Commitments And Contingencies - Additional Information (Detail) (USD $)	1 Months Ended		12 Months Ended			1 Months Ended		12 Months Ended					1 Months Ended
	Feb. 28, 2011 Person	Jul. 31, 2010 Person	Dec. 31, 2012	Dec. 31, 2011	Jun. 20, 2011	Feb. 28, 2011 Residential Mortgage Backed Securities	Jul. 31, 2010 Residential Mortgage Backed Securities	Dec. 31, 2012 Discontinued Operations	Dec. 31, 2011 Discontinued Operations	Dec. 31, 2012 Minimum	Dec. 31, 2012 Maximum	Dec. 31, 2012 Breach of Employment Contracts LegalMatter	Feb. 28, 2010 Faigin Matter	Aug. 31, 2007 Colburn Matter	Jun. 30, 2011 Walker Matter
Commitments and Contingencies Disclosure [Line Items]
Court awarded amount to plaintiff													$ 1,400,000
Total amount claimed by plaintiff														2,600,000	2,500,000
Plaintiff superior court claim														3,200,000	4,600,000
Number of Defendants	30	50
Cambridge Clients Invest in Securities						825,000,000	2,000,000,000
Loss on Investment						260,000,000	1,200,000,000
U.S. Central Investment in RMBS					1,700,000,000
Bankruptcy claims filed in court												5,100,000
Number of Bankruptcy claims filed												2
Contingent consideration due within one year			4,000,000
Contingent consideration, noncurrent				3,597,000
Rental expense net of sublease rental			$ 500,000	$ 200,000				$ 41,000	$ 33,000
Operating lease term										1 year	10 years