Long-Term Debt - Outstanding Debt (Detail) - USD ($)	3 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Principal	$ 720,000,000	$ 765,000,000
Debt Issuance Costs	(5,708,000)	(6,089,000)
Carrying Amount	$ 714,292,000	758,911,000
Amended Credit Facility
Debt Instrument [Line Items]
Maturity Date	Sep. 14, 2023
Principal	$ 95,000,000	140,000,000
Debt Issuance Costs	0	0
Carrying Amount	$ 95,000,000	140,000,000
7.0% Senior Notes
Debt Instrument [Line Items]
Maturity Date	Oct. 15, 2022
Principal	$ 350,000,000	350,000,000
Debt Issuance Costs	(2,163,000)	(2,372,000)
Carrying Amount	$ 347,837,000	347,628,000
Debt, stated interest rate	7.00%
8.75% Senior Notes
Debt Instrument [Line Items]
Maturity Date	Jun. 15, 2025
Principal	$ 275,000,000	275,000,000
Debt Issuance Costs	(3,545,000)	(3,717,000)
Carrying Amount	$ 271,455,000	$ 271,283,000
Debt, stated interest rate	8.75%

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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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.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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