Investments - Summary of Condensed Financial Information for Company's Equity Method Investments (Detail) (USD $) In Thousands, unless otherwise specified					12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013 Equity Method Investments [Member]	Dec. 31, 2012 Equity Method Investments [Member]	Dec. 31, 2011 Equity Method Investments [Member]
Statements of operations:
Total revenues					$ 49,033	$ 41,104	$ 44,078
Total expenses					64,987	63,826	67,972
Net loss					(15,954)	(22,722)	(23,894)
Statements of financial condition:
Cash and cash equivalents	716,919	388,409	369,713	364,104	18,568	24,719
Fixed assets, net	127,615	141,109			2,440	12,064
Other assets	174,984	101,536			6,350	6,868
Total assets					27,358	43,651
Payables to related parties	15,382	40,700			6,454	15,006
Other liabilities					9,134	5,897
Total equity and partners' capital					11,770	22,748
Total liabilities, redeemable partnership interest, and equity					$ 27,358	$ 43,651