Schedule of Debt Obligations (Detail) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total debt	[1]	$ 1,159,627	$ 1,254,160
Unamortized debt issuance costs		(16,343)	(20,048)
Less current maturities		453,464	160,435
Total long-term debt		706,163	1,093,725
Senior Secured Notes
Debt Instrument [Line Items]
Total debt		599,845	651,784
Less current maturities		57,700	95,300
Convertible Notes | 1.50% Senior Subordinated Notes Due March 15, 2018
Debt Instrument [Line Items]
Total debt	[2]	281,002	277,518
Variable Funding Notes
Debt Instrument [Line Items]
Total debt		100,000	100,000
Senior Secured Term Loan
Debt Instrument [Line Items]
Total debt		$ 195,123	$ 244,906

[1] Carrying amounts include aggregate unamortized debt discount and debt issuance costs.

[2] During FY 2016, the Company repurchased a total of $104.9 million par value (of which $51.7 million and $53.2 million were purchased in June 2016 and July 2016, respectively) of the 1.50% Convertible Notes. See below for further details.