Segment Information Revenue by Segment (Details) (USD $) In Thousands, unless otherwise specified	3 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	Jun. 30, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Number of Segments [Line Items]
Revenue	$ 139,917	$ 108,413	$ 114,489	$ 106,345	$ 118,980	$ 92,028	$ 87,886	$ 85,046		$ 469,164	$ 383,940	$ 365,546
Net client reimbursable expenses										(197)	(139)	(62)
Equity-based compensation										(25,537)	(21,884)	(20,444)
Depreciation and amortization										(18,138)	(11,164)	(9,916)
Acquisition retention expenses										(9,536)	(1,624)	(11)
Restructuring charges										(1,796)	(4,090)	0
Acquisition, integration and corporate development costs										(6,865)	(2,372)	(704)
Charge from realignment of senior management									3,610	0	0	(3,100)
Charge from impairment of certain intangible assets										0	0	(674)
Operating income	13,993	10,340	13,318	9,741	18,312	9,117	8,267	9,577		47,392	45,273	43,222
Financial Advisory Segment [Member]
Number of Segments [Line Items]
Revenue										271,947	250,888	231,281
Operating income										50,778	45,212	29,819
Segment operating income as a percent of revenue										18.70%	18.00%	12.90%
Alternative Asset Advisory Segment [Member]
Number of Segments [Line Items]
Revenue										57,050	55,666	44,035
Operating income										12,759	12,890	9,208
Segment operating income as a percent of revenue										22.40%	23.20%	20.90%
Investment Banking Segment [Member]
Number of Segments [Line Items]
Revenue										140,167	77,386	90,230
Operating income										20,409	6,767	22,061
Segment operating income as a percent of revenue										14.60%	8.70%	24.40%
Reportable Segment [Member]
Number of Segments [Line Items]
Operating income										83,946	64,869	61,088
Equity-based compensation from Legacy Units and IPO Options [Member]
Number of Segments [Line Items]
Equity-based compensation										$ (22)	$ (207)	$ (3,399)