CME (CME) 10-Q 5 May 21 2021 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2021	Apr. 14, 2021
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-31553
Entity Registrant Name	CME GROUP INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-4459170
Entity Address, Street Address	20 South Wacker Drive
Entity Address, City	Chicago
Entity Address, State	IL
Entity Address, Postal Zip Code	60606
City Area Code	312
Local Phone Number	930-1000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of each class	Class A Common Stock
Trading symbol	CME
Name of each exchange on which registered	NASDAQ
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2021
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001156375
Amendment Flag	false
Class A Common Stock [Member]
Entity Common Stock, Shares Outstanding		359,094,042
Class B Common Stock, Class B-1 [Member]
Entity Common Stock, Shares Outstanding		625
Class B Common Stock, Class B-2 [Member]
Entity Common Stock, Shares Outstanding		813
Class B Common Stock, Class B-3 [Member]
Entity Common Stock, Shares Outstanding		1,287
Class B Common Stock, Class B-4 [Member]
Entity Common Stock, Shares Outstanding		413

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Assets
Cash and cash equivalents		$ 936.4	$ 1,633.2
Marketable securities		105.2	100.9
Accounts receivable, net of allowance of $6.0 and $5.4		547	461.3
Assets held for sale		1,447.5	0
Other current assets (includes $4.5 and $4.7 in restricted cash)		295.4	306.7
Performance bonds and guaranty fund contributions		123,414	86,781.8
Total current assets		126,745.5	89,283.9
Property, net of accumulated depreciation and amortization of $946.5 and $961.2		528.6	579.2
Intangible assets—trading products	[1]	17,175.3	17,175.3
Intangible assets—other, net		3,716.8	4,865.3
Goodwill		10,534.3	10,798.8
Other assets (includes $3.1 and $0.6 in restricted cash)		1,951.6	1,957.1
Total Assets		160,652.1	124,659.6
Liabilities and Equity
Accounts payable		51.6	69.3
Liabilities held for sale		278.8	0
Other current liabilities		478.1	1,346.8
Performance bonds and guaranty fund contributions		123,414	86,781.8
Total current liabilities		124,222.5	88,197.9
Long-term debt		3,443.6	3,443.8
Deferred income tax liabilities, net		5,371.9	5,607
Other liabilities		1,058.2	1,059.4
Total Liabilities		134,096.2	98,308.1
Shareholders' Equity:
Preferred stock, $0.01 par value, 10,000 shares authorized at March 31, 2021 and December 31, 2020; none issued		0	0
Additional paid-in capital		21,193.5	21,185.5
Retained earnings		5,247.3	4,995.9
Accumulated other comprehensive income (loss)		83.5	134.9
Total CME Group Shareholders’ Equity		26,527.9	26,319.9
Non-controlling interests		28	31.6
Total Equity		26,555.9	26,351.5
Total Liabilities and Equity		160,652.1	124,659.6
Class A Common Stock [Member]
Shareholders' Equity:
Common stock		3.6	3.6
Class B Common Stock [Member]
Shareholders' Equity:
Common stock		$ 0	$ 0
[1]	Trading products represent futures and options products acquired in our business combinations with CBOT Holdings, Inc., NYMEX Holdings, Inc. and The Board of Trade of Kansas City, Missouri, Inc. Clearing and transaction fees are generated through the trading of these products. These trading products, most of which have traded for decades, require authorization from the Commodity Futures Trading Commission (CFTC). Product authorizations from the CFTC have no term limits.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts receivable, allowance	$ 6	$ 5.4
Short-term restricted cash	4.5	4.7
Accumulated depreciation and amortization, property	946.5	961.2
Long-term restricted cash	$ 3.1	$ 0.6
Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	10,000	10,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Class A Common Stock [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, shares issued (in shares)	358,240	358,110
Common stock, shares outstanding (in shares)	358,240	358,110
Class B Common Stock [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	3	3
Common stock, shares issued (in shares)	3	3
Common stock, shares outstanding (in shares)	3	3

Consolidated Statements Of Inco

Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues
Total Revenues	$ 1,253.3	$ 1,522.1
Expenses
Compensation and benefits	225	207.5
Technology	48.2	47.7
Professional fees and outside services	37.4	41.7
Amortization of purchased intangibles	60.6	77.3
Depreciation and amortization	37.6	35.3
Licensing and other fee agreements	64.7	73.9
Other	54.7	78.8
Total Expenses	528.2	562.2
Operating Income	725.1	959.9
Non-Operating Income (Expense)
Investment income	30.9	95.9
Interest and other borrowing costs	(41.5)	(40.9)
Equity in net earnings of unconsolidated subsidiaries	56.2	51.2
Other non-operating income (expense)	(18.4)	(76.8)
Total Non-Operating Income (Expense)	27.2	29.4
Income before Income Taxes	752.3	989.3
Income tax provision	177.5	222.5
Net Income	574.8	766.8
Less: net (income) loss attributable to non-controlling interests	(0.4)	(0.6)
Net Income Attributable to CME Group	$ 574.4	$ 766.2
Earnings per Common Share Attributable to CME Group:
Basic (in dollars per share)	$ 1.60	$ 2.14
Diluted (in dollars per share)	$ 1.60	$ 2.14
Weighted Average Number of Common Shares:
Basic (in shares)	358,147	357,524
Diluted (in shares)	358,817	358,455
Clearing and transaction fees [Member]
Revenues
Total Revenues	$ 1,007	$ 1,278.8
Market data and information services
Revenues
Total Revenues	144.2	131.5
Other
Revenues
Total Revenues	$ 102.1	$ 111.8

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 574.8	$ 766.8
Other comprehensive income (loss), net of tax:
Net unrealized holding gains (losses) arising during the period	(1.1)	(0.6)
Income tax benefit (expense)	0.3	0.2
Investment securities, net	(0.8)	(0.4)
Net change in defined benefit plans arising during the period	0	(2)
Amortization of net actuarial (gains) losses included in compensation and benefits expense	1.1	1.2
Income tax benefit (expense)	(0.3)	0.2
Defined benefit plans, net	0.8	(0.6)
Reclassification of net unrealized (gains) losses to interest expense and other non-operating income (expense)	(0.3)	(1.8)
Income tax benefit (expense)	0.1	0.4
Derivative investments, net	(0.2)	(1.4)
Foreign currency translation adjustments	(51.2)	(27.8)
Reclassification of net currency (gains) losses from foreign entities to other expenses	0	0.6
Foreign currency translation, net	(51.2)	(27.2)
Other comprehensive income (loss), net of tax	(51.4)	(29.6)
Comprehensive income	523.4	737.2
Less: comprehensive (income) loss attributable to non-controlling interests	(0.4)	(0.6)
Comprehensive income attributable to CME Group	$ 523	$ 736.6

Consolidated Statements Of Shar

Consolidated Statements Of Shareholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Common Stock And Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Parent [Member]	Noncontrolling Interest [Member]	Class A Common Stock [Member]	Class A Common Stock [Member]Common Stock And Additional Paid-In Capital [Member]	Class B Common Stock [Member]	Class B Common Stock [Member]Common Stock And Additional Paid-In Capital [Member]
Balance (in shares) at Dec. 31, 2019								357,469		3
Balance at Dec. 31, 2019	$ 26,159.3	$ 21,116.8	$ 5,008.7	$ 3.4	$ 26,128.9
Balance at Dec. 31, 2019						$ 30.4
Less: net (income) loss attributable to non-controlling interests	(0.6)					(0.6)
Net Income Attributable to CME Group	766.2		766.2		766.2
Net Income	766.8
Other comprehensive income (loss), net of tax	(29.6)			(29.6)	(29.6)
Dividends, Cash	(304.7)		(304.7)		(304.7)
Impact of accounting standards update adoption	(0.3)		(0.3)		(0.3)
Exercise of stock options, shares								55
Exercise of stock options	3.2	3.2			3.2
Vesting of issued restricted Class A common stock, shares								153
Vesting of issued restricted Class A common stock	(19.1)	(19.1)			(19.1)
Stock-based compensation	23.1	23.1			23.1
Balance (in shares) at Mar. 31, 2020								357,677		3
Balance at Mar. 31, 2020	26,598.7	21,124	5,469.9	(26.2)	26,567.7
Balance at Mar. 31, 2020						31
Balance (in shares) at Dec. 31, 2020							358,110	358,110	3	3
Balance at Dec. 31, 2020	26,319.9	21,189.1	4,995.9	134.9	26,319.9
Balance at Dec. 31, 2020						31.6
Total Equity at Dec. 31, 2020	26,351.5
Less: net (income) loss attributable to non-controlling interests	(0.4)					0.4
Net Income Attributable to CME Group	574.4		574.4		574.4
Net Income	574.8
Other comprehensive income (loss), net of tax	(51.4)			(51.4)	(51.4)
Dividends, Cash	(323)		(323)		(323)
Purchase of noncontrolling interest	(6.2)	(2.2)			(2.2)	(4)
Exercise of stock options, shares								31
Exercise of stock options	1.7	1.7			1.7
Vesting of issued restricted Class A common stock, shares								99
Vesting of issued restricted Class A common stock	(13.1)	(13.1)			(13.1)
Stock-based compensation	21.6	21.6			21.6
Balance (in shares) at Mar. 31, 2021							358,240	358,240	3	3
Balance at Mar. 31, 2021	26,527.9	$ 21,197.1	$ 5,247.3	$ 83.5	$ 26,527.9
Balance at Mar. 31, 2021						$ 28
Total Equity at Mar. 31, 2021	$ 26,555.9

Consolidated Statements Of Sh_2

Consolidated Statements Of Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Cash dividends on common stock, per share (in dollars per share)	$ 0.90	$ 0.85

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash Flows from Operating Activities
Net Income	$ 574.8	$ 766.8
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation	21.6	23.1
Amortization of purchased intangibles	60.6	77.3
Depreciation and amortization	37.6	35.3
Net losses on impaired assets	0	23.1
Net (gain) loss on derivative contracts	0	(1.5)
Net realized and unrealized (gains) on investments	(0.8)	(2.9)
Cash dividends in excess of earnings (undistributed net earnings) of unconsolidated subsidiaries	13.1	(0.2)
Deferred income taxes	(7.8)	(9.7)
Change in:
Accounts receivable	(146.2)	(309.5)
Other current assets	(30.5)	(14.5)
Other assets	12.3	18.8
Accounts payable	(8.7)	12.4
Income taxes payable	115.7	186.1
Other current liabilities	(32.3)	(22.1)
Other liabilities	(8.6)	(29.5)
Other	1.9	4.1
Net Cash Provided by (Used in) Operating Activities	602.7	757.1
Cash Flows from Investing Activities
Proceeds from maturities of available-for-sale marketable securities	2.2	2.2
Purchases of available-for-sale marketable securities	(1.5)	(2.4)
Purchases of property, net	(28.5)	(42.8)
Purchase of non-controlling interest	(6.2)	0
Net Cash Used in Investing Activities	(34)	(43)
Cash Flows from Financing Activities
Repayment of commercial paper, net	0	(204.6)
Cash dividends	(1,217.5)	(1,197.6)
Employee taxes paid on restricted stock vesting	(13.1)	(19.1)
Other	(2.6)	7.4
Net Cash Used in Financing Activities	(1,233.2)	(1,413.9)
Net change in cash, cash equivalents and restricted cash	(664.5)	(699.8)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, beginning balance	1,638.5	1,556.6
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, ending balance	974	856.8
Cash and cash equivalents	936.4	851.7
Cash classified as assets held for sale	30	0
Short-term restricted cash	4.5	4.3
Long-term restricted cash	3.1	0.8
Income taxes paid	65.8	39
Interest paid	$ 42.4	$ 42.4

Basis Of Presentation

Basis Of Presentation	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis Of Presentation	Basis of Presentation The consolidated financial statements consist of CME Group Inc. (CME Group) and its subsidiaries (collectively, the company), including Chicago Mercantile Exchange Inc. (CME), Board of Trade of the City of Chicago, Inc. (CBOT), New York Mercantile Exchange, Inc. (NYMEX), Commodity Exchange, Inc. (COMEX) and NEX Group Limited (NEX). The clearing house is operated by CME. The accompanying interim consolidated financial statements have been prepared by CME Group without audit. Certain notes and other information normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted. In the opinion of management, the accompanying consolidated financial statements include all normal recurring adjustments considered necessary to present fairly the financial position of the company at March 31, 2021 and December 31, 2020 and the results of operations and cash flows for the periods indicated. Quarterly results are not necessarily indicative of results for any subsequent period. The accompanying consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto in CME Group’s Annual Report on Form 10-K for the year ended December 31, 2020, filed with the Securities and Exchange Commission (SEC) on February 26, 2021.

Revenue Recognition (Notes)

Revenue Recognition (Notes)	3 Months Ended
	Mar. 31, 2021
Revenue Recognition [Abstract]
Revenue Recognition, Deferred Revenue [Policy Text Block]	Revenue Recognition The company generates revenue from customers from the following sources: Clearing and transaction fees. Clearing and transaction fees include electronic trading fees and brokerage commissions, surcharges for privately-negotiated transactions, portfolio reconciliation and compression services, risk mitigation and other volume-related charges for trade contracts. Clearing and transaction fees are assessed upfront at the time of trade execution. As such, the company recognizes the majority of the fee revenue upon successful execution of the trade. The minimal remaining portion of the fee revenue related to settlement activities performed after trade execution is recognized over the short-term period that the contract is outstanding, based on management’s estimates of the average contract lifecycle. These estimates are based on various assumptions to approximate the amount of fee revenue to be attributed to services performed through contract settlement, expiration, or termination. For cleared trades, these assumptions include the average number of days that a contract remains in open interest, contract turnover, average revenue per day, and revenue remaining in open interest at the end of each period. The nature of contracts gives rise to several types of variable consideration, including volume-based pricing tiers, customer incentives associated with market maker programs and other fee discounts. The company includes fee discounts and incentives in the estimated transaction price when there is a basis to reasonably estimate the amount of the fee reduction. These estimates are based on historical experience, anticipated performance, and best judgment at the time. Because of the company's certainty in estimating these amounts, they are included in the transaction price of contracts. Market data and information services. Market data and information services represent revenue from the dissemination of market data to subscribers, distributors, and other third-party licensees of market data. Pricing for market data is primarily based on the number of reportable devices used as well as the number of subscribers enrolled under the arrangement. Fees for these services are generally billed monthly. Market data services are satisfied over time and revenue is recognized on a monthly basis as the customers receive and consume the benefit of the market data services. However, the company also maintains certain annual license arrangements with one-time upfront fees. The fees for annual licenses are initially recorded as a contract liability and recognized as revenue monthly over the term of the annual period. Other. Other revenues include certain access and communication fees, fees for collateral management, equity membership subscription fees, and fees for trade order routing through agreements from various strategic relationships. Access and communication fees are charges to customers that utilize various telecommunications networks and communications services. Fees for these services are generally billed monthly and the associated fee revenue is recognized as billed. Collateral management fees are charged to clearing firms that have collateral on deposit with the clearing house to meet their minimum performance bond and guaranty fund obligations on the exchange. These fees are calculated based on daily collateral balances and are billed monthly. This fee revenue is recognized monthly as billed as the customers receive and consume the benefits of the services. The company also has an equity membership program which provides equity members the option to substitute a monthly subscription fee for their existing requirement to hold CME Group Class A common stock. Choosing to pay this fee in lieu of holding Class A shares is entirely voluntary and the client's choice. Fee revenue under this program is earned monthly as billed over the contractual term. Pricing for strategic relationships may be driven by customer levels and activity. There are fee arrangements which provide for monthly as well as quarterly payments in arrears. Revenue is recognized monthly for strategic relationship arrangements as the customers receive and consume the benefits of the services. The following table represents a disaggregation of revenue from contracts with customers by product line for the quarters ended March 31, 2021 and 2020: Quarter Ended (in millions) 2021 2020 Interest rates $ 299.7 $ 418.3 Equity indexes 198.5 248.2 Foreign exchange 40.5 48.2 Agricultural commodities 120.5 117.7 Energy 158.1 221.8 Metals 58.3 78.8 Cash markets business 115.1 124.4 Interest rate swap 16.3 21.4 Total clearing and transaction fees 1,007.0 1,278.8 Market data and information services 144.2 131.5 Other 102.1 111.8 Total revenues $ 1,253.3 $ 1,522.1 Timing of Revenue Recognition Services transferred at a point in time $ 945.1 $ 1,211.2 Services transferred over time 305.2 307.5 One-time charges and miscellaneous revenues 3.0 3.4 Total revenues $ 1,253.3 $ 1,522.1 The timing of revenue recognition, billings and cash collections results in billed accounts receivable, and customer advances and deposits (contract liabilities) on the consolidated balance sheets. Certain fees for transactions, annual licenses, and other revenue arrangements are billed upfront before revenue is recognized, which results in the recognition of contract liabilities. These liabilities are recognized on the consolidated balance sheets on a contract-by-contract basis upon commencement of services under the customer contract. These upfront customer payments are recognized as revenue over time as the obligations under the contracts are satisfied. Changes in the contract liability balances during the three months ended March 31, 2021 were not materially impacted by any other factors. The balance of contract liabilities was $62.8 million

Assets and Liabilities Held for

Assets and Liabilities Held for Sale	3 Months Ended
	Mar. 31, 2021
Restructuring and Related Activities [Abstract]
Assets and Liabilities Held for Sale	Assets and Liabilities Held for Sale On January 12, 2021, the company announced that it has agreed with IHS Markit to combine their post-trade services into a new joint venture. The new company will perform trade processing and risk mitigation services . The company will contribute it's optimization business, which includes Traiana, TriOptima and Reset, to the new joint venture for an equity interest in the new company. The transaction is expected to close in mid-2021, subject to customary antitrust and regulatory approvals and other customary closing conditions. In January 2021, the net assets that will be contributed to the joint venture were classified as held for sale following approval of the transaction by the company's Board of Directors. The reclassification of the assets and liabilities to held for sale did not have an impact on earnings.

Performance Bonds and Guaranty

Performance Bonds and Guaranty Fund Contributions (Notes)	3 Months Ended
	Mar. 31, 2021
Performance Bonds and Guaranty Fund Contributions [Abstract]
Performance Bonds and Guaranty Fund Contributions	Performance Bonds and Guaranty Fund Contributions Performance Bonds and Guaranty Fund Contributions. CME has been designated as a systemically important financial market utility by the Financial Stability Oversight Council and is authorized to maintain cash accounts at the Federal Reserve Bank of Chicago. At March 31, 2021, CME maintained $111.5 billion within the cash account at the Federal Reserve Bank of Chicago. The cash deposit at the Federal Reserve Bank of Chicago is included within performance bonds and guaranty fund contributions on the consolidated balance sheets. Clearing House Contract Settlement. The clearing house marks-to-market open positions for all futures and options contracts twice a day (once a day for CME's cleared-only interest rate swap contracts). Based on values derived from the mark-to-market process, the clearing house requires payments from clearing firms whose positions have lost value and makes payments to clearing firms whose positions have gained value. Under the extremely unlikely scenario of simultaneous default by every clearing firm who has open positions with unrealized losses, the maximum exposure related to positions other than cleared-only interest rate swap contracts would be one half day of changes in fair value of all open positions, before considering the clearing house's ability to access defaulting clearing firms' collateral deposits. For CME's cleared-only interest rate swap contracts, the maximum exposure related to CME's guarantee would be one full day of changes in fair value of all open positions, before considering CME's ability to access defaulting clearing firms' collateral.

Intangible Assets And Goodwill

Intangible Assets And Goodwill	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets And Goodwill	Intangible Assets and Goodwill In January 2021, the net assets that will be contributed to a joint venture with IHS Markit were classified as held for sale. As a result, $1.1 billion of amortizable intangible assets were reclassified to assets held for sale on the consolidated balance sheet. Amortization expense is no longer taken on these intangible assets once reclassified to assets held for sale. Intangible assets consisted of the following at March 31, 2021 and December 31, 2020: March 31, 2021 December 31, 2020 (in millions) Assigned Value Reclassified as Held for Sale Accumulated Net Book Assigned Value Accumulated Net Book Amortizable Intangible Assets: Clearing firm, market data and other customer relationships $ 5,822.7 $ (946.7) $ (1,684.0) $ 3,192.0 $ 5,858.0 $ (1,632.5) $ 4,225.5 Technology-related intellectual property 174.8 (84.3) (69.6) 20.9 178.4 (68.2) 110.2 Other 106.4 (23.1) (29.4) 53.9 106.9 (27.3) 79.6 Total amortizable intangible assets $ 6,103.9 $ (1,054.1) $ (1,783.0) 3,266.8 $ 6,143.3 $ (1,728.0) 4,415.3 Indefinite-Lived Intangible Assets: Trade names 450.0 450.0 Total intangible assets – other, net $ 3,716.8 $ 4,865.3 Trading products (1) $ 17,175.3 $ 17,175.3 (1) Trading products represent futures and options products acquired in our business combinations with CBOT Holdings, Inc., NYMEX Holdings, Inc. and The Board of Trade of Kansas City, Missouri, Inc. Clearing and transaction fees are generated through the trading of these products. These trading products, most of which have traded for decades, require authorization from the Commodity Futures Trading Commission (CFTC). Product authorizations from the CFTC have no term limits. Total amortization expense for intangible assets was $60.6 million and $77.3 million for the quarters ended March 31, 2021 and 2020, respectively. As of March 31, 2021, the future estimated amortization expense related to amortizable intangible assets is expected to be as follows: (in millions) Amortization Expense Remainder of 2021 $ 174.8 2022 233.1 2023 231.7 2024 225.0 2025 225.0 2026 225.0 Thereafter 1,952.2 Goodwill activity consisted of the following for the periods ended March 31, 2021 and December 31, 2020 : (in millions) Balance at December 31, 2020 Reclassified as Held for Sale Other Activity (1) Balance at March 31, 2021 CBOT Holdings $ 5,066.4 $ — $ — $ 5,066.4 NYMEX Holdings 2,462.2 — — 2,462.2 NEX 3,229.8 (246.1) (18.4) 2,965.3 Other 40.4 — — 40.4 Total Goodwill $ 10,798.8 $ (246.1) $ (18.4) $ 10,534.3 (in millions) Balance at December 31, 2019 Reclassified as Held for Sale Other Activity (1) Balance at December 31, 2020 CBOT Holdings $ 5,066.4 $ — $ — $ 5,066.4 NYMEX Holdings 2,462.2 — — 2,462.2 NEX 3,173.5 — 56.3 3,229.8 Other 40.4 — — 40.4 Total Goodwill $ 10,742.5 $ — $ 56.3 $ 10,798.8 __________ 1) Other activity includes currency translation adjustments.

Debt

Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Debt	Debt Long-term debt consisted of the following at March 31, 2021 and December 31, 2020: (in millions) March 31, 2021 December 31, 2020 $750.0 million fixed rate notes due September 2022, stated rate of 3.00% (1) $ 748.8 $ 748.6 €15.0 million fixed rate notes due May 2023, stated rate of 4.30% 17.3 18.1 $750.0 million fixed rate notes due March 2025, stated rate of 3.00% (2) 747.2 747.0 $500.0 million fixed rate notes due June 2028, stated rate of 3.75% 496.9 496.8 $750.0 million fixed rate notes due September 2043, stated rate of 5.30% (3) 743.1 743.1 $700.0 million fixed rate notes due June 2048, stated rate of 4.15% 690.3 690.2 Total long-term debt $ 3,443.6 $ 3,443.8 (1) The company maintained a forward-starting interest rate swap agreement that modified the interest obligation associated with these notes so that the interest payable on the notes effectively became fixed at a rate of 3.32%. (2) The company maintained a forward-starting interest rate swap agreement that modified the interest obligation associated with these notes so that the interest payable on the notes effectively became fixed at a rate of 3.11%. (3) The company maintained a forward-starting interest rate swap agreement that modified the interest obligation associated with these notes so that the interest payable on the notes effectively became fixed at a rate of 4.73%. Long-term debt maturities, at par value (in U.S. dollar equivalent), were as follows at March 31, 2021: (in millions) Par Value 2022 $ 750.0 2023 17.6 2024 — 2025 750.0 2026 — Thereafter 1,950.0

Contingencies

Contingencies	3 Months Ended
	Mar. 31, 2021
Loss Contingency [Abstract]
Contingencies	Contingencies Legal and Regulatory Matters. In the normal course of business, the company discusses matters with its regulators raised during regulatory examinations or otherwise subject to their inquiry and oversight. These matters could result in censures, fines, penalties or other sanctions. Management believes the outcome of any resulting actions will not have a material impact on its consolidated financial position or results of operations. However, the company is 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. In addition, the company is a defendant in, and has potential for, various other legal proceedings arising from its regular business activities. While the ultimate results of such proceedings against the company cannot be predicted with certainty, the company believes that the resolution of any of these matters on an individual or aggregate basis will not have a material impact on its co nsolidated financial position or results of operations. No accrual was required for legal and regulatory matters as none were probable and estimable as of March 31, 2021 and December 31, 2020. Intellectual Property Indemnifications . Certain agreements with customers and other third parties related to accessing the CME Group platforms, utilizing market data services and licensing CME SPAN software may contain indemnifications from intellectual property claims that may be made against them as a result of their use of the applicable products and/or services. The potential future claims relating to these indemnifications cannot be estimated and therefore no liability has been recorded.

Leases (Notes)

Leases (Notes)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Lessee, Leases [Policy Text Block]	Leases The company has operating leases for corporate offices. The operating leases have remaining lease terms of up to 17 years, some of which include options to extend or renew the leases for up to an additional five years, and some of which include options to early terminate the leases in less than 12 months. Management evaluates whether these options are exercisable at least quarterly in order to determine whether the contract term must be reassessed. For a small number of the leases, primarily the international locations, management's approach is to enter into short-term leases for a lease term of 12 months or less in order to provide for greater flexibility in the local environment. For certain office spaces, the company has entered into arrangements to sublease excess space to third parties, while the original lease contract remains in effect with the landlord. The company also has one finance lease, which is related to the sale of our data center in March 2016. In connection with the sale, the company leased back a portion of the property. The sale leaseback transaction was recognized under the financing method and not as a sale leaseback arrangement. The right-of-use lease asset is recorded within other assets, and the present value of the lease liability is recorded within other liabilities (segregated between short term and long term) on the consolidated balance sheets. The discount rate applied to the lease payments represents the company's incremental borrowing rate. The components of lease costs were as follows: Quarter Ended (in millions) 2021 2020 Operating lease expense: Operating lease cost $ 16.8 $ 14.9 Short-term lease cost 0.2 0.2 Total operating lease expense included in other expense $ 17.0 $ 15.1 Finance lease expense: Interest expense $ 0.8 $ 0.9 Depreciation expense 2.2 2.2 Total finance lease expense $ 3.0 $ 3.1 Sublease revenue included in other revenue $ 2.5 $ 3.6 Supplemental cash flow information related to leases was as follows: Quarter Ended (in millions) 2021 2020 Cash outflows for operating leases $ 15.3 $ 15.9 Cash outflows for finance leases 4.2 4.2 Supplemental balance sheet information related to leases was as follows: Operating leases (in millions) March 31, 2021 December 31, 2020 Operating lease right-of-use assets $ 386.5 $ 390.3 Operating lease liabilities: Other current liabilities $ 47.3 $ 44.5 Other liabilities 491.3 492.2 Total operating lease liabilities $ 538.6 $ 536.7 Weighted average remaining lease term (in months) 137 138 Weighted average discount rate 3.9 % 3.9 % Finance leases (in millions) March 31, 2021 December 31, 2020 Finance lease right-of-use assets $ 86.7 $ 88.8 Finance lease liabilities: Other current liabilities $ 7.7 $ 7.7 Other liabilities 81.9 83.8 Total finance lease liabilities $ 89.6 $ 91.5 Weighted average remaining lease term (in months) 120 123 Weighted average discount rate 3.5 % 3.5 % Future minimum lease payments were as follows as of March 31, 2021 for operating and finance leases: (in millions) Operating Leases Remainder of 2021 $ 49.7 2022 69.7 2023 68.0 2024 61.7 2025 58.8 2026 54.3 Thereafter 306.7 Total lease payments 668.9 Less: imputed interest (130.3) Present value of lease liability $ 538.6 (in millions) Finance Leases Remainder of 2021 $ 12.7 2022 17.1 2023 17.2 2024 17.4 2025 17.5 2026 17.6 Thereafter 76.7 Total lease payments 176.2 Less: imputed interest (86.6) Present value of lease liability $ 89.6

Guarantees

Guarantees	3 Months Ended
	Mar. 31, 2021
Guarantees [Abstract]
Guarantees	Guarantees Mutual Offset Agreement. CME and Singapore Exchange Limited (SGX) maintain a mutual offset agreement with a current term through May 2023. This agreement enables market participants to open a futures position on one exchange and liquidate it on the other. The term of the agreement will automatically renew for a one-year period after May 2023 unless either party provides advance notice of their intent to terminate. CME can maintain collateral in the form of irrevocable, standby letters of credit. At March 31, 2021, CME was contingently liable to SGX on letters of credit totaling $310.0 million . CME also maintains a $350.0 million line of credit to meet its obligations under this agreement. Regardless of the collateral, CME guarantees all cleared transactions submitted through SGX and would initiate procedures designed to satisfy these financial obligations in the event of a default, such as the use of performance bonds and guaranty fund contributions of the defaulting clearing firm. Management has assessed the fair value of the company's guarantee liability under this mutual offset agreement by taking the following factors into consideration: the design and operations of the clearing risk management process, the financial safeguard packages in place, historical evidence of default by a clearing member and the estimated probability of potential payouts by the clearing house. Based on the assessment performed, management estimates the guarantee liability to be nominal and therefore has not recorded any liability at March 31, 2021. Family Farmer and Rancher Protection Fund. In 2012, the company established the Family Farmer and Rancher Protection Fund (the Fund). The Fund is designed to provide payments, up to certain maximum levels, to family farmers, ranchers and other agricultural industry participants who use the company's agricultural commodity products and who suffer losses to their segregated account balances due to their CME clearing member becoming insolvent. Under the terms of the Fund, farmers and ranchers are eligible for up to $25,000 per participant. Farming and ranching cooperatives are eligible for up to $100,000 per cooperative. The Fund was established with a maximum of $100.0 million available for distribution to participants. Since its establishment, the Fund has made payments of approximately $2.0 million, which leaves $98.0 million available for future claims. If, at any time, payments due to participants were to exceed the amount remaining in the fund, payments would be pro-rated. Clearing members and customers must register with the company in advance and provide certain documentation in order to substantiate their eligibility. The company believes that its guarantee liability is nominal and therefore has not recorded any liability at March 31, 2021.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Notes)	3 Months Ended
	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following tables present changes in the accumulated balances for each component of other comprehensive income (loss), including current period other comprehensive income (loss) and reclassifications out of accumulated other comprehensive income (loss): (in millions) Investment Securities Defined Benefit Plans Derivative Investments Foreign Currency Translation Total Balance at December 31, 2020 $ 1.6 $ (57.1) $ 67.0 $ 123.4 $ 134.9 Other comprehensive income (loss) before reclassifications and income tax benefit (expense) (1.1) — — (51.2) (52.3) Amounts reclassified from accumulated other comprehensive income (loss) — 1.1 (0.3) — 0.8 Income tax benefit (expense) 0.3 (0.3) 0.1 — 0.1 Net current period other comprehensive income (loss) (0.8) 0.8 (0.2) (51.2) (51.4) Balance at March 31, 2021 $ 0.8 $ (56.3) $ 66.8 $ 72.2 $ 83.5 (in millions) Investment Securities Defined Benefit Plans Derivative Investments Foreign Currency Translation Total Balance at December 31, 2019 $ 0.8 $ (55.1) $ 69.0 $ (11.3) $ 3.4 Other comprehensive income (loss) before reclassifications and income tax benefit (expense) (0.6) (2.0) — (27.8) (30.4) Amounts reclassified from accumulated other comprehensive income (loss) — 1.2 (1.8) 0.6 — Income tax benefit (expense) 0.2 0.2 0.4 — 0.8 Net current period other comprehensive income (loss) (0.4) (0.6) (1.4) (27.2) (29.6) Balance at March 31, 2020 $ 0.4 $ (55.7) $ 67.6 $ (38.5) $ (26.2)

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value by Fair Value Hierarchy Level Extensible List [Abstract]
Fair Value Measurements	Fair Value Measurements The company uses a three-level classification hierarchy of fair value measurements for disclosure purposes: • Level 1 inputs, which are considered the most reliable evidence of fair value, consist of quoted prices (unadjusted) for identical assets or liabilities in active markets. • Level 2 inputs consist of observable market data, such as quoted prices for similar assets and liabilities in active markets, or inputs other than quoted prices that are directly observable. • Level 3 inputs consist of unobservable inputs which are derived and cannot be corroborated by market data or other entity-specific inputs. The company's level 1 assets generally include investments in publicly traded mutual funds, equity securities and corporate debt securities with quoted market prices. In general, the company uses quoted prices in active markets for identical assets to determine the fair value of marketable securities. The company's level 2 assets and liabilities generally consist of asset-backed securities and long-term debt notes. Asset-backed securities were measured at fair value based on matrix pricing using prices of similar securities with similar inputs such as maturity dates, interest rates and credit ratings. The fair values of the long-term debt notes were based on quoted market prices in an inactive market. The company's level 3 assets and liabilities include certain fixed assets and investments that were impaired or written up in fair value. Recurring Fair Value Measurements. Financial assets and liabilities recorded at fair value on the consolidated balance sheet as of March 31, 2021 were classified in their entirety based on the lowest level of input that was significant to each asset and liability's fair value measurement. The following table presents financial instruments measured at fair value on a recurring basis: March 31, 2021 (in millions) Level 1 Level 2 Level 3 Total Assets at Fair Value: Marketable securities: Corporate debt securities $ 17.0 $ — $ — $ 17.0 Mutual funds 87.7 — — 87.7 Equity securities 0.2 — — 0.2 Asset-backed securities — 0.3 — 0.3 Total Marketable Securities 104.9 0.3 — 105.2 Total Assets at Fair Value $ 104.9 $ 0.3 $ — $ 105.2 Non-Recurring Fair Value Measurements. The company recognized impairment charges of $0.5 million related to certain fixed assets. The fair values of these fixed assets were estimated to be zero at March 31, 2021. The company also recognized a net unrealized gain on an investment of $0.8 million . The fair value of the investment was estimated to be $9.4 million at March 31, 2021. These assessments were based on quantitative and qualitative indicators of fair value. The fair value measurements of the fixed assets and investment are considered level 3 and non-recurring. Fair Values of Long-Term Debt Notes. The following presents the estimated fair values of long-term debt notes, which are carried at amortized cost on the consolidated balance sheets. The fair values below are classified as level 2 under the fair value hierarchy and were estimated using quoted market prices in inactive markets. At March 31, 2021, the fair values (in U.S. dollar equivalent) were as follows: (in millions) Fair Value Level $750.0 million fixed rate notes due September 2022 $ 779.4 Level 2 €15.0 million fixed rate notes due May 2023 19.2 Level 2 $750.0 million fixed rate notes due March 2025 802.8 Level 2 $500.0 million fixed rate notes due June 2028 557.4 Level 2 $750.0 million fixed rate notes due September 2043 1,015.3 Level 2 $700.0 million fixed rate notes due June 2048 845.1 Level 2

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic earnings per share is computed by dividing net income by the weighted average number of shares of all classes of CME Group common stock outstanding for each reporting period. Diluted earnings per share reflects the increase in shares using the treasury stock method to reflect the impact of an equivalent number of shares of common stock if stock options were exercised and restricted stock awards were converted into common stock. Anti-dilutive stock awards were as follows for the periods presented: Quarter Ended (in thousands) 2021 2020 Stock awards 154 68 Total 154 68 The following table presents the earnings per share calculation for the periods presented: Quarter Ended 2021 2020 Net Income Attributable to CME Group (in millions) $ 574.4 $ 766.2 Weighted Average Number of Common Shares (in thousands): Basic 358,147 357,524 Effect of stock options, restricted stock and performance shares 670 931 Diluted 358,817 358,455 Earnings per Common Share Attributable to CME Group: Basic $ 1.60 $ 2.14 Diluted 1.60 2.14

Subsequent Events (Notes)

Subsequent Events (Notes)	3 Months Ended
	Mar. 31, 2021
Subsequent Event [Line Items]
Subsequent Events [Text Block]	Subsequent EventsThe company has evaluated subsequent events through the date the financial statements were issued. The company has determined that there were no subsequent events.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	3 Months Ended
	Mar. 31, 2021
Revenue Recognition [Abstract]
Disaggregation of Revenue [Table Text Block]	The following table represents a disaggregation of revenue from contracts with customers by product line for the quarters ended March 31, 2021 and 2020: Quarter Ended (in millions) 2021 2020 Interest rates $ 299.7 $ 418.3 Equity indexes 198.5 248.2 Foreign exchange 40.5 48.2 Agricultural commodities 120.5 117.7 Energy 158.1 221.8 Metals 58.3 78.8 Cash markets business 115.1 124.4 Interest rate swap 16.3 21.4 Total clearing and transaction fees 1,007.0 1,278.8 Market data and information services 144.2 131.5 Other 102.1 111.8 Total revenues $ 1,253.3 $ 1,522.1 Timing of Revenue Recognition Services transferred at a point in time $ 945.1 $ 1,211.2 Services transferred over time 305.2 307.5 One-time charges and miscellaneous revenues 3.0 3.4 Total revenues $ 1,253.3 $ 1,522.1

Intangible Assets And Goodwill

Intangible Assets And Goodwill (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Components of intangible assets	Intangible assets consisted of the following at March 31, 2021 and December 31, 2020: March 31, 2021 December 31, 2020 (in millions) Assigned Value Reclassified as Held for Sale Accumulated Net Book Assigned Value Accumulated Net Book Amortizable Intangible Assets: Clearing firm, market data and other customer relationships $ 5,822.7 $ (946.7) $ (1,684.0) $ 3,192.0 $ 5,858.0 $ (1,632.5) $ 4,225.5 Technology-related intellectual property 174.8 (84.3) (69.6) 20.9 178.4 (68.2) 110.2 Other 106.4 (23.1) (29.4) 53.9 106.9 (27.3) 79.6 Total amortizable intangible assets $ 6,103.9 $ (1,054.1) $ (1,783.0) 3,266.8 $ 6,143.3 $ (1,728.0) 4,415.3 Indefinite-Lived Intangible Assets: Trade names 450.0 450.0 Total intangible assets – other, net $ 3,716.8 $ 4,865.3 Trading products (1) $ 17,175.3 $ 17,175.3 (1) Trading products represent futures and options products acquired in our business combinations with CBOT Holdings, Inc., NYMEX Holdings, Inc. and The Board of Trade of Kansas City, Missouri, Inc. Clearing and transaction fees are generated through the trading of these products. These trading products, most of which have traded for decades, require authorization from the Commodity Futures Trading Commission (CFTC). Product authorizations from the CFTC have no term limits.
Future estimated amortization expense	As of March 31, 2021, the future estimated amortization expense related to amortizable intangible assets is expected to be as follows: (in millions) Amortization Expense Remainder of 2021 $ 174.8 2022 233.1 2023 231.7 2024 225.0 2025 225.0 2026 225.0 Thereafter 1,952.2
Schedule of Goodwill	Goodwill activity consisted of the following for the periods ended March 31, 2021 and December 31, 2020 : (in millions) Balance at December 31, 2020 Reclassified as Held for Sale Other Activity (1) Balance at March 31, 2021 CBOT Holdings $ 5,066.4 $ — $ — $ 5,066.4 NYMEX Holdings 2,462.2 — — 2,462.2 NEX 3,229.8 (246.1) (18.4) 2,965.3 Other 40.4 — — 40.4 Total Goodwill $ 10,798.8 $ (246.1) $ (18.4) $ 10,534.3 (in millions) Balance at December 31, 2019 Reclassified as Held for Sale Other Activity (1) Balance at December 31, 2020 CBOT Holdings $ 5,066.4 $ — $ — $ 5,066.4 NYMEX Holdings 2,462.2 — — 2,462.2 NEX 3,173.5 — 56.3 3,229.8 Other 40.4 — — 40.4 Total Goodwill $ 10,742.5 $ — $ 56.3 $ 10,798.8 __________ 1) Other activity includes currency translation adjustments.

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	Long-term debt consisted of the following at March 31, 2021 and December 31, 2020: (in millions) March 31, 2021 December 31, 2020 $750.0 million fixed rate notes due September 2022, stated rate of 3.00% (1) $ 748.8 $ 748.6 €15.0 million fixed rate notes due May 2023, stated rate of 4.30% 17.3 18.1 $750.0 million fixed rate notes due March 2025, stated rate of 3.00% (2) 747.2 747.0 $500.0 million fixed rate notes due June 2028, stated rate of 3.75% 496.9 496.8 $750.0 million fixed rate notes due September 2043, stated rate of 5.30% (3) 743.1 743.1 $700.0 million fixed rate notes due June 2048, stated rate of 4.15% 690.3 690.2 Total long-term debt $ 3,443.6 $ 3,443.8 (1) The company maintained a forward-starting interest rate swap agreement that modified the interest obligation associated with these notes so that the interest payable on the notes effectively became fixed at a rate of 3.32%. (2) The company maintained a forward-starting interest rate swap agreement that modified the interest obligation associated with these notes so that the interest payable on the notes effectively became fixed at a rate of 3.11%.
Schedule of Maturities of Long-term Debt [Table Text Block]	Long-term debt maturities, at par value (in U.S. dollar equivalent), were as follows at March 31, 2021: (in millions) Par Value 2022 $ 750.0 2023 17.6 2024 — 2025 750.0 2026 — Thereafter 1,950.0

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Lease, Cost [Table Text Block]	The components of lease costs were as follows: Quarter Ended (in millions) 2021 2020 Operating lease expense: Operating lease cost $ 16.8 $ 14.9 Short-term lease cost 0.2 0.2 Total operating lease expense included in other expense $ 17.0 $ 15.1 Finance lease expense: Interest expense $ 0.8 $ 0.9 Depreciation expense 2.2 2.2 Total finance lease expense $ 3.0 $ 3.1 Sublease revenue included in other revenue $ 2.5 $ 3.6
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]	Supplemental cash flow information related to leases was as follows: Quarter Ended (in millions) 2021 2020 Cash outflows for operating leases $ 15.3 $ 15.9 Cash outflows for finance leases 4.2 4.2
Schedule of Amounts Recognized in Balance Sheet [Table Text Block]	Supplemental balance sheet information related to leases was as follows: Operating leases (in millions) March 31, 2021 December 31, 2020 Operating lease right-of-use assets $ 386.5 $ 390.3 Operating lease liabilities: Other current liabilities $ 47.3 $ 44.5 Other liabilities 491.3 492.2 Total operating lease liabilities $ 538.6 $ 536.7 Weighted average remaining lease term (in months) 137 138 Weighted average discount rate 3.9 % 3.9 % Finance leases (in millions) March 31, 2021 December 31, 2020 Finance lease right-of-use assets $ 86.7 $ 88.8 Finance lease liabilities: Other current liabilities $ 7.7 $ 7.7 Other liabilities 81.9 83.8 Total finance lease liabilities $ 89.6 $ 91.5 Weighted average remaining lease term (in months) 120 123 Weighted average discount rate 3.5 % 3.5 %
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	Future minimum lease payments were as follows as of March 31, 2021 for operating and finance leases: (in millions) Operating Leases Remainder of 2021 $ 49.7 2022 69.7 2023 68.0 2024 61.7 2025 58.8 2026 54.3 Thereafter 306.7 Total lease payments 668.9 Less: imputed interest (130.3) Present value of lease liability $ 538.6
Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]	(in millions) Finance Leases Remainder of 2021 $ 12.7 2022 17.1 2023 17.2 2024 17.4 2025 17.5 2026 17.6 Thereafter 76.7 Total lease payments 176.2 Less: imputed interest (86.6) Present value of lease liability $ 89.6

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following tables present changes in the accumulated balances for each component of other comprehensive income (loss), including current period other comprehensive income (loss) and reclassifications out of accumulated other comprehensive income (loss): (in millions) Investment Securities Defined Benefit Plans Derivative Investments Foreign Currency Translation Total Balance at December 31, 2020 $ 1.6 $ (57.1) $ 67.0 $ 123.4 $ 134.9 Other comprehensive income (loss) before reclassifications and income tax benefit (expense) (1.1) — — (51.2) (52.3) Amounts reclassified from accumulated other comprehensive income (loss) — 1.1 (0.3) — 0.8 Income tax benefit (expense) 0.3 (0.3) 0.1 — 0.1 Net current period other comprehensive income (loss) (0.8) 0.8 (0.2) (51.2) (51.4) Balance at March 31, 2021 $ 0.8 $ (56.3) $ 66.8 $ 72.2 $ 83.5 (in millions) Investment Securities Defined Benefit Plans Derivative Investments Foreign Currency Translation Total Balance at December 31, 2019 $ 0.8 $ (55.1) $ 69.0 $ (11.3) $ 3.4 Other comprehensive income (loss) before reclassifications and income tax benefit (expense) (0.6) (2.0) — (27.8) (30.4) Amounts reclassified from accumulated other comprehensive income (loss) — 1.2 (1.8) 0.6 — Income tax benefit (expense) 0.2 0.2 0.4 — 0.8 Net current period other comprehensive income (loss) (0.4) (0.6) (1.4) (27.2) (29.6) Balance at March 31, 2020 $ 0.4 $ (55.7) $ 67.6 $ (38.5) $ (26.2)

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial instruments measured at fair value on a recurring basis	The following table presents financial instruments measured at fair value on a recurring basis: March 31, 2021 (in millions) Level 1 Level 2 Level 3 Total Assets at Fair Value: Marketable securities: Corporate debt securities $ 17.0 $ — $ — $ 17.0 Mutual funds 87.7 — — 87.7 Equity securities 0.2 — — 0.2 Asset-backed securities — 0.3 — 0.3 Total Marketable Securities 104.9 0.3 — 105.2 Total Assets at Fair Value $ 104.9 $ 0.3 $ — $ 105.2
Fair value of Debt Instruments	At March 31, 2021, the fair values (in U.S. dollar equivalent) were as follows: (in millions) Fair Value Level $750.0 million fixed rate notes due September 2022 $ 779.4 Level 2 €15.0 million fixed rate notes due May 2023 19.2 Level 2 $750.0 million fixed rate notes due March 2025 802.8 Level 2 $500.0 million fixed rate notes due June 2028 557.4 Level 2 $750.0 million fixed rate notes due September 2043 1,015.3 Level 2 $700.0 million fixed rate notes due June 2048 845.1 Level 2

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	Anti-dilutive stock awards were as follows for the periods presented: Quarter Ended (in thousands) 2021 2020 Stock awards 154 68 Total 154 68
Basic And Diluted Earnings Per Share	The following table presents the earnings per share calculation for the periods presented: Quarter Ended 2021 2020 Net Income Attributable to CME Group (in millions) $ 574.4 $ 766.2 Weighted Average Number of Common Shares (in thousands): Basic 358,147 357,524 Effect of stock options, restricted stock and performance shares 670 931 Diluted 358,817 358,455 Earnings per Common Share Attributable to CME Group: Basic $ 1.60 $ 2.14 Diluted 1.60 2.14

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Revenue Recognition [Abstract]
Deferred Revenue	$ 62.8	$ 37.3

Revenue Recognition Disaggregat

Revenue Recognition Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Total Revenues	$ 1,253.3	$ 1,522.1
Services transferred at a point in time [Member]
Revenues	945.1	1,211.2
Services transferred over time [Member]
Revenues	305.2	307.5
One-time charges and miscellaneous revenues [Member]
Revenues	3	3.4
Clearing and transaction fees [Member]
Revenues	1,007	1,278.8
Total Revenues	1,007	1,278.8
Clearing and transaction fees [Member] | Interest rate [Member]
Revenues	299.7	418.3
Clearing and transaction fees [Member] | Equities [Member]
Revenues	198.5	248.2
Clearing and transaction fees [Member] | Foreign Exchange [Member]
Revenues	40.5	48.2
Clearing and transaction fees [Member] | Agricultural commodity [Member]
Revenues	120.5	117.7
Clearing and transaction fees [Member] | Energy [Member]
Revenues	158.1	221.8
Clearing and transaction fees [Member] | Metal [Member]
Revenues	58.3	78.8
Clearing and transaction fees [Member] | Cash Markets [Member]
Revenues	115.1	124.4
Clearing and transaction fees [Member] | Interest Rate Swap [Member]
Revenues	16.3	21.4
Market data and information services
Revenues	144.2	131.5
Total Revenues	144.2	131.5
Other
Revenues	102.1	111.8
Total Revenues	$ 102.1	$ 111.8

Performance Bonds and Guarant_2

Performance Bonds and Guaranty Fund Contributions (Details) $ in Billions	3 Months Ended
	Mar. 31, 2021USD ($)
Guarantor Obligations [Line Items]
Average Daily Clearing Settlement	$ 4.6
Federal Reserve Reinvestment [Member]
Guarantor Obligations [Line Items]
Cash Equivalents, at Carrying Value	$ 111.5

Intangible Assets And Goodwil_2

Intangible Assets And Goodwill (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Jan. 12, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of purchased intangibles	$ 60.6	$ 77.3
Disposal Group, Including Discontinued Operation, Intangible Assets			$ 1,100

Intangible Assets And Goodwil_3

Intangible Assets And Goodwill (Components Of Intangible Assets) (Details) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Intangible Assets [Line Items]
Net book value		$ 3,716.8	$ 4,865.3
Intangible assets—other, net		3,716.8	4,865.3
Intangible assets—trading products	[1]	17,175.3	17,175.3
Trade Names [Member]
Intangible Assets [Line Items]
Total intangible assets - other, net		450	450
Clearing Firm, Market Data And Other Customer Relationships [Member]
Intangible Assets [Line Items]
Assigned Value		5,822.7	5,858
Intangible Assets Reclassified as Held for Sale		(946.7)
Accumulated amortization		(1,684)	(1,632.5)
Net book value		3,192	4,225.5
Technology-Related Intellectual Property [Member]
Intangible Assets [Line Items]
Assigned Value		174.8	178.4
Intangible Assets Reclassified as Held for Sale		(84.3)
Accumulated amortization		(69.6)	(68.2)
Net book value		20.9	110.2
Other [Member]
Intangible Assets [Line Items]
Assigned Value		106.4	106.9
Intangible Assets Reclassified as Held for Sale		(23.1)
Accumulated amortization		(29.4)	(27.3)
Net book value		53.9	79.6
Total Amortizable Intangible Assets [Member]
Intangible Assets [Line Items]
Assigned Value		6,103.9	6,143.3
Intangible Assets Reclassified as Held for Sale		(1,054.1)
Accumulated amortization		(1,783)	(1,728)
Net book value		$ 3,266.8	$ 4,415.3
[1]	Trading products represent futures and options products acquired in our business combinations with CBOT Holdings, Inc., NYMEX Holdings, Inc. and The Board of Trade of Kansas City, Missouri, Inc. Clearing and transaction fees are generated through the trading of these products. These trading products, most of which have traded for decades, require authorization from the Commodity Futures Trading Commission (CFTC). Product authorizations from the CFTC have no term limits.

Intangible Assets And Goodwil_4

Intangible Assets And Goodwill (Future Estimated Amortization Expense) (Details) $ in Millions	Mar. 31, 2021USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2021	$ 174.8
2022	233.1
2023	231.7
2024	225
2025	225
2026	225
Thereafter	$ 1,952.2

Intangible Assets And Goodwil_5

Intangible Assets And Goodwill (Components of Goodwill) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill	$ 10,534.3	$ 10,798.8
CBOT
Goodwill [Line Items]
Goodwill	5,066.4	5,066.4	$ 5,066.4
Goodwill, Other Increase (Decrease)	0	0
Disposal Group, Including Discontinued Operation, Goodwill	0	0
NYMEX
Goodwill [Line Items]
Goodwill	2,462.2	2,462.2	2,462.2
Goodwill, Other Increase (Decrease)	0	0
Disposal Group, Including Discontinued Operation, Goodwill	0	0
NEX
Goodwill [Line Items]
Goodwill	2,965.3	3,229.8	3,173.5
Goodwill, Other Increase (Decrease)	(18.4)	56.3
Disposal Group, Including Discontinued Operation, Goodwill	(246.1)	0
Other CME Segments
Goodwill [Line Items]
Goodwill	40.4	40.4	40.4
Goodwill, Other Increase (Decrease)	0	0
Disposal Group, Including Discontinued Operation, Goodwill	0	0
CME Group Inc.
Goodwill [Line Items]
Goodwill	10,534.3	10,798.8	$ 10,742.5
Goodwill, Other Increase (Decrease)	(18.4)	56.3
Disposal Group, Including Discontinued Operation, Goodwill	$ (246.1)	$ 0

Debt (Schedule Of Short-Term An

Debt (Schedule Of Short-Term And Long-Term Debt) (Details) € in Millions, $ in Millions	1 Months Ended			3 Months Ended
	Mar. 31, 2015	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2021USD ($)	Mar. 31, 2021EUR (€)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Long-term debt				$ 3,443.6		$ 3,443.8
Forward starting interest rate swap agreement fixed rate	3.11%	4.73%	3.32%
$750.0 million Fixed Rate Notes Due September 2022, stated rate of 3.00% [Member]
Debt Instrument [Line Items]
Long-term debt				748.8		748.6
Debt Instrument, Face Amount				$ 750
Debt Instrument, Maturity Date				Sep. 15, 2022
Debt Instrument, Interest Rate, Stated Percentage				3.00%	3.00%
€15.0 million fixed rate notes due May 2023 [Member]
Debt Instrument [Line Items]
Long-term debt				$ 17.3		18.1
Debt Instrument, Face Amount | €					€ 15
Debt Instrument, Maturity Date				May 1, 2023
Debt Instrument, Interest Rate, Stated Percentage				4.30%	4.30%
$750.0 Million Fixed Rate Notes Due March 2025, stated rate of 3.00% [Member]
Debt Instrument [Line Items]
Long-term debt				$ 747.2		747
Debt Instrument, Face Amount				$ 750
Debt Instrument, Maturity Date				Mar. 15, 2025
Debt Instrument, Interest Rate, Stated Percentage				3.00%	3.00%
$500.0 Million Fixed Rate Notes Due June 2028, stated rate of 3.75% [Member] [Domain]
Debt Instrument [Line Items]
Long-term debt				$ 496.9		496.8
Debt Instrument, Face Amount				$ 500
Debt Instrument, Maturity Date				Jun. 15, 2028
Debt Instrument, Interest Rate, Stated Percentage				3.75%	3.75%
$750.0 million Fixed Rate Notes Due September 2043, stated rate of 5.30% [Member]
Debt Instrument [Line Items]
Long-term debt				$ 743.1		743.1
Debt Instrument, Face Amount				$ 750
Debt Instrument, Maturity Date				Sep. 15, 2043
Debt Instrument, Interest Rate, Stated Percentage				5.30%	5.30%
$700.0 Million Fixed Rate Notes Due June 2048, stated rate of 4.15% [Member] [Domain] [Domain]
Debt Instrument [Line Items]
Long-term debt				$ 690.3		$ 690.2
Debt Instrument, Face Amount				$ 700
Debt Instrument, Maturity Date				Jun. 15, 2048
Debt Instrument, Interest Rate, Stated Percentage				4.15%	4.15%

Debt (Schedule Of Maturities Of

Debt (Schedule Of Maturities Of Long-Term Debt) (Details) $ in Millions	Mar. 31, 2021USD ($)
Debt Disclosure [Abstract]
2022	$ 750
2023	17.6
2024	0
2025	750
2026	0
Thereafter	$ 1,950

Leases (Details)

Leases (Details)	Mar. 31, 2021
Leases [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	17
Lessee, Operating Lease, Renewal Term	5
Lessee, Operating Lease, Option to Terminate	12
Lessee, Operating Lease, Term of Contract	12

Leases Lease Costs (Details)

Leases Lease Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating Lease, Cost	$ 16.8	$ 14.9
Short-term Lease, Cost	0.2	0.2
Operating Lease, Expense	17	15.1
Finance Lease, Interest Expense	0.8	0.9
Finance Lease, Right-of-Use Asset, Amortization	2.2	2.2
Finance Lease, Expense	3	3.1
Sublease Income	$ 2.5	$ 3.6

Leases Supplemental Cash Flow I

Leases Supplemental Cash Flow Information-Leases (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating Lease, Payments	$ 15.3	$ 15.9
Finance Lease, Principal Payments	$ 4.2	$ 4.2

Leases Supplemental Balance She

Leases Supplemental Balance Sheet Information-Leases (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating Lease, Right-of-Use Asset	$ 386.5	$ 390.3
Operating Lease, Liability, Current	47.3	44.5
Operating Lease, Liability, Noncurrent	491.3	492.2
Operating Lease, Liability	$ 538.6	$ 536.7
Operating Lease, Weighted Average Remaining Lease Term	137 months	138 months
Operating Lease, Weighted Average Discount Rate, Percent	3.90%	3.90%
Finance Lease, Right-of-Use Asset	$ 86.7	$ 88.8
Finance Lease, Liability, Current	7.7	7.7
Finance Lease, Liability, Noncurrent	81.9	83.8
Finance Lease, Liability	$ 89.6	$ 91.5
Finance Lease, Weighted Average Remaining Lease Term	120 months	123 months
Finance Lease, Weighted Average Discount Rate, Percent	3.50%	3.50%

Leases Operating Leases Future

Leases Operating Leases Future Minimum Payments (Details) $ in Millions	Mar. 31, 2021USD ($)
Operating Leases, Future Minimum Payments Due [Line Items]
Remainder of 2021	$ 49.7
2022	69.7
2023	68
2024	61.7
2025	58.8
2026	54.3
Thereafter	306.7
Total Operating Lease Payments	668.9
Operating Lease Payments, Less Imputed Interest	(130.3)
Present Value of Operating Lease Liability	$ 538.6

Leases Capital Leases, Future M

Leases Capital Leases, Future Minimum Payments Due (Details) $ in Millions	Mar. 31, 2021USD ($)
Finance Leases, Future Minimum Payments Due [Line Items]
Remainder of 2021	$ 12.7
2022	17.1
2023	17.2
2024	17.4
2025	17.5
2026	17.6
Thereafter	76.7
Total Finance Lease Payments	176.2
Finance Lease Payments, Less Imputed Interest	(86.6)
Present Value of Finance Lease Liability	$ 89.6

Guarantees (Details)

Guarantees (Details)	3 Months Ended
	Mar. 31, 2021USD ($)years
Guarantor Obligations [Line Items]
Agreement automatic renewal period (in years) | years	1
Contingent liability to SGX, amount of irrevocable letters of credit	$ 310,000,000
Line of Credit Facility, Commitment Fee Amount	350,000,000
Family Farmer and Ranchers Protection Fund [Member]
Guarantor Obligations [Line Items]
Payment per participant	25,000
Payment per cooperative	100,000
FutureLosses	100,000,000
Payments under Guarantee	2,000,000
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 98,000,000

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Balance	$ 26,319.9	$ 26,159.3
Other comprehensive income (loss), net of tax	(51.4)	(29.6)
Balance	26,527.9	26,598.7
Investment Securities [Member]
Balance	1.6	0.8
Other comprehensive income (loss) before reclassifications and income tax benefit (expense)	(1.1)	(0.6)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Income tax benefit (expense)	0.3	0.2
Other comprehensive income (loss), net of tax	(0.8)	(0.4)
Balance	0.8	0.4
Defined Benefit Plans [Member]
Balance	(57.1)	(55.1)
Other comprehensive income (loss) before reclassifications and income tax benefit (expense)	0	(2)
Amounts reclassified from accumulated other comprehensive income (loss)	1.1	1.2
Income tax benefit (expense)	(0.3)	0.2
Other comprehensive income (loss), net of tax	0.8	(0.6)
Balance	(56.3)	(55.7)
Derivative Investments [Member]
Balance	67	69
Other comprehensive income (loss) before reclassifications and income tax benefit (expense)	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	(0.3)	(1.8)
Income tax benefit (expense)	0.1	0.4
Other comprehensive income (loss), net of tax	(0.2)	(1.4)
Balance	66.8	67.6
Foreign Currency Translation [Member]
Balance	123.4	(11.3)
Other comprehensive income (loss) before reclassifications and income tax benefit (expense)	(51.2)	(27.8)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0.6
Income tax benefit (expense)	0	0
Other comprehensive income (loss), net of tax	(51.2)	(27.2)
Balance	72.2	(38.5)
Accumulated Other Comprehensive Income (Loss) [Member]
Balance	134.9	3.4
Other comprehensive income (loss) before reclassifications and income tax benefit (expense)	(52.3)	(30.4)
Amounts reclassified from accumulated other comprehensive income (loss)	0.8	0
Income tax benefit (expense)	0.1	0.8
Other comprehensive income (loss), net of tax	(51.4)	(29.6)
Balance	$ 83.5	$ (26.2)

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other than Temporary Impairment Losses, Investments	$ 0.5
Net losses on impaired assets	0	$ 23.1
Other Assets, Fair Value Disclosure	0
Unrealized Gain (Loss) on Investments	0.8
Investments, Fair Value Disclosure	$ 9.4

Fair Value Measurements (Financ

Fair Value Measurements (Financial Instruments Measured At Fair Value On A Recurring Basis) (Details) - Fair Value, Recurring [Member] $ in Millions	Mar. 31, 2021USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	$ 105.2
Total Assets at Fair Value	105.2
Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	17
Mutual Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading Securities at Fair Value	87.7
Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	0.2
Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	0.3
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	104.9
Total Assets at Fair Value	104.9
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	17
Fair Value, Inputs, Level 1 [Member] | Mutual Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading Securities at Fair Value	87.7
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	0.2
Fair Value, Inputs, Level 1 [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	0.3
Total Assets at Fair Value	0.3
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	0
Fair Value, Inputs, Level 2 [Member] | Mutual Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading Securities at Fair Value	0
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	0
Fair Value, Inputs, Level 2 [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	0.3
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable Securities	0
Total Assets at Fair Value	0
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	0
Fair Value, Inputs, Level 3 [Member] | Mutual Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading Securities at Fair Value	0
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	0
Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities at Fair Value	$ 0

Fair Value Measurements (Estima

Fair Value Measurements (Estimated Fair Values of Long-Term Debt) (Details) - 3 months ended Mar. 31, 2021 € in Millions, $ in Millions	USD ($)	EUR (€)
$750.0 million Fixed Rate Notes Due September 2022, stated rate of 3.00% [Member]
Debt Instrument, Face Amount	$ 750
Debt Instrument, Maturity Date	Sep. 15, 2022
€15.0 million fixed rate notes due May 2023 [Member]
Debt Instrument, Face Amount | €		€ 15
Debt Instrument, Maturity Date	May 1, 2023
$750.0 Million Fixed Rate Notes Due March 2025, stated rate of 3.00% [Member]
Debt Instrument, Face Amount	$ 750
Debt Instrument, Maturity Date	Mar. 15, 2025
$500.0 Million Fixed Rate Notes Due June 2028, stated rate of 3.75% [Member] [Domain]
Debt Instrument, Face Amount	$ 500
Debt Instrument, Maturity Date	Jun. 15, 2028
$750.0 million Fixed Rate Notes Due September 2043, stated rate of 5.30% [Member]
Debt Instrument, Face Amount	$ 750
Debt Instrument, Maturity Date	Sep. 15, 2043
$700.0 Million Fixed Rate Notes Due June 2048, stated rate of 4.15% [Member] [Domain] [Domain]
Debt Instrument, Face Amount	$ 700
Debt Instrument, Maturity Date	Jun. 15, 2048
Fair Value, Inputs, Level 2 [Member] | $750.0 million Fixed Rate Notes Due September 2022, stated rate of 3.00% [Member]
Debt Instrument, Fair Value Disclosure	$ 779.4
Debt Instrument, Face Amount	$ 750
Debt Instrument, Maturity Date	Sep. 15, 2022
Fair Value, Inputs, Level 2 [Member] | €15.0 million fixed rate notes due May 2023 [Member]
Debt Instrument, Fair Value Disclosure	$ 19.2
Debt Instrument, Face Amount	$ 15
Debt Instrument, Maturity Date	May 31, 2023
Fair Value, Inputs, Level 2 [Member] | $750.0 Million Fixed Rate Notes Due March 2025, stated rate of 3.00% [Member]
Debt Instrument, Fair Value Disclosure	$ 802.8
Debt Instrument, Face Amount	$ 750
Debt Instrument, Maturity Date	Mar. 15, 2025
Fair Value, Inputs, Level 2 [Member] | $500.0 Million Fixed Rate Notes Due June 2028, stated rate of 3.75% [Member] [Domain]
Debt Instrument, Fair Value Disclosure	$ 557.4
Debt Instrument, Face Amount	$ 500
Debt Instrument, Maturity Date	Jun. 15, 2028
Fair Value, Inputs, Level 2 [Member] | $750.0 million Fixed Rate Notes Due September 2043, stated rate of 5.30% [Member]
Debt Instrument, Fair Value Disclosure	$ 1,015.3
Debt Instrument, Face Amount	$ 750
Debt Instrument, Maturity Date	Sep. 15, 2043
Fair Value, Inputs, Level 2 [Member] | $700.0 Million Fixed Rate Notes Due June 2048, stated rate of 4.15% [Member] [Domain] [Domain]
Debt Instrument, Fair Value Disclosure	$ 845.1
Debt Instrument, Face Amount	$ 700
Debt Instrument, Maturity Date	Jun. 15, 2048

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	154	68
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities	154	68

Earnings Per Share (Net Income

Earnings Per Share (Net Income Attributable To CME Group) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net Income Attributable to CME Group	$ 574.4	$ 766.2
Basic (in shares)	358,147	357,524
Effect of stock options, restricted stock and performance shares	670	931
Diluted (in shares)	358,817	358,455
Earnings per common share, basic (in dollars per share)	$ 1.60	$ 2.14
Earnings per common share, diluted (in dollars per share)	$ 1.60	$ 2.14