Goodwill and Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Goodwill [Line Items]
Goodwill	$ 192,970	$ 139,170	$ 122,876
Goodwill, Translation Adjustments	1,189	(789)	271
Goodwill	205,653	192,970	139,170
Financial Advisory Segment [Member]
Goodwill [Line Items]
Goodwill	89,508	89,679	75,597
Goodwill, Translation Adjustments	289	(191)	271
Goodwill	100,445	89,508	89,679
Alternative Asset Advisory Segment [Member]
Goodwill [Line Items]
Goodwill	17,935	17,935	15,723
Goodwill, Translation Adjustments	0	0	0
Goodwill	17,935	17,935	17,935
Investment Banking Segment [Member]
Goodwill [Line Items]
Goodwill	85,527	31,556	31,556
Goodwill, Translation Adjustments	900	(598)	0
Goodwill	87,273	85,527	31,556
Series of Individually Immaterial Business Acquisitions [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period	11,494	20	16,023
Series of Individually Immaterial Business Acquisitions [Member] | Financial Advisory Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period	10,648	20	13,811
Series of Individually Immaterial Business Acquisitions [Member] | Alternative Asset Advisory Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period	0	0	2,212
Series of Individually Immaterial Business Acquisitions [Member] | Investment Banking Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period	846	0	0
Acquisition of Growth Capital Partners [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		7,806
Acquisition of Growth Capital Partners [Member] | Financial Advisory Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		0
Acquisition of Growth Capital Partners [Member] | Alternative Asset Advisory Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		0
Acquisition of Growth Capital Partners [Member] | Investment Banking Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		7,806
Acquisition of MCR [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		20,177
Acquisition of MCR [Member] | Financial Advisory Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		0
Acquisition of MCR [Member] | Alternative Asset Advisory Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		0
Acquisition of MCR [Member] | Investment Banking Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		20,177
Acquisition of RSM Richter Toronto Restructuring [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		4,514
Acquisition of RSM Richter Toronto Restructuring [Member] | Financial Advisory Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		0
Acquisition of RSM Richter Toronto Restructuring [Member] | Alternative Asset Advisory Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		0
Acquisition of RSM Richter Toronto Restructuring [Member] | Investment Banking Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		4,514
Acquisition of Pagemill Partners [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		22,072
Acquisition of Pagemill Partners [Member] | Financial Advisory Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		0
Acquisition of Pagemill Partners [Member] | Alternative Asset Advisory Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		0
Acquisition of Pagemill Partners [Member] | Investment Banking Segment [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period		$ 22,072