Notes Payable, Collateralized and Short-Term Borrowings - Summary of Interest Expense Related to Company's Convertible Notes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Amortization of discount			$ (2,414)	$ 4,427
4.50% Convertible Notes [Member]
Debt Instrument [Line Items]
Coupon interest	$ 280	$ 1,800	3,880	5,400
Amortization of discount	207	1,206	2,666	3,590
Total interest expense	$ 487	$ 3,006	$ 6,546	8,990
8.75% Convertible Notes [Member]
Debt Instrument [Line Items]
Coupon interest				3,828
Total interest expense				$ 3,828