Net Carrying Amount of Debt (Detail) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total debt	[1]	$ 800,842	$ 1,254,160
Unamortized debt issuance costs		(7,406)	(20,048)
Less current maturities		44,349	160,435
Total long-term debt		756,493	1,093,725
Senior Secured Notes
Debt Instrument [Line Items]
Total debt		408,174	651,784
Less current maturities		42,700	42,700
Convertible Notes | 1.50% Senior Subordinated Notes Due March 15, 2018
Debt Instrument [Line Items]
Total debt	[2]	233,898	277,518
Variable Funding Notes
Debt Instrument [Line Items]
Total debt	[3]	91,363	100,000
Senior Secured Term Loan
Debt Instrument [Line Items]
Total debt	[4]		$ 244,906
2017 Senior Secured Term Loan Due 2022
Debt Instrument [Line Items]
Total debt	[5]	74,813
Less current maturities		$ 1,700

[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. During FY 2017, the Company repurchased a total of $58.9 million par value of the 1.50% Convertible Notes. See below for further details. On February 22, 2018, the Company exchanged $125 million of aggregate principal amount of 1.50% Convertible Notes for $125 million of aggregate principal amount of 5.75% Convertible Notes, and on March 14, 2018, the Company drew down $110 million under the Second Delayed Draw Term Loan and used those proceeds, along with cash on hand, to make a payment to the trustee under the indenture governing the 1.50% Convertible Notes to repay the remaining 1.50% Convertible Notes at maturity on March 15, 2018.

[3] On August 18, 2017, the Company entered into an amendment of its Variable Funding Note which extended the anticipated repayment date for the Variable Funding Notes from January 2018 to January 2020. See below for further details

[4] In December 2016, the Company made a mandatory principal prepayment of $28.7 million on its Senior Secured Term Loan. See below for further details. On June 30, 2017, the Company repaid the remaining outstanding principal balance of the Senior Secured Term Loan and accordingly, the Company wrote off the remaining portion of the deferred financing costs and original issue discount associated with the debt facility. See below for further details.

[5] On August 2, 2017, the Company entered into the DB Credit Agreement for an aggregate principal amount of $300 million. See below for further details.