Segment Operating Results (Information Regarding Company's Operations By Segment) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Dec. 31, 2011
Segment Reporting Information [Line Items]
Net Revenues	$ 153,029	[1]	$ 163,181	[1]	$ 428,324	[1]	$ 411,483	[1]
Operating Expenses	126,049		131,946		363,023		331,756
Other Expenses	12,735	[2]	17,793	[2]	42,004	[2]	42,906	[2]
Income (Loss) Before Income from Equity Method Investments and Income Taxes	14,245		13,442		23,297		36,821
Income (Loss) from Equity Method Investments	415		195		3,519		664
Pre-Tax Income (Loss) from Continuing Operations	14,660		13,637		26,816		37,485
Identifiable Segment Assets	1,028,764		1,069,825		1,028,764		1,069,825		1,043,592
Investment Banking [Member]
Segment Reporting Information [Line Items]
Net Revenues	133,415	[1]	139,166	[1]	370,364	[1]	335,521	[1]
Operating Expenses, Investment Banking	106,897		109,376		304,556		263,037
Other Expenses, Investment Banking	12,057	[2]	16,969	[2]	40,062	[2]	37,836	[2]
Income (Loss) Before Income from Equity Method Investments and Income Taxes	14,461		12,821		25,746		34,648
Income (Loss) from Equity Method Investments	(200)		256		1,395		1,172
Pre-Tax Income (Loss) from Continuing Operations	14,261		13,077		27,141		35,820
Identifiable Segment Assets	519,000		569,741		519,000		569,741
Investment Management [Member]
Segment Reporting Information [Line Items]
Net Revenues	19,614	[1]	24,015	[1]	57,960	[1]	75,962	[1]
Operating Expenses, Investment Management	19,152		22,570		58,467		68,719
Other Expenses, Investment Management	678	[2]	824	[2]	1,942	[2]	5,070	[2]
Income (Loss) Before Income from Equity Method Investments and Income Taxes	(216)		621		(2,449)		2,173
Income (Loss) from Equity Method Investments	615		(61)		2,124		(508)
Pre-Tax Income (Loss) from Continuing Operations	399		560		(325)		1,665
Identifiable Segment Assets	$ 509,764		$ 500,084		$ 509,764		$ 500,084

[1] Net revenues include Other Revenue, net, allocated to the segments as follows: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2012 2011 2012 2011 Investment Banking (A) $ (435 ) $ (829 ) $ (2,407 ) $ (2,222 ) Investment Management (B) (820 ) (708 ) (2,274 ) (2,192 ) Total Other Revenue, net $ (1,255 ) $ (1,537 ) $ (4,681 ) $ (4,414 ) (A) Investment Banking Other Revenue, net, includes interest expense on the Senior Notes of $1,082 and $3,227 for the three and nine months ended September 30, 2012, respectively, and $1,059 and $3,171 for the three and nine months ended September 30, 2011, respectively. (B) Investment Management Other Revenue, net, includes interest expense on the Senior Notes of $914 and $2,727 for the three and nine months ended September 30, 2012, respectively, and $894 and $2,678 for the three and nine months ended September 30, 2011, respectively.

[2] Other Expenses are as follows: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2012 2011 2012 2011 Investment Banking Amortization of LP Units and Certain Other Awards $ 4,866 $ 4,580 $ 13,577 $ 15,603 Vesting of Event-based Awards - - - 8,906 Acquisition Related Compensation Charges 6,802 7,729 22,799 7,729 Special Charges - 2,626 662 2,626 Intangible Asset Amortization 389 2,034 3,024 2,972 Total Investment Banking 12,057 16,969 40,062 37,836 Investment Management Amortization of LP Units and Certain Other Awards 596 741 1,696 2,338 Vesting of Event-based Awards - - - 2,483 Intangible Asset Amortization 82 83 246 249 Total Investment Management 678 824 1,942 5,070 Total Other Expenses $ 12,735 $ 17,793 $ 42,004 $ 42,906