Disposition and Discontinued Operations - Schedule of Value of Assets and Liabilities Disposed (Parenthetical) (Detail) - Institutional Shareholder Services Inc. [Member] $ in Thousands	Dec. 31, 2014 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property, equipment and leasehold improvements, accumulated depreciation and amortization	$ 4,213
Intangible assets, accumulated amortization	$ 50,283

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services associated with a disposal group including, but not limited to, discontinued operation.

No definition available.

Name:	msci_DisposalGroupIncludingDiscontinuedOperationsAccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Namespace Prefix:	msci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant