Notes Payable, Collateralized and Short-Term Borrowings - Carrying Amounts and Estimated Fair Values of Company's Long-Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Carrying amount of the Company's long-term debt	$ 406,774	$ 402,134
Estimated fair value of the Company's long-term debt	461,161	419,873
8.75% Convertible Notes [Member]
Debt Instrument [Line Items]
Carrying amount of the Company's long-term debt	150,000	150,000
Estimated fair value of the Company's long-term debt	177,101	155,718
4.50% Convertible Notes [Member]
Debt Instrument [Line Items]
Carrying amount of the Company's long-term debt	147,870	143,354
Estimated fair value of the Company's long-term debt	167,600	147,200
8.125% Senior Notes [Member]
Debt Instrument [Line Items]
Carrying amount of the Company's long-term debt	108,904	108,780
Estimated fair value of the Company's long-term debt	$ 116,460	$ 116,955