Investments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended				12 Months Ended						12 Months Ended						12 Months Ended				12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Other Expense	Dec. 31, 2012 ECP II Minimum	Dec. 31, 2012 ECP II Maximum	Dec. 31, 2010 CSI Capital	Dec. 31, 2012 EMCP III	Dec. 31, 2012 Trilantic	Dec. 31, 2011 Trilantic	Dec. 31, 2012 G5	Dec. 31, 2011 G5	Dec. 31, 2010 G5	Dec. 31, 2012 ABS	Dec. 31, 2011 ABS	Dec. 29, 2011 ABS	Dec. 31, 2012 Pan Seat	Dec. 31, 2011 Pan	Dec. 31, 2010 Pan	Dec. 31, 2008 Pan	Dec. 31, 2012 Pan MaturityPeriodOneMember	Dec. 31, 2012 Pan MaturityPeriodTwoMember	Dec. 31, 2009 CSIP
Schedule of Investments [Line Items]
Subscribed capital commitments																$ 96,500
Capital commitment																3,600	5,000
Carried interest earned by the general partner, percent													8.00%	9.00%
Investment															3,164		14,999	15,549
Net realized and unrealized gains on private equity fund investments, including performance fees									(206)	6,200	2,148
Previously received carried interest subject to repayment	2,701								2,701
Income (Loss) from Equity Method Investments	1,333	415	719	2,385	255	195	69	400	4,852	919	(557)								1,368	1,340	64	3,394			90	(420)	(621)
Equity method investment, percent																			49.00%			45.00%		45.00%	50.00%
Equity method investment	69,320				68,230				69,320	68,230									19,720	20,595		46,851	45,104		2,749	2,531		4,158
Carrying value of notes receivable																									1,122
Notes due date																													2016	2017
Number of seats holds in board																									2
Total number of board seats																									4
Amortization of intangible assets									2,696	944	236
Cost basis investment																															1,250
Cost basis investments exchange noncontrolling interest, percent																															5.00%
Cost basis investment												$ 1,250