Notes Payable, Collateralized and Short-Term Borrowings - Summary of Interest Expense Related to Company's Convertible Notes (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
4.50% Convertible Notes [Member]
Debt Instrument [Line Items]
Coupon interest	$ 1,800	$ 1,800	$ 5,400	$ 5,400
Amortization of discount	1,133	1,099	3,374	3,271
Total interest expense	2,933	2,899	8,774	8,671
8.75% Convertible Notes [Member]
Debt Instrument [Line Items]
Coupon interest	3,281	3,281	9,844	9,844
Amortization of discount
Total interest expense	$ 3,281	$ 3,281	$ 9,844	$ 9,844