Investments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended						3 Months Ended			3 Months Ended			3 Months Ended				3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Feb. 28, 2013 EMCP III	Mar. 31, 2013 Trilantic	Dec. 31, 2012 Trilantic	Mar. 31, 2013 G5	Mar. 31, 2012 G5	Dec. 31, 2012 G5	Mar. 31, 2013 ABS	Mar. 31, 2012 ABS	Dec. 31, 2012 ABS	Mar. 31, 2013 Pan	Mar. 31, 2012 Pan	Dec. 31, 2012 Pan	Dec. 31, 2008 Pan	Mar. 31, 2013 Pan Variable Interest Entity, Primary Beneficiary
Schedule of Investments [Line Items]
Subscribed capital commitments				$ 18,300
Capital commitment				915
Net realized and unrealized gains on private equity fund investments, including performance fees	477	(307)
Previously received carried interest subject to repayment	2,701
Investments					14,999	14,999
Income (Loss) from Equity Method Investments	756	2,385					(63)	1,363		874	710		(55)	312
Equity method investment, percent							49.00%			45.00%			68.00%		50.00%
Equity method investment	63,957		69,320				20,323		19,720	43,634		46,851			2,749	4,158
Assets	976,489	942,117	1,145,218														731
Liabilities	434,081		604,742														490
Goodwill																	3,020
Intangible assets	34,822		35,397														1,440
Intangible assets, useful life																	7 years
Amortization of intangible assets	$ 647	$ 747