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Common Stock Shares Issued for Debt Exchange

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Debt Instrument Call Feature Redemption Price As Percentage Of Principal Redeemed

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- Definition

Face Amount of Outstanding 7.625% Senior Notes Exchanged for Common Stock

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Implicit Interest Rate Financing Arrangement

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Letters Of Credit Issued Amount

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Line of Credit Facility, Reduced Borrowing Capacity

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Maximum Credit Amount, Maximum Commitments That Could Be Elected By Lenders

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Redemption Price As Percentage Of Principal Redeemed If Equity Offering Proceeds Used

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Revolving Credit Facility Interest Rate Percent Above LIBOR.

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Revolving credit facility interest rate percent above Libor alternate interest rate

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- Definition

Sale Leaseback Transaction, Early Buyout Option To Purchase Equipment

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Represents the caption on the face of the balance sheet to indicate that the entity has entered into (1) purchase or supply arrangements that will require expending a portion of its resources to meet the terms thereof, and (2) is exposed to potential losses or, less frequently, gains, arising from (a) possible claims against a company's resources due to future performance under contract terms, and (b) possible losses or likely gains from uncertainties that will ultimately be resolved when one or more future events that are deemed likely to occur do occur or fail to occur.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Percentage of principal amount of debt redeemed.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Long-Term Debt - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Line of credit facility, reduced borrowing capacity	$ 474,000,000
Principal amount	625,000,000	$ 626,859,000
(Gain) loss on extinguishment of debt	257,000	8,239,000	$ (8,726,000)
Debt Instrument, Fair Value Disclosure	$ 594,400,000	661,400,000
Common Stock Shares Issued for Debt Exchange	0
Purchase of equipment	$ 1,800,000
Maximum Credit Amount, Maximum Commitments That Could Be Elected By Lenders	1,500,000,000
Commitments and Contingencies
Minimum [Member]
Debt Instrument [Line Items]
Revolving credit facility, interest rate above London Interbank Offered Rate	1.50%
Revolving credit facility interest rate percent above LIBOR alternate interest rate	0.50%
Commitment fee percentage	0.375%
Maximum [Member]
Debt Instrument [Line Items]
Revolving credit facility, interest rate above London Interbank Offered Rate	2.50%
Revolving credit facility interest rate percent above LIBOR alternate interest rate	1.50%
Commitment fee percentage	0.50%
Amended Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 500,000,000
Letters of credit issued amount	26,000,000.0
Principal amount	0	0
Debt Instrument, Fair Value Disclosure	$ 0
7.625% Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Debt, stated interest rate			7.625%
7.0% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date	Oct. 15, 2022
7.625% Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount			$ 315,300,000
(Gain) loss on extinguishment of debt		7,900,000	(8,700,000)
Debt, stated interest rate	7.625%
Face Amount of Outstanding 7.625% Senior Notes Exchanged for Common Stock			$ 84,700,000
Common Stock Shares Issued for Debt Exchange			10,000,000
7.0% Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount	$ 350,000,000.0	350,000,000
Debt, stated interest rate	7.00%
Debt Instrument, Fair Value Disclosure	$ 329,700,000	$ 356,100,000
Common Stock Shares Issued for Debt Exchange		10,863,000
Eight Point Seven Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount	$ 275,000,000	$ 275,000,000
Debt, stated interest rate	8.75%
Debt Instrument, Fair Value Disclosure	$ 264,700,000	305,300,000
Lease Financing Obligation [Member]
Debt Instrument [Line Items]
Principal amount	1,859,000	2,328,000
Debt Instrument, Fair Value Disclosure	$ 1,800,000	$ 2,100,000
Weighted average implicit rate based on interest expense	3.30%
2018 [Member] \| 7.0% Senior Notes [Member]
Debt Instrument [Line Items]
Par value of senior notes	102.333%
2019 [Member] \| 7.0% Senior Notes [Member]
Debt Instrument [Line Items]
Par value of senior notes	101.167%
2020 [Member] \| 7.0% Senior Notes [Member]
Debt Instrument [Line Items]
Par value of senior notes	100.00%
2020 [Member] \| Eight Point Seven Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Par value of senior notes	106.563%
2021 [Member] \| Eight Point Seven Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Par value of senior notes	104.375%
2022 [Member] \| Eight Point Seven Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Par value of senior notes	102.188%
2023 [Member] \| Eight Point Seven Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Par value of senior notes	100.00%
Prior to June 15, 2020 [Member] \| Eight Point Seven Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Par value of senior notes	100.00%
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	35.00%
Redemption Price As Percentage Of Principal Redeemed If Equity Offering Proceeds Used	108.75%