Schedule of Debt Obligations (Detail) - USD ($) $ in Thousands		Sep. 30, 2019		Dec. 31, 2018
Debt Instrument [Line Items]
Total debt		$ 647,565
Unamortized debt issuance costs		(2,466)		$ (4,738)
Total debt	[1],[2]	645,099		675,229
Less current maturities		61,417		54,263
Total long-term debt		583,682		620,966
Senior Secured Notes
Debt Instrument [Line Items]
Total debt		345,862		365,481
Less current maturities		42,100		42,700
Variable Funding Notes
Debt Instrument [Line Items]
Total debt		98,472	[3]	95,273
Senior Secured Term Loan
Debt Instrument [Line Items]
Total debt		168,165		171,137
Less current maturities		19,300		11,600
Convertible Notes | 5.75% Senior Subordinated Notes Due August 2023
Debt Instrument [Line Items]
Total debt		35,066	[4]	48,076
Total debt		$ 94,400		$ 109,700

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

[2] Includes the 5.75% Convertible Notes accounted for under the fair value option. See to Note 7.

[3] Reflects the net debt carrying amount, effected by the outstanding balance of the original issue discount, in the condensed consolidated balance sheet as of September 30, 2019. The actual principal outstanding balance of the Variable Funding Notes is $100.0 million as of September 30, 2019.

[4] Reflects the debt carrying amount which is accounted for under the Fair Value Option in the condensed consolidated balance sheet as of September 30, 2019. The actual principal outstanding balance of the 5.75% Convertible Notes is $94.4 million as of September 30, 2019.