Reasonable Representation of Each Segment's Contribution (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Segment Reporting Information [Line Items]
Total Other Revenue, net	$ (1,500)		$ (1,461)
Investment Banking Other Revenue, net, includes interest expense on the Senior Notes	1,088		1,070
Investment Management Other Revenue, net, includes interest expense on the Senior Notes	919		904
Total Other Expenses	10,605	[1]	16,715	[1]
Investment Banking
Segment Reporting Information [Line Items]
Total Other Revenue, net	213	[2]	(710)	[2]
Amortization of LP Units and Certain Other Awards	4,909		4,216
Acquisition Related Compensation Charges	4,946		9,645
Intangible Asset Amortization			2,246
Total Investment Banking	9,855	[1]	16,107	[1]
Investment Management
Segment Reporting Information [Line Items]
Total Other Revenue, net	(1,713)	[3]	(751)	[3]
Amortization of LP Units and Certain Other Awards	668		526
Intangible Asset Amortization	82		82
Total Investment Management	$ 750	[1]	$ 608	[1]

[1] Other Expenses are as follows: For the Three Months Ended March 31, 2013 2012 Investment Banking Amortization of LP Units and Certain Other Awards $ 4,909 $ 4,216 Acquisition Related Compensation Charges 4,946 9,645 Intangible Asset Amortization - 2,246 Total Investment Banking 9,855 16,107 Investment Management Amortization of LP Units and Certain Other Awards 668 526 Intangible Asset Amortization 82 82 Total Investment Management 750 608 Total Other Expenses $ 10,605 $ 16,715

[2] Investment Banking Other Revenue, net, includes interest expense on the Senior Notes of $1,088 and $1,070 for the three months ended March 31, 2013 and 2012, respectively.

[3] Investment Management Other Revenue, net, includes interest expense on the Senior Notes of $919 and $904 for the three months ended March 31, 2013 and 2012, respectively.