Fair Value Measurements - Summary of Changes in Fair Value of Company's Level 3 Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 115,533	$ 116,101
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	5,584	776
Purchases/Acquisitions	347
Sales/Dispositions	(4,669)	(3,513)
Foreign Currency Translation Adjustments	79	(1,380)
Ending Balance	116,874	111,984
Equities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,340	190
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	2
Purchases/Acquisitions
Sales/Dispositions
Foreign Currency Translation Adjustments	(5)	(6)
Ending Balance	1,337	184
Alternative Investment Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		3,457
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other		94
Purchases/Acquisitions
Sales/Dispositions		(2,247)
Foreign Currency Translation Adjustments
Ending Balance		1,304
Equity Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		10
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other
Purchases/Acquisitions
Sales/Dispositions		(10)
Foreign Currency Translation Adjustments
Ending Balance
Private Equity Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	114,193	112,444
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	5,582	682
Purchases/Acquisitions	347
Sales/Dispositions	(4,669)	(1,256)
Foreign Currency Translation Adjustments	84	(1,374)
Ending Balance	$ 115,537	$ 110,496