Notes Payable, Warrants and Subordinated Borrowings - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands			12 Months Ended
	Nov. 02, 2015	Aug. 21, 2008	Dec. 31, 2015	Nov. 30, 2015	Dec. 31, 2014	Oct. 31, 2014
Notes Payable And Warrants [Line Items]
Senior Notes			$ 120,000,000
Cash Received For Settlement Of Warrant				$ 11,020,000
Loans Payable	$ 120,000,000		120,000,000
Loans Payable Final Payment After Closing (in years)	5 years
Strategic Alliance Term (in years)	3 years
Strategic Alliance Automatic Renewals (in years)	1 year
Subordinated Borrowings			$ 22,550,000		$ 22,550,000	$ 22,550,000
Subordinated Borrowing, Interest Rate (as a percent)			5.50%
Class A [Member]
Notes Payable And Warrants [Line Items]
Common Stock, Par or Stated Value Per Share (in dollars per share)			$ 0.01		$ 0.01
Public Offering, Shares				5,455
Public Offering, Shares Offered To Public				3,100
Share Repurchase During Offering				2,355
Class A [Member] | Warrant [Member]
Notes Payable And Warrants [Line Items]
Warrants to purchase Class A shares (in shares)		5,455		5,455
Class A Shares purchase price per share (in dollars per share)		$ 22.00
Senior Notes [Member]
Notes Payable And Warrants [Line Items]
Senior Notes		$ 120,000,000
Senior Notes coupon interest (as a percent)		5.20%
Senior notes effective yield (as a percent)			7.94%