Forward starting interest rate swap agreement, fixed rate

No definition available.

Name:	cme_ForwardStartingInterestRateSwapAgreementFixedRate
Namespace Prefix:	cme_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_UnsecuredLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cme_A750.0MillionFixedRateNotesDueMarch2025InterestEqualTo3.00Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cme_SevenHundredFiftyMillionFixedRateNotesDueMarchTwoThousandFortyThreeInterestEqualToFivePointThreePercentMember
Namespace Prefix:
Data Type:	na
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Debt (Schedule Of Short-Term And Long-Term Debt) (Details) - USD ($) $ in Millions	1 Months Ended			9 Months Ended
	Mar. 31, 2015	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term debt				$ 2,230.7	$ 2,229.3
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				745.0	744.4
Debt Instrument, Face Amount				$ 750.0
Debt Instrument, Maturity Date				Sep. 01, 2022
Debt Instrument, Interest Rate, Stated Percentage				3.00%
$750.0 million fixed rate notes due March 2025, stated rate of 3.00% [Member]
Debt Instrument [Line Items]
Long-term debt				$ 744.0	743.4
Debt Instrument, Face Amount				$ 750.0
Debt Instrument, Maturity Date				Mar. 01, 2025
Debt Instrument, Interest Rate, Stated Percentage				3.00%
$750.0 million fixed rate notes due September 2043, stated rate of 5.30% [Member]
Debt Instrument [Line Items]
Long-term debt				$ 741.7	$ 741.5
Debt Instrument, Face Amount				$ 750.0
Debt Instrument, Maturity Date				Sep. 01, 2043
Debt Instrument, Interest Rate, Stated Percentage				5.30%