Fair Value Measurements - Summary of Changes in Fair Value of Company's Level 3 Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 23,566	$ 1,370	$ 1,315	$ 1,340
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	635		3,416	14
Purchases/Acquisitions/Transfers	2,291		22,178
Sales/Dispositions			(391)
Foreign Currency Translation Adjustments	(25)	(36)	(51)	(20)
Ending Balance	26,467	1,334	26,467	1,334
Equities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,299	1,370	1,315	1,340
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	2		12	14
Foreign Currency Translation Adjustments	(25)	(36)	(51)	(20)
Ending Balance	1,276	$ 1,334	1,276	$ 1,334
Private Equity Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	22,267
Net Unrealized/Realized Gains (Losses) Included In Revenue-Other	633		3,404
Purchases/Acquisitions/Transfers	2,291		22,178
Sales/Dispositions			(391)
Ending Balance	$ 25,191		$ 25,191