Segment Information Revenue by Geographic Area (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	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues from External Customers and Long-Lived Assets [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
Disclosure on Geographic Areas, Long-Lived Assets in Foreign Countries	7,916				2,393				7,916	2,393
Financial Advisory revenue from cross utilization of professionals on Alternative Asset Advisory engagements									10,554	11,824	9,544
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									398,756	344,801	326,039
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									64,958	35,261	36,132
Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									$ 5,450	$ 3,878	$ 3,375