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		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 118,265	$ 113,481	$ 115,533	$ 116,101
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	2,500	5,165	9,350	9,037
Purchases/Acquisitions	7,498	3,557	8,709	7,261
Sales/Dispositions	(5,769)	(6,848)	(10,854)	(16,300)
Foreign Currency Translation Adjustments	(4,056)	1,536	(4,300)	792
Ending Balance	118,438	116,891	118,438	116,891
Equities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,370	637	1,340	190
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other		2	14	8
Purchases/Acquisitions		650		1,095
Foreign Currency Translation Adjustments	(36)	34	(20)	30
Ending Balance	1,334	1,323	1,334	1,323
Alternative Investment Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		11		3,457
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other		(11)		117
Sales/Dispositions				(3,574)
Equity Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance				10
Sales/Dispositions				(10)
Private Equity Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	116,895	112,833	114,193	112,444
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	2,500	5,174	9,336	8,912
Purchases/Acquisitions	7,498	2,907	8,709	6,166
Sales/Dispositions	(5,769)	(6,848)	(10,854)	(12,716)
Foreign Currency Translation Adjustments	(4,020)	1,502	(4,280)	762
Ending Balance	$ 117,104	$ 115,568	$ 117,104	$ 115,568