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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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

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

- Details

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- Details

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- Details

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- Details

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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	Feb. 28, 2010	Sep. 30, 2015	Apr. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term debt					$ 2,241.2		$ 2,107.9
Forward starting interest rate swap agreement fixed rate	3.11%	4.73%	3.32%	4.46%
$612.5 million fixed rate notes due March 2018, interest equal to 4.40% [Member]
Debt Instrument [Line Items]
Long-term debt					0.0		611.0
Debt Instrument, Face Amount					$ 612.5	$ 612.5
Debt Instrument, Maturity Date					Mar. 01, 2018
Debt Instrument, Interest Rate, Stated Percentage					4.40%
$750 Million Fixed Rate Notes Due March 2022, Interest Equal To 3.0% [Member]
Debt Instrument [Line Items]
Long-term debt					$ 748.4		748.2
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, Interest Equal To 3.00%
Debt Instrument [Line Items]
Long-term debt					$ 744.1		0.0
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 March 2043, Interest Equal To 5.3% [Member]
Debt Instrument [Line Items]
Long-term debt					$ 748.7		$ 748.7
Debt Instrument, Face Amount					$ 750.0
Debt Instrument, Maturity Date					Sep. 01, 2043
Debt Instrument, Interest Rate, Stated Percentage					5.30%