Date the debt agreement requires the first payment to be made, in YYYY-MM-DD format.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823

+ Details

Name:	us-gaap_DebtInstrumentDateOfFirstRequiredPayment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-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=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types: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

- Details

Name:	us-gaap_DebtInstrumentAxis=msci_ThreePointSixTwoFivePercentSeniorUnsecuredNotesDueTwoThousandThirtyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=msci_ThreePointTwoFiveZeroPercentSeniorUnsecuredNotesDueTwoThousandThirtyThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=msci_FourPointZeroZeroZeroPercentSeniorUnsecuredNotesDueTwoThousandTwentyNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=msci_ThreePointSixTwoFivePercentSeniorUnsecuredNotesDueTwoThousandThirtyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=msci_ThreePointEightSevenFivePercentSeniorUnsecuredNotesDueTwoThousandThirtyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies - Schedule of Interest Payments Due Attributable to Senior Notes (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2021	Aug. 17, 2021	May 14, 2021	Mar. 26, 2021	May 26, 2020	Mar. 04, 2020
3.625% Senior Unsecured Notes Due 2031 [Member]
Debt Instrument [Line Items]
First payment occurred date	Nov. 01, 2021
Debt instrument interest rate	3.625%		3.625%
3.250% Senior Unsecured Notes Due 2033 [Member]
Debt Instrument [Line Items]
First payment occurred date	Feb. 15, 2022
Debt instrument interest rate	3.25%	3.25%
4.000% Senior Unsecured Notes Due 2029 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	4.00%
3.625% Senior Unsecured Notes Due 2030 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	3.625%			3.625%		3.625%
3.875% Senior Unsecured Notes Due 2031 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	3.875%				3.875%