The impairment expense recorded to reduce the value of proved oil and gas assets.

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Definition

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.

+ Details

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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- Details

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Fair Value Measurements Long-term Debt (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impairment of Proved Oil and Gas Properties	$ 0	$ 0
6.50% Senior Notes Due 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	6.50%
Senior Notes, face amount			$ 344,611
6.125% Senior Notes Due 2022 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	6.125%
Senior Notes, face amount			561,796
6.50% Senior Notes Due 2023 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	6.50%
Senior Notes, face amount			394,985
5% Senior Notes Due 2024 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	5.00%
Senior Notes, face amount			500,000
5.625% Senior Notes Due 2025 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	5.625%
Senior Notes, face amount			500,000
6.75% Senior Notes Due 2026 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	6.75%
Senior Notes, face amount			500,000
Senior Notes [Member] \| 6.50% Senior Notes Due 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	6.50%
Senior Notes, face amount	$ 344,611		344,611
Long-term Debt, Fair Value	$ 347,626		351,682
Senior Notes [Member] \| 6.125% Senior Notes Due 2022 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	6.125%
Senior Notes, face amount	$ 561,796		561,796
Long-term Debt, Fair Value	$ 563,200		571,627
Senior Notes [Member] \| 6.50% Senior Notes Due 2023 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	6.50%
Senior Notes, face amount	$ 394,985		394,985
Long-term Debt, Fair Value	$ 394,124		403,434
Senior Notes [Member] \| 5% Senior Notes Due 2024 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	5.00%
Senior Notes, face amount	$ 500,000		500,000
Long-term Debt, Fair Value	$ 466,750		483,440
Senior Notes [Member] \| 5.625% Senior Notes Due 2025 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	5.625%
Senior Notes, face amount	$ 500,000		500,000
Long-term Debt, Fair Value	$ 473,750		494,355
Senior Notes [Member] \| 6.75% Senior Notes Due 2026 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	6.75%
Senior Notes, face amount	$ 500,000		500,000
Long-term Debt, Fair Value	$ 497,500		516,350
Convertible Debt [Member] \| 1.50% Senior Convertible Notes Due 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, interest rate, stated percentage	1.50%
Senior Notes, face amount	$ 172,500		172,500
Long-term Debt, Fair Value	$ 164,091		$ 168,291