v3.24.3

SUBSEQUENT EVENTS (Details) - USD ($)		1 Months Ended		3 Months Ended						9 Months Ended
	Oct. 28, 2024	Oct. 29, 2024	Sep. 30, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Jul. 28, 2022
Subsequent Event [Line Items]
Dividend declared per common share (in USD per share)				$ 1.60	$ 1.60	$ 1.60	$ 1.38	$ 1.38	$ 1.38	$ 4.80	$ 4.14
Revolving Credit Facility | Variable rate revolving loan commitments | Line of Credit
Subsequent Event [Line Items]
Payment on credit facility			$ 25,000,000.0
2022 Repurchase Program
Subsequent Event [Line Items]
Repurchase program authorizing the purchase of shares												$ 1,000,000,000
Stock repurchase program, remaining authorized repurchase amount			$ 405,400,000	$ 405,400,000						$ 405,400,000		$ 1,539,100,000
Subsequent Event
Subsequent Event [Line Items]
Dividend declared per common share (in USD per share)	$ 1.60
Subsequent Event | Revolving Credit Facility | Variable rate revolving loan commitments | Line of Credit
Subsequent Event [Line Items]
Payment on credit facility		$ 125,000,000.0
Subsequent Event | 2024 Repurchase Program
Subsequent Event [Line Items]
Repurchase program authorizing the purchase of shares	$ 1,500,000,000

X

- Definition

Amount authorized for purchase of share under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481520/505-30-50-4

+ Details

Name:	srt_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

+ Details

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 15
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-15

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

+ Details

Name:	us-gaap_RepaymentsOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount remaining authorized for purchase of share under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 830
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481674/830-30-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483399/855-10-50-2

+ Details

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

X

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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

X

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_ShareRepurchaseProgramAxis=msci_TwoThousandTwentyTwoRepurchaseProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_ShareRepurchaseProgramAxis=msci_TwoThousandTwentyFourRepurchaseProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: