicators of net reporting: • We are the administrator for the UTP Plan, in addition to being a participant in the UTP Plan. In our unique role as administrator, we facilitate the collection and dissemination of revenues on behalf of the UTP Plan participants. As a participant, we share in the net distribution of revenues according to the plan on the same terms as all other plan participants. • The operating committee of the UTP Plan, which is comprised of representatives from each of the participants, including us solely in our capacity as a UTP Plan participant, is responsible for setting the level of fees to be paid by distributors and subscribers and taking action in accordance with the provisions of the UTP Plan, subject to SEC approval. • Risk of loss on the revenue is shared equally among plan participants according to the UTP Plan. The exchanges that comprise Nasdaq Nordic and Nasdaq Baltic do not have any market data products revenue sharing agreements. Index We develop and license Nasdaq branded indexes, associated derivatives and financial products as part of our Global Index Family. We also provide index data products and custom calculation services for third-party clients. Revenues primarily include license fees from these branded indexes, associated derivatives and financial products in the U.S. and abroad. We primarily have two types of license agreements: transaction-based licenses and asset-based licenses. Transaction-based licenses are generally renewable agreements. Customers are charged based on transaction volume or a minimum contract amount, or both. If a customer is charged based on transaction volume, we recognize revenue when the transaction occurs. If a customer is charged based on a minimum contract amount, we recognize revenue on a pro-rata basis over the licensing term since the customer receives and consumes the benefit as Nasdaq provides the service. Asset-based licenses are also generally renewable agreements. Customers are charged based on a percentage of assets under management for licensed products, per the agreement, on a monthly or quarterly basis. These revenues are recognized over the term of the license agreement since the customer receives and consumes the benefit as Nasdaq provides the service. Revenue from index data subscriptions are recognized on a monthly basis. Investment Data & Analytics Investment data & analytics revenues are earned from investment content and analytics products. We earn revenues primarily based on the number of content and analytics subscribers and distributors. Subscription agreements are generally annual in term, payable in advance, and provide for automatic renewal. Subscription-based revenues are recognized over time on a ratable basis over the contract period beginning on the date that our service is made available to the customer since the customer receives and consumes the benefit as Nasdaq provides the service. Market Technology Market Technology provides technology solutions for trading, clearing, settlement, surveillance and information dissemination, as well as risk management solutions. Revenues primarily consist of software, license and support revenues, change request and advisory revenues, and software as a service revenues. In our Market Technology business, we enter into long-term contracts with customers to develop customized technology solutions, license the right to use software, and provide post-contract support and other services to our customers. We also enter into agreements to modify the system solutions sold by Nasdaq after delivery has occurred. In addition, we enter into subscription agreements which allow customers to connect to our servers to access our software. Our long-term contracts with customers to develop customized technology solutions, license the right to use software and provide post-contract support and other services to our customers have multiple performance obligations. The performance obligations are generally: 1) software license and installation service and 2) software support. We have determined that the software license and installation service are not distinct as the license and the customized installation service are inputs to produce the combined output, a functional and integrated software system. For contracts with multiple performance obligations, we allocate the contract transaction price to each performance obligation using our best estimate of the standalone selling price of each distinct good or service in the contract. In instances where standalone selling price is not directly observable, such as when we do not sell the product or service separately, we determine the standalone selling price predominately through an expected cost plus a margin approach. Contract modifications are routine in the performance of our contracts. Contracts are often modified to account for changes in contract specifications or requirements. In most instances, contract modifications are for goods and services that are not distinct, and, therefore, are accounted for as part of the existing contract. For our long-term contracts, payments are generally made throughout the contract life and can be dependent on either reaching certain milestones or paid upfront in advance of the service period depending on the stage of the contract. For subscription agreements, contract payment terms can be quarterly, annually or monthly, in advance. For all other contracts, payment terms vary. We generally recognize revenue over time as our customers simultaneously receive and consume the benefits provided by our performance because our customer controls the asset for which we are creating, our performance does not create an asset with alternative use, and we have a right to payment for performance completed to date. For these services, we recognize revenue over time using costs incurred to date relative to total estimated costs at completion to measure progress toward satisfying our performance obligation. Incurred costs represent work performed, which corresponds with, and thereby depicts, the transfer of control to the customer. Contract costs generally include labor and overhead. For software support and update services, and for subscription agreements which allow customers to connect to our servers to access our software, we generally recognize revenue ratably over the service period beginning on the date our service is made available to the customer since the customer receives and consumes the benefit consistently over the period as Nasdaq provides the services. Accounting for our long-term contracts requires judgment relative to assessing risks and their impact on the estimate of revenues and costs. Our estimates are impacted by factors such as the potential for schedule and technical issues, productivity, and the complexity of work performed. When adjustments in estimated total contract costs are required, any changes in the estimated revenues from prior estimates are recognized in the current period for the effect of such change. If estimates of total costs to be incurred on a contract exceed estimates of total revenues, a provision for the entire estimated loss on the contract is recorded in the period in which the loss is determined. Other Revenues Other revenues include the revenues from the Public Relations Solutions and Digital Media Services businesses which were sold in April 2018. Prior to the sale date, these revenues were included in our Corporate Solutions business and were primarily transaction-based revenues. * * * * * * The following table summarizes the amount of the transaction price allocated to performance obligations that are unsatisfied as of September 30, 2018 and relates to our Market Technology segment: (in millions) 2018 (1) $ 63 2019 238 2020 157 2021 90 2022 55 2023 and thereafter 100 Total $ 703 ____________ (1) Represents performance obligations to be recognized over the remaining three months of 2018. Market technology deferred revenue, as discussed in Note 8, “Deferred Revenue,” to the condensed consolidated financial statements, represents consideration received that is yet to be recognized as revenue for unsatisfied performance obligations. The following tables summarize the disaggregation of revenue by major product and service and by segment for the three months ended September 30, 2018 and 2017 : Three Months Ended September 30, 2018 Market Services Corporate Services Information Services Market Technology Other Revenues Consolidated (in millions) Transaction-based trading and clearing, net $ 150 $ — $ — $ — $ — $ 150 Trade management services 72 — — — — 72 Corporate solutions — 59 — — — 59 Listing services — 72 — — — 72 Market data products — — 95 — — 95 Index — — 52 — — 52 Investment data & analytics — — 32 — — 32 Market technology — — — 68 — 68 Other revenues — — — — — — Revenues less transaction-based expenses $ 222 $ 131 $ 179 $ 68 $ — $ 600 Three Months Ended September 30, 2017 Market Services Corporate Services Information Services Market Technology Other Revenues Consolidated (in millions) Transaction-based trading and clearing, net $ 144 $ — $ — $ — $ — $ 144 Trade management services 75 — — — — 75 Corporate solutions — 59 — — — 59 Listing services — 67 — — — 67 Market data products — — 97 — — 97 Index — — 43 — — 43 Investment data & analytics — — 10 — — 10 Market technology — — — 62 — 62 Other revenues — — — — 46 46 Revenues less transaction-based expenses $ 219 $ 126 $ 150 $ 62 $ 46 $ 603 For the three months ended September 30, 2018 , approximately 63.0% of Market Services revenues were recognized at a point in time and 37.0% were recognized over time. For the three months ended September 30, 2017 , approximately 62.0% of Market Services revenues were recognized at a point in time and 38.0% were recognized over time. Substantially all revenues from the Corporate Services, Information Services and Market Technology segments were recognized over time for both the three months ended September 30, 2018 and 2017. The following tables summarize the disaggregation of revenue by major product and service and by segment for the nine months ended September 30, 2018 and 2017 : Nine Months Ended September 30, 2018 Market Services Corporate Services Information Services Market Technology Other Revenues Consolidated (in millions) Transaction-based trading and clearing, net $ 489 $ — $ — $ — $ — $ 489 Trade management services 220 — — — — 220 Corporate solutions — 178 — — — 178 Listing services — 217 — — — 217 Market data products — — 293 — — 293 Index — — 152 — — 152 Investment data & analytics — — 83 — — 83 Market technology — — — 194 — 194 Other revenues — — — — 56 56 Revenues less transaction-based expenses $ 709 $ 395 $ 528 $ 194 $ 56 $ 1,882 Nine Months Ended September 30, 2017 Market Services Corporate Services Information Services Market Technology Other Revenues Consolidated (in millions) Transaction-based trading and clearing, net $ 441 $ — $ — $ — $ — $ 441 Trade management services 218 — — — — 218 Corporate solutions — 173 — — — 173 Listing services — 197 — — — 197 Market data products — — 276 — — 276 Index — — 125 — — 125 Investment data & analytics — — 31 — — 31 Market technology — — — 176 — 176 Other revenues — — — — 143 143 Revenues less transaction-based expenses $ 659 $ 370 $ 432 $ 176 $ 143 $ 1,780 For the nine months ended September 30, 2018 , approximately 64.0% of Market Services revenues were recognized at a point in time and 36.0% were recognized over time. For the nine months ended September 30, 2017 , approximately 63.0% of Market Services revenues were recognized at a point in time and 37.0% were recognized over time. Substantially all revenues from the Corporate Services, Information Services and Market Technology segments were recognized over time for both the nine months ended September 30, 2018 and 2017. * * * * * * Equity Securities On January 1, 2018, we adopted ASU 2016-01 which requires that investments in equity securities (excluding equity method investments) be measured at fair value with changes in fair value recognized in net income. Equity securities are no longer classified as trading or available for sale. We elected the measurement alternative for equity securities which were historically accounted for under the cost method of accounting. Since these equity securities do not have readily determinable fair values, they are measured at cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. We evaluate these securities for impairment by considering a variety of factors such as the earnings capacity of the investment. If a qualitative assessment indicates that the security is impaired, Nasdaq will estimate the fair value of the security, and if the fair value is less than the carrying amount of the security, recognize an impairment loss in net income equal to the difference between the carrying amount and fair value. There was no impact on our condensed consolidated financial statements as a result of this change. The guidance for classifying and measuring investments in debt securities is unchanged. Therefore, changes in debt securities classified as trading securities are included in dividend and investment income in the Condensed Consolidated Statements of Income and debt securities classified as available-for-sale investment securities are carried at fair value with unrealized gains and losses, net of tax, reported in accumulated other comprehensive loss within stockholders’ equity in the Condensed Consolidated Balance Sheets. Realized gains and losses on these securities are included in earnings upon disposition of the securities using the specific identification method. In addition, realized losses are recognized when management determines that a decline in value is other than temporary, which requires judgment regarding the amount and timing of recovery. For financial investments that are classified as available-for-sale securities, we also consider the extent to which cost exceeds fair value, the duration of that difference, management’s judgment about the issuer’s current and prospective financial condition, as well as our intent and ability to hold the security until recovery of the unrealized losses.

Acquisitions and Divestiture

Acquisitions and Divestiture	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Acquisitions and Divestiture	Divestiture 2018 Pending Acquisition In September 2018, we announced that we made a SEK 75 per share and SEK 85 per warrant, or approximately $190 million (based on an exchange rate of USD 1.00 = SEK 8.96 as of September 13, 2018), all cash recommended public offer to the shareholders and warrant holders of Cinnober, a major Swedish financial technology provider to brokers, exchanges and clearinghouses worldwide. Our acquisition of Cinnober would be included in our Market Technology segment. Nasdaq expects to fund the acquisition with either cash on hand or liquidity available under existing credit facilities. The public tender offer is expected to be completed during the fourth quarter of 2018, subject to certain customary conditions. 2018 Divestiture and 2017 Acquisitions We completed the following divestiture in 2018 and acquisitions in 2017 . Financial results of each transaction are included in our Condensed Consolidated Statements of Income from the date of each divestiture or acquisition. 2018 Divestiture In April 2018, we sold our Public Relations Solutions and Digital Media Services businesses which were part of our Corporate Solutions business to West Corporation and recognized a pre-tax net gain on the sale of $33 million , net of disposal costs ( $14 million after tax), which includes a post-closing working capital adjustment of $8 million ( $5 million after tax) recorded during the three months ended September 30, 2018. The total net pre-tax gain is included in net gain on divestiture of businesses in the Condensed Consolidated Statements of Income for the nine months ended September 30, 2018. As of December 31, 2017, the assets and liabilities of the above businesses were held for sale. See Note 5, “Assets and Liabilities Held For Sale,” for further discussion. Through a multi-year partnership with West, Nasdaq will continue to provide eligible Nasdaq-listed clients with access to public relations, webcasting and webhosting products and services as part of the terms of the transaction. As part of the terms of the transaction, we are providing transition services to West, such as technology, finance and facilities related services for a period of time, and the compensation received for such transition services is being reflected as a reduction to the underlying expenses incurred by Nasdaq to provide such transition services. * * * * * * 2017 Acquisitions Purchase Consideration Total Net Liabilities Acquired Total Net Deferred Tax Liability Acquired Goodwill (in millions) eVestment $ 744 $ (10 ) $ (104 ) $ 405 $ 453 The amounts in the table above represent the preliminary allocation of purchase price as of September 30, 2018 and are subject to revision during the remainder of the measurement period, a period not to exceed 12 months from the acquisition date. Adjustments to the provisional values, which may include tax and other estimates, during the measurement period will be recorded in the reporting period in which the adjustment amounts are determined. Changes to amounts recorded as assets and liabilities may result in a corresponding adjustment to goodwill. See “Intangible Assets” below for further discussion of intangible assets acquired in the eVestment acquisition. Acquisition of eVestment In October 2017, we acquired eVestment for $705 million . The aggregate cash consideration of $744 million , which is net of cash acquired of $22 million , included $39 million of estimated tax benefits associated with the transaction. We acquired net liabilities, at fair value, totaling $10 million and we recorded a net deferred tax liability of $104 million , which is net of the $39 million in estimated tax benefits associated with the transaction. The deferred tax liability recorded of $143 million relates to differences in the U.S. GAAP and tax basis of our investment in eVestment. eVestment is part of our Information Services segment. Nasdaq used cash on hand and issuances of commercial paper to fund this acquisition. Acquisition of Sybenetix In September 2017, we acquired Sybenetix for an immaterial amount. Sybenetix is part of our Market Technology segment. Intangible Assets The following table presents the details of acquired intangible assets for eVestment at the date of the acquisition. All acquired intangible assets with finite lives are amortized using the straight-line method. Intangible Assets ($ in millions) Customer relationships $ 378 Discount rate used 9.3 % Estimated average useful life 14 years Trade name $ 13 Discount rate used 9.2 % Estimated average useful life 8 years Technology $ 14 Discount rate used 9.2 % Estimated average useful life 8 years Total intangible assets $ 405 Customer Relationships Customer relationships represent the non-contractual and contractual relationships with customers. Methodology For our acquisition of eVestment, customer relationships were valued using the income approach, specifically an excess earnings method. The excess earnings method examines the economic returns contributed by the identified tangible and intangible assets of a company, and then isolates the excess return that is attributable to the intangible asset being valued. Discount Rates The discount rates used reflect the amount of risk associated with the hypothetical cash flows for the customer relationships relative to the overall business. In developing a discount rate for the customer relationships, we estimated a weighted-average cost of capital for the overall business and we employed this rate when discounting the cash flows. The resulting discounted cash flows were then tax-effected at the applicable statutory rate. For our acquisition of eVestment, a discounted tax amortization benefit was added to the fair value of the assets under the assumption that the customer relationships would be amortized for tax purposes over a period of 15 years . Estimated Useful Life We estimate the useful life based on the historical behavior of the customers and a parallel analysis of the customers using the excess earnings method. Trade Name As part of our acquisition of eVestment, we acquired a trade name. This trade name is recognized in the industry and carries a reputation for quality. As such, the reputation and positive recognition embodied in this trade name is a valuable asset to Nasdaq. Methodology The eVestment trade name was valued using the income approach, specifically the relief-from-royalty method, or RFRM. The RFRM is used to es timate the cost savings that accrue to the owner of an intangible asset who would otherwise have to pay royalties or license fees on revenues earned through the use of the asset. The royalty rate is applied to the projected revenue over the expected remaining life of the intangible asset to estimate royalty savings. The net after-tax royalty savings are calculated for each year in the remaining economic life of the trade name and discounted to present value. Discount Rates The discount rate used reflects the amount of risk associated with the hypothetical cash flows for the trade name relative to the overall business as discussed above in “Customer Relationships.” Estimated Useful Life We have estimated the useful life of the eVestment trade name to be 8 years. Technology As part of our acquisition of eVestment, we acquired developed technology. Methodology The developed technology was valued using the income approach, specifically the RFRM as discussed above in “Trade Names.” Discount rate The discount rate used reflects the amount of risk associated with the hypothetical cash flows for the developed technology relative to the overall business as discussed above in “Customer Relationships.” Estimated Useful Life We have estimated the useful life of the eVestment technology to be 8 years. Pro Forma Results and Acquisition-related Costs The condensed consolidated financial statements for the three and nine months ended September 30, 2018 and 2017 include the financial results of the above 2017 acquisitions from the date of each acquisition. Pro forma financial results have not been presented since these acquisitions both individually and in the aggregate were not material to our financial results. Acquisition-related costs for the transactions described above were expensed as incurred and are included in merger and strategic initiatives expense in the Condensed Consolidated Statements of Income.

Assets and Liabilities Held For

Assets and Liabilities Held For Sale	9 Months Ended
	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Assets and Liabilities Held For Sale	Assets and Liabilities Held For Sale In September 2017, we commenced a process to evaluate strategic alternatives for our Public Relations Solutions and Digital Media Services businesses within our Corporate Solutions business as part of our strategic refinement and subsequently committed to a plan to divest these businesses. The Corporate Solutions business is part of our Corporate Services segment. The Public Relations Solutions and Digital Media Services businesses included the following products and services: • Nasdaq GlobeNewswire; • Nasdaq Influencers; • Nasdaq Media Intelligence; • Nasdaq IR Websites and Newsrooms; and • Nasdaq Webcasts. We determined that we met all of the criteria to classify the assets and liabilities of these businesses as held for sale. The disposal of these businesses did not represent a strategic shift that would have a major effect on our operations and financial results and were, therefore, not classified as discontinued operations. As a result of this classification, the assets and liabilities of these businesses were separately presented within the Condensed Consolidated Balance Sheets as held for sale and were recorded at the lower of their carrying amount or fair value less costs to sell. In January 2018, we entered into a definitive agreement to sell the above businesses. See “2018 Divestiture,” of Note 4, “Acquisitions and Divestiture,” for further discussion. Based on the sales price in the agreement, no impairment charge was recorded at the time of the sale as the carrying amount of the net assets was less than the sales price in the agreement less costs to sell. The carrying amounts of the major classes of assets and liabilities that were classified as held for sale at December 31, 2017 in the Condensed Consolidated Balance Sheets were as follows: December 31, 2017 (in millions) Receivables, net $ 27 Property and equipment, net 21 Goodwill (1) 202 Intangible assets, net (2) 38 Other assets 9 Total assets held for sale $ 297 Deferred tax liabilities $ 16 Other current liabilities 29 Total liabilities held for sale $ 45 ____________ (1) The assignment of goodwill was based on the relative fair value of the disposal group and the portion of the remaining reporting unit. (2) Primarily represents customer relationships.

Goodwill and Acquired Intangibl

Goodwill and Acquired Intangible Assets	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Acquired Intangible Assets	Goodwill and Acquired Intangible Assets Goodwill The following table presents the changes in goodwill by business segment during the nine months ended September 30, 2018 : Market Services Corporate Services Information Services Market Technology Total (in millions) Balance at December 31, 2017 $ 3,546 $ 490 $ 2,362 $ 188 $ 6,586 Reclassification of goodwill (1) — 29 — (29 ) — Foreign currency translation adjustment (111 ) (16 ) (79 ) (11 ) (217 ) Balance at September 30, 2018 $ 3,435 $ 503 $ 2,283 $ 148 $ 6,369 ____________ (1) Concurrent with the realignment of our BWise corporate enterprise risk management solutions from our Market Technology segment to our Corporate Services segment, goodwill was reassigned to the Corporate Services segment using a relative fair value approach. As of September 30, 2018 , the amount of goodwill that is expected to be deductible for tax purposes in future periods is $749 million . Goodwill represents the excess of purchase price over the value assigned to the net assets, including identifiable intangible assets, of a business acquired. Goodwill is allocated to our reporting units based on the assignment of the fair values of each reporting unit of the acquired company. We test goodwill for impairment at the reporting unit level annually, or in interim periods if certain events occur indicating that the carrying amount may be impaired, such as changes in the business climate, poor indicators of operating performance or the sale or disposition of a significant portion of a reporting unit. There was no impairment of goodwill for the nine months ended September 30, 2018 and 2017 ; however, events such as extended economic weakness or unexpected significant declines in operating results of a reporting unit may result in goodwill impairment charges in the future. * * * * * * Acquired Intangible Assets The following table presents details of our total acquired intangible assets, both finite- and indefinite-lived: September 30, 2018 December 31, 2017 Gross Amount Accumulated Amortization Net Amount Weighted-Average Useful Life (in Years) Gross Amount Accumulated Amortization Net Amount Weighted-Average Useful Life (in Years) (in millions) (in millions) Finite-Lived Intangible Assets Technology $ 50 $ (13 ) $ 37 9 $ 65 $ (22 ) $ 43 8 Customer relationships 1,708 (606 ) 1,102 18 1,708 (526 ) 1,182 18 Other 17 (5 ) 12 8 17 (4 ) 13 8 Foreign currency translation adjustment (143 ) 62 (81 ) (111 ) 46 (65 ) Total finite-lived intangible assets $ 1,632 $ (562 ) $ 1,070 $ 1,679 $ (506 ) $ 1,173 Indefinite-Lived Intangible Assets Exchange and clearing registrations $ 1,257 $ — $ 1,257 $ 1,257 $ — $ 1,257 Trade names 127 — 127 129 — 129 Licenses 52 — 52 52 — 52 Foreign currency translation adjustment (178 ) — (178 ) (143 ) — (143 ) Total indefinite-lived intangible assets $ 1,258 $ — $ 1,258 $ 1,295 $ — $ 1,295 Total intangible assets $ 2,890 $ (562 ) $ 2,328 $ 2,974 $ (506 ) $ 2,468 Amortization expense for acquired finite-lived intangible assets was $27 million for the three months ended September 30, 2018 , $22 million for the three months ended September 30, 2017 , $83 million for the nine months ended September 30, 2018 , and $67 million for the nine months ended September 30, 2017 . Amortization expense increased in 2018 primarily due to additional amortization expense associated with acquired intangible assets in 2017. These amounts are included in depreciation and amortization expense in the Condensed Consolidated Statements of Income. The estimated future amortization expense (excluding the impact of foreign currency translation adjustments of $81 million as of September 30, 2018 ) of acquired finite-lived intangible assets as of September 30, 2018 is as follows: (in millions) 2018 (1) $ 27 2019 99 2020 98 2021 97 2022 94 2023 and thereafter 736 Total $ 1,151 ____________ (1) Represents the estimated amortization to be recognized for the remaining three months of 2018. In April 2018, in connection with the sale of the Public Relations Solutions and Digital Media Services businesses, we recorded a $2 million pre-tax, non-cash write-off related to an indefinite-lived intangible asset trade name.

Investments

Investments	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Investments	Investments The following table presents the details of our investments: September 30, December 31, (in millions) Trading securities $ 202 $ 221 Available-for-sale investment securities — 14 Financial investments, at fair value $ 202 $ 235 Equity method investments $ 131 $ 131 Equity securities $ 76 $ 152 Financial Investments, at Fair Value Trading Securities Trading securities, which are included in financial investments, at fair value in the Condensed Consolidated Balance Sheets, are primarily comprised of highly rated European government debt securities, of which $174 million as of September 30, 2018 and $160 million as of December 31, 2017 , are assets utilized to meet regulatory capital requirements, primarily for our clearing operations at Nasdaq Clearing. Available-for-Sale Investment Securities As of December 31, 2017 , available-for-sale investment securities, which are included in financial investments, at fair value in the Condensed Consolidated Balance Sheets, were primarily comprised of commercial paper debt securities. As of December 31, 2017 , the cumulative unrealized gains and losses on these securities were immaterial. Equity Method Investments As of September 30, 2018 and December 31, 2017 , our equity method investments primarily included equity interests in OCC and EuroCCP N.V. The carrying amounts of our equity method investments are included in other non-current assets in the Condensed Consolidated Balance Sheets. Net income recognized from our equity interest in the earnings and losses of these equity method investments was $6 million for the three months ended September 30, 2018 , $4 million for the three months ended September 30, 2017 , $13 million for the nine months ended September 30, 2018 , and $10 million for the nine months ended September 30, 2017 . Capital Contribution to OCC In March 2015, OCC implemented a capital plan under which the options exchanges that are OCC’s stockholders contributed $150 million of new equity capital to OCC, committed to make future replenishment capital contributions under certain circumstances, and received commitments regarding future dividend payments and related matters. See “Other Commitments,” of Note 16, “Commitments, Contingencies and Guarantees,” for further discussion of our commitment to make future replenishment capital contributions. Nasdaq and ISE each contributed $30 million of new equity capital under the OCC capital plan. OCC adopted specific policies with respect to fees, customer refunds and stockholder dividends, which envision an annual dividend equal to the portion of OCC’s after-tax income that exceeds OCC’s capital requirements after payment of refunds to OCC’s clearing members (such refunds are generally 50% of the portion of OCC’s pre-tax income that exceeds OCC’s capital requirements). In February 2016, the SEC approved the OCC capital plan and certain industry participants appealed that approval in the Federal Court of Appeals. The Court of Appeals denied a requested stay, permitting OCC to pay a dividend which Nasdaq received in February 2016. In August 2017, the Court of Appeals remanded the case to the SEC for further examination of the record and an independent assessment by the SEC of the evidence OCC submitted. The Court directed that the SEC approval of the OCC capital plan remain in place during the SEC’s examination unless the SEC determined not to preserve it. The SEC has allowed OCC to preserve the capital plan, and in September 2018 and 2017, OCC disbursed annual dividends. Nasdaq, as the owner of two shares, received $13 million in 2018 and $10 million in 2017. There has been no final ruling by the SEC at this time, and there is no deadline for the SEC to issue its ruling. Equity Securities The carrying amounts of our equity securities are included in other non-current assets in the Condensed Consolidated Balance Sheets. As of September 30, 2018 , our equity securities primarily represent our 5% ownership interest in LCH. As of December 31, 2017, our equity securities primarily represented our 5% ownership in Borsa Istanbul and our 5% ownership interest in LCH. For the nine months ended September 30, 2018 , no impairment charges were recorded on our equity securities and there were no upward or downward adjustments recorded. The Borsa Istanbul shares, which were issued to us in the first quarter of 2014, were part of the consideration received under a market technology agreement. This investment had a carrying amount of $75 million which was guaranteed to us via a put option negotiated as part of the market technology agreement. During the second quarter of 2018, we exercised the put option and we expect to receive cash consideration in installments through 2022 . In October 2018, we entered into an agreement to sell our ownership interest in LCH. See “Sale of Equity Security,” of Note 19, “Subsequent Events,” for further discussion.

Deferred Revenue

Deferred Revenue	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Deferred Revenue	Deferred Revenue Deferred revenue represents consideration received that is yet to be recognized as revenue. The changes in our deferred revenue during the nine months ended September 30, 2018 are reflected in the following table: Initial Listing Revenues Annual Listings Revenues Market Technology Revenues Corporate Solutions and Other Revenues (2) Information Services Revenues Other (3) Total (in millions) Balance at December 31, 2017 $ 64 $ 3 $ 109 $ 37 $ 40 $ 34 $ 287 Additions 30 231 118 189 128 18 714 Revenue recognized (27 ) (173 ) (131 ) (191 ) (91 ) (29 ) (642 ) Reclassification of deferred revenue (1) — — (11 ) 11 — — — Translation adjustment (2 ) (1 ) (8 ) — 1 (1 ) (11 ) Balance at September 30, 2018 $ 65 $ 60 $ 77 $ 46 $ 78 $ 22 $ 348 ____________ (1) Concurrent with the realignment of our BWise corporate enterprise risk management solutions from our Market Technology segment to our Corporate Services segment, deferred revenue was reassigned to the Corporate Services segment. (2) Other revenues include the revenues from the Public Relations Solutions and Digital Media Services businesses through the date of sale (April 2018). See “2018 Divestiture,” of Note 4, “Acquisitions and Divestiture,” to the condensed consolidated financial statements for further discussion. (3) The balance as of September 30, 2018 and December 31, 2017 primarily includes deferred revenue from listing of additional shares fees which are included in our Listing Services segment. The activity during the period primarily pertains to our Trade Management Services and FICC businesses, which are included in our Market Services segment, for contracts paid monthly or quarterly in advance of the service. On January 1, 2018, we adopted Topic 606. As a result, a portion of revenues that were previously deferred were recognized either in prior period revenues, through restatement, or as an adjustment to retained earnings upon adoption of the new standard. See “Revenue From Contracts With Customers,” of Note 3, “Significant Accounting Policies Update,” for a description of our initial listing, annual listing, market technology, corporate solutions, and information services revenues and the revenue recognition policy for each of these revenue streams. As of September 30, 2018 , we estimate that our deferred revenue will be recognized in the following years: Initial Listing Revenues Annual Listings Revenues Market Technology Revenues Corporate Solutions Revenues Information Services Revenues Other (2) Total (in millions) Fiscal year ended: 2018 (1) $ 6 $ 60 $ 18 $ 24 $ 35 $ 3 $ 146 2019 23 — 34 21 43 10 131 2020 15 — 18 1 — 6 40 2021 10 — 7 — — 3 20 2022 7 — — — — — 7 2023 and thereafter 4 — — — — — 4 Total $ 65 $ 60 $ 77 $ 46 $ 78 $ 22 $ 348 ____________ (1) Represents deferred revenue that is anticipated to be recognized over the remaining three months of 2018. (2) Other primarily includes revenues from listing of additional shares fees which are included in our Listing Services business. The timing of recognition of our deferred market technology revenues is primarily dependent upon the completion of customization and any significant modifications made pursuant to existing market technology contracts. As such, as it relates to market technology revenues, the timing represents our best estimate.

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt Obligations	Debt Obligations The following table presents the changes in the carrying amount of our debt obligations during the nine months ended September 30, 2018 : December 31, 2017 Additions Payments, Accretion and Other September 30, 2018 Short-term debt: (in millions) Commercial paper $ 480 $ 3,192 $ (3,363 ) $ 309 Senior unsecured floating rate notes due March 22, 2019 (1) 498 — 1 499 Total short-term debt 978 3,192 (3,362 ) 808 Long-term debt: 5.55% senior unsecured notes due January 15, 2020 599 — — 599 3.875% senior unsecured notes due June 7, 2021 716 — (22 ) 694 4.25% senior unsecured notes due June 1, 2024 496 — 1 497 1.75% senior unsecured notes due May 19, 2023 712 — (22 ) 690 3.85% senior unsecured notes due June 30, 2026 496 — — 496 $400 million senior unsecured term loan facility due November 25, 2019 (average interest rate of 3.37% for the period January 1, 2018 through September 30, 2018) 100 — — 100 $1 billion revolving credit commitment due April 25, 2022 (average interest rate of 2.74% for the period January 1, 2018 through September 30, 2018) 110 — (114 ) (4 ) Total long-term debt 3,229 — (157 ) 3,072 Total debt obligations $ 4,207 $ 3,192 $ (3,519 ) $ 3,880 ____________ (1) Balance was reclassified to short-term debt as of March 31, 2018. Commercial Paper Program Our U.S. dollar commercial paper program is supported by our 2017 Credit Facility which provides liquidity support for the repayment of commercial paper issued through the commercial paper program. See “2017 Credit Facility” below for further discussion of our 2017 Credit Facility. The effective interest rate of commercial paper issuances fluctuate as short term interest rates and demand fluctuate. The fluctuation of these rates due to market conditions may impact our interest expense. As of September 30, 2018 , commercial paper notes in the table above reflect the aggregate principal amount, less the unamortized discount which is being accreted through interest expense over the life of the applicable notes. The original maturities of these notes range from 7 days to 63 days and the weighted-average maturity is 29 days . The weighted-average effective interest rate is 2.45% per annum. Senior Unsecured Notes Our senior unsecured notes were all issued at a discount. As a result of the discount, the proceeds received from each issuance were less than the aggregate principal amount. As of September 30, 2018 , the amounts in the table above reflect the aggregate principal amount, less the unamortized debt discount and the unamortized debt issuance costs which are being accreted through interest expense over the life of the applicable notes. Our senior unsecured notes are general unsecured obligations of ours and rank equally with all of our existing and future unsubordinated obligations and they are not guaranteed by any of our subsidiaries. The senior unsecured notes were issued under indentures that, among other things, limit our ability to consolidate, merge or sell all or substantially all of our assets, create liens, and enter into sale and leaseback transactions. With the exception of the 2020 Notes, upon a change of control triggering event (as defined in the various note indentures), the terms require us to repurchase all or part of each holder’s notes for cash equal to 101% of the aggregate principal amount purchased plus accrued and unpaid interest, if any. Senior Unsecured Floating Rate Notes In September 2017, Nasdaq issued the 2019 Notes. The 2019 Notes pay interest quarterly in arrears at a rate equal to the three-month U.S. dollar LIBOR as determined at the beginning of each quarterly period plus 0.39% per annum until March 22, 2019. 5.55% Senior Unsecured Notes In January 2010, Nasdaq issued the 2020 Notes. The 2020 Notes pay interest semiannually at a rate of 5.55% per annum until January 15, 2020 . 3.875% Senior Unsecured Notes In June 2013, Nasdaq issued the 2021 Notes. The 2021 Notes pay interest annually at a rate of 3.875% per annum until June 7, 2021 and such rate may vary with Nasdaq’s debt rating up to a rate not to exceed 5.875% . The 2021 Notes have been designated as a hedge of our net investment in certain foreign subsidiaries to mitigate the foreign exchange risk associated with certain investments in these subsidiaries. The decrease in the carrying amount of $22 million noted in the “Payments, Accretion and Other” column in the table above primarily reflects the translation of the 2021 Notes into U.S. dollars and is recorded in accumulated other comprehensive loss within stockholders’ equity in the Condensed Consolidated Balance Sheets as of September 30, 2018 . 4.25% Senior Unsecured Notes In May 2014, Nasdaq issued the 2024 Notes. The 2024 Notes pay interest semiannually at a rate of 4.25% per annum until June 1, 2024 and such rate may vary with Nasdaq’s debt rating up to a rate not to exceed 6.25% . 1.75% Senior Unsecured Notes In May 2016, Nasdaq issued the 2023 Notes. The 2023 Notes pay interest annually at a rate of 1.75% per annum until May 19, 2023 and such rate may vary with Nasdaq’s debt rating up to a rate not to exceed 3.75% . The 2023 Notes have been designated as a hedge of our net investment in certain foreign subsidiaries to mitigate the foreign exchange rate risk associated with certain investments in these subsidiaries. The decrease in the carrying amount of $22 million noted in the “Payments, Accretion and Other” column in the table above reflects the translation of the 2023 Notes into U.S. dollars and is recorded in accumulated other comprehensive loss within stockholders’ equity in the Condensed Consolidated Balance Sheets as of September 30, 2018 . 3.85% Senior Unsecured Notes In June 2016, Nasdaq issued the 2026 Notes. The 2026 Notes pay interest semiannually at a rate of 3.85% per annum until June 30, 2026 and such rate may vary with Nasdaq’s debt rating up to a rate not to exceed 5.85% . Credit Facilities As of September 30, 2018 , the amounts in the table above reflect the aggregate principal amount, less the unamortized debt issuance costs which are being accreted through interest expense over the life of the applicable credit facility. Nasdaq is permitted to repay borrowings under our credit facilities at any time in whole or in part, without penalty. Our credit facilities contain financial and operating covenants. Financial covenants include a minimum interest expense coverage ratio and a maximum leverage ratio. Operating covenants include, among other things, limitations on Nasdaq’s ability to incur additional indebtedness, grant liens on assets, dispose of assets and pay dividends. Our credit facilities allow us to pay cash dividends on our common stock. The facilities also contain customary affirmative covenants, including access to financial statements, notice of defaults and certain other material events, maintenance of properties and insurance, and events of default, including cross-defaults to our material indebtedness. 2017 Credit Facility In April 2017, Nasdaq entered into the 2017 Credit Facility. The 2017 Credit Facility consists of a $1 billion five -year revolving credit facility (with sublimits for non-dollar borrowings, swingline borrowings and letters of credit), which replaced a former credit facility. Nasdaq intends to use funds available under the 2017 Credit Facility for general corporate purposes and to provide liquidity support for the repayment of commercial paper issued through the commercial paper program. As of September 30, 2018 , no amounts were outstanding on the 2017 Credit Facility. The $4 million credit balance represents unamortized debt issuance costs. Of the $1 billion that is available for borrowing, $311 million provides liquidity support for the commercial paper program and for a letter of credit. As such, as of September 30, 2018 , the total remaining amount available under the 2017 Credit Facility was $689 million . See “Commercial Paper Program” above for further discussion of our commercial paper program. Under our 2017 Credit Facility, borrowings under the revolving credit facility and swingline borrowings bear interest on the principal amount outstanding at a variable interest rate based on either the LIBOR or the base rate (as defined in the credit agreement) (or other applicable rate with respect to non-dollar borrowings), plus an applicable margin that varies with Nasdaq’s debt rating. The 2017 Credit Facility includes an option for Nasdaq to increase the available aggregate amount by up to $500 million , subject to the consent of the lenders funding the increase and certain other conditions. 2016 Credit Facility In March 2016, Nasdaq entered into the 2016 Credit Facility. Under our 2016 Credit Facility, borrowings bear interest on the principal amount outstanding at a variable interest rate based on either the LIBOR or the base rate (or other applicable rate with respect to non-dollar borrowings), plus an applicable margin that varies with Nasdaq’s debt rating. As of September 30, 2018 , the amount outstanding of $100 million is due upon maturity at November 25, 2019. Other Credit Facilities We also have credit facilities related to our Nasdaq Clearing operations in order to provide further liquidity. Credit facilities, which are available in multiple currencies, totaled $219 million as of September 30, 2018 and $187 million as of December 31, 2017 in available liquidity, none of which was utilized. Debt Covenants As of September 30, 2018 , we were in compliance with the covenants of all of our debt obligations.

Retirement Plans

Retirement Plans	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Retirement Plans	Retirement Plans Defined Contribution Savings Plan We sponsor a 401(k) Plan for U.S. employees. Employees are immediately eligible to make contributions to the plan and are also eligible for an employer contribution match at an amount equal to 100.0% of the first 6.0% of eligible employee contributions. Savings plan expense included in compensation and benefits expense in the Condensed Consolidated Statements of Income was $3 million for both the three months ended September 30, 2018 and 2017 and $10 million for both the nine months ended September 30, 2018 and 2017. Pension and Supplemental Executive Retirement Plans We maintain non-contributory, defined-benefit pension plans, non-qualified SERPs for certain senior executives and other post-retirement benefit plans for eligible employees in the U.S., collectively referred to as the Nasdaq Benefit Plans. Our pension plans and SERPs are frozen. Future service and salary for all participants do not count toward an accrual of benefits under the pension plans and SERPs. Most employees outside the U.S. are covered by local retirement plans or by applicable social laws. Benefits under social laws are generally expensed in the periods in which the costs are incurred. The total expense for these plans is included in compensation and benefits expense in the Condensed Consolidated Statements of Income and was $4 million for the three months September 30, 2018 , $5 million for the three months ended September 30, 2017 , $15 million for the nine months September 30, 2018 , and $13 million for the nine months ended September 30, 2017 . During the third quarter of 2018, we contributed $22 million to our U.S. defined-benefit pension plans. This contribution increased our funded status to approximately 100.0% . We will continue to monitor the plan's funded status.

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation We have a share-based compensation program for employees and non-employee directors. Share-based awards granted under this program include stock options, restricted stock (consisting of restricted stock units), and PSUs. For accounting purposes, we consider PSUs to be a form of restricted stock. Summary of Share-Based Compensation Expense The following table shows the total share-based compensation expense resulting from equity awards and the 15.0% discount for the ESPP for the three and nine months ended September 30, 2018 and 2017 in the Condensed Consolidated Statements of Income: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Share-based compensation expense before income taxes $ 18 $ 18 $ 51 $ 52 Income tax benefit (5 ) (7 ) (14 ) (21 ) Share-based compensation expense after income taxes $ 13 $ 11 $ 37 $ 31 Common Shares Available Under Our Equity Plan As of September 30, 2018 , we had approximately 11.0 million shares of common stock authorized for future issuance under our Equity Plan. Restricted Stock We grant restricted stock to most active employees. The grant date fair value of restricted stock awards is based on the closing stock price at the date of grant less the present value of future cash dividends. Restricted stock awards granted generally vest 25.0% on the second anniversary of the grant date, 25.0% on the third anniversary of the grant date, and 50.0% on the fourth anniversary of the grant date. We generally recognize compensation expense for restricted stock awards on a straight-line basis over the requisite service period of the award, taking into account an estimated forfeiture rate. Granted but unvested shares are generally forfeited upon termination of employment. Summary of Restricted Stock Activity The following table summarizes our restricted stock activity for the nine months ended September 30, 2018 : Restricted Stock Number of Awards Weighted-Average Grant Date Fair Value Unvested balances at January 1, 2018 1,988,500 $ 57.34 Granted 489,203 $ 81.77 Vested (669,577 ) $ 47.54 Forfeited (229,214 ) $ 63.29 Unvested balances at September 30, 2018 1,578,912 $ 68.20 As of September 30, 2018 , $58 million of total unrecognized compensation cost related to restricted stock is expected to be recognized over a weighted-average period of 1.9 years . PSUs PSUs are based on performance measures that impact the amount of shares that each recipient will receive upon vesting. We have two performance-based long-term PSU programs for certain officers, a one -year performance-based program and a three -year cumulative performance-based program that focuses on TSR. One -Year PSU Program The grant date fair value of PSUs under the one -year performance-based program is based on the closing stock price at the date of grant less the present value of future cash dividends. Under this program, an eligible employee receives a target grant of PSUs, but may receive from 0.0% to 150.0% of the target amount granted, depending on the achievement of performance measures. These awards vest ratably on an annual basis over a three -year period commencing with the end of the one -year performance period. Compensation cost is recognized over the performance period and the three -year vesting period based on the probability that such performance measures will be achieved, taking into account an estimated forfeiture rate. Granted but unvested shares are generally forfeited upon termination of employment. During 2017, certain grants of PSUs with a one -year performance period exceeded the applicable performance parameters. As a result, an additional 14,497 units above target were considered granted in the first quarter of 2018 and are included in the below table. Three -Year PSU Program Under the three -year performance-based program, each eligible individual receives PSUs, subject to market conditions, with a three -year cumulative performance period that vest at the end of the performance period. Compensation cost is recognized over the three -year vesting period, taking into account an estimated forfeiture rate, regardless of whether the market condition is satisfied, provided that the requisite service period has been completed. Granted but unvested shares are generally forfeited upon termination of employment. Performance will be determined by comparing Nasdaq’s TSR to two peer groups, each weighted 50.0% . The first peer group consists of exchange companies, and the second peer group consists of all companies in the S&P 500. Nasdaq’s relative performance ranking against each of these groups will determine the final number of shares delivered to each individual under the program. The payout under this program will be between 0.0% and 200.0% of the number of PSUs granted and will be determined by Nasdaq’s overall performance against both peer groups. However, if Nasdaq’s TSR is negative for the three -year performance period, regardless of TSR ranking, the payout will not exceed 100.0% of the number of PSUs granted. We estimate the fair value of PSUs granted under the three -year PSU program using the Monte Carlo simulation model, as these awards contain a market condition. Certain grants of PSUs that were issued in 2015 with a three -year performance period exceeded the applicable performance parameters. As a result, an additional 237,876 units above target were considered granted in the first quarter of 2018 and are included in the below table. The following weighted-average assumptions were used to determine the weighted-average fair values of the PSU awards granted under the three -year PSU program: Nine Months Ended September 30, 2018 2017 Weighted-average risk free interest rate (1) 2.36 % 1.44 % Expected volatility (2) 18.7 % 19.2 % Weighted-average grant date share price $86.24 $69.45 Weighted-average fair value at grant date $116.86 $81.57 ____________ (1) The risk-free interest rate for periods within the expected life of the award is based on the U.S. Treasury yield curve in effect at the time of grant. (2) We use historic volatility for PSU awards issued under the three -year PSU program, as implied volatility data could not be obtained for all the companies in the peer groups used for relative performance measurement within the program. In addition, the annual dividend assumption utilized in the Monte Carlo simulation model is based on Nasdaq’s dividend yield at the date of grant. Summary of PSU Activity The following table summarizes our PSU activity for the nine months ended September 30, 2018 : PSUs One-Year Program Three-Year Program Number of Awards Weighted-Average Grant Date Fair Value Number of Awards Weighted-Average Grant Date Fair Value Unvested balances at January 1, 2018 333,004 $ 61.39 1,009,958 $ 78.18 Granted (1) 132,019 $ 80.36 484,075 $ 90.92 Vested (6,702 ) $ 49.40 (655,204 ) $ 64.08 Forfeited (22,650 ) $ 60.84 — $ — Unvested balances at September 30, 2018 435,671 $ 67.35 838,829 $ 96.55 ____________ (1) Includes target awards granted and certain additional awards granted based on overachievement of performance parameters. As of September 30, 2018 , $12 million of total unrecognized compensation cost related to the one -year PSU program is expected to be recognized over a weighted-average period of 1.5 years . For the three -year PSU program, $34 million of total unrecognized compensation cost is expected to be recognized over a weighted-average period of 1.5 years . Stock Options No stock option awards were granted during the nine months ended September 30, 2018 . In January 2017, our CEO received 268,817 performance-based non-qualified stock options which will vest annually over a three -year period, with each vesting contingent upon the achievement of annual performance parameters. On January 30, 2018, Nasdaq's management compensation committee and board of directors determined that the performance goal for 2017 was met, resulting in the settlement of the first one-third of the grant. The weighted-average grant date fair value was $66.68 . We estimated the fair value of this stock option award using the Black-Scholes valuation model using the following assumptions: Expected life (in years) 6 Weighted-average risk free interest rate 2.1 % Expected volatility 25.6 % Dividend yield 1.92 % Our computation of expected life was based on an estimate of the average length of time between option grant and exercise. The interest rate for periods within the expected life of the award was based on the U.S. Treasury yield curve in effect at the time of grant. Our computation of expected volatility was an estimate of the future upward/downward fluctuations in the underlying share price. We used Nasdaq's historical volatility for the trailing 6 -year period as of the grant date. Our computation of dividend yield was based on annualized dividends expressed as a percentage of share price. Summary of Stock Option Activity A summary of stock option activity for the nine months ended September 30, 2018 is as follows: Number of Stock Options Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in millions) Outstanding at January 1, 2018 571,380 $ 43.84 5.40 $ 19 Exercised (99,953 ) 24.52 Forfeited (3,182 ) 26.86 Outstanding at September 30, 2018 468,245 $ 48.08 5.48 $ 18 Exercisable at September 30, 2018 289,033 $ 36.55 3.83 $ 14 The net cash proceeds from the exercise of 11,953 stock options for the three months ended September 30, 2018 was immaterial. We received net cash proceeds of $2 million from the exercise of 99,953 stock options for the nine months ended September 30, 2018 . We received net cash proceeds of $1 million from the exercise of 40,160 stock options for the three months ended September 30, 2017 and received net cash proceeds of $24 million from the exercise of 1,074,321 stock options for the nine months ended September 30, 2017. The aggregate intrinsic value in the above table represents the total pre-tax intrinsic value (i.e., the difference between our closing stock price on September 28, 2018 of $85.80 and the exercise price, times the number of shares) based on stock options with an exercise price less than Nasdaq’s closing price of $85.80 as of September 28, 2018, which would have been received by the option holders had the option holders exercised their stock options on that date. This amount can change based on the fair market value of our common stock. The total number of in-the-money stock options exercisable as of September 30, 2018 was 0.3 million and the weighted-average exercise price was $36.55 . As of September 30, 2017 , 0.3 million outstanding stock options were exercisable and the weighted-average exercise price was $23.77 . The total pre-tax intrinsic value of stock options exercised was $1 million for the three months ended September 30, 2018 , $2 million for the three months ended September 30, 2017, $6 million for the nine months ended September 30, 2018 , and $53 million for the nine months ended September 30, 2017. ESPP We have an ESPP under which approximately 2.0 million shares of our common stock have been reserved for future issuance as of September 30, 2018 . Under our ESPP, employees may purchase shares having a value not exceeding 10.0% of their annual compensation, subject to applicable annual Internal Revenue Service limitations. We record compensation expense related to the 15.0% discount that is given to our employees which totaled $1 million for both the three months ended September 30, 2018 and 2017 and $3 million for both the nine months ended September 30, 2018 and 2017.

Nasdaq Stockholders_ Equity

Nasdaq Stockholders’ Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Nasdaq Stockholders' Equity	Nasdaq Stockholders’ Equity Common Stock As of September 30, 2018 , 300,000,000 shares of our common stock were authorized, 169,423,805 shares were issued and 163,949,047 shares were outstanding. The holders of common stock are entitled to one vote per share, except that our certificate of incorporation limits the ability of any person to vote in excess of 5.0% of the then-outstanding shares of Nasdaq common stock. Common Stock in Treasury, at Cost We account for the purchase of treasury stock under the cost method with the shares of stock repurchased reflected as a reduction to Nasdaq stockholders’ equity and included in common stock in treasury, at cost in the Condensed Consolidated Balance Sheets. Shares repurchased under our share repurchase program are currently retired and canceled. When treasury shares are reissued, they are recorded at the average cost of the treasury shares acquired. We held 5,474,758 shares of common stock in treasury as of September 30, 2018 and 4,932,402 shares as of December 31, 2017, most of which are related to shares of our common stock repurchased for the settlement of employee tax withholding obligations arising from the vesting of restricted stock. Share Repurchase Program In January 2018, our board of directors authorized an additional $500 million for the share repurchase program bringing the total capacity to $726 million . These purchases may be made from time to time at prevailing market prices in open market purchases, privately-negotiated transactions, block purchase techniques or otherwise, as determined by our management. The purchases are primarily funded from existing cash balances. The share repurchase program may be suspended, modified or discontinued at any time. The share repurchase program has no defined expiration date. The following table summarizes our share repurchase activity: Nine Months Ended September 30, 2018 2017 Number of shares of common stock repurchased 4,508,426 2,455,171 Average price paid per share $ 87.43 $ 71.15 Total purchase price (in millions) $ 394 $ 175 As discussed above in “Common Stock in Treasury, at Cost,” shares repurchased under our share repurchase program are currently retired and cancelled. As of September 30, 2018 , the remaining amount authorized for share repurchases under the program was $332 million . Other Repurchases of Common Stock During the first nine months of 2018, we repurchased 542,356 shares of our common stock in settlement of employee tax withholding obligations arising from the vesting of restricted stock. Preferred Stock Our certificate of incorporation authorizes the issuance of 30,000,000 shares of preferred stock, par value $0.01 per share, issuable from time to time in one or more series. As of September 30, 2018 and December 31, 2017, no shares of preferred stock were issued or outstanding. * * * * * * Cash Dividends on Common Stock During the nine months ended September 30, 2018 , our board of directors declared the following cash dividends: Declaration Date Dividend Per Common Share Record Date Total Amount Paid Payment Date (in millions) January 30, 2018 $ 0.38 March 16, 2018 $ 63 March 30, 2018 March 26, 2018 0.44 June 15, 2018 73 June 29, 2018 July 24, 2018 0.44 September 14, 2018 72 September 28, 2018 $ 208 The total amount paid of $208 million was recorded in retained earnings in the Condensed Consolidated Balance Sheets at September 30, 2018 . In October 2018, the board of directors declared a regular quarterly cash dividend of $0.44 per share on our outstanding common stock. The dividend is payable on December 28, 2018 to shareholders of record at the close of business on December 14, 2018. The estimated amount of this dividend is $72 million . In March 2018, the board of directors approved a regular quarterly cash dividend of $0.44 per share on our outstanding common stock which reflects a 16.0% increase from our prior quarterly cash dividend of $0.38 . Future declarations of quarterly dividends and the establishment of future record and payment dates are subject to approval by the board of directors. Our board of directors maintains a dividend policy with the intention to provide stockholders with regular and growing dividends over the long term as earnings and cash flow grow.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The following table sets forth the computation of basic and diluted earnings per share: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Numerator: (in millions, except share and per share amounts) Net income attributable to common shareholders $ 163 $ 170 $ 502 $ 483 Denominator: Weighted-average common shares outstanding for basic earnings per share 164,227,243 166,694,755 165,622,428 166,195,433 Weighted-average effect of dilutive securities: Employee equity awards (1) 2,071,426 2,315,145 1,931,307 3,036,349 Contingent issuance of common stock 992,247 992,247 330,749 334,384 Weighted-average common shares outstanding for diluted earnings per share 167,290,916 170,002,147 167,884,484 169,566,166 Basic and diluted earnings per share: Basic earnings per share $ 0.99 $ 1.02 $ 3.03 $ 2.91 Diluted earnings per share $ 0.97 $ 1.00 $ 2.99 $ 2.85 ____________ (1) PSUs, which are considered contingently issuable, are included in the computation of dilutive earnings per share on a weighted average basis when management determines the related performance criteria are met. There were no securities that were antidilutive for both the three and nine months ended September 30, 2018 . Securities that were not included in the computation of diluted earnings per share because their effect was antidilutive totaled 179,712 for the three months ended September 30, 2017 and 325,187 for the nine months ended September 30, 2017 .

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The following tables present our financial assets and financial liabilities that are measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017 . We did not have any financial liabilities measured at fair value on a recurring basis as of December 31, 2017 . September 30, 2018 Total Level 1 Level 2 Level 3 (in millions) Assets at Fair Value Financial investments, at fair value $ 202 $ 148 $ 54 $ — Default fund and margin deposit investments 1,617 215 1,402 — Total Assets at Fair Value $ 1,819 $ 363 $ 1,456 $ — Liabilities at Fair Value Other financial instruments $ 56 $ — $ 56 $ — Total Liabilities at Fair Value $ 56 $ — $ 56 $ — December 31, 2017 Total Level 1 Level 2 Level 3 (in millions) Assets at Fair Value Financial investments, at fair value $ 235 $ 135 $ 100 $ — Default fund and margin deposit investments 2,129 371 1,758 — Total Assets at Fair Value $ 2,364 $ 506 $ 1,858 $ — As of September 30, 2018 and December 31, 2017, Level 1 financial investments, at fair value were primarily comprised of trading securities, mainly highly rated European government debt securities. As of September 30, 2018 and December 31, 2017, Level 2 financial investments, at fair value were primarily comprised of trading securities, mainly corporate bonds and European mortgage bonds. Of the Level 1 and Level 2 financial investments, at fair value, $174 million as of September 30, 2018 and $160 million as of December 31, 2017 are assets utilized to meet regulatory capital requirements, primarily for our clearing operations at Nasdaq Clearing. Our Level 1 default fund and margin deposit investments were primarily comprised of highly rated European and U.S. government debt securities. Level 2 default fund and margin deposit investments were primarily comprised of central bank certificates and reverse repurchase agreements, as of September 30, 2018 and December 31, 2017. Our Level 2 other financial instruments include a liability associated with Nasdaq Clearing's requirement to fulfill the settlement of certain contracts of a defaulted member. As of September 30, 2018 , the fair value of this guarantee was $56 million and is included in other current liabilities in the Condensed Consolidated Balance Sheets. See Note 15, “Clearing Operations,” for further discussion of default fund contributions and margin deposits. Financial Instruments Not Measured at Fair Value on a Recurring Basis Some of our financial instruments are not measured at fair value on a recurring basis but are recorded at amounts that approximate fair value due to their liquid or short-term nature. Such financial assets and financial liabilities include: cash and cash equivalents, restricted cash, receivables, net, certain other current assets, accounts payable and accrued expenses, Section 31 fees payable to SEC, accrued personnel costs, commercial paper and certain other current liabilities. Our investments in OCC and EuroCCP N.V. are accounted for under the equity method of accounting. Our investment in LCH is accounted for using the measurement alternative as this investment does not have a readily determinable fair value. See “Equity Securities,” of Note 3, “Significant Accounting Policies Update,” and “Equity Method Investments,” and “Equity Securities,” of Note 7, “Investments,” for further discussion. We also consider our debt obligations to be financial instruments. The fair value of our debt obligations, utilizing discounted cash flow analyses for our floating rate debt and prevailing market rates for our fixed rate debt, was $4.0 billion as of September 30, 2018 and $4.4 billion as of December 31, 2017 . The discounted cash flow analyses are based on borrowing rates currently available to us for debt with similar terms and maturities. The fair value of our commercial paper approximates the carrying value since the rates of interest on this short-term debt approximate market rates as of September 30, 2018 . Our commercial paper and our fixed rate and floating rate debt are categorized as Level 2 in the fair value hierarchy. For further discussion of our debt obligations, see Note 9, “Debt Obligations.” Non-Financial Assets Measured at Fair Value on a Non-Recurring Basis Our non-financial assets, which include goodwill, intangible assets, and other long-lived assets, are not required to be carried at fair value on a recurring basis. Fair value measures of non-financial assets are primarily used in the impairment analysis of these assets. Any resulting asset impairment would require that the non-financial asset be recorded at its fair value. Nasdaq uses Level 3 inputs to measure the fair value of the above assets on a non-recurring basis. As of September 30, 2018 and December 31, 2017 , there were no non-financial assets measured at fair value on a non-recurring basis.

Clearing Operations

Clearing Operations	9 Months Ended
	Sep. 30, 2018
Due to and from Broker-Dealers and Clearing Organizations [Abstract]
Clearing Operations	Clearing Operations Nasdaq Clearing Nasdaq Clearing is authorized and supervised under EMIR as a multi-asset clearinghouse by the SFSA. Such authorization is effective for all member states of the European Union and certain other non-member states that are part of the European Economic Area, including Norway. The clearinghouse acts as the CCP for exchange and OTC trades in equity derivatives, fixed income derivatives, resale and repurchase contracts, power derivatives, emission allowance derivatives, fuel oil derivatives, and seafood derivatives. Through our clearing operations in the financial markets, which include the resale and repurchase market, the commodities markets, and the seafood market, Nasdaq Clearing is the legal counterparty for, and guarantees the fulfillment of, each contract cleared. These contracts are not used by Nasdaq Clearing for the purpose of trading on its own behalf. As the legal counterparty of each transaction, Nasdaq Clearing bears the counterparty risk between the purchaser and seller in the contract. In its guarantor role, Nasdaq Clearing has precisely equal and offsetting claims to and from clearing members on opposite sides of each contract, standing as the CCP on every contract cleared. In accordance with the rules and regulations of Nasdaq Clearing, default fund and margin collateral requirements are calculated for each clearing member’s positions in accounts with the CCP. See “Default Fund Contributions and Margin Deposits” below for further discussion of Nasdaq Clearing’s default fund and margin requirements. Nasdaq Clearing maintains four member sponsored default funds: one related to financial markets, one related to commodities markets, one related to the seafood market, and a mutualized fund. Under this structure, Nasdaq Clearing and its clearing members must contribute to the total regulatory capital related to the clearing operations of Nasdaq Clearing. This structure applies an initial separation of default fund contributions for the financial, commodities and seafood markets in order to create a buffer for each market’s counterparty risks. Simultaneously, a mutualized default fund provides capital efficiencies to Nasdaq Clearing’s members with regard to total regulatory capital required. See “Default Fund Contributions” below for further discussion of Nasdaq Clearing’s default fund. Power of assessment and a liability waterfall also have been implemented. See “Power of Assessment” and “Liability Waterfall” below for further discussion. These requirements ensure the alignment of risk between Nasdaq Clearing and its clearing members. Nasdaq Commodities Clearing Default In September 2018, a member of the Nasdaq Clearing commodities market defaulted due to inability to post sufficient collateral to cover increased margin requirements for the positions of the relevant member, which had experienced losses due to sharp adverse movements in the Nordic - German power market spread. Nasdaq Clearing followed default procedures and offset the future market risk on the defaulting member’s positions. The default resulted in a loss of $133 million which was allocated to Nasdaq Clearing and the members of the commodities default fund in accordance with the liability waterfall as follows: • the first $8 million of the loss was allocated to Nasdaq Clearing’s junior capital; and • the remainder was allocated on a pro-rata basis to the commodities clearing members’ default funds. Nasdaq Clearing is exploring rights and available options to pursue recovery of the members’ default fund losses. Any funds recovered will be apportioned to the commodities default fund participants and thereafter to Nasdaq Clearing in accordance with the default fund rules. During September 2018, Nasdaq Clearing replenished the utilized junior capital of $8 million for the commodities market and the commodities clearing members replenished their pro rata portions of the default fund. In addition, Nasdaq Clearing contributed approximately $22 million of temporary capital (which will remain in place for 90 days from September 11, 2018). In the event of a default during this time period, the temporary junior capital contribution would be utilized first, followed by the liability waterfall as of September 30, 2018 as described below. In order to reduce the risk profile of commodities clearing operations, Nasdaq Clearing has increased margin levels by increasing the confidence level on commodity products and thereby shifted the risk from waterfall resources more to each portfolio holder's collateral. As a result of the default, a $56 million liability was recorded in other current liabilities and $56 million of collateral was recorded in other current assets in the Condensed Consolidated Balance Sheets as of September 30, 2018 in order to allow Nasdaq Clearing to fulfill the settlement of certain contracts of the defaulted member arising from the default management process. We have established mitigating positions. The collateral and liability were previously included in Default Funds and Margin Deposits. Default Fund Contributions and Margin Deposits As of September 30, 2018 , clearing member default fund contributions and margin deposits were as follows: September 30, 2018 Cash Contributions Non-Cash Contributions Total Contributions (in millions) Default fund contributions $ 407 $ 108 $ 515 Margin deposits 3,812 3,922 7,734 Total $ 4,219 $ 4,030 $ 8,249 In accordance with its investment policy, of the total cash contributions of $4,219 million , Nasdaq Clearing has invested $1,187 million in highly rated European and U.S. government debt securities or central bank certificates with maturity dates primarily 90 days or less and $430 million in reverse repurchase agreements secured with highly rated government securities with maturity dates that range from 1 days to 19 days. The carrying value of these securities approximates their fair value due to the short-term nature of the instruments and reverse repurchase agreements. The remainder of this balance was held in cash in demand deposit accounts at central banks and large, highly rated financial institutions. Of the total default fund contributions of $515 million , Nasdaq Clearing can utilize $463 million as capital resources in the event of a counterparty default. The remaining balance of $52 million pertains to member posted surplus balances. In the investment activity related to default fund and margin contributions, we are exposed to counterparty risk related to reverse repurchase agreement transactions, which reflect the risk that the counterparty might become insolvent and, thus, fail to meet its obligations to Nasdaq Clearing. We mitigate this risk by only engaging in transactions with high credit quality reverse repurchase agreement counterparties and by limiting the acceptable collateral under the reverse repurchase agreement to high quality issuers, primarily government securities and other securities explicitly guaranteed by a government. The value of the underlying security is monitored during the lifetime of the contract and in the event the market value of the underlying security falls below the reverse repurchase amount our clearinghouse may require additional collateral or a reset of the contract. Default Fund Contributions Required contributions to the default funds are proportional to the exposures of each clearing member. When a clearing member is active in more than one market, contributions must be made to all markets’ default funds in which the member is active. Clearing members’ eligible contributions may include cash and non-cash contributions. Cash contributions received are held in cash or invested by Nasdaq Clearing, in accordance with its investment policy, either in highly rated government debt securities, time deposits, central bank certificates or reverse repurchase agreements with highly rated government debt securities as collateral. Nasdaq Clearing maintains and manages all cash deposits related to margin collateral. All risks and rewards of collateral ownership, including interest, belong to Nasdaq Clearing. Clearing members’ cash contributions are included in default funds and margin deposits in the Condensed Consolidated Balance Sheets as both a current asset and a current liability. Non-cash contributions include highly rated government debt securities that must meet specific criteria approved by Nasdaq Clearing. Non-cash contributions are pledged assets that are not recorded in the Condensed Consolidated Balance Sheets as Nasdaq Clearing does not take legal ownership of these assets and the risks and rewards remain with the clearing members. These balances may fluctuate over time due to changes in the amount of deposits required and whether members choose to provide cash or non-cash contributions. Assets pledged are held at a nominee account in Nasdaq Clearing’s name for the benefit of the clearing members and are immediately accessible by Nasdaq Clearing in the event of a default. In addition to clearing members’ required contributions to the liability waterfall, Nasdaq Clearing is also required to contribute capital to the liability waterfall and overall regulatory capital as specified under its clearinghouse rules. As of September 30, 2018 , Nasdaq Clearing committed capital totaling $128 million to the liability waterfall and overall regulatory capital, in the form of government debt securities, which are recorded as financial investments, at fair value in the Condensed Consolidated Balance Sheets. This includes temporary capital of $22 million (related to the Nasdaq commodities clearing default), which will remain in place for 90 days from September 11, 2018. The combined regulatory capital of the clearing members and Nasdaq Clearing will serve to secure the obligations of a clearing member exceeding such member’s own margin and default fund deposits and may be used to cover losses sustained by a clearing member in the event of a default. Margin Deposits Nasdaq Clearing requires all clearing members to provide collateral, which may consist of cash and non-cash contributions, to guarantee performance on the clearing members’ open positions, or initial margin. In addition, clearing members must also provide collateral to cover the daily margin call if needed. See “Default Fund Contributions” above for further discussion of cash and non-cash contributions. Similar to default fund contributions, Nasdaq Clearing maintains and manages all cash deposits related to margin collateral. All risks and rewards of collateral ownership, including interest, belong to Nasdaq Clearing and are recorded in revenues. These cash deposits are recorded in default funds and margin deposits in the Condensed Consolidated Balance Sheets as both a current asset and current liability. Pledged margin collateral is not recorded in our Condensed Consolidated Balance Sheets as all risks and rewards of collateral ownership, including interest, belong to the counterparty. Assets pledged are held at a nominee account in Nasdaq Clearing’s name for the benefit of the clearing members and are immediately accessible by Nasdaq Clearing in the event of a default. Nasdaq Clearing marks to market all outstanding contracts and requires payment from clearing members whose positions have lost value. The mark-to-market process helps identify any clearing members that may not be able to satisfy their financial obligations in a timely manner allowing Nasdaq Clearing the ability to mitigate the risk of a clearing member defaulting due to exceptionally large losses. In the event of a default, Nasdaq Clearing can access the defaulting member’s margin and default fund deposits to cover the defaulting member’s losses. Regulatory Capital and Risk Management Calculations Nasdaq Clearing manages risk through a comprehensive counterparty risk management framework, which is comprised of policies, procedures, standards and financial resources. The level of regulatory capital is determined in accordance with Nasdaq Clearing’s regulatory capital policy, as approved by the SFSA. Regulatory capital calculations are continuously updated through a proprietary capital-at-risk calculation model that establishes the appropriate level of capital. As mentioned above, Nasdaq Clearing is the legal counterparty for each contract cleared and thereby guarantees the fulfillment of each contract. Nasdaq Clearing accounts for this guarantee as a performance guarantee. We determine the fair value of the performance guarantee by considering daily settlement of contracts and other margining and default fund requirements, the risk management program, historical evidence of default payments, and the estimated probability of potential default payouts. The calculation is determined using proprietary risk management software that simulates gains and losses based on historical market prices, extreme but plausible market scenarios, volatility and other factors present at that point in time for those particular unsettled contracts. Based on this analysis, excluding any liability related to the Nasdaq commodities clearing default (see discussion above), the estimated liability was nominal and no liability was recorded as of September 30, 2018 . Power of Assessment To further strengthen the contingent financial resources of the clearinghouse, Nasdaq Clearing has power of assessment that provides the ability to collect additional funds from its clearing members to cover a defaulting member’s remaining obligations up to the limits established under the terms of the clearinghouse rules. The power of assessment corresponds to 100.0% of the clearing member’s aggregate contribution to the financial, commodities and seafood markets’ default funds. Liability Waterfall The liability waterfall is the priority order in which the capital resources would be utilized in the event of a default where the defaulting clearing member’s collateral would not be sufficient to cover the cost to settle its portfolio. If a default occurs and the defaulting clearing member’s collateral, including cash deposits and pledged assets, is depleted, then capital is utilized in the following amount and order: • junior capital contributed by Nasdaq Clearing, which totaled $31 million as of September 30, 2018 ( $22 million which is temporary capital related to the Nasdaq commodities clearing default and will remain in place for 90 days from September 11, 2018); • a loss sharing pool related only to the financial market that is contributed to by clearing members and only applies if the defaulting member’s portfolio includes interest rate swap products; • specific market default fund where the loss occurred (i.e., the financial, commodities, or seafood market), which includes capital contributions of the clearing members on a pro-rata basis; • senior capital contributed to each specific market by Nasdaq Clearing, calculated in accordance with clearinghouse rules, which totaled $22 million as of September 30, 2018 ; • mutualized default fund, which includes capital contributions of the clearing members on a pro-rata basis; • replenished junior capital for the commodities market contributed by Nasdaq Clearing, which totaled $8 million as of September 30, 2018 (see below); and • replenished default fund for the commodities market, which includes capital contributions of the clearing members on a pro-rata basis (see below). If additional funds are needed after utilization of the liability waterfall, then Nasdaq Clearing will utilize its power of assessment and additional capital contributions will be required by non-defaulting members up to the limits established under the terms of the clearinghouse rules. In addition to the capital held to withstand counterparty defaults described above, Nasdaq Clearing also has committed capital of $67 million to ensure that it can handle an orderly wind-down of its operation, and that it is adequately protected against investment, operational, legal, and business risks. Market Value of Derivative Contracts Outstanding The following table includes the market value of derivative contracts outstanding prior to netting: September 30, 2018 (in millions) Commodity and seafood options, futures and forwards (1)(2)(3) $ 1,106 Fixed-income options and futures (1)(2) 520 Stock options and futures (1)(2) 187 Index options and futures (1)(2) 91 Total $ 1,904 ____________ (1) We determined the fair value of our option contracts using standard valuation models that were based on market-based observable inputs including implied volatility, interest rates and the spot price of the underlying instrument. (2) We determined the fair value of our futures contracts based upon quoted market prices and average quoted market yields. (3) We determined the fair value of our forward contracts using standard valuation models that were based on market-based observable inputs including LIBOR rates and the spot price of the underlying instrument. Derivative Contracts Cleared The following table includes the total number of derivative contracts cleared through Nasdaq Clearing for the nine months ended September 30, 2018 and 2017 : September 30, 2018 September 30, 2017 Commodity and seafood options, futures and forwards (1) 1,506,560 2,040,033 Fixed-income options and futures 16,833,278 14,788,850 Stock options and futures 17,735,228 20,070,584 Index options and futures 35,569,046 32,748,357 Total 71,644,112 69,647,824 ____________ (1) The total volume in cleared power related to commodity contracts was 853 Terawatt hours (TWh) for the nine months ended September 30, 2018 and 911 TWh for the nine months ended September 30, 2017 . The outstanding contract value of resale and repurchase agreements was $4.1 billion as of September 30, 2018 and $5.0 billion as of September 30, 2017 . The total number of contracts cleared was 6,835,634 for the nine months ended September 30, 2018 and was 5,891,900 for the nine months ended September 30, 2017 .

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Guarantees	Commitments, Contingencies and Guarantees Guarantees Issued and Credit Facilities Available In addition to the default fund contributions and margin collateral pledged by clearing members discussed in Note 15, “Clearing Operations,” we have obtained financial guarantees and credit facilities which are guaranteed by us through counter indemnities, to provide further liquidity related to our clearing businesses. Financial guarantees issued to us totaled $12 million as of September 30, 2018 and $14 million as of December 31, 2017 . As discussed in “Other Credit Facilities,” of Note 9, “Debt Obligations,” clearing-related credit facilities, which are available in multiple currencies, totaled $219 million as of September 30, 2018 and $187 million as of December 31, 2017 , in available liquidity, none of which was utilized. Execution Access is an introducing broker which operates the trading platform for our Fixed Income business to trade in U.S. Treasury securities. Execution Access has a clearing arrangement with Industrial and Commercial Bank of China Financial Services LLC, or ICBC. As of September 30, 2018 , we have contributed $15 million of clearing deposits to ICBC in connection with this clearing arrangement. These deposits are recorded in other current assets in our Condensed Consolidated Balance Sheets. Some of the trading activity in Execution Access is cleared by ICBC through the Fixed Income Clearing Corporation, with ICBC acting as agent. Execution Access assumes the counterparty risk of clients that do not clear through the Fixed Income Clearing Corporation. Counterparty risk of clients exists for Execution Access between the trade date and the settlement date of the individual transactions, which is at least one business day (or more, if specified by the U.S. Treasury issuance calendar). Counterparties that do not clear through the Fixed Income Clearing Corporation are subject to a credit due diligence process and may be required to post collateral, provide principal letters, or provide other forms of credit enhancement to Execution Access for the purpose of mitigating counterparty risk. Daily position trading limits are also enforced for such counterparties. We believe that the potential for us to be required to make payments under these arrangements is mitigated through the pledged collateral and our risk management policies. Accordingly, no contingent liability is recorded in the Condensed Consolidated Balance Sheets for these arrangements. However, no guarantee can be provided that these arrangements will at all times be sufficient. Lease Commitments We lease some of our office space under non-cancelable operating leases with third parties and sublease office space to third parties. Some of our lease agreements contain renewal options and escalation clauses based on increases in property taxes and building operating costs. Other Guarantees We have provided other guarantees of $4 million as of September 30, 2018 and $3 million as of December 31, 2017 . These guarantees are primarily related to obligations for our rental and leasing contracts as well as performance guarantees on certain market technology contracts related to the delivery of software technology and support services. We have received financial guarantees from various financial institutions to support the above guarantees. Through our clearing operations in the financial markets, Nasdaq Clearing is the legal counterparty for, and guarantees the performance of, its clearing members. See Note 15, “Clearing Operations,” for further discussion of Nasdaq Clearing performance guarantees. We have provided a guarantee related to lease obligations for The Nasdaq Entrepreneurial Center, Inc., which is a not-for-profit organization designed to convene, connect and engage aspiring and current entrepreneurs. This entity is not included in the consolidated financial statements of Nasdaq. We believe that the potential for us to be required to make payments under these arrangements is unlikely. Accordingly, no contingent liability is recorded in the Condensed Consolidated Balance Sheets for the above guarantees. Non-Cash Contingent Consideration As part of the purchase price consideration of a prior acquisition, we have agreed to future annual issuances of 992,247 shares of Nasdaq common stock which approximated certain tax benefits associated with the transaction. Such contingent future issuances of Nasdaq common stock will be paid ratably through 2027 if Nasdaq’s total gross revenues equal or exceed $25 million in each such year. The contingent future issuances of Nasdaq common stock are subject to anti-dilution protections and acceleration upon certain events. Escrow Agreements In connection with prior acquisitions, we entered into escrow agreements to secure the payment of post-closing adjustments and to ensure other closing conditions. As of September 30, 2018 , these escrow agreements provide for future payment of $11 million , of which $9 million is included in other current liabilities and $2 million is included in other non-current liabilities in the Condensed Consolidated Balance Sheets. Routing Brokerage Activities One of our broker-dealer subsidiaries, Nasdaq Execution Services, provides a guarantee to securities clearinghouses and exchanges under its standard membership agreements, which require members to guarantee the performance of other members. If a member becomes unable to satisfy its obligations to a clearinghouse or exchange, other members would be required to meet its shortfalls. To mitigate these performance risks, the exchanges and clearinghouses often require members to post collateral, as well as meet certain minimum financial standards. Nasdaq Execution Services’ maximum potential liability under these arrangements cannot be quantified. However, we believe that the potential for Nasdaq Execution Services to be required to make payments under these arrangements is unlikely. Accordingly, no contingent liability is recorded in the Condensed Consolidated Balance Sheets for these arrangements. Pending Acquisition of Cinnober In September 2018, we announced that we made a SEK 75 per share and SEK 85 per warrant, or approximately $190 million (based on an exchange rate of USD 1.00 = SEK 8.96 as of September 13, 2018), all cash recommended public offer to the shareholders and warrant holders of Cinnober, a major Swedish financial technology provider to brokers, exchanges and clearinghouses worldwide. See “2018 Pending Acquisition,” of Note 4, “Acquisitions and Divestiture,” for further discussion. Other Commitments We have a 40.0% ownership in OCC. Under the OCC's capital plan, the OCC shareholders have committed to contribute up to $200 million in equity capital if certain capital thresholds are breached, including up to $80 million to be contributed by Nasdaq. See “Equity Method Investments,” of Note 7, “Investments,” for further discussion of our equity method investment in OCC. Legal and Regulatory Matters As previously disclosed, we are named as one of many defendants in City of Providence v. BATS Global Markets, Inc., et al., 14 Civ. 2811 (S.D.N.Y.), which was filed on April 18, 2014 in the United States District Court for the Southern District of New York. The district court appointed lead counsel, who filed an amended complaint on September 2, 2014. The amended complaint names as defendants seven national exchanges, as well as Barclays PLC, which operated a private alternative trading system. On behalf of a putative class of securities traders, the plaintiffs allege that the defendants engaged in a scheme to manipulate the markets through high-frequency trading; the amended complaint asserts claims against us under Section 10(b) of the Exchange Act and Rule 10b-5, as well as under Section 6(b) of the Exchange Act. The plaintiffs seek injunctive and monetary relief of an unspecified amount. We filed a motion to dismiss the amended complaint on November 3, 2014. In response, the plaintiffs filed a second amended complaint on November 24, 2014, which names the same defendants and alleges essentially the same violations. We then filed a motion to dismiss the second amended complaint on January 23, 2015. On August 26, 2015, the district court entered an order dismissing the second amended complaint in its entirety with prejudice, concluding that most of the plaintiffs’ theories were foreclosed by absolute immunity and in any event that the plaintiffs failed to state any claim. The plaintiffs appealed the judgment of dismissal to the United States Court of Appeals for the Second Circuit. On December 19, 2017, the Second Circuit issued an opinion vacating the district court’s judgment of dismissal and remanding to the district court for further proceedings. The exchanges filed a petition before the Second Circuit seeking panel or en banc rehearing on January 31, 2018, which the Second Circuit denied on March 13, 2018. On May 18, 2018, the exchanges filed a motion to dismiss the amended complaint, raising issues not addressed in the proceedings to date. Given the preliminary nature of the proceedings, we are unable to estimate what, if any, liability may result from this litigation. However, we believe that the claims are without merit and will continue to litigate vigorously. During September 2018, a clearing member of Nasdaq Clearing's commodities market was declared in default. Consistent with our regulatory obligations, we notified all relevant regulators and are cooperating fully with information requests. We are engaging in discussions with the other members regarding the default and recovery process towards the defaulting member. We are unable to predict the outcome or exact timing of this matter. See “Nasdaq Commodities Clearing Default,” of Note 15, “Clearing Operations,” for further information on this event. In addition, see “SEC Decisions,” of Note 19, “Subsequent Events,” for a discussion of recent SEC decisions. Except as disclosed above and in prior reports filed under the Exchange Act, we are not currently a party to any litigation or proceeding that we believe could have a material adverse effect on our business, consolidated financial condition, or operating results. However, from time to time, we have been threatened with, or named as a defendant in, lawsuits or involved in regulatory proceedings. In the normal course of business, Nasdaq discusses matters with its regulators raised during regulatory examinations or otherwise subject to their inquiries. Management believes that censures, fines, penalties or other sanctions that could result from any ongoing examinations or inquiries will not have a material impact on its consolidated financial position or results of operations. However, we are unable to predict the outcome or the timing of the ultimate resolution of these matters, or the potential fines, penalties or injunctive or other equitable relief, if any, that may result from these matters. Tax Audits We are engaged in ongoing discussions and audits with taxing authorities on various tax matters, the resolutions of which are uncertain. Currently, there are matters that may lead to assessments, some of which may not be resolved for several years. Based on currently available information, we believe we have adequately provided for any assessments that could result from those proceedings where it is more likely than not that we will be assessed. We review our positions on these matters as they progress.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We use the asset and liability method to determine income taxes on all transactions recorded in the consolidated financial statements. Deferred tax assets (net of valuation allowances) and deferred tax liabilities are presented net by jurisdiction as either a non-current asset or liability in our Condensed Consolidated Balance Sheets, as appropriate. Deferred tax assets and liabilities are determined based on differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities (i.e., temporary differences) and are measured at the enacted rates that will be in effect when these differences are realized. If necessary, a valuation allowance is established to reduce deferred tax assets to the amount that is more likely than not to be realized. As of September 30, 2018 and December 31, 2017, net deferred tax assets are included in other non-current assets in the Condensed Consolidated Balance Sheets. In order to recognize and measure our unrecognized tax benefits, management determines whether a tax position is more likely than not to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Once it is determined that a position meets the recognition thresholds, the position is measured to determine the amount of benefit to be recognized in the consolidated financial statements. Interest and/or penalties related to income tax matters are recognized in income tax expense. The following table shows our income tax provision and effective tax rate: Three Months Ended September 30, Percentage Change Nine Months Ended September 30, Percentage Change 2018 2017 2018 2017 ($ in millions) ($ in millions) Income tax provision $ 46 $ 64 (28.1 )% $ 234 $ 178 31.5 % Effective tax rate 22.0 % 27.4 % 31.8 % 26.9 % The lower effective tax rate in the third quarter of 2018 when compared with the same period in 2017 is primarily due to the reduction of the U.S. corporate tax rate from 35% to 21%, effective January 1, 2018, and a decrease in tax expense related to a provisional adjustment due to the remeasurement of our deferred tax assets and liabilities under SEC Staff Accounting Bulletin No. 118, “Income Tax Accounting Implications of the Tax Cuts and Jobs Act,” or SAB 118. These decreases are partially offset by a lower recognition of excess tax benefits associated with the vesting of employee share-based compensation arrangements and previously unrecognized tax benefits associated with positions taken in prior years in the first nine months of 2018 compared to the same period in 2017. The higher effective tax rate in the first nine months of 2018 when compared to the same period in 2017 is primarily due to the reversal of certain Swedish tax benefits recorded in prior periods and the tax expense associated with the sale of the Public Relations Solutions and Digital Media Services businesses. Also, we recorded a lower recognition of excess tax benefits associated with the vesting of employee share-based compensation arrangements and previously unrecognized tax benefits associated with positions taken in prior years in the first nine months of 2018 compared to the same period in 2017. These increases are partially offset by a decrease in tax expense due to the reduction of the U.S. corporate tax rate from 35% to 21%, effective January 1, 2018, and a decrease in tax expense related to a provisional adjustment due to the remeasurement of our deferred tax assets and liabilities under SAB 118. The effective tax rate may also vary from period to period depending on, among other factors, the geographic and business mix of earnings and losses. These same and other factors, including history of pre-tax earnings and losses, are taken into account in assessing the ability to realize deferred tax assets. Nasdaq and its eligible subsidiaries file a consolidated U.S. federal income tax return and applicable state and local income tax returns and non-U.S. income tax returns. Federal income tax returns for the years 2008 through 2015 are currently under examination by the Internal Revenue Services and we are subject to examination by the Internal Revenue Service for 2016 and 2017. Several state tax returns are currently under examination by the respective tax authorities for the years 2007 through 2016. Non-U.S. tax returns are subject to examination by the respective tax authorities for the years 2009 through 2017. Although the results of such examinations may have an impact on our unrecognized tax benefits, we do not anticipate that such impact will be material to our consolidated financial position or results of operations. In addition, we anticipate that the amount of unrecognized tax benefits as of September 30, 2018 will decrease in the next twelve months as we expect to settle certain tax audits. The Swedish Tax Agency has disallowed certain interest expense deductions for the years 2013 - 2016. We appealed to the Lower Administrative Court for the years 2013 - 2015. In the first quarter of 2018, the Lower Administrative Court denied our appeal. We have appealed to the Administrative Court of Appeal. Through March 31, 2018, we had recorded tax benefits of $57 million associated with this matter. We continue to pay all assessments from the Swedish Tax Agency while this matter is pending and have paid $40 million through September 30, 2018. In the second quarter of 2018, the Administrative Court of Appeal decided similar cases against other taxpayers. Although we continue to assert the validity of these interest expense deductions, the decisions of the court lead us to conclude that we can no longer assert that we are more than likely to be successful in our appeal. As such, in the second quarter of 2018, we recorded tax expense of $41 million , or $0.24 per diluted share, which is net of any related U.S. tax benefits and reflects the impact of foreign currency translation. We expect to record future quarterly net tax expense of $1 million related to this matter. The Tax Cuts and Jobs Act was enacted on December 22, 2017 and was effective January 1, 2018. The new legislation contains several key provisions, including a reduction of the U.S. corporate income tax rate from 35% to 21%. We were required to remeasure all of our U.S. deferred tax assets and liabilities as of December 22, 2017 and record the impact of such remeasurement in our 2017 financial statements. For the year ended December 31, 2017, we recorded a decrease to tax expense of $89 million , substantially all of which reflects the estimated impact associated with the remeasurement of our net U.S. deferred tax liability at the lower U.S. federal corporate income tax rate. The Tax Cuts and Jobs Act also imposes a transition tax on unremitted aggregate accumulated earnings of non-U.S. subsidiaries, which did not impact us. SAB 118 has provided guidance which allows us to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. As of December 31, 2017, we recorded a provisional estimate of the effects of the new legislation. In the first quarter of 2018, we recorded an increase to tax expense of $5 million , which reflects the reduced federal tax benefit associated with state unrecognized tax benefits. In the third quarter of 2018, we recorded a decrease to tax expense of $4 million related to the remeasurement of our deferred tax assets and liabilities as of the enactment date. We will continue to analyze the Tax Cuts and Jobs Act and related accounting guidance and interpretations in order to finalize any impacts within the measurement period. On January 1, 2018, we adopted Topic 220. See “Recent Accounting Pronouncements,” of Note 2, “Basis of Presentation and Principles of Consolidation,” for further discussion of this standard. As a result of the adoption of this standard, in the first quarter of 2018, we recorded a reclassification of $142 million for stranded tax effects related to the Tax Cuts and Jobs Act from accumulated other comprehensive loss to retained earnings within stockholders’ equity in the Condensed Consolidated Balance Sheets. Of the $142 million of stranded tax effects, $135 million relates to the effect on net foreign currency translation gains and losses and $7 million relates to the effect on employee benefit plan adjustment gains and losses.

Business Segments

Business Segments	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Business Segments	Business Segments We manage, operate and provide our products and services in four business segments: Market Services, Corporate Services, Information Services and Market Technology. See Note 1, “Organization and Nature of Operations,” for further discussion of our reportable segments. Our management allocates resources, assesses performance and manages these businesses as four separate segments. We evaluate the performance of our segments based on several factors, of which the primary financial measure is operating income. Results of individual businesses are presented based on our management accounting practices and structure. The following table presents certain information regarding our operating segments for the three and nine months ended September 30, 2018 and 2017 : Market Services Corporate Services Information Services Market Technology Corporate Items Consolidated (in millions) Three Months Ended September 30, 2018 Total revenues $ 586 $ 131 $ 179 $ 68 $ — $ 964 Transaction-based expenses (364 ) — — — — (364 ) Revenues less transaction-based expenses 222 131 179 68 — 600 Operating income (loss) $ 121 $ 42 $ 117 $ 9 $ (43 ) $ 246 Three Months Ended September 30, 2017 Total revenues $ 581 $ 126 $ 150 $ 62 $ 46 $ 965 Transaction-based expenses (362 ) — — — — (362 ) Revenues less transaction-based expenses 219 126 150 62 46 603 Operating income (loss) $ 118 $ 41 $ 111 $ 14 $ (22 ) $ 262 Nine Months Ended September 30, 2018 Total revenues $ 1,968 $ 395 $ 528 $ 194 $ 56 $ 3,141 Transaction-based expenses (1,259 ) — — — — (1,259 ) Revenues less transaction-based expenses 709 395 528 194 56 1,882 Operating income (loss) $ 402 $ 122 $ 342 $ 20 $ (99 ) $ 787 Nine Months Ended September 30, 2017 Total revenues $ 1,808 $ 370 $ 432 $ 176 $ 143 $ 2,929 Transaction-based expenses (1,149 ) — — — — (1,149 ) Revenues less transaction-based expenses 659 370 432 176 143 1,780 Operating income (loss) $ 359 $ 115 $ 318 $ 39 $ (81 ) $ 750 Certain amounts are allocated to corporate items in our management reports as we believe they do not contribute to a meaningful evaluation of a particular segment's ongoing operating performance. These items include the following: 2018 Divestiture: We have included in corporate items the revenues and expenses of the Public Relations Solutions and Digital Media Services businesses which were part of the Corporate Solutions business within our Corporate Services segment as these businesses were sold in April 2018. See “2018 Divestiture,” of Note 4, “Acquisitions and Divestiture,” for further discussion. Amortization expense of acquired intangible assets: We amortize intangible assets acquired in connection with various acquisitions. Intangible asset amortization expense can vary from period to period due to episodic acquisitions completed, rather than from our ongoing business operations. As such, if intangible asset amortization is included in performance measures, it is more difficult to assess the day-to-day operating performance of the segments, and the relative operating performance of the segments between periods. Management does not consider intangible asset amortization expense for the purpose of evaluating the performance of our segments or their managers or when making decisions to allocate resources. Therefore, we believe performance measures excluding intangible asset amortization expense provide management with a more useful representation of our segments' ongoing activity in each period. Merger and strategic initiatives expense: We have pursued various strategic initiatives and completed a divestiture and a number of acquisitions in recent years which have resulted in expenses which would not have otherwise been incurred. These expenses generally include integration costs, as well as legal, due diligence and other third party transaction costs. The frequency and the amount of such expenses vary significantly based on the size, timing and complexity of the transaction. Clearing Default Loss: In September 2018, we recorded an $8 million loss related to a default of a Nasdaq Clearing commodities member. See “Nasdaq Commodities Clearing Default,” of Note 15, “Clearing Operations,” for further discussion of the default. We have included the loss related to the default in corporate items as we believe it is non-recurring, as there has never been a loss due to member default in our clearinghouse, and should be excluded when evaluating the ongoing operating performance of the Market Services segment. Any expenses associated with the evaluation and enhancement of processes and procedures will be reflected within the Market Services segment. Other significant items: We have included certain other charges or gains in corporate items, to the extent we believe they should be excluded when evaluating the ongoing operating performance of each individual segment. For the three and nine months ended September 30, 2018 , other significant items included litigation costs and for the nine months ended September 30, 2018 , out of period tax charges. For the nine months ended September 30, 2017, other significant items included loss on extinguishment of debt. We believe the exclusion of such amounts allows management and investors to better understand the ongoing financial results of each segment. Accordingly, we do not allocate these costs for purposes of disclosing segment results because they do not contribute to a meaningful evaluation of a particular segment’s ongoing operating performance. * * * * * * A summary of our corporate items is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Revenues - divested businesses $ — $ 46 $ 56 $ 143 Expenses: Amortization expense of acquired intangible assets 27 22 83 67 Merger and strategic initiatives expense 6 3 7 20 Clearing default loss 8 — 8 — Extinguishment of debt — — — 10 Expenses - divested businesses — 42 51 125 Other 2 1 6 2 Total expenses 43 68 155 224 Operating loss $ (43 ) $ (22 ) $ (99 ) $ (81 ) * * * * * *

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events SEC Decisions In recent years, certain industry groups have challenged the level of fees that U.S. exchanges charge for market data and connectivity. We have defeated two challenges in federal appeals court pertaining to market data and an additional challenge at the administrative level within the SEC. However, in October 2018, the SEC reversed that administrative decision and found that Nasdaq had not met a burden of demonstrating that certain challenged fees were fair and reasonable; we estimate that this decision will reduce our revenues by approximately $1 million . Nasdaq has appealed this decision to the U.S. Court of Appeals for the District of Columbia Circuit. In addition, the SEC remanded a series of additional challenges to market data and connectivity fees back to Nasdaq for further consideration. Nasdaq has petitioned the SEC to reconsider this decision. We are unable to predict the outcome or the timing of the ultimate resolution of these matters. Sale of Equity Security In October 2018, we entered into an agreement to sell our 5% ownership interest in LCH for aggregate pre-tax cash proceeds of approximately €148 million , or approximately $171 million (based on an exchange rate of 1 USD = 0.87 Euro as of October 18, 2018). Subject to regulatory non-objection, the transaction is expected to close in the fourth quarter of 2018.

Basis of Presentation and Pri_2

Basis of Presentation and Principles of Consolidation (Policies)	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The condensed consolidated financial statements are prepared in accordance with U.S. GAAP and include the accounts of Nasdaq, its wholly-owned subsidiaries and other entities in which Nasdaq has a controlling financial interest. When we do not have a controlling interest in an entity but exercise significant influence over the entity’s operating and financial policies, such investment is accounted for under the equity method of accounting. We recognize our share of earnings or losses of an equity method investee based on our ownership percentage. See “Equity Method Investments,” of Note 7, “Investments,” for further discussion of our equity method investments.
Consolidation	The accompanying condensed consolidated financial statements reflect all adjustments which are, in the opinion of management, necessary for a fair statement of the results for the interim periods presented. These adjustments are of a normal recurring nature. All significant intercompany accounts and transactions have been eliminated in consolidation. As permitted under U.S. GAAP, certain footnotes or other financial information can be condensed or omitted in the interim condensed consolidated financial statements. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the consolidated financial statements and accompanying notes included in Nasdaq’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017 that was filed with the SEC on February 28, 2018. Certain prior year amounts have been reclassified to conform to the current year presentation primarily due to the adoption of ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” on January 1, 2018. See Note 3, “Significant Accounting Policies Update,” for further discussion.
Use of Estimates	The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts and the disclosure of contingent amounts in the condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates.
Recently Accounting Pronouncements	Recent Accounting Pronouncements Accounting Standard Description Effective Date Effect on the Financial Statements or Other Significant Matters Intangibles - Goodwill and Other - Internal-Use Software In August 2018, the FASB issued ASU 2018-15, “Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract.” This ASU clarifies the accounting for implementation costs of a hosting arrangement and aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). Capitalized implementation costs should be expensed over the term of the hosting arrangement and recognized in the same line item in the statement of income as the hosted service costs. Payments for capitalized implementation costs should be classified in the statement of cash flows in the same manner as payments made for fees associated with the hosting element. Capitalized implementation costs should be presented in the balance sheet in the same line item as a prepayment for the fees of the associated hosting arrangement. January 1, 2020, with early adoption permitted. We early adopted this standard as of July 1, 2018. There was no impact to the financial statements as a result of the adoption of this standard, as we are currently accounting for costs incurred in a cloud computing arrangement in accordance with the guidance provided in this standard. Fair Value Measurements In August 2018, the FASB issued ASU 2018-13 “Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement.” This ASU modifies the disclosure requirements on fair value measurements by removing certain disclosure requirements related to the fair value hierarchy, modifying existing disclosure requirements related to measurement uncertainty, and adding new requirements, mainly for Level 3 fair value measurements. January 1, 2020, with early adoption permitted. We early adopted this standard as of July 1, 2018 on a prospective basis. There was no impact to the financial statements or our disclosures as a result of the adoption of this standard. Accounting Standard Description Effective Date Effect on the Financial Statements or Other Significant Matters Income Statement - Reporting Comprehensive Income In February 2018, the FASB issued ASU 2018-02, “Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (Topic 220).” This ASU provides an election to reclassify tax effects that are stranded in accumulated other comprehensive income as a result of tax reform to retained earnings. An election is also available to reclassify other stranded tax effects that relate to the Tax Cuts and Jobs Act but do not directly relate to the change in the federal rate. Tax effects that are stranded in accumulated other comprehensive income for other reasons (e.g., prior changes in tax law, a change in valuation allowance) may not be reclassified. Previously, the effects of changes in tax rates and laws on deferred tax balances were required to be recorded as a component of tax expense related to continuing operations for the period in which the law was enacted, even if the assets and liabilities related to items of accumulated other comprehensive income. In other words, backward tracing of the income tax effects of items originally recognized through accumulated other comprehensive income was prohibited. January 1, 2019, with early adoption permitted. We early adopted this standard as of January 1, 2018. As a result of the adoption of this standard, in the first quarter of 2018, we recorded a reclassification of $142 million for stranded tax effects related to the Tax Cuts and Jobs Act from accumulated other comprehensive loss to retained earnings within stockholders’ equity in the Condensed Consolidated Balance Sheets. See Note 17, “Income Taxes,” for further discussion. Goodwill In January 2017, the FASB issued ASU 2017-04, “Simplifying the Test for Goodwill Impairment.” This ASU simplifies how an entity is required to test goodwill for impairment and removes the second step of the goodwill impairment test, which required a hypothetical purchase price allocation if the fair value of a reporting unit is less than its carrying amount. Goodwill impairment will now be measured using the difference between the carrying amount and the fair value of the reporting unit and the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The amendments in this ASU should be applied on a prospective basis. January 1, 2020, with early adoption permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We do not anticipate a material impact on our consolidated financial statements at the time of adoption of this new standard as the carrying amounts of our reporting units have been less than their corresponding fair values in recent years. Therefore, the second step of the goodwill impairment test was not required. However, changes in future projections, market conditions and other factors may cause a change in the excess of fair value of our reporting units over their corresponding carrying amounts. We do not anticipate early adoption of this standard. Financial Instruments - Credit Losses In June 2016, the FASB issued ASU 2016-13, “Measurement of Credit Losses on Financial Instruments.” This ASU changes the impairment model for certain financial instruments. The new model is a forward looking expected loss model and will apply to financial assets subject to credit losses and measured at amortized cost and certain off-balance sheet credit exposures. This includes loans, held-to-maturity debt securities, loan commitments, financial guarantees and net investments in leases, as well as trade receivables. For available-for-sale debt securities with unrealized losses, credit losses will be measured in a manner similar to today, except that the losses will be recognized as allowances rather than reductions in the amortized cost of the securities. January 1, 2020, with early adoption permitted as of January 1, 2019. We expect to adopt this standard on January 1, 2020. We are currently assessing the impact that this standard will have on our consolidated financial statements. We do not anticipate early adoption of this standard. Accounting Standard Description Effective Date Effect on the Financial Statements or Other Significant Matters Leases In February 2016, the FASB issued ASU 2016-02, “Leases.” Under this ASU, at the commencement date, lessees will be required to recognize a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. This guidance is not applicable for leases with a term of 12 months or less. Recognition, measurement and presentation of expenses will depend on classification as a finance or operating lease. The guidance also requires certain quantitative and qualitative disclosures about leasing arrangements. Lessor accounting is largely unchanged. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. January 1, 2019. See discussion below. Leases We will adopt ASU 2016-02 on January 1, 2019. When adopted, this new standard will result in an increase in the assets and liabilities reflected on our consolidated balance sheets. In addition, we will be required to disclose key information about our leases. Nasdaq’s current operating lease portfolio is primarily comprised of real estate and data center leases. As of September 30, 2018, we had future contractual lease payment obligations of $636 million . We expect that we will elect the alternative transition approach allowed under the guidance and expect to implement new accounting policies as well as to elect certain practical expedients available under the guidance, including those related to leases with a term of 12 months or less and our application of discount rates. We do not expect the adoption of this new standard to have a material impact on our consolidated balance sheets or statements of income and it will not impact our cash flows.
Revenue From Contracts With Customers	On January 1, 2018, we adopted Topic 606 using the full retrospective method. The adoption of Topic 606 impacted the revenue and expense recognition for our Market Technology business and revenue recognition for our Listing Services business. However, the adoption of Topic 606 did not have a material impact on our consolidated financial statements at the time of adoption or in any prior reporting periods. There was no impact to revenue and expense recognition for our other businesses. Additional disclosures required by Topic 606 are provided below. Contract Balances Substantially all of our revenues are considered to be revenues from contracts with customers. The related accounts receivable balances are recorded in our Condensed Consolidated Balance Sheets as receivables which is net of allowance for doubtful accounts of $13 million as of September 30, 2018 and $9 million as of December 31, 2017 . The changes in the balance between periods were immaterial. We do not have obligations for warranties, returns or refunds to customers. For the majority of our contracts with customers, except for our market technology and listings services contracts, our performance obligations are short-term in nature and there is no significant variable consideration. We do not have revenues recognized from performance obligations that were satisfied in prior periods. We have elected not to provide disclosures about transaction price allocated to unsatisfied performance obligations if contract durations are less than one year. For contract durations that are one-year or greater, we do not have a material portion of transaction price allocated to unsatisfied performance obligations that are not included in deferred revenue other than for our market technology contracts which are discussed below under “Market Technology.” Deferred revenue primarily represents our contract liabilities related to our fees for annual and initial listings, market technology, corporate solutions and information services contracts. Deferred revenue is the only significant contract asset or liability impacted by our adoption of Topic 606. See Note 8, “Deferred Revenue,” for our discussion on deferred revenue balances, activity, and expected timing of recognition. See “Revenue Recognition” below for further descriptions of our revenue contracts. Sales commissions earned by our sales force are considered incremental and recoverable costs of obtaining a contract with a customer. These costs are deferred and amortized on a straight-line basis over the period of benefit that we have determined to be the contract term or estimated service periods. Sales commissions for renewal contracts are deferred and amortized on a straight-line basis over the related contractual renewal period. Amortization expense is included in compensation and benefits expense in the Condensed Consolidated Statements of Income. The balance of deferred costs and related amortization expense are not material to our consolidated financial statements. We elected the practical expedient of recognizing sales commissions as an expense when incurred if contract durations are one year or less. We also have elected the practical expedient of excluding sales taxes from transaction prices. Certain judgments and estimates were used in the identification and timing of satisfaction of performance obligations and the related allocation of transaction price and are discussed below. We believe that these represent a faithful depiction of the transfer of services to our customers. Revenue Recognition Our primary revenue contract classifications are described below. Though we discuss additional revenue details in our “Management's Discussion and Analysis of Financial Condition and Results of Operations,” the categories below best represent those that depict similar economic characteristics of the nature, amount, timing and uncertainty of our revenues and cash flows. Market Services Transaction-Based Trading and Clearing Transaction-based trading and clearing includes equity derivative trading and clearing revenues, cash equity trading revenues and FICC revenues. Nasdaq charges transaction fees for trades executed on our exchanges, as well as on orders that are routed to and executed on other market venues. Nasdaq charges clearing fees for contracts cleared with Nasdaq Clearing. In the U.S., transaction fees are based on trading volumes for trades executed on our U.S. exchanges and in Europe, transaction fees are based on the volume and value of traded and cleared contracts. In Canada, transaction fees are based on trading volumes for trades executed on our Canadian exchange. Nasdaq satisfies its performance obligation for trading services upon the execution of a customer trade and clearing services when a contract is cleared, as trading and clearing transactions are substantially complete when they are executed and we have no further obligation to the customer at that time. Transaction-based trading and clearing fees can be variable and are based on trade volume tiered discounts. Transaction revenues, as well as any tiered volume discounts, are calculated and billed monthly in accordance with our published fee schedules. In the U.S., we also pay liquidity payments to customers based on our published fee schedules. We use these payments to improve the liquidity on our markets and therefore recognize those payments as a cost of revenue. The majority of our FICC trading and clearing customers are charged transaction fees, as discussed above, which are based on the volume and value of traded and cleared contracts. We also enter into annual fixed contracts with customers trading U.S. Treasury securities. The customers are charged an annual fixed fee which is billed per the agreement, on a monthly or quarterly basis. Revenues earned on fixed contracts are recognized over time on a ratable basis over the contract period beginning on the date that our service is made available to the customer since the customer receives and consumes the benefit as Nasdaq provides the service. For U.S. equity derivative trading, we credit a portion of the per share execution charge to the market participant that provides the liquidity. For U.S. cash equity trading, for Nasdaq and Nasdaq PSX, we credit a portion of the per share execution charge to the market participant that provides the liquidity and for Nasdaq BX, we credit a portion of the per share execution charge to the market participant that takes the liquidity. We record these credits as transaction rebates that are included in transaction-based expense in the Condensed Consolidated Statements of Income. These transaction rebates are paid on a monthly basis and the amounts due are included in accounts payable and accrued expenses in the Condensed Consolidated Balance Sheets. In the U.S., we pay Section 31 fees to the SEC for supervision and regulation of securities markets. We pass these costs along to our customers through our equity derivative trading and clearing fees and our cash equity trading fees. We collect the fees as a pass-through charge from organizations executing eligible trades on our options exchanges and our cash equity platforms and we recognize these amounts in transaction-based expenses when incurred. Section 31 fees received are included in cash and cash equivalents in the Condensed Consolidated Balance Sheets at the time of receipt and, as required by law, the amount due to the SEC is remitted semiannually and recorded as Section 31 fees payable to the SEC in the Condensed Consolidated Balance Sheets until paid. Since the amount recorded as revenues is equal to the amount recorded as transaction-based expenses, there is no impact on our revenues less transaction-based expenses. As we hold the cash received until payment to the SEC, we earn interest income on the related cash balances. Under our Limitation of Liability Rule and procedures, we may, subject to certain caps, provide compensation for losses directly resulting from the systems’ actual failure to correctly process an order, quote, message or other data into our platform. We do not record a liability for any potential claims that may be submitted under the Limitation of Liability Rule unless they meet the provisions required in accordance with U.S. GAAP. As such, losses arising as a result of the rule are accrued and charged to expense only if the loss is probable and estimable. Trade Management Services We provide market participants with a wide variety of alternatives for connecting to and accessing our markets for a fee. We also offer market participants co-location services, whereby firms may lease cabinet space and power to house their own equipment and servers within our data centers. These participants are charged monthly fees for cabinet space, connectivity and support in accordance with our published fee schedules. These fees are recognized on a monthly basis when the performance obligation is met. We also earn revenues from annual and monthly exchange membership and registration fees. Revenues for providing access to our markets, co-location services and monthly exchange membership and registration fees are recognized on a monthly basis as the service is provided. Revenues from annual fees for exchange membership and registration fees are recognized ratably over the following 12 -month period since the customer receives and consumes the benefit as Nasdaq provides the service. We also offer broker services to financial participants in the Nordic market primarily providing flexible back-office systems, which allow customers to entirely or partly outsource their company’s back-office functions. Revenues from broker services are based on a fixed basic fee for administration or licensing, maintenance and operations, and an incremental fee depending on the number of transactions completed. Broker services revenues are generally billed and recognized monthly. Corporate Solutions As of September 30, 2018 , corporate solutions revenues primarily include subscription and transaction-based income from our investor relations, board & leadership, and governance, risk and compliance products and services. In April 2018, we completed the sale of our Public Relations Solutions and Digital Media Services businesses. See “2018 Divestiture,” of Note 4, “Acquisitions and Divestiture,” for further discussion. Subscription-based revenues earned are recognized over time on a ratable basis over the contract period beginning on the date that our service is made available to the customer since the customer receives and consumes the benefit as Nasdaq provides the service. Generally, fees are billed quarterly in advance and the contract provides for automatic renewal. As part of the subscription agreements, customers can also be charged usage fees based upon actual usage of the services provided. Revenues from usage fees are recognized at a point in time upon completion of the service. Listing Services Listing services revenues primarily include initial listing fees and annual renewal fees. Under Topic 606, the initial listing fee is allocated to multiple performance obligations including initial and subsequent listing services and corporate solutions services (when a company qualifies to receive these services under the applicable Nasdaq rule), as well as a customer's material right to renew the option to list on our exchanges. In performing this allocation, the standalone selling price of the performance obligations is based on the initial and annual listing fees and the standalone selling price of the corporate solutions services is based on its market value. All listing fees are billed upfront and the identified performance obligations are satisfied over time since the customer receives and consumes the benefit as Nasdaq provides the listing service. Upon adoption of Topic 606, the amount of revenue related to the corporate solutions services performance obligation is recognized ratably over a two -year period, which is based on contract terms, with the remaining revenue recognized ratably over time as customers continue to list on our exchanges, which is estimated to be over a period of six years based on our historical listing experience and projected future listing duration. In the U.S., annual renewal fees are charged based on the number of outstanding shares of companies listed in the U.S. at the end of the prior year and are recognized ratably over the following 12 -month period since the customer receives and consumes the benefit as Nasdaq provides the service. European annual renewal fees, which are received from companies listed on our Nasdaq Nordic and Nasdaq Baltic exchanges and Nasdaq First North, are directly related to the listed companies’ market capitalization on a trailing 12 -month basis and are recognized ratably over the following 12 -month period since the customer receives and consumes the benefit as Nasdaq provides the service. Market Data Products Market data products revenues are earned from U.S. and European proprietary market data products. In the U.S., we also earn revenues from U.S. shared tape plans. We earn revenues primarily based on the number of data subscribers and distributors of our data. Market data products revenues are subscription-based and are recognized on a monthly basis net of amounts due under revenue sharing arrangements with market participants. For U.S. tape plans, revenues are collected monthly based on published fee schedules and distributed quarterly to the U.S. exchanges based on a formula required by Regulation NMS that takes into account both trading and quoting activity. Revenues are presented on a net basis as we are acting as an agent in this arrangement. Market Data Products Revenue Sharing The most significant component of market data products revenues recorded on a net basis is the UTP Plan revenue sharing in the U.S. All indicators of principal versus agent reporting under U.S. GAAP have been considered in analyzing the appropriate presentation of UTP Plan revenue sharing. However, the following are the primary indicators of net reporting: • We are the administrator for the UTP Plan, in addition to being a participant in the UTP Plan. In our unique role as administrator, we facilitate the collection and dissemination of revenues on behalf of the UTP Plan participants. As a participant, we share in the net distribution of revenues according to the plan on the same terms as all other plan participants. • The operating committee of the UTP Plan, which is comprised of representatives from each of the participants, including us solely in our capacity as a UTP Plan participant, is responsible for setting the level of fees to be paid by distributors and subscribers and taking action in accordance with the provisions of the UTP Plan, subject to SEC approval. • Risk of loss on the revenue is shared equally among plan participants according to the UTP Plan. The exchanges that comprise Nasdaq Nordic and Nasdaq Baltic do not have any market data products revenue sharing agreements. Index We develop and license Nasdaq branded indexes, associated derivatives and financial products as part of our Global Index Family. We also provide index data products and custom calculation services for third-party clients. Revenues primarily include license fees from these branded indexes, associated derivatives and financial products in the U.S. and abroad. We primarily have two types of license agreements: transaction-based licenses and asset-based licenses. Transaction-based licenses are generally renewable agreements. Customers are charged based on transaction volume or a minimum contract amount, or both. If a customer is charged based on transaction volume, we recognize revenue when the transaction occurs. If a customer is charged based on a minimum contract amount, we recognize revenue on a pro-rata basis over the licensing term since the customer receives and consumes the benefit as Nasdaq provides the service. Asset-based licenses are also generally renewable agreements. Customers are charged based on a percentage of assets under management for licensed products, per the agreement, on a monthly or quarterly basis. These revenues are recognized over the term of the license agreement since the customer receives and consumes the benefit as Nasdaq provides the service. Revenue from index data subscriptions are recognized on a monthly basis. Investment Data & Analytics Investment data & analytics revenues are earned from investment content and analytics products. We earn revenues primarily based on the number of content and analytics subscribers and distributors. Subscription agreements are generally annual in term, payable in advance, and provide for automatic renewal. Subscription-based revenues are recognized over time on a ratable basis over the contract period beginning on the date that our service is made available to the customer since the customer receives and consumes the benefit as Nasdaq provides the service. Market Technology Market Technology provides technology solutions for trading, clearing, settlement, surveillance and information dissemination, as well as risk management solutions. Revenues primarily consist of software, license and support revenues, change request and advisory revenues, and software as a service revenues. In our Market Technology business, we enter into long-term contracts with customers to develop customized technology solutions, license the right to use software, and provide post-contract support and other services to our customers. We also enter into agreements to modify the system solutions sold by Nasdaq after delivery has occurred. In addition, we enter into subscription agreements which allow customers to connect to our servers to access our software. Our long-term contracts with customers to develop customized technology solutions, license the right to use software and provide post-contract support and other services to our customers have multiple performance obligations. The performance obligations are generally: 1) software license and installation service and 2) software support. We have determined that the software license and installation service are not distinct as the license and the customized installation service are inputs to produce the combined output, a functional and integrated software system. For contracts with multiple performance obligations, we allocate the contract transaction price to each performance obligation using our best estimate of the standalone selling price of each distinct good or service in the contract. In instances where standalone selling price is not directly observable, such as when we do not sell the product or service separately, we determine the standalone selling price predominately through an expected cost plus a margin approach. Contract modifications are routine in the performance of our contracts. Contracts are often modified to account for changes in contract specifications or requirements. In most instances, contract modifications are for goods and services that are not distinct, and, therefore, are accounted for as part of the existing contract. For our long-term contracts, payments are generally made throughout the contract life and can be dependent on either reaching certain milestones or paid upfront in advance of the service period depending on the stage of the contract. For subscription agreements, contract payment terms can be quarterly, annually or monthly, in advance. For all other contracts, payment terms vary. We generally recognize revenue over time as our customers simultaneously receive and consume the benefits provided by our performance because our customer controls the asset for which we are creating, our performance does not create an asset with alternative use, and we have a right to payment for performance completed to date. For these services, we recognize revenue over time using costs incurred to date relative to total estimated costs at completion to measure progress toward satisfying our performance obligation. Incurred costs represent work performed, which corresponds with, and thereby depicts, the transfer of control to the customer. Contract costs generally include labor and overhead. For software support and update services, and for subscription agreements which allow customers to connect to our servers to access our software, we generally recognize revenue ratably over the service period beginning on the date our service is made available to the customer since the customer receives and consumes the benefit consistently over the period as Nasdaq provides the services. Accounting for our long-term contracts requires judgment relative to assessing risks and their impact on the estimate of revenues and costs. Our estimates are impacted by factors such as the potential for schedule and technical issues, productivity, and the complexity of work performed. When adjustments in estimated total contract costs are required, any changes in the estimated revenues from prior estimates are recognized in the current period for the effect of such change. If estimates of total costs to be incurred on a contract exceed estimates of total revenues, a provision for the entire estimated loss on the contract is recorded in the period in which the loss is determined. Other Revenues Other revenues include the revenues from the Public Relations Solutions and Digital Media Services businesses which were sold in April 2018. Prior to the sale date, these revenues were included in our Corporate Solutions business and were primarily transaction-based revenues. Revenue From Contracts With Customers On January 1, 2018, we adopted Topic 606 using the full retrospective method. The adoption of Topic 606 impacted the revenue and expense recognition for our Market Technology business and revenue recognition for our Listing Services business. However, the adoption of Topic 606 did not have a material impact on our consolidated financial statements at the time of adoption or in any prior reporting periods. There was no impact to revenue and expense recognition for our other businesses. Additional disclosures required by Topic 606 are provided below. Contract Balances Substantially all of our revenues are considered to be revenues from contracts with customers. The related accounts receivable balances are recorded in our Condensed Consolidated Balance Sheets as receivables which is net of allowance for doubtful accounts of $13 million as of September 30, 2018 and $9 million as of December 31, 2017 . The changes in the balance between periods were immaterial. We do not have obligations for warranties, returns or refunds to customers. For the majority of our contracts with customers, except for our market technology and listings services contracts, our performance obligations are short-term in nature and there is no significant variable consideration. We do not have revenues recognized from performance obligations that were satisfied in prior periods. We have elected not to provide disclosures about transaction price allocated to unsatisfied performance obligations if contract durations are less than one year. For contract durations that are one-year or greater, we do not have a material portion of transaction price allocated to unsatisfied performance obligations that are not included in deferred revenue other than for our market technology contracts which are discussed below under “Market Technology.” Deferred revenue primarily represents our contract liabilities related to our fees for annual and initial listings, market technology, corporate solutions and information services contracts. Deferred revenue is the only significant contract asset or liability impacted by our adoption of Topic 606. See Note 8, “Deferred Revenue,” for our discussion on deferred revenue balances, activity, and expected timing of recognition. See “Revenue Recognition” below for further descriptions of our revenue contracts. Sales commissions earned by our sales force are considered incremental and recoverable costs of obtaining a contract with a customer. These costs are deferred and amortized on a straight-line basis over the period of benefit that we have determined to be the contract term or estimated service periods. Sales commissions for renewal contracts are deferred and amortized on a straight-line basis over the related contractual renewal period. Amortization expense is included in compensation and benefits expense in the Condensed Consolidated Statements of Income. The balance of deferred costs and related amortization expense are not material to our consolidated financial statements. We elected the practical expedient of recognizing sales commissions as an expense when incurred if contract durations are one year or less. We also have elected the practical expedient of excluding sales taxes from transaction prices. Certain judgments and estimates were used in the identification and timing of satisfaction of performance obligations and the related allocation of transaction price and are discussed below. We believe that these represent a faithful depiction of the transfer of services to our customers. Revenue Recognition Our primary revenue contract classifications are described below. Though we discuss additional revenue details in our “Management's Discussion and Analysis of Financial Condition and Results of Operations,” the categories below best represent those that depict similar economic characteristics of the nature, amount, timing and uncertainty of our revenues and cash flows. Market Services Transaction-Based Trading and Clearing Transaction-based trading and clearing includes equity derivative trading and clearing revenues, cash equity trading revenues and FICC revenues. Nasdaq charges transaction fees for trades executed on our exchanges, as well as on orders that are routed to and executed on other market venues. Nasdaq charges clearing fees for contracts cleared with Nasdaq Clearing. In the U.S., transaction fees are based on trading volumes for trades executed on our U.S. exchanges and in Europe, transaction fees are based on the volume and value of traded and cleared contracts. In Canada, transaction fees are based on trading volumes for trades executed on our Canadian exchange. Nasdaq satisfies its performance obligation for trading services upon the execution of a customer trade and clearing services when a contract is cleared, as trading and clearing transactions are substantially complete when they are executed and we have no further obligation to the customer at that time. Transaction-based trading and clearing fees can be variable and are based on trade volume tiered discounts. Transaction revenues, as well as any tiered volume discounts, are calculated and billed monthly in accordance with our published fee schedules. In the U.S., we also pay liquidity payments to customers based on our published fee schedules. We use these payments to improve the liquidity on our markets and therefore recognize those payments as a cost of revenue. The majority of our FICC trading and clearing customers are charged transaction fees, as discussed above, which are based on the volume and value of traded and cleared contracts. We also enter into annual fixed contracts with customers trading U.S. Treasury securities. The customers are charged an annual fixed fee which is billed per the agreement, on a monthly or quarterly basis. Revenues earned on fixed contracts are recognized over time on a ratable basis over the contract period beginning on the date that our service is made available to the customer since the customer receives and consumes the benefit as Nasdaq provides the service. For U.S. equity derivative trading, we credit a portion of the per share execution charge to the market participant that provides the liquidity. For U.S. cash equity trading, for Nasdaq and Nasdaq PSX, we credit a portion of the per share execution charge to the market participant that provides the liquidity and for Nasdaq BX, we credit a portion of the per share execution charge to the market participant that takes the liquidity. We record these credits as transaction rebates that are included in transaction-based expense in the Condensed Consolidated Statements of Income. These transaction rebates are paid on a monthly basis and the amounts due are included in accounts payable and accrued expenses in the Condensed Consolidated Balance Sheets. In the U.S., we pay Section 31 fees to the SEC for supervision and regulation of securities markets. We pass these costs along to our customers through our equity derivative trading and clearing fees and our cash equity trading fees. We collect the fees as a pass-through charge from organizations executing eligible trades on our options exchanges and our cash equity platforms and we recognize these amounts in transaction-based expenses when incurred. Section 31 fees received are included in cash and cash equivalents in the Condensed Consolidated Balance Sheets at the time of receipt and, as required by law, the amount due to the SEC is remitted semiannually and recorded as Section 31 fees payable to the SEC in the Condensed Consolidated Balance Sheets until paid. Since the amount recorded as revenues is equal to the amount recorded as transaction-based expenses, there is no impact on our revenues less transaction-based expenses. As we hold the cash received until payment to the SEC, we earn interest income on the related cash balances. Under our Limitation of Liability Rule and procedures, we may, subject to certain caps, provide compensation for losses directly resulting from the systems’ actual failure to correctly process an order, quote, message or other data into our platform. We do not record a liability for any potential claims that may be submitted under the Limitation of Liability Rule unless they meet the provisions required in accordance with U.S. GAAP. As such, losses arising as a result of the rule are accrued and charged to expense only if the loss is probable and estimable. Trade Management Services We provide market participants with a wide variety of alternatives for connecting to and accessing our markets for a fee. We also offer market participants co-location services, whereby firms may lease cabinet space and power to house their own equipment and servers within our data centers. These participants are charged monthly fees for cabinet space, connectivity and support in accordance with our published fee schedules. These fees are recognized on a monthly basis when the performance obligation is met. We also earn revenues from annual and monthly exchange membership and registration fees. Revenues for providing access to our markets, co-location services and monthly exchange membership and registration fees are recognized on a monthly basis as the service is provided. Revenues from annual fees for exchange membership and registration fees are recognized ratably over the following 12 -month period since the customer receives and consumes the benefit as Nasdaq provides the service. We also offer broker services to financial participants in the Nordic market primarily providing flexible back-office systems, which allow customers to entirely or partly outsource their company’s back-office functions. Revenues from broker services are based on a fixed basic fee for administration or licensing, maintenance and operations, and an incremental fee depending on the number of transactions completed. Broker services revenues are generally billed and recognized monthly. Corporate Solutions As of September 30, 2018 , corporate solutions revenues primarily include subscription and transaction-based income from our investor relations, board & leadership, and governance, risk and compliance products and services. In April 2018, we completed the sale of our Public Relations Solutions and Digital Media Services businesses. See “2018 Divestiture,” of Note 4, “Acquisitions and Divestiture,” for further discussion. Subscription-based revenues earned are recognized over time on a ratable basis over the contract period beginning on the date that our service is made available to the customer since the customer receives and consumes the benefit as Nasdaq provides the service. Generally, fees are billed quarterly in advance and the contract provides for automatic renewal. As part of the subscription agreements, customers can also be charged usage fees based upon actual usage of the services provided. Revenues from usage fees are recognized at a point in time upon completion of the service. Listing Services Listing ser
Equity Securities	Equity Securities On January 1, 2018, we adopted ASU 2016-01 which requires that investments in equity securities (excluding equity method investments) be measured at fair value with changes in fair value recognized in net income. Equity securities are no longer classified as trading or available for sale. We elected the measurement alternative for equity securities which were historically accounted for under the cost method of accounting. Since these equity securities do not have readily determinable fair values, they are measured at cost, less any impairment, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. We evaluate these securities for impairment by considering a variety of factors such as the earnings capacity of the investment. If a qualitative assessment indicates that the security is impaired, Nasdaq will estimate the fair value of the security, and if the fair value is less than the carrying amount of the security, recognize an impairment loss in net income equal to the difference between the carrying amount and fair value. There was no impact on our condensed consolidated financial statements as a result of this change. The guidance for classifying and measuring investments in debt securities is unchanged. Therefore, changes in debt securities classified as trading securities are included in dividend and investment income in the Condensed Consolidated Statements of Income and debt securities classified as available-for-sale investment securities are carried at fair value with unrealized gains and losses, net of tax, reported in accumulated other comprehensive loss within stockholders’ equity in the Condensed Consolidated Balance Sheets. Realized gains and losses on these securities are included in earnings upon disposition of the securities using the specific identification method. In addition, realized losses are recognized when management determines that a decline in value is other than temporary, which requires judgment regarding the amount and timing of recovery. For financial investments that are classified as available-for-sale securities, we also consider the extent to which cost exceeds fair value, the duration of that difference, management’s judgment about the issuer’s current and prospective financial condition, as well as our intent and ability to hold the security until recovery of the unrealized losses.

Basis of Presentation and Pri_3

Basis of Presentation and Principles of Consolidation (Tables)	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of the Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Standard Description Effective Date Effect on the Financial Statements or Other Significant Matters Intangibles - Goodwill and Other - Internal-Use Software In August 2018, the FASB issued ASU 2018-15, “Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract.” This ASU clarifies the accounting for implementation costs of a hosting arrangement and aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). Capitalized implementation costs should be expensed over the term of the hosting arrangement and recognized in the same line item in the statement of income as the hosted service costs. Payments for capitalized implementation costs should be classified in the statement of cash flows in the same manner as payments made for fees associated with the hosting element. Capitalized implementation costs should be presented in the balance sheet in the same line item as a prepayment for the fees of the associated hosting arrangement. January 1, 2020, with early adoption permitted. We early adopted this standard as of July 1, 2018. There was no impact to the financial statements as a result of the adoption of this standard, as we are currently accounting for costs incurred in a cloud computing arrangement in accordance with the guidance provided in this standard. Fair Value Measurements In August 2018, the FASB issued ASU 2018-13 “Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement.” This ASU modifies the disclosure requirements on fair value measurements by removing certain disclosure requirements related to the fair value hierarchy, modifying existing disclosure requirements related to measurement uncertainty, and adding new requirements, mainly for Level 3 fair value measurements. January 1, 2020, with early adoption permitted. We early adopted this standard as of July 1, 2018 on a prospective basis. There was no impact to the financial statements or our disclosures as a result of the adoption of this standard. Accounting Standard Description Effective Date Effect on the Financial Statements or Other Significant Matters Income Statement - Reporting Comprehensive Income In February 2018, the FASB issued ASU 2018-02, “Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (Topic 220).” This ASU provides an election to reclassify tax effects that are stranded in accumulated other comprehensive income as a result of tax reform to retained earnings. An election is also available to reclassify other stranded tax effects that relate to the Tax Cuts and Jobs Act but do not directly relate to the change in the federal rate. Tax effects that are stranded in accumulated other comprehensive income for other reasons (e.g., prior changes in tax law, a change in valuation allowance) may not be reclassified. Previously, the effects of changes in tax rates and laws on deferred tax balances were required to be recorded as a component of tax expense related to continuing operations for the period in which the law was enacted, even if the assets and liabilities related to items of accumulated other comprehensive income. In other words, backward tracing of the income tax effects of items originally recognized through accumulated other comprehensive income was prohibited. January 1, 2019, with early adoption permitted. We early adopted this standard as of January 1, 2018. As a result of the adoption of this standard, in the first quarter of 2018, we recorded a reclassification of $142 million for stranded tax effects related to the Tax Cuts and Jobs Act from accumulated other comprehensive loss to retained earnings within stockholders’ equity in the Condensed Consolidated Balance Sheets. See Note 17, “Income Taxes,” for further discussion. Goodwill In January 2017, the FASB issued ASU 2017-04, “Simplifying the Test for Goodwill Impairment.” This ASU simplifies how an entity is required to test goodwill for impairment and removes the second step of the goodwill impairment test, which required a hypothetical purchase price allocation if the fair value of a reporting unit is less than its carrying amount. Goodwill impairment will now be measured using the difference between the carrying amount and the fair value of the reporting unit and the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The amendments in this ASU should be applied on a prospective basis. January 1, 2020, with early adoption permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We do not anticipate a material impact on our consolidated financial statements at the time of adoption of this new standard as the carrying amounts of our reporting units have been less than their corresponding fair values in recent years. Therefore, the second step of the goodwill impairment test was not required. However, changes in future projections, market conditions and other factors may cause a change in the excess of fair value of our reporting units over their corresponding carrying amounts. We do not anticipate early adoption of this standard. Financial Instruments - Credit Losses In June 2016, the FASB issued ASU 2016-13, “Measurement of Credit Losses on Financial Instruments.” This ASU changes the impairment model for certain financial instruments. The new model is a forward looking expected loss model and will apply to financial assets subject to credit losses and measured at amortized cost and certain off-balance sheet credit exposures. This includes loans, held-to-maturity debt securities, loan commitments, financial guarantees and net investments in leases, as well as trade receivables. For available-for-sale debt securities with unrealized losses, credit losses will be measured in a manner similar to today, except that the losses will be recognized as allowances rather than reductions in the amortized cost of the securities. January 1, 2020, with early adoption permitted as of January 1, 2019. We expect to adopt this standard on January 1, 2020. We are currently assessing the impact that this standard will have on our consolidated financial statements. We do not anticipate early adoption of this standard. Accounting Standard Description Effective Date Effect on the Financial Statements or Other Significant Matters Leases In February 2016, the FASB issued ASU 2016-02, “Leases.” Under this ASU, at the commencement date, lessees will be required to recognize a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. This guidance is not applicable for leases with a term of 12 months or less. Recognition, measurement and presentation of expenses will depend on classification as a finance or operating lease. The guidance also requires certain quantitative and qualitative disclosures about leasing arrangements. Lessor accounting is largely unchanged. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. January 1, 2019. See discussion below.

Significant Accounting Polici_2

Significant Accounting Policies Update (Tables)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Remaining Performance Obligation, Expected Timing of Satisfaction	The following table summarizes the amount of the transaction price allocated to performance obligations that are unsatisfied as of September 30, 2018 and relates to our Market Technology segment: (in millions) 2018 (1) $ 63 2019 238 2020 157 2021 90 2022 55 2023 and thereafter 100 Total $ 703 ____________ (1) Represents performance obligations to be recognized over the remaining three months of 2018.
Disaggregation of Revenue	The following tables summarize the disaggregation of revenue by major product and service and by segment for the nine months ended September 30, 2018 and 2017 : Nine Months Ended September 30, 2018 Market Services Corporate Services Information Services Market Technology Other Revenues Consolidated (in millions) Transaction-based trading and clearing, net $ 489 $ — $ — $ — $ — $ 489 Trade management services 220 — — — — 220 Corporate solutions — 178 — — — 178 Listing services — 217 — — — 217 Market data products — — 293 — — 293 Index — — 152 — — 152 Investment data & analytics — — 83 — — 83 Market technology — — — 194 — 194 Other revenues — — — — 56 56 Revenues less transaction-based expenses $ 709 $ 395 $ 528 $ 194 $ 56 $ 1,882 Nine Months Ended September 30, 2017 Market Services Corporate Services Information Services Market Technology Other Revenues Consolidated (in millions) Transaction-based trading and clearing, net $ 441 $ — $ — $ — $ — $ 441 Trade management services 218 — — — — 218 Corporate solutions — 173 — — — 173 Listing services — 197 — — — 197 Market data products — — 276 — — 276 Index — — 125 — — 125 Investment data & analytics — — 31 — — 31 Market technology — — — 176 — 176 Other revenues — — — — 143 143 Revenues less transaction-based expenses $ 659 $ 370 $ 432 $ 176 $ 143 $ 1,780 The following tables summarize the disaggregation of revenue by major product and service and by segment for the three months ended September 30, 2018 and 2017 : Three Months Ended September 30, 2018 Market Services Corporate Services Information Services Market Technology Other Revenues Consolidated (in millions) Transaction-based trading and clearing, net $ 150 $ — $ — $ — $ — $ 150 Trade management services 72 — — — — 72 Corporate solutions — 59 — — — 59 Listing services — 72 — — — 72 Market data products — — 95 — — 95 Index — — 52 — — 52 Investment data & analytics — — 32 — — 32 Market technology — — — 68 — 68 Other revenues — — — — — — Revenues less transaction-based expenses $ 222 $ 131 $ 179 $ 68 $ — $ 600 Three Months Ended September 30, 2017 Market Services Corporate Services Information Services Market Technology Other Revenues Consolidated (in millions) Transaction-based trading and clearing, net $ 144 $ — $ — $ — $ — $ 144 Trade management services 75 — — — — 75 Corporate solutions — 59 — — — 59 Listing services — 67 — — — 67 Market data products — — 97 — — 97 Index — — 43 — — 43 Investment data & analytics — — 10 — — 10 Market technology — — — 62 — 62 Other revenues — — — — 46 46 Revenues less transaction-based expenses $ 219 $ 126 $ 150 $ 62 $ 46 $ 603

Acquisitions and Divestiture (T

Acquisitions and Divestiture (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition	2017 Acquisitions Purchase Consideration Total Net Liabilities Acquired Total Net Deferred Tax Liability Acquired Goodwill (in millions) eVestment $ 744 $ (10 ) $ (104 ) $ 405 $ 453
Acquired Finite Lived Intangible Assets in Acquisition	The following table presents the details of acquired intangible assets for eVestment at the date of the acquisition. All acquired intangible assets with finite lives are amortized using the straight-line method. Intangible Assets ($ in millions) Customer relationships $ 378 Discount rate used 9.3 % Estimated average useful life 14 years Trade name $ 13 Discount rate used 9.2 % Estimated average useful life 8 years Technology $ 14 Discount rate used 9.2 % Estimated average useful life 8 years Total intangible assets $ 405

Assets and Liabilities Held F_2

Assets and Liabilities Held For Sale (Tables)	9 Months Ended
	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Schedule of carrying amounts of assets and liabilities classified as held for sale	The carrying amounts of the major classes of assets and liabilities that were classified as held for sale at December 31, 2017 in the Condensed Consolidated Balance Sheets were as follows: December 31, 2017 (in millions) Receivables, net $ 27 Property and equipment, net 21 Goodwill (1) 202 Intangible assets, net (2) 38 Other assets 9 Total assets held for sale $ 297 Deferred tax liabilities $ 16 Other current liabilities 29 Total liabilities held for sale $ 45 ____________ (1) The assignment of goodwill was based on the relative fair value of the disposal group and the portion of the remaining reporting unit. (2) Primarily represents customer relationships.

Goodwill and Acquired Intangi_2

Goodwill and Acquired Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in Goodwill	The following table presents the changes in goodwill by business segment during the nine months ended September 30, 2018 : Market Services Corporate Services Information Services Market Technology Total (in millions) Balance at December 31, 2017 $ 3,546 $ 490 $ 2,362 $ 188 $ 6,586 Reclassification of goodwill (1) — 29 — (29 ) — Foreign currency translation adjustment (111 ) (16 ) (79 ) (11 ) (217 ) Balance at September 30, 2018 $ 3,435 $ 503 $ 2,283 $ 148 $ 6,369 ____________ (1) Concurrent with the realignment of our BWise corporate enterprise risk management solutions from our Market Technology segment to our Corporate Services segment, goodwill was reassigned to the Corporate Services segment using a relative fair value approach.
Schedule of Acquired Finite-Lived Intangible Assets	The following table presents details of our total acquired intangible assets, both finite- and indefinite-lived: September 30, 2018 December 31, 2017 Gross Amount Accumulated Amortization Net Amount Weighted-Average Useful Life (in Years) Gross Amount Accumulated Amortization Net Amount Weighted-Average Useful Life (in Years) (in millions) (in millions) Finite-Lived Intangible Assets Technology $ 50 $ (13 ) $ 37 9 $ 65 $ (22 ) $ 43 8 Customer relationships 1,708 (606 ) 1,102 18 1,708 (526 ) 1,182 18 Other 17 (5 ) 12 8 17 (4 ) 13 8 Foreign currency translation adjustment (143 ) 62 (81 ) (111 ) 46 (65 ) Total finite-lived intangible assets $ 1,632 $ (562 ) $ 1,070 $ 1,679 $ (506 ) $ 1,173 Indefinite-Lived Intangible Assets Exchange and clearing registrations $ 1,257 $ — $ 1,257 $ 1,257 $ — $ 1,257 Trade names 127 — 127 129 — 129 Licenses 52 — 52 52 — 52 Foreign currency translation adjustment (178 ) — (178 ) (143 ) — (143 ) Total indefinite-lived intangible assets $ 1,258 $ — $ 1,258 $ 1,295 $ — $ 1,295 Total intangible assets $ 2,890 $ (562 ) $ 2,328 $ 2,974 $ (506 ) $ 2,468
Schedule of Acquired Indefinite-lived Intangible Assets	The following table presents details of our total acquired intangible assets, both finite- and indefinite-lived: September 30, 2018 December 31, 2017 Gross Amount Accumulated Amortization Net Amount Weighted-Average Useful Life (in Years) Gross Amount Accumulated Amortization Net Amount Weighted-Average Useful Life (in Years) (in millions) (in millions) Finite-Lived Intangible Assets Technology $ 50 $ (13 ) $ 37 9 $ 65 $ (22 ) $ 43 8 Customer relationships 1,708 (606 ) 1,102 18 1,708 (526 ) 1,182 18 Other 17 (5 ) 12 8 17 (4 ) 13 8 Foreign currency translation adjustment (143 ) 62 (81 ) (111 ) 46 (65 ) Total finite-lived intangible assets $ 1,632 $ (562 ) $ 1,070 $ 1,679 $ (506 ) $ 1,173 Indefinite-Lived Intangible Assets Exchange and clearing registrations $ 1,257 $ — $ 1,257 $ 1,257 $ — $ 1,257 Trade names 127 — 127 129 — 129 Licenses 52 — 52 52 — 52 Foreign currency translation adjustment (178 ) — (178 ) (143 ) — (143 ) Total indefinite-lived intangible assets $ 1,258 $ — $ 1,258 $ 1,295 $ — $ 1,295 Total intangible assets $ 2,890 $ (562 ) $ 2,328 $ 2,974 $ (506 ) $ 2,468
Estimated Future Amortization Expense	The estimated future amortization expense (excluding the impact of foreign currency translation adjustments of $81 million as of September 30, 2018 ) of acquired finite-lived intangible assets as of September 30, 2018 is as follows: (in millions) 2018 (1) $ 27 2019 99 2020 98 2021 97 2022 94 2023 and thereafter 736 Total $ 1,151 ____________ (1) Represents the estimated amortization to be recognized for the remaining three months of 2018.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Investments	The following table presents the details of our investments: September 30, December 31, (in millions) Trading securities $ 202 $ 221 Available-for-sale investment securities — 14 Financial investments, at fair value $ 202 $ 235 Equity method investments $ 131 $ 131 Equity securities $ 76 $ 152

Deferred Revenue (Tables)

Deferred Revenue (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Changes in Deferred Revenue	The changes in our deferred revenue during the nine months ended September 30, 2018 are reflected in the following table: Initial Listing Revenues Annual Listings Revenues Market Technology Revenues Corporate Solutions and Other Revenues (2) Information Services Revenues Other (3) Total (in millions) Balance at December 31, 2017 $ 64 $ 3 $ 109 $ 37 $ 40 $ 34 $ 287 Additions 30 231 118 189 128 18 714 Revenue recognized (27 ) (173 ) (131 ) (191 ) (91 ) (29 ) (642 ) Reclassification of deferred revenue (1) — — (11 ) 11 — — — Translation adjustment (2 ) (1 ) (8 ) — 1 (1 ) (11 ) Balance at September 30, 2018 $ 65 $ 60 $ 77 $ 46 $ 78 $ 22 $ 348 ____________ (1) Concurrent with the realignment of our BWise corporate enterprise risk management solutions from our Market Technology segment to our Corporate Services segment, deferred revenue was reassigned to the Corporate Services segment. (2) Other revenues include the revenues from the Public Relations Solutions and Digital Media Services businesses through the date of sale (April 2018). See “2018 Divestiture,” of Note 4, “Acquisitions and Divestiture,” to the condensed consolidated financial statements for further discussion. (3) The balance as of September 30, 2018 and December 31, 2017 primarily includes deferred revenue from listing of additional shares fees which are included in our Listing Services segment. The activity during the period primarily pertains to our Trade Management Services and FICC businesses, which are included in our Market Services segment, for contracts paid monthly or quarterly in advance of the service.
Estimated Deferred Revenue	As of September 30, 2018 , we estimate that our deferred revenue will be recognized in the following years: Initial Listing Revenues Annual Listings Revenues Market Technology Revenues Corporate Solutions Revenues Information Services Revenues Other (2) Total (in millions) Fiscal year ended: 2018 (1) $ 6 $ 60 $ 18 $ 24 $ 35 $ 3 $ 146 2019 23 — 34 21 43 10 131 2020 15 — 18 1 — 6 40 2021 10 — 7 — — 3 20 2022 7 — — — — — 7 2023 and thereafter 4 — — — — — 4 Total $ 65 $ 60 $ 77 $ 46 $ 78 $ 22 $ 348 ____________ (1) Represents deferred revenue that is anticipated to be recognized over the remaining three months of 2018. (2) Other primarily includes revenues from listing of additional shares fees which are included in our Listing Services business.

Debt Obligations (Tables)

Debt Obligations (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Changes in Debt Obligations	The following table presents the changes in the carrying amount of our debt obligations during the nine months ended September 30, 2018 : December 31, 2017 Additions Payments, Accretion and Other September 30, 2018 Short-term debt: (in millions) Commercial paper $ 480 $ 3,192 $ (3,363 ) $ 309 Senior unsecured floating rate notes due March 22, 2019 (1) 498 — 1 499 Total short-term debt 978 3,192 (3,362 ) 808 Long-term debt: 5.55% senior unsecured notes due January 15, 2020 599 — — 599 3.875% senior unsecured notes due June 7, 2021 716 — (22 ) 694 4.25% senior unsecured notes due June 1, 2024 496 — 1 497 1.75% senior unsecured notes due May 19, 2023 712 — (22 ) 690 3.85% senior unsecured notes due June 30, 2026 496 — — 496 $400 million senior unsecured term loan facility due November 25, 2019 (average interest rate of 3.37% for the period January 1, 2018 through September 30, 2018) 100 — — 100 $1 billion revolving credit commitment due April 25, 2022 (average interest rate of 2.74% for the period January 1, 2018 through September 30, 2018) 110 — (114 ) (4 ) Total long-term debt 3,229 — (157 ) 3,072 Total debt obligations $ 4,207 $ 3,192 $ (3,519 ) $ 3,880 ____________ (1) Balance was reclassified to short-term debt as of March 31, 2018.

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Share-Based Compensation Expense	The following table shows the total share-based compensation expense resulting from equity awards and the 15.0% discount for the ESPP for the three and nine months ended September 30, 2018 and 2017 in the Condensed Consolidated Statements of Income: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Share-based compensation expense before income taxes $ 18 $ 18 $ 51 $ 52 Income tax benefit (5 ) (7 ) (14 ) (21 ) Share-based compensation expense after income taxes $ 13 $ 11 $ 37 $ 31
Summary of Restricted Stock Activity	The following table summarizes our restricted stock activity for the nine months ended September 30, 2018 : Restricted Stock Number of Awards Weighted-Average Grant Date Fair Value Unvested balances at January 1, 2018 1,988,500 $ 57.34 Granted 489,203 $ 81.77 Vested (669,577 ) $ 47.54 Forfeited (229,214 ) $ 63.29 Unvested balances at September 30, 2018 1,578,912 $ 68.20
Schedule of Weighted-Average Assumptions Used to Determine the Weighted-Average Fair Values	The following weighted-average assumptions were used to determine the weighted-average fair values of the PSU awards granted under the three -year PSU program: Nine Months Ended September 30, 2018 2017 Weighted-average risk free interest rate (1) 2.36 % 1.44 % Expected volatility (2) 18.7 % 19.2 % Weighted-average grant date share price $86.24 $69.45 Weighted-average fair value at grant date $116.86 $81.57 ____________ (1) The risk-free interest rate for periods within the expected life of the award is based on the U.S. Treasury yield curve in effect at the time of grant. (2) We use historic volatility for PSU awards issued under the three -year PSU program, as implied volatility data could not be obtained for all the companies in the peer groups used for relative performance measurement within the program.
Summary of PSU Activity	The following table summarizes our PSU activity for the nine months ended September 30, 2018 : PSUs One-Year Program Three-Year Program Number of Awards Weighted-Average Grant Date Fair Value Number of Awards Weighted-Average Grant Date Fair Value Unvested balances at January 1, 2018 333,004 $ 61.39 1,009,958 $ 78.18 Granted (1) 132,019 $ 80.36 484,075 $ 90.92 Vested (6,702 ) $ 49.40 (655,204 ) $ 64.08 Forfeited (22,650 ) $ 60.84 — $ — Unvested balances at September 30, 2018 435,671 $ 67.35 838,829 $ 96.55
Summary of Stock Options, Valuation Assumptions	We estimated the fair value of this stock option award using the Black-Scholes valuation model using the following assumptions: Expected life (in years) 6 Weighted-average risk free interest rate 2.1 % Expected volatility 25.6 % Dividend yield 1.92 %
Summary of Stock Option Activity	A summary of stock option activity for the nine months ended September 30, 2018 is as follows: Number of Stock Options Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in millions) Outstanding at January 1, 2018 571,380 $ 43.84 5.40 $ 19 Exercised (99,953 ) 24.52 Forfeited (3,182 ) 26.86 Outstanding at September 30, 2018 468,245 $ 48.08 5.48 $ 18 Exercisable at September 30, 2018 289,033 $ 36.55 3.83 $ 14

Nasdaq Stockholders_ Equity (Ta

Nasdaq Stockholders’ Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Common Stock in Treasury, at Cost	The following table summarizes our share repurchase activity: Nine Months Ended September 30, 2018 2017 Number of shares of common stock repurchased 4,508,426 2,455,171 Average price paid per share $ 87.43 $ 71.15 Total purchase price (in millions) $ 394 $ 175
Schedule of Dividends Declared	During the nine months ended September 30, 2018 , our board of directors declared the following cash dividends: Declaration Date Dividend Per Common Share Record Date Total Amount Paid Payment Date (in millions) January 30, 2018 $ 0.38 March 16, 2018 $ 63 March 30, 2018 March 26, 2018 0.44 June 15, 2018 73 June 29, 2018 July 24, 2018 0.44 September 14, 2018 72 September 28, 2018 $ 208

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Summary of Computation of Basic and Diluted Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per share: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Numerator: (in millions, except share and per share amounts) Net income attributable to common shareholders $ 163 $ 170 $ 502 $ 483 Denominator: Weighted-average common shares outstanding for basic earnings per share 164,227,243 166,694,755 165,622,428 166,195,433 Weighted-average effect of dilutive securities: Employee equity awards (1) 2,071,426 2,315,145 1,931,307 3,036,349 Contingent issuance of common stock 992,247 992,247 330,749 334,384 Weighted-average common shares outstanding for diluted earnings per share 167,290,916 170,002,147 167,884,484 169,566,166 Basic and diluted earnings per share: Basic earnings per share $ 0.99 $ 1.02 $ 3.03 $ 2.91 Diluted earnings per share $ 0.97 $ 1.00 $ 2.99 $ 2.85 ____________ (1) PSUs, which are considered contingently issuable, are included in the computation of dilutive earnings per share on a weighted average basis when management determines the related performance criteria are met.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Financial Assets Measured at Fair Value on Recurring Basis	The following tables present our financial assets and financial liabilities that are measured at fair value on a recurring basis as of September 30, 2018 and December 31, 2017 . We did not have any financial liabilities measured at fair value on a recurring basis as of December 31, 2017 . September 30, 2018 Total Level 1 Level 2 Level 3 (in millions) Assets at Fair Value Financial investments, at fair value $ 202 $ 148 $ 54 $ — Default fund and margin deposit investments 1,617 215 1,402 — Total Assets at Fair Value $ 1,819 $ 363 $ 1,456 $ — Liabilities at Fair Value Other financial instruments $ 56 $ — $ 56 $ — Total Liabilities at Fair Value $ 56 $ — $ 56 $ — December 31, 2017 Total Level 1 Level 2 Level 3 (in millions) Assets at Fair Value Financial investments, at fair value $ 235 $ 135 $ 100 $ — Default fund and margin deposit investments 2,129 371 1,758 — Total Assets at Fair Value $ 2,364 $ 506 $ 1,858 $ —

Clearing Operations (Tables)

Clearing Operations (Tables)	9 Months Ended
	Sep. 30, 2018
Due to and from Broker-Dealers and Clearing Organizations [Abstract]
Schedule of Clearing Member Default Fund Contributions	As of September 30, 2018 , clearing member default fund contributions and margin deposits were as follows: September 30, 2018 Cash Contributions Non-Cash Contributions Total Contributions (in millions) Default fund contributions $ 407 $ 108 $ 515 Margin deposits 3,812 3,922 7,734 Total $ 4,219 $ 4,030 $ 8,249
Schedule of Derivative Contracts Outstanding	The following table includes the market value of derivative contracts outstanding prior to netting: September 30, 2018 (in millions) Commodity and seafood options, futures and forwards (1)(2)(3) $ 1,106 Fixed-income options and futures (1)(2) 520 Stock options and futures (1)(2) 187 Index options and futures (1)(2) 91 Total $ 1,904 ____________ (1) We determined the fair value of our option contracts using standard valuation models that were based on market-based observable inputs including implied volatility, interest rates and the spot price of the underlying instrument. (2) We determined the fair value of our futures contracts based upon quoted market prices and average quoted market yields. (3) We determined the fair value of our forward contracts using standard valuation models that were based on market-based observable inputs including LIBOR rates and the spot price of the underlying instrument.
Schedule of Derivative Contracts Cleared	The following table includes the total number of derivative contracts cleared through Nasdaq Clearing for the nine months ended September 30, 2018 and 2017 : September 30, 2018 September 30, 2017 Commodity and seafood options, futures and forwards (1) 1,506,560 2,040,033 Fixed-income options and futures 16,833,278 14,788,850 Stock options and futures 17,735,228 20,070,584 Index options and futures 35,569,046 32,748,357 Total 71,644,112 69,647,824 ____________ (1) The total volume in cleared power related to commodity contracts was 853 Terawatt hours (TWh) for the nine months ended September 30, 2018 and 911 TWh for the nine months ended September 30, 2017 .

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Reconciliation of Provision of Income Taxes	The following table shows our income tax provision and effective tax rate: Three Months Ended September 30, Percentage Change Nine Months Ended September 30, Percentage Change 2018 2017 2018 2017 ($ in millions) ($ in millions) Income tax provision $ 46 $ 64 (28.1 )% $ 234 $ 178 31.5 % Effective tax rate 22.0 % 27.4 % 31.8 % 26.9 %

Business Segments (Tables)

Business Segments (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Schedule of Operating Segments	The following table presents certain information regarding our operating segments for the three and nine months ended September 30, 2018 and 2017 : Market Services Corporate Services Information Services Market Technology Corporate Items Consolidated (in millions) Three Months Ended September 30, 2018 Total revenues $ 586 $ 131 $ 179 $ 68 $ — $ 964 Transaction-based expenses (364 ) — — — — (364 ) Revenues less transaction-based expenses 222 131 179 68 — 600 Operating income (loss) $ 121 $ 42 $ 117 $ 9 $ (43 ) $ 246 Three Months Ended September 30, 2017 Total revenues $ 581 $ 126 $ 150 $ 62 $ 46 $ 965 Transaction-based expenses (362 ) — — — — (362 ) Revenues less transaction-based expenses 219 126 150 62 46 603 Operating income (loss) $ 118 $ 41 $ 111 $ 14 $ (22 ) $ 262 Nine Months Ended September 30, 2018 Total revenues $ 1,968 $ 395 $ 528 $ 194 $ 56 $ 3,141 Transaction-based expenses (1,259 ) — — — — (1,259 ) Revenues less transaction-based expenses 709 395 528 194 56 1,882 Operating income (loss) $ 402 $ 122 $ 342 $ 20 $ (99 ) $ 787 Nine Months Ended September 30, 2017 Total revenues $ 1,808 $ 370 $ 432 $ 176 $ 143 $ 2,929 Transaction-based expenses (1,149 ) — — — — (1,149 ) Revenues less transaction-based expenses 659 370 432 176 143 1,780 Operating income (loss) $ 359 $ 115 $ 318 $ 39 $ (81 ) $ 750
Schedule of Corporate Items	A summary of our corporate items is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (in millions) Revenues - divested businesses $ — $ 46 $ 56 $ 143 Expenses: Amortization expense of acquired intangible assets 27 22 83 67 Merger and strategic initiatives expense 6 3 7 20 Clearing default loss 8 — 8 — Extinguishment of debt — — — 10 Expenses - divested businesses — 42 51 125 Other 2 1 6 2 Total expenses 43 68 155 224 Operating loss $ (43 ) $ (22 ) $ (99 ) $ (81 )

Organization and Nature of Op_2

Organization and Nature of Operations (Details) $ in Billions	9 Months Ended
	Sep. 30, 2018USD ($)marketplacesegmentcompanyexchangeexchange_traded_productcountry
Organization And Basis Of Presentation [Line Items]
Number of operating segments | segment	4
Market Services
Organization And Basis Of Presentation [Line Items]
Number of derivative exchanges listing commodities offerings | exchange	2
Market Services | United States | Options Markets
Organization And Basis Of Presentation [Line Items]
Number of exchanges | exchange	6
Market Services | United States | Cash Equities Trading Markets
Organization And Basis Of Presentation [Line Items]
Number of exchanges | exchange	3
Corporate Services
Organization And Basis Of Presentation [Line Items]
Total number of listings on The Nasdaq Stock Market | company	3,049
ETPs and other listings listed on Nasdaq Stock Market | company	390
Approximate combined market capitalization, U.S. | $	$ 13,400
Total number of listed companies within Nordic and Baltic exchanges | company	1,010
Approximate combined market capitalization within Nordic and Baltic exchanges | $	$ 1,500
Information Services
Organization And Basis Of Presentation [Line Items]
Number of exchange traded products licensed to Nasdaq's Indexes | exchange_traded_product	358
Assets management value | $	$ 206
Market Technology
Organization And Basis Of Presentation [Line Items]
Number of exchanges | marketplace	100
Number of countries services are provided (more than) | country	50

Basis of Presentation and Pri_4

Basis of Presentation and Principles of Consolidation (ASU Update 2018-02) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Future contractual lease payment obligations		$ 636
Accumulated Other Comprehensive Loss | Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI, tax amount	$ (142)
Retained Earnings | Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI, tax amount	$ 142

Significant Accounting Polici_3

Significant Accounting Policies Update (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Allowance for doubtful accounts	$ 13		$ 13		$ 9
Trade management services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction	12 months		12 months
United States | Listing services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction	12 months		12 months
Europe | Listing services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction	12 months		12 months
Minimum | Listing services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction	2 years		2 years
Maximum | Listing services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction	6 years		6 years
Services transferred at a point in time | Market Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognized (percentage)	63.00%	62.00%	64.00%	63.00%
Services transferred over time | Market Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognized (percentage)	37.00%	38.00%	36.00%	37.00%

Significant Accounting Polici_4

Significant Accounting Policies Update (Remaining Performance Obligation) (Details) - Market Technology $ in Millions	Sep. 30, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 63
Revenue, remaining performance obligation, expected timing of satisfaction	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 238
Revenue, remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 157
Revenue, remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 90
Revenue, remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 55
Revenue, remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 703
Revenue, remaining performance obligation, expected timing of satisfaction

Significant Accounting Polici_5

Significant Accounting Policies Update (Revenue by Product, Service and Segment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	$ 600	$ 603	$ 1,882	$ 1,780
Transaction-based trading and clearing, net
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	150	144	489	441
Trade management services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	72	75	220	218
Corporate solutions
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	59	59	178	173
Listing services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	72	67	217	197
Market data products
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	95	97	293	276
Index
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	52	43	152	125
Investment data & analytics
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	32	10	83	31
Market technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	68	62	194	176
Other revenues
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	46	56	143
Operating Segments | Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	222	219	709	659
Operating Segments | Corporate Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	131	126	395	370
Operating Segments | Information Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	179	150	528	432
Operating Segments | Market Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	68	62	194	176
Operating Segments | Transaction-based trading and clearing, net | Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	150	144	489	441
Operating Segments | Transaction-based trading and clearing, net | Corporate Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Transaction-based trading and clearing, net | Information Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Transaction-based trading and clearing, net | Market Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Trade management services | Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	72	75	220	218
Operating Segments | Trade management services | Corporate Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Trade management services | Information Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Trade management services | Market Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Corporate solutions | Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Corporate solutions | Corporate Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	59	59	178	173
Operating Segments | Corporate solutions | Information Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Corporate solutions | Market Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Listing services | Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Listing services | Corporate Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	72	67	217	197
Operating Segments | Listing services | Information Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Listing services | Market Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Market data products | Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Market data products | Corporate Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Market data products | Information Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	95	97	293	276
Operating Segments | Market data products | Market Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Index | Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Index | Corporate Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Index | Information Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	52	43	152	125
Operating Segments | Index | Market Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Investment data & analytics | Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Investment data & analytics | Corporate Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Investment data & analytics | Information Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	32	10	83	31
Operating Segments | Investment data & analytics | Market Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Market technology | Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Market technology | Corporate Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Market technology | Information Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Market technology | Market Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	68	62	194	176
Operating Segments | Other revenues | Market Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Other revenues | Corporate Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Other revenues | Information Services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Operating Segments | Other revenues | Market Technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Segment Reconciling Items
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	46	56	143
Segment Reconciling Items | Transaction-based trading and clearing, net
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Segment Reconciling Items | Trade management services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Segment Reconciling Items | Corporate solutions
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Segment Reconciling Items | Listing services
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Segment Reconciling Items | Market data products
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Segment Reconciling Items | Index
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Segment Reconciling Items | Investment data & analytics
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Segment Reconciling Items | Market technology
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	0	0	0	0
Segment Reconciling Items | Other revenues
Disaggregation of Revenue [Line Items]
Revenues less transaction-based expenses	$ 0	$ 46	$ 56	$ 143

Acquisitions and Divestiture (2

Acquisitions and Divestiture (2018 Pending Acquisition) (Details) $ in Millions	1 Months Ended
	Sep. 30, 2018kr / shares	Sep. 30, 2018USD ($)	Sep. 13, 2018kr / $
Business Acquisition [Line Items]
SEK exchange rate | kr / $			8.96
Cinnober
Business Acquisition [Line Items]
SEK per share offering (in SEK per share)	kr 75
SEK per warrant offering (in SEK per warrant)	kr 85
Payments to acquire businesses | $		$ 190

Acquisitions and Divestiture _2

Acquisitions and Divestiture (2018 Divestiture) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on divestiture of businesses		$ (8)	$ 0	$ 33	$ 0
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Public Relations Solutions and Digital Media Services
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on divestiture of businesses	$ 33
Gain on divestiture of business, after tax	$ 14
Working capital adjustment		8
Working capital adjustment, after tax		$ 5

Acquisitions and Divestiture _3

Acquisitions and Divestiture (2017 Acquisitions) (Details) - USD ($) $ in Millions	1 Months Ended
	Oct. 31, 2017	Sep. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 6,369	$ 6,586
eVestment
Business Acquisition [Line Items]
Purchase Consideration	$ 744
Total Net Liabilities Acquired	(10)
Total Net Deferred Tax Liability	(104)
Acquired Intangible Assets	405
Goodwill	453
Cash consideration	705
Acquisition of businesses, net of cash and cash equivalents acquired	22
Purchase price allocation deferred tax assets	39
Purchase price allocation deferred tax liabilities	$ 143

Acquisitions and Divestiture (I

Acquisitions and Divestiture (Intangible Assets) (Details) - eVestment $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2017USD ($)	Dec. 31, 2017
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Intangible Assets	$ 405
Customer relationships
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Intangible Assets	$ 378
Estimated average useful life	14 years
Amortization period of intangible assets for tax purposes	15 years
Trade name
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Intangible Assets	$ 13
Estimated average useful life	8 years	8 years
Technology
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Intangible Assets	$ 14
Estimated average useful life	8 years	8 years
Discount rate used | Customer relationships
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Discount rate used	0.093
Discount rate used | Trade name
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Discount rate used	0.092
Discount rate used | Technology
Finite Lived And Indefinite Lived Intangible Assets [Line Items]
Discount rate used	0.092

Assets and Liabilities Held F_3

Assets and Liabilities Held For Sale (Details) - USD ($)	1 Months Ended
	Apr. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charge	$ 0
Carrying Amount of Assets and Liabilities Held for Sale [Abstract]
Total assets held for sale		$ 0	$ 297,000,000
Total liabilities held for sale		$ 0	45,000,000
Public Relations Solutions and Digital Media Services | Disposal Group, Not Discontinued Operations
Carrying Amount of Assets and Liabilities Held for Sale [Abstract]
Receivables, net			27,000,000
Property and equipment, net			21,000,000
Goodwill			202,000,000
Intangible assets, net			38,000,000
Other assets			9,000,000
Total assets held for sale			297,000,000
Deferred tax liabilities			16,000,000
Other current liabilities			29,000,000
Total liabilities held for sale			$ 45,000,000

Goodwill and Acquired Intangi_3

Goodwill and Acquired Intangible Assets (Schedule of Changes in Goodwill) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Goodwill [Roll Forward]
Balance at beginning of period	$ 6,586
Reclassification of goodwill	0
Foreign currency translation adjustment	(217)
Balance at end of period	6,369
Market Services
Goodwill [Roll Forward]
Balance at beginning of period	3,546
Reclassification of goodwill	0
Foreign currency translation adjustment	(111)
Balance at end of period	3,435
Corporate Services
Goodwill [Roll Forward]
Balance at beginning of period	490
Reclassification of goodwill	29
Foreign currency translation adjustment	(16)
Balance at end of period	503
Information Services
Goodwill [Roll Forward]
Balance at beginning of period	2,362
Reclassification of goodwill	0
Foreign currency translation adjustment	(79)
Balance at end of period	2,283
Market Technology
Goodwill [Roll Forward]
Balance at beginning of period	188
Reclassification of goodwill	(29)
Foreign currency translation adjustment	(11)
Balance at end of period	$ 148

Goodwill and Acquired Intangi_4

Goodwill and Acquired Intangible Assets (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Indefinite-lived Intangible Assets [Line Items]
Amount of goodwill expected to be deductible for tax purposes		$ 749,000,000		$ 749,000,000
Goodwill, impairment loss				0	$ 0
Amortization expense for purchased finite-lived intangible assets		27,000,000	$ 22,000,000	83,000,000	$ 67,000,000
Foreign currency translation amortization expense		1,070,000,000		1,070,000,000		$ 1,173,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Public Relations Solutions and Digital Media Services | Trade name
Indefinite-lived Intangible Assets [Line Items]
Non-cash write-off related to indefinite-lived intangible asset	$ 2,000,000
Foreign currency translation adjustment
Indefinite-lived Intangible Assets [Line Items]
Foreign currency translation amortization expense		$ (81,000,000)		$ (81,000,000)		$ (65,000,000)

Goodwill and Acquired Intangi_5

Goodwill and Acquired Intangible Assets (Finite-Lived and Indefinite-Lived Intangible Assets) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 1,632	$ 1,679
Accumulated Amortization	(562)	(506)
Net Amount	1,070	1,173
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	1,258	1,295
Total intangible assets	2,890	2,974
Intangible assets, net	2,328	2,468
Exchange and clearing registrations
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	1,257	1,257
Trade name
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	127	129
Licenses
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	52	52
Foreign currency translation adjustment
Indefinite-lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	(178)	(143)
Technology
Finite-Lived Intangible Assets [Line Items]
Gross Amount	50	65
Accumulated Amortization	(13)	(22)
Net Amount	$ 37	$ 43
Weighted-Average Useful Life (in Years)	9 years	8 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 1,708	$ 1,708
Accumulated Amortization	(606)	(526)
Net Amount	$ 1,102	$ 1,182
Weighted-Average Useful Life (in Years)	18 years	18 years
Other
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 17	$ 17
Accumulated Amortization	(5)	(4)
Net Amount	$ 12	$ 13
Weighted-Average Useful Life (in Years)	8 years	8 years
Foreign currency translation adjustment
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ (143)	$ (111)
Accumulated Amortization	62	46
Net Amount	$ (81)	$ (65)

Goodwill and Acquired Intangi_6

Goodwill and Acquired Intangible Assets (Estimated Future Amortization Expense) (Details) $ in Millions	Sep. 30, 2018USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2,018	$ 27
2,019	99
2,020	98
2,021	97
2,022	94
2023 and thereafter	736
Total	$ 1,151

Investments (Schedule of Invest

Investments (Schedule of Investments) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Trading securities	$ 202	$ 221
Available-for-sale investment securities	0	14
Financial investments, at fair value	202	235
Equity method investments	131	131
Equity securities	$ 76	$ 152

Investments (Narrative) (Detail

Investments (Narrative) (Details) - USD ($)	1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2015	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Mar. 31, 2014
Investments, Debt and Securities [Line Items]
Trading securities		$ 202,000,000			$ 202,000,000		$ 202,000,000		$ 221,000,000
Gains and losses on available-for-sale investment securities							0		0
Net income from unconsolidated investees					6,000,000	$ 4,000,000	13,000,000	$ 10,000,000
Equity security impairment loss							0
Equity securities		76,000,000			76,000,000		76,000,000		$ 152,000,000
OCC
Investments, Debt and Securities [Line Items]
Committed equity contribution				$ 150,000,000
Capital contribution				$ 30,000,000
Annual dividend from shareholders percentage				50.00%
Shares owned (in shares)			2			2		2
Annual dividend received		13,000,000	$ 10,000,000
Borsa Istanbul Cost Method Investment
Investments, Debt and Securities [Line Items]
Ownership percentage									5.00%
Equity securities										$ 75,000,000
Foreign Government Debt Securities
Investments, Debt and Securities [Line Items]
Trading securities		$ 174,000,000			$ 174,000,000		$ 174,000,000		$ 160,000,000
LCH
Investments, Debt and Securities [Line Items]
Ownership percentage							5.00%		5.00%
LCH | Subsequent Event
Investments, Debt and Securities [Line Items]
Ownership percentage	5.00%

Deferred Revenue (Changes in De

Deferred Revenue (Changes in Deferred Revenue) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	$ 287
Additions	714
Revenue recognized	(642)
Reclassification of deferred revenue	0
Translation adjustment	(11)
Ending balance	348
Initial Listing Revenues
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	64
Additions	30
Revenue recognized	(27)
Reclassification of deferred revenue	0
Translation adjustment	(2)
Ending balance	65
Annual Listings Revenues
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	3
Additions	231
Revenue recognized	(173)
Reclassification of deferred revenue	0
Translation adjustment	(1)
Ending balance	60
Market Technology Revenues
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	109
Additions	118
Revenue recognized	(131)
Reclassification of deferred revenue	(11)
Translation adjustment	(8)
Ending balance	77
Corporate Solutions and Other Revenues
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	37
Additions	189
Revenue recognized	(191)
Reclassification of deferred revenue	11
Translation adjustment	0
Ending balance	46
Information Services Revenues
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	40
Additions	128
Revenue recognized	(91)
Reclassification of deferred revenue	0
Translation adjustment	1
Ending balance	78
Other
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	34
Additions	18
Revenue recognized	(29)
Reclassification of deferred revenue	(1)
Translation adjustment	0
Ending balance	$ 22

Deferred Revenue (Estimated Def

Deferred Revenue (Estimated Deferred Revenue) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Fiscal year ended:
2,018	$ 146
2,019	131
2,020	40
2,021	20
2,022	7
2023 and thereafter	4
Total	348	$ 287
Initial Listing Revenues
Fiscal year ended:
2,018	6
2,019	23
2,020	15
2,021	10
2,022	7
2023 and thereafter	4
Total	65	64
Annual Listings Revenues
Fiscal year ended:
2,018	60
2,019	0
2,020	0
2,021	0
2,022	0
2023 and thereafter	0
Total	60	3
Market Technology Revenues
Fiscal year ended:
2,018	18
2,019	34
2,020	18
2,021	7
2,022	0
2023 and thereafter	0
Total	77	109
Corporate Solutions Revenues
Fiscal year ended:
2,018	24
2,019	21
2,020	1
2,021	0
2,022	0
2023 and thereafter	0
Total	46
Information Services Revenues
Fiscal year ended:
2,018	35
2,019	43
2,020	0
2,021	0
2,022	0
2023 and thereafter	0
Total	78	40
Other
Fiscal year ended:
2,018	3
2,019	10
2,020	6
2,021	3
2,022	0
2023 and thereafter	0
Total	$ 22	$ 34

Debt Obligations (Changes in De

Debt Obligations (Changes in Debt Obligations) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2018	Apr. 30, 2017	Jun. 30, 2016	May 31, 2016	May 31, 2014	Jun. 30, 2013	Jan. 31, 2010
Changes In Short-Term Debt Obligations [Roll Forward]
Short-term debt - commercial paper beginning balance	$ 978,000,000
Additions	3,192,000,000
Payments, Accretion and Other	(3,362,000,000)
Short-term debt - commercial paper ending balance	808,000,000
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period	3,229,000,000
Additions	0
Payments, Accretion and Other	(157,000,000)
Long-term debt obligations at end of period	3,072,000,000
Changes In Debt Obligations [Roll Forward]
Total debt obligations at beginning of period	4,207,000,000
Additions	3,192,000,000
Payments, Accretion and Other	(3,519,000,000)
Total debt obligations at end of period	3,880,000,000
$400 million senior unsecured term loan facility due November 25, 2019 (average interest rate of 3.37% for the period January 1, 2018 through September 30, 2018)
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period	100,000,000
Additions	0
Payments, Accretion and Other	0
Long-term debt obligations at end of period	100,000,000
Credit facility, borrowing capacity	$ 400,000,000
Interest rate during period	3.37%
Commercial paper
Changes In Short-Term Debt Obligations [Roll Forward]
Short-term debt - commercial paper beginning balance	$ 480,000,000
Additions	3,192,000,000
Payments, Accretion and Other	(3,363,000,000)
Short-term debt - commercial paper ending balance	309,000,000
Senior unsecured floating rate notes due March 22, 2019
Changes In Short-Term Debt Obligations [Roll Forward]
Short-term debt - commercial paper beginning balance	498,000,000
Additions	0
Payments, Accretion and Other	1,000,000
Short-term debt - commercial paper ending balance	499,000,000
Senior Notes | 5.55% senior unsecured notes due January 15, 2020
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period	599,000,000
Additions	0
Payments, Accretion and Other	0
Long-term debt obligations at end of period	$ 599,000,000
Stated rate	5.55%						5.55%
Senior Notes | 3.875% senior unsecured notes due June 7, 2021
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period	$ 716,000,000
Additions	0
Payments, Accretion and Other	(22,000,000)
Long-term debt obligations at end of period	$ 694,000,000
Stated rate	3.875%					3.875%
Senior Notes | 4.25% senior unsecured notes due June 1, 2024
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period	$ 496,000,000
Additions	0
Payments, Accretion and Other	1,000,000
Long-term debt obligations at end of period	$ 497,000,000
Stated rate	4.25%				4.25%
Senior Notes | 1.75% senior unsecured notes due May 19, 2023
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period	$ 712,000,000
Additions	0
Payments, Accretion and Other	(22,000,000)
Long-term debt obligations at end of period	$ 690,000,000
Stated rate	1.75%			1.75%
Senior Notes | 3.85% senior unsecured notes due June 30, 2026
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period	$ 496,000,000
Additions	0
Payments, Accretion and Other	0
Long-term debt obligations at end of period	$ 496,000,000
Stated rate	3.85%		3.85%
Revolving Credit Facility | $1 billion revolving credit commitment due April 25, 2022 (average interest rate of 2.74% for the period January 1, 2018 through September 30, 2018)
Changes in Long-Term Debt Obligations [Roll Forward]
Long-term debt obligations at beginning of period	$ 110,000,000
Additions	0
Payments, Accretion and Other	(114,000,000)
Long-term debt obligations at end of period	(4,000,000)
Credit facility, borrowing capacity	$ 1,000,000,000	$ 1,000,000,000
Interest rate during period	2.74%

Debt Obligations (Commercial Pa

Debt Obligations (Commercial Paper) (Details) - Commercial paper	9 Months Ended
	Sep. 30, 2018
Short-term Debt [Line Items]
Weighted average interest rate	2.45%
Minimum
Short-term Debt [Line Items]
Maturity period	7 days
Maximum
Short-term Debt [Line Items]
Maturity period	63 days
Weighted Average
Short-term Debt [Line Items]
Maturity period	29 days

Debt Obligations (Senior Unsecu

Debt Obligations (Senior Unsecured Notes) (Details)	9 Months Ended
	Sep. 30, 2018
Senior Notes | Senior Notes Excluding 2020 Notes
Debt Instrument [Line Items]
Aggregate principal amount purchased plus accrued and unpaid interest	101.00%

Debt Obligations (Senior Unse_2

Debt Obligations (Senior Unsecured Floating Rate Notes) (Details)	1 Months Ended
	Sep. 30, 2017
Senior Notes | Senior unsecured floating rate notes due March 22, 2019 | LIBOR
Debt Instrument [Line Items]
Spread on variable rate	0.39%

Debt Obligations (5.55% Senior

Debt Obligations (5.55% Senior Unsecured Notes) (Details)	Sep. 30, 2018	Jan. 31, 2010
5.55% senior unsecured notes due January 15, 2020 | Senior Notes
Debt Instrument [Line Items]
Stated rate	5.55%	5.55%

Debt Obligations (3.875% Senior

Debt Obligations (3.875% Senior Unsecured Notes) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Jun. 30, 2013
Debt Instrument [Line Items]
Decrease in carrying amount	$ 157
Senior Notes | 3.875% senior unsecured notes due June 7, 2021
Debt Instrument [Line Items]
Stated rate	3.875%	3.875%
Decrease in carrying amount	$ 22
Senior Notes | 3.875% senior unsecured notes due June 7, 2021 | Maximum
Debt Instrument [Line Items]
Maximum interest rate on debt instrument		5.875%

Debt Obligations (4.25% Senior

Debt Obligations (4.25% Senior Unsecured Notes) (Details) - Senior Notes - 4.25% senior unsecured notes due June 1, 2024	Sep. 30, 2018	May 31, 2014
Debt Instrument [Line Items]
Stated rate	4.25%	4.25%
Maximum
Debt Instrument [Line Items]
Maximum interest rate on debt instrument		6.25%

Debt Obligations (1.75% Senior

Debt Obligations (1.75% Senior Unsecured Notes) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	May 31, 2016
Debt Instrument [Line Items]
Increase in carrying amount	$ (157)
Senior Notes | 1.75% senior unsecured notes due May 19, 2023
Debt Instrument [Line Items]
Stated rate	1.75%	1.75%
Increase in carrying amount	$ (22)
Senior Notes | 1.75% senior unsecured notes due May 19, 2023 | Maximum
Debt Instrument [Line Items]
Maximum interest rate on debt instrument		3.75%

Debt Obligations (3.85% Senior

Debt Obligations (3.85% Senior Unsecured Notes) (Details) - Senior Notes - 3.85% senior unsecured notes due June 30, 2026	Sep. 30, 2018	Jun. 30, 2016
Debt Instrument [Line Items]
Stated rate	3.85%	3.85%
Maximum
Debt Instrument [Line Items]
Maximum interest rate on debt instrument		5.85%

Debt Obligations (2017 Credit F

Debt Obligations (2017 Credit Facility) (Details) - Revolving Credit Facility - $1 billion revolving credit commitment due April 25, 2022 (average interest rate of 2.74% for the period January 1, 2018 through September 30, 2018) - USD ($)	1 Months Ended	9 Months Ended
	Apr. 30, 2017	Sep. 30, 2018
Debt Instrument [Line Items]
Credit facility, borrowing capacity	$ 1,000,000,000	$ 1,000,000,000
Credit facility term	5 years
Line of Credit Facility, Fair Value of Amount Outstanding		0
Unamortized debt issuance expense		4,000,000
Remaining amount available		1,000,000,000
Option to increase available aggregate amount		500,000,000
Commercial Paper And Letter Of Credit
Debt Instrument [Line Items]
Remaining amount available		689,000,000
Credit facility, remaining residual borrowing capacity		$ 311,000,000

Debt Obligations (2016 Credit F

Debt Obligations (2016 Credit Facility) (Details) $ in Millions	Sep. 30, 2018USD ($)
$400 million senior unsecured term loan facility due November 25, 2019 (average interest rate of 3.37% for the period January 1, 2018 through September 30, 2018)
Debt Instrument [Line Items]
Remaining amount outstanding	$ 100

Debt Obligations (Other Credit

Debt Obligations (Other Credit Facilities) (Details) - Clearinghouse Credit Facilities - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Letter of Credit
Debt Instrument [Line Items]
Remaining amount available	$ 219
Commercial Paper And Letter Of Credit
Debt Instrument [Line Items]
Remaining amount available		$ 187

Retirement Plans (Narrative) (D

Retirement Plans (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Retirement Benefits [Abstract]
Employer contribution match, percent match			100.00%
Employer contribution match, percentage of employee contribution			6.00%
Defined contributions plan expense	$ 3	$ 3	$ 10	$ 10
Cost or expenses included in compensation and benefit expense	4	$ 5	$ 15	$ 13
Employer contributions, amount	$ 22
Funded status, percentage	100.00%

Share-Based Compensation (Narra

Share-Based Compensation (Narrative) (Details) $ / shares in Units, $ in Millions	Jan. 30, 2018	Jan. 31, 2017$ / sharesshares	Sep. 30, 2018USD ($)$ / sharespeer_groupshares	Mar. 31, 2018shares	Sep. 30, 2017USD ($)$ / sharesshares	Sep. 30, 2018USD ($)program$ / sharespeer_groupshares	Sep. 30, 2017USD ($)$ / sharesshares	Dec. 31, 2017	Jun. 29, 2018$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares reserved for future issuance (in shares)			11,000,000			11,000,000
Stock options exercised in period (in shares)			11,953		40,160	99,953	1,074,321
Net cash proceeds from the exercise of stock options | $					$ 1	$ 2	$ 24
Share price (in dollars per share) | $ / shares									$ 85.8
Stock options, exercisable (in shares)			289,033		300,000	289,033	300,000
Options exercisable, weighted average exercise price (in dollars per share) | $ / shares			$ 36.55		$ 23.77	$ 36.55	$ 23.77
Total pre-tax intrinsic value of stock options exercised | $			$ 1		$ 2	$ 6	$ 53
Compensation expense | $			$ 18		$ 18	$ 51	$ 52
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discount from market price			15.00%		15.00%	15.00%	15.00%
Common stock shares reserved for future issuance (in shares)			2,000,000			2,000,000
Maximum percentage of shares purchased from annual compensation						10.00%
Discount given to employees						15.00%
Compensation expense | $			$ 1		$ 1	$ 3	$ 3
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost | $			58			$ 58
Weighted-average period unrecognized compensation cost is expected to be recognized, in years						1 year 10 months 15 days
PSUs | One-Year Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost | $			12			$ 12
Weighted-average period unrecognized compensation cost is expected to be recognized, in years						1 year 6 months
Performance period						1 year		1 year
Percentage of target amount granted, minimum						0.00%
Percentage of target amount granted, maximum						150.00%
Vesting period						3 years
Additional units granted above target (in shares)				14,497
PSUs | Three-Year Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost | $			$ 34			$ 34
Weighted-average period unrecognized compensation cost is expected to be recognized, in years						1 year 5 months 20 days
Performance period						3 years
Vesting period						3 years
Additional units granted above target (in shares)				237,876
Number of peer groups | peer_group			2			2
Performance-based long-term incentive program weighted percentage						50.00%
Minimum payout						0.00%
Maximum payout						200.00%
Share price (in dollars per share) | $ / shares			$ 86.24		$ 69.45	$ 86.24	$ 69.45
PSUs | Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance-based programs | program						2
PSUs, Negative TSR | Three-Year Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum payout						100.00%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option awards granted (in shares)						0
Weighted-average grant date fair value (in dollars per share) | $ / shares		$ 66.68
Expected life (in years)						6 years
Employee Stock Option | CEO
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Stock option awards granted (in shares)		268,817
Second Anniversary | Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage						25.00%
Second Anniversary | Employee Stock Option | CEO
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	33.33%
Third Anniversary | Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage						25.00%
Fourth Anniversary | Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage						50.00%

Share-Based Compensation (Summa

Share-Based Compensation (Summary of Share-Based Compensation Expense) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based compensation expense before income taxes	$ 18	$ 18	$ 51	$ 52
Income tax benefit	(5)	(7)	(14)	(21)
Share-based compensation expense after income taxes	$ 13	$ 11	$ 37	$ 31

Share-Based Compensation (Sum_2

Share-Based Compensation (Summary of Restricted Stock Activity) (Details) - Restricted stock	9 Months Ended
	Sep. 30, 2018$ / sharesshares
Number of Awards
Number of Awards, Unvested balances at beginning of period (in shares) | shares	1,988,500
Number of Awards, Granted (in shares) | shares	489,203
Number of Awards, Vested (in shares) | shares	(669,577)
Number of Awards, Forfeited (in shares) | shares	(229,214)
Number of Awards, Unvested balances at end of period (in shares) | shares	1,578,912
Weighted-Average Grant Date Fair Value
Weighted-Average Grant Date Fair Value, Unvested balances at beginning of period (in dollars per share) | $ / shares	$ 57.34
Weighted-Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	81.77
Weighted-Average Grant Date Fair Value, Vested (in dollars per share) | $ / shares	47.54
Weighted-Average Grant Date Fair Value, Forfeited (in dollars per share) | $ / shares	63.29
Weighted-Average Grant Date Fair Value, Unvested balances at end of period (in dollars per share) | $ / shares	$ 68.20

Share-Based Compensation (Sched

Share-Based Compensation (Schedule of Weighted- Average Assumptions Used to Determine Weighted-Average Fair Values) (Details) - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 29, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date share price (in dollars per share)			$ 85.8
PSUs | Three-Year Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average risk free interest rate	2.36%	1.44%
Expected volatility	18.70%	19.20%
Weighted-average grant date share price (in dollars per share)	$ 86.24	$ 69.45
Weighted-average fair value at grant date (in dollars per share)	$ 116.86	$ 81.57
Performance period	3 years

Share-Based Compensation (Sum_3

Share-Based Compensation (Summary of PSU Activity) (Details) - PSUs	9 Months Ended
	Sep. 30, 2018$ / sharesshares
One-Year Program
Number of Awards
Number of Awards, Unvested balances at beginning of period (in shares) | shares	333,004
Number of Awards, Granted (in shares) | shares	132,019
Number of Awards, Vested (in shares) | shares	(6,702)
Number of Awards, Forfeited (in shares) | shares	(22,650)
Number of Awards, Unvested balances at end of period (in shares) | shares	435,671
Weighted-Average Grant Date Fair Value
Weighted-Average Grant Date Fair Value, Unvested balances at beginning of period (in dollars per share) | $ / shares	$ 61.39
Weighted-Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	80.36
Weighted-Average Grant Date Fair Value, Vested (in dollars per share) | $ / shares	49.40
Weighted-Average Grant Date Fair Value, Forfeited (in dollars per share) | $ / shares	60.84
Weighted-Average Grant Date Fair Value, Unvested balances at end of period (in dollars per share) | $ / shares	$ 67.35
Three-Year Program
Number of Awards
Number of Awards, Unvested balances at beginning of period (in shares) | shares	1,009,958
Number of Awards, Granted (in shares) | shares	484,075
Number of Awards, Vested (in shares) | shares	(655,204)
Number of Awards, Forfeited (in shares) | shares	0
Number of Awards, Unvested balances at end of period (in shares) | shares	838,829
Weighted-Average Grant Date Fair Value
Weighted-Average Grant Date Fair Value, Unvested balances at beginning of period (in dollars per share) | $ / shares	$ 78.18
Weighted-Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	90.92
Weighted-Average Grant Date Fair Value, Vested (in dollars per share) | $ / shares	64.08
Weighted-Average Grant Date Fair Value, Forfeited (in dollars per share) | $ / shares	0
Weighted-Average Grant Date Fair Value, Unvested balances at end of period (in dollars per share) | $ / shares	$ 96.55

Share-Based Compensation Share-

Share-Based Compensation Share-Based Compensation (Summary of Stock Options Valuation Assumptions) (Details) - Employee Stock Option	9 Months Ended
	Sep. 30, 2018USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	6 years
Weighted-average risk free interest rate	2.10%
Expected volatility	25.60%
Dividend yield	$ 0.0192

Share-Based Compensation (Sum_4

Share-Based Compensation (Summary of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Number of Stock Options
Number of Stock Options, Outstanding at Beginning of period (in shares)			571,380
Number of Stock Options, Exercised (in shares)	(11,953)	(40,160)	(99,953)	(1,074,321)
Number of Stock Options, Forfeited (in shares)			(3,182)
Number of Stock Options, Outstanding at End of period (in shares)	468,245		468,245		571,380
Stock options, exercisable (in shares)	289,033	300,000	289,033	300,000
Weighted-Average Exercise Price
Weighted-Average Exercise Price, Outstanding at Beginning of period (in dollars per share)			$ 43.84
Weighted-Average Exercise Price, Exercised (in dollars per share)			24.52
Weighted-Average Exercise Price, Forfeited (in dollars per share)			26.86
Weighted-Average Exercise Price, Outstanding at End of period (in dollars per share)	$ 48.08		48.08		$ 43.84
Options exercisable, weighted average exercise price (in dollars per share)	$ 36.55	$ 23.77	$ 36.55	$ 23.77
Weighted-Average Remaining Contractual Term (in years)			5 years 5 months 22 days		5 years 4 months 25 days
Weighted-Average Remaining Contractual Term, Exercisable (in years)			3 years 10 months
Aggregate Intrinsic Value (in millions)	$ 18		$ 18		$ 19
Aggregate Intrinsic Value, Exercisable (in millions)	$ 14		$ 14

Nasdaq Stockholders' Equity (Na

Nasdaq Stockholders' Equity (Narrative) (Details)	Jul. 24, 2018USD ($)$ / shares	Mar. 26, 2018USD ($)$ / shares	Jan. 30, 2018USD ($)$ / shares	Oct. 31, 2018USD ($)$ / shares	Mar. 31, 2018$ / shares	Sep. 30, 2018USD ($)vote$ / sharesshares	Sep. 30, 2017$ / shares	Sep. 30, 2018USD ($)vote$ / sharesshares	Sep. 30, 2017$ / sharesshares	Jan. 31, 2018USD ($)	Dec. 31, 2017shares
Stockholders Equity [Line Items]
Common stock, shares authorized (in shares)						300,000,000		300,000,000			300,000,000
Common stock, shares issued (in shares)						169,423,805		169,423,805			172,373,432
Common stock, shares outstanding (in shares)						163,949,047		163,949,047			167,441,030
Common stock (in votes per share) | vote						1		1
Common stock holder voting rights, maximum percentage of the then-outstanding shares of Nasdaq common stock						5.00%		5.00%
Common stock in treasury (in shares)						5,474,758		5,474,758			4,932,402
Share repurchase program additional amount authorized | $										$ 500,000,000
Share repurchase program, authorized amount | $						$ 726,000,000		$ 726,000,000
Remaining authorized share repurchase amounts under repurchase program | $						$ 332,000,000		$ 332,000,000
Number of shares of common stock repurchased (in shares)								4,508,426	2,455,171
Preferred stock, shares authorized (in shares)						30,000,000		30,000,000
Preferred stock par value (in dollars per share) | $ / shares						$ 0.01		$ 0.01
Payments of dividends | $								$ 208,000,000
Cash dividends declared per common share (in dollars per share) | $ / shares	$ 0.44	$ 0.44	$ 0.38		$ 0.44	$ 0.44	$ 0.38	$ 1.26	$ 1.08
Dividends declared | $	$ 72,000,000	$ 73,000,000	$ 63,000,000					$ 208,000,000
Percent increase over prior quarter dividend								16.00%
Other Repurchases of Common Stock
Stockholders Equity [Line Items]
Number of shares of common stock repurchased (in shares)								542,356
Series A Preferred Stock
Stockholders Equity [Line Items]
Preferred stock, series A convertible preferred stock, shares issued (in shares)						0		0			0
Preferred stock, series A convertible preferred stock, shares outstanding (in shares)						0		0			0
Subsequent Event
Stockholders Equity [Line Items]
Cash dividends declared per common share (in dollars per share) | $ / shares				$ 0.44
Dividends declared | $				$ 72,000,000

Nasdaq Stockholders' Equity (Co

Nasdaq Stockholders' Equity (Common Stock in Treasury) (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Number of shares of common stock repurchased (in shares)	4,508,426	2,455,171
Average price paid per share (in dollars per share)	$ 87.43	$ 71.15
Total purchase price (in millions)	$ 394	$ 175

Nasdaq Stockholders' Equity (Sc

Nasdaq Stockholders' Equity (Schedule of Dividends Declared) (Details) - USD ($) $ / shares in Units, $ in Millions	Jul. 24, 2018	Mar. 26, 2018	Jan. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Dividend per common share (in dollars per share)	$ 0.44	$ 0.44	$ 0.38	$ 0.44	$ 0.44	$ 0.38	$ 1.26	$ 1.08
Total Amount	$ 72	$ 73	$ 63				$ 208

Earnings Per Share (Summary of

Earnings Per Share (Summary of Computation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net income attributable to common shareholders	$ 163	$ 170	$ 502	$ 483
Denominator:
Weighted-average common shares outstanding for basic earnings per share (in shares)	164,227,243	166,694,755	165,622,428	166,195,433
Weighted-average effect of dilutive securities:
Employee equity awards (in shares)	2,071,426	2,315,145	1,931,307	3,036,349
Contingent issuance of common stock	992,247	992,247	330,749	334,384
Weighted-average common shares outstanding for diluted earnings per share (in shares)	167,290,916	170,002,147	167,884,484	169,566,166
Basic and diluted earnings per share:
Basic earnings per share (in dollars per share)	$ 0.99	$ 1.02	$ 3.03	$ 2.91
Diluted earnings per share (in dollars per share)	$ 0.97	$ 1	$ 2.99	$ 2.85

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Antidilutive securities	0	179,712	0	325,187

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Assets at Fair Value
Financial investments, at fair value	$ 202	$ 235
Fair Value, Measurements, Recurring
Assets at Fair Value
Financial investments, at fair value	202	235
Default fund and margin deposit investments	1,617	2,129
Total Assets at Fair Value	1,819	2,364
Liabilities at Fair Value
Other financial instruments	56
Total Liabilities at Fair Value	56
Fair Value, Measurements, Recurring | Level 1
Assets at Fair Value
Financial investments, at fair value	148	135
Default fund and margin deposit investments	215	371
Total Assets at Fair Value	363	506
Liabilities at Fair Value
Other financial instruments	0
Total Liabilities at Fair Value	0
Fair Value, Measurements, Recurring | Level 2
Assets at Fair Value
Financial investments, at fair value	54	100
Default fund and margin deposit investments	1,402	1,758
Total Assets at Fair Value	1,456	1,858
Liabilities at Fair Value
Other financial instruments	56
Total Liabilities at Fair Value	56
Fair Value, Measurements, Recurring | Level 3
Assets at Fair Value
Financial investments, at fair value	0	0
Default fund and margin deposit investments	0	0
Total Assets at Fair Value	0	$ 0
Liabilities at Fair Value
Other financial instruments	0
Total Liabilities at Fair Value	$ 0

Fair Value of Financial Instr_4

Fair Value of Financial Instruments (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	$ 202	$ 221
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other financial instruments	56
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other financial instruments	56
Fair Value, Measurements, Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt utilizing discounted cash flow analyses	4,000	4,400
Foreign Government Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	$ 174	$ 160

Clearing Operations (Narrative)

Clearing Operations (Narrative) (Details) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)fundcontract	Sep. 30, 2017USD ($)contract	Dec. 31, 2017USD ($)
Clearing Operations [Line Items]
Number of member sponsored default funds | fund				4
Loss due to commodities market default	$ 133
Loss due to commodities market default allocated to junior capital	8
Temporary capital	22	$ 22		$ 22
Liability due to market default	56	56		56
Collateral due to market default	56	56		56
Default funds and margin deposits	4,219	4,219		4,219		$ 3,988
Default fund contributions	515	515		515
Committed capital	202	202		202		$ 235
Liability Waterfall
Clearing Operations [Line Items]
Loss due to commodities market default allocated to junior capital	8	8	$ 0	8	$ 0
Junior capital, cash deposits and pledged assets	31	31		31
Senior capital, cash deposits and pledged assets	22	22		22
Committed capital	67	67		67
Utilize as capital resources
Clearing Operations [Line Items]
Default fund contributions	463	463		463
Utilize as member posted surplus balance
Clearing Operations [Line Items]
Default fund contributions	52	52		52
Nasdaq Clearing
Clearing Operations [Line Items]
Temporary capital	22	22		$ 22
Temporary capital, holding time period				90 days
Default fund cash contributions invested in highly rated government debt securities				$ 1,187
Maturity period of time deposits				90 days
Committed capital	128	128		$ 128
Power of assessment of the clearing member's contribution to the financial markets and commodities markets default funds				100.00%
Contract value of resale and repurchase agreements	4,100	4,100	$ 5,000	$ 4,100	$ 5,000
Total number of derivative contracts cleared | contract				6,835,634	5,891,900
Nasdaq Clearing | Reverse Repurchase Agreements
Clearing Operations [Line Items]
Default funds and margin deposits	$ 430	$ 430		$ 430
Minimum
Clearing Operations [Line Items]
Reverse purchase agreements, maturity range				1 day
Maximum
Clearing Operations [Line Items]
Reverse purchase agreements, maturity range				19 days

Clearing Operations (Schedule o

Clearing Operations (Schedule of Clearing Member Default Fund Contributions And Margin Deposits) (Details) $ in Millions	Sep. 30, 2018USD ($)
Clearing Operations [Line Items]
Default fund contributions	$ 515
Margin deposits	7,734
Total	8,249
Cash Contributions
Clearing Operations [Line Items]
Default fund contributions	407
Margin deposits	3,812
Total	4,219
Non-Cash Contributions
Clearing Operations [Line Items]
Default fund contributions	108
Margin deposits	3,922
Total	$ 4,030

Clearing Operations (Schedule_2

Clearing Operations (Schedule of Derivative Contracts) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)TWhshares	Sep. 30, 2017TWhshares
Clearing Operations [Line Items]
Market value of derivative contracts | $	$ 1,904
Total number of cleared contracts | shares	71,644,112	69,647,824
Total volume in cleared power, in Terawatt hours (TWh) | TWh	853	911
Commodity and seafood options, futures and forwards
Clearing Operations [Line Items]
Market value of derivative contracts | $	$ 1,106
Total number of cleared contracts | shares	1,506,560	2,040,033
Fixed-income options and futures
Clearing Operations [Line Items]
Market value of derivative contracts | $	$ 520
Total number of cleared contracts | shares	16,833,278	14,788,850
Stock options and futures
Clearing Operations [Line Items]
Market value of derivative contracts | $	$ 187
Total number of cleared contracts | shares	17,735,228	20,070,584
Index options and futures
Clearing Operations [Line Items]
Market value of derivative contracts | $	$ 91
Total number of cleared contracts | shares	35,569,046	32,748,357

Commitments, Contingencies an_2

Commitments, Contingencies and Guarantees (Details)	Sep. 02, 2014exchange	Sep. 30, 2018kr / shares	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)shares	Sep. 30, 2018USD ($)	Sep. 13, 2018kr / $	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Line Items]
Financial guarantees obtained						$ 12,000,000		$ 14,000,000
SEK exchange rate | kr / $							8.96
National exchanges named as defendants | exchange	7
eSpeed
Commitments and Contingencies Disclosure [Line Items]
Contingent future issuance of common stock (in shares) | shares					992,247
Revenue required to trigger annual issuance of Nasdaq common stock					$ 25,000,000
Property Lease Guarantee
Commitments and Contingencies Disclosure [Line Items]
Other guarantees						4,000,000		3,000,000
Escrow Agreement
Commitments and Contingencies Disclosure [Line Items]
Contingency, accrual						11,000,000
Escrow Agreement | Other current liabilities
Commitments and Contingencies Disclosure [Line Items]
Contingency, accrual						9,000,000
Escrow Agreement | Other non-current liabilities
Commitments and Contingencies Disclosure [Line Items]
Contingency, accrual						2,000,000
Clearinghouse Credit Facilities
Commitments and Contingencies Disclosure [Line Items]
Credit facility, available liquidity						219,000,000		$ 187,000,000
ICBC
Commitments and Contingencies Disclosure [Line Items]
Margin deposits contributed to brokers						15,000,000
Contribution of Equity Capital | OCC
Commitments and Contingencies Disclosure [Line Items]
Commitment contributions						$ 200,000,000
OCC
Commitments and Contingencies Disclosure [Line Items]
Ownership percentage						40.00%
OCC | Contribution of Equity Capital
Commitments and Contingencies Disclosure [Line Items]
Commitment contributions						$ 80,000,000
Cinnober
Commitments and Contingencies Disclosure [Line Items]
SEK per share offering (in SEK per share) | kr / shares		kr 75
SEK per warrant offering (in SEK per warrant) | kr / shares		kr 85
Payments to acquire businesses			$ 190,000,000
Scenario, Forecast | Cinnober
Commitments and Contingencies Disclosure [Line Items]
Payments to acquire businesses				$ 190,000,000

Income Taxes (Income Tax Provis

Income Taxes (Income Tax Provision) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income tax provision	$ 46	$ 64	$ 234	$ 178
Percentage Change	(28.10%)		31.50%
Effective tax rate	22.00%	27.40%	31.80%	26.90%

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Jun. 30, 2018
Operating Loss Carryforwards [Line Items]
Payments for tax settlements			$ 40
Adjustment to tax expense	$ (4)	$ 5		$ (89)
Sweden | Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Tax expense (benefits) associated with foreign tax agency		57			$ 41
Tax expense (benefits), per diluted share (in dollars per share)					$ 0.24
Quarterly recurring tax benefits			$ 1
Retained Earnings | Accounting Standards Update 2018-02
Operating Loss Carryforwards [Line Items]
Reclassification from AOCI, tax amount		142
Accumulated Other Comprehensive Loss | Accounting Standards Update 2018-02
Operating Loss Carryforwards [Line Items]
Reclassification from AOCI, tax amount		(142)
Employee Benefit Plan Adjustment Gains And Losses | Accounting Standards Update 2018-02
Operating Loss Carryforwards [Line Items]
Reclassification from AOCI, tax amount		(135)
Net Foreign Currency Transaction Gains And Losses | Accounting Standards Update 2018-02
Operating Loss Carryforwards [Line Items]
Reclassification from AOCI, tax amount		$ (7)

Business Segments (Narrative) (

Business Segments (Narrative) (Details) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)segment	Sep. 30, 2017USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment				4
Segment Reporting Information [Line Items]
Loss due to commodities market default allocated to junior capital	$ 8
Liability Waterfall
Segment Reporting Information [Line Items]
Loss due to commodities market default allocated to junior capital	$ 8	$ 8	$ 0	$ 8	$ 0

Business Segments (Schedule of

Business Segments (Schedule of Operating Segments) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 964	$ 965	$ 3,141	$ 2,929
Transaction-based expenses	(364)	(362)	(1,259)	(1,149)
Revenues less transaction-based expenses	600	603	1,882	1,780
Operating income (loss)	246	262	787	750
Operating Segments | Market Services
Segment Reporting Information [Line Items]
Total revenues	586	581	1,968	1,808
Transaction-based expenses	(364)	(362)	(1,259)	(1,149)
Revenues less transaction-based expenses	222	219	709	659
Operating income (loss)	121	118	402	359
Operating Segments | Corporate Services
Segment Reporting Information [Line Items]
Total revenues	131	126	395	370
Transaction-based expenses	0	0	0	0
Revenues less transaction-based expenses	131	126	395	370
Operating income (loss)	42	41	122	115
Operating Segments | Information Services
Segment Reporting Information [Line Items]
Total revenues	179	150	528	432
Transaction-based expenses	0	0	0	0
Revenues less transaction-based expenses	179	150	528	432
Operating income (loss)	117	111	342	318
Operating Segments | Market Technology
Segment Reporting Information [Line Items]
Total revenues	68	62	194	176
Transaction-based expenses	0	0	0	0
Revenues less transaction-based expenses	68	62	194	176
Operating income (loss)	9	14	20	39
Corporate Items
Segment Reporting Information [Line Items]
Total revenues	0	46	56	143
Transaction-based expenses	0	0	0	0
Revenues less transaction-based expenses	0	46	56	143
Operating income (loss)	$ (43)	$ (22)	$ (99)	$ (81)

Business Segments (Corporate It

Business Segments (Corporate Items) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenues - divested businesses		$ 964	$ 965	$ 3,141	$ 2,929
Expenses:
Amortization expense of acquired intangible assets		27	22	83	67
Merger and strategic initiatives expense		6	3	7	20
Clearing default loss	$ 8
Extinguishment of debt				0	(9)
Operating loss		246	262	787	750
Corporate Items
Segment Reporting Information [Line Items]
Revenues - divested businesses		0	46	56	143
Expenses:
Amortization expense of acquired intangible assets		27	22	83	67
Merger and strategic initiatives expense		6	3	7	20
Extinguishment of debt		0	0	0	10
Expenses - divested businesses		0	42	51	125
Other		2	1	6	2
Total expenses		43	68	155	224
Operating loss		(43)	(22)	(99)	(81)
Liability Waterfall
Expenses:
Clearing default loss	$ 8	$ 8	$ 0	$ 8	$ 0

Subsequent Events (Details)

Subsequent Events (Details) € in Millions, $ in Millions	1 Months Ended		3 Months Ended			9 Months Ended		12 Months Ended
	Oct. 31, 2018USD ($)	Oct. 31, 2018EUR (€)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017	Oct. 18, 2018€ / $	Sep. 13, 2018kr / $
Subsequent Event [Line Items]
Reduction of revenue				$ (964)	$ (965)	$ (3,141)	$ (2,929)
Proceeds from sale of noncontrolling interests						$ 286	$ 0
SEK exchange rate | kr / $										8.96
Subsequent Event
Subsequent Event [Line Items]
SEK exchange rate | € / $									0.87
LCH
Subsequent Event [Line Items]
Ownership percentage						5.00%		5.00%
LCH | Subsequent Event
Subsequent Event [Line Items]
Ownership percentage	5.00%	5.00%
Proceeds from sale of noncontrolling interests	$ 171	€ 148
Restatement Adjustment | Scenario, Forecast
Subsequent Event [Line Items]
Reduction of revenue			$ 1