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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 ($)			1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 19, 2020	Jun. 23, 2020	May 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Principal				$ 500,000,000		$ 500,000,000
Loss on early extinguishment of debt				$ 0	$ 0	861,000	$ 0
Net proceeds of sale of senior notes						751,500,000	$ 0
7.5% Senior Notes due 2025
Debt Instrument [Line Items]
Senior notes retire upon exchange of common stock			$ 5,600,000
Long term debt principal amount retired			$ 4,200,000
Loss on early extinguishment of debt						$ 900,000
Interest rate on debt instrument				7.50%		7.50%
7.5% Senior Notes due 2025 \| Common Stock
Debt Instrument [Line Items]
Common stock issued upon retirement of senior notes (in shares)			767,096
Common stock issued upon retirement of senior notes, value			$ 5,000,000.0
9.75% Senior Notes due 2026
Debt Instrument [Line Items]
Principal amount of senior notes issued	$ 300,000,000.0	$ 500,000,000.0
Net proceeds of sale of senior notes	$ 296,400,000	$ 441,100,000
Interest rate on debt instrument		9.75%		9.75%		9.75%
Bank Credit Facility
Debt Instrument [Line Items]
Principal				$ 500,000,000.0		$ 500,000,000.0
Bank credit facility				$ 1,400,000,000		$ 1,400,000,000
Leverage ratio						400.00%
Current ratio						100.00%
Bank Credit Facility \| Minimum
Debt Instrument [Line Items]
Commitment fee on unused borrowing base						0.375%
Bank Credit Facility \| Maximum
Debt Instrument [Line Items]
Commitment fee on unused borrowing base						0.50%
Bank Credit Facility \| LIBOR \| Minimum
Debt Instrument [Line Items]
Spread rate for interest rate on credit facility						2.25%
Bank Credit Facility \| LIBOR \| Maximum
Debt Instrument [Line Items]
Spread rate for interest rate on credit facility						3.25%
Bank Credit Facility \| Base Rate \| Minimum
Debt Instrument [Line Items]
Spread rate for interest rate on credit facility						1.25%
Bank Credit Facility \| Base Rate \| Maximum
Debt Instrument [Line Items]
Spread rate for interest rate on credit facility						2.25%