Debt Facilities - Components of Total Interest Expense Recognized Related to Convertible Subordinated Notes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Interest charges incurred	$ 309,998	$ 289,557	$ 259,400
Effective interest rate of the liability component (percent)	8.17%
Convertible Subordinated Debt [Member] | 4.75% Convertible Subordinated Notes [Member]
Debt Instrument [Line Items]
Contractual interest expense	$ 7,501	10,976
Amortization of debt issuance costs	428	629
Amortization of debt discount	8,060	10,448
Interest charges incurred	$ 15,989	$ 22,053
Effective interest rate of the liability component (percent)	10.65%	10.88%