Debt Instrument, Collateral, Oil and Gas Properties Eligible, Percent of Reserve value Required

No definition available.

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- Definition

Debt Instrument, Redemption, Term

+ References

No definition available.

+ Details

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- Definition

The aggregate amount of certain final judgments for which failure to pay would qualify as an event of default under the Indenture of the Notes.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

The principal amount of payment defaults that would qualify as an event of default under the Indenture of the Notes.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

The aggregate commitment may be increased to this amount by increasing the commitment of one or more lender(s) under the credit facility.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The minimum current ratio as required by the entity's debt agreement.

+ References

No definition available.

+ Details

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- Definition

Percentage of minimum outstanding principal amount.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

The minimum ratio of consolidated EBITDAX to consolidated Interest Expense as required by the entity's debt agreement.

+ References

No definition available.

+ Details

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- Definition

Redemption Percentage, Maximum.

+ References

No definition available.

+ Details

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- Definition

Amount of noncash expense included in interest expense to issue debt and obtain financing associated with the related debt instruments. Alternate captions include noncash interest expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.8)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 8

-Article 9

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

+ 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

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- Details

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

For an unclassified balance sheet, the carrying amount (net of accumulated amortization) as of the balance sheet date of capitalized costs associated with the issuance of debt instruments (for example, legal, accounting, underwriting, printing, and registration costs) that will be charged against earnings over the life of the debt instruments to which such costs pertain.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28555-108399

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.17)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

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+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The maximum amount of borrowing capacity under a line of credit that is available as of the balance sheet date for a specific purpose other than for financing goods acquired for inventory or imminent delivery to a customer.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

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.

+ 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 210.5-02.19(b),22(b))

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ 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 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow from the issuance of long-term debt that is not secured by collateral. Excludes proceeds from tax exempt unsecured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3255-108585

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Long-Term Debt Long-Term Debt - Additional Information (Details) (USD $)	3 Months Ended		24 Months Ended	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2014
Debt Instrument [Line Items]
Deferred financing costs	$ 33,900,000us-gaap_DeferredFinanceCostsNet
Amortization of deferred financing costs	1,600,000us-gaap_AmortizationOfFinancingCosts	1,600,000us-gaap_AmortizationOfFinancingCosts
Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Net proceeds from issuance of notes			1,175,800,000
Redemption percentage, maximum	35.00%
Redemption term	180 days
Percentage of minimum outstanding principal amount	65.00%
Event of default by payment default ($10.0 million or more)	10,000,000.0
Event of default by final judgments (in excess of $10.0 million)	10,000,000.0
Second Amended Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility maximum increase to aggregate commitments	2,000,000,000
Line of credit facility, maximum borrowing capacity	1,500,000,000
Line of credit facility, capacity available for specific purpose other than for trade purchases	2,500,000,000
Commitment fee of borrowing base capacity not utilized	0.375%
Minimum current ratio	1.0
Line of credit facility, amount outstanding	165,000,000
Outstanding letters of credit	5,200,000
Line of credit facility, remaining borrowing capacity	1,329,800,000
Weighted average interest rate	1.70%				1.90%
Minimum [Member] \| Second Amended Credit Facility [Member]
Debt Instrument [Line Items]
Percentage of the reserve value of assets as determined by reserve reports (at least 80%)	80.00%
Ratio of EBITDAX to interest expense necessary to maintain covenants	2.5
2022 Notes [Member] \| Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal debt amount				1,000,000,000.0
Stated interest rate				6.875%
Net proceeds from issuance of notes				983,600,000
2019 Notes [Member] \| Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal debt amount			400,000,000.0
Stated interest rate			7.25%
2021 Notes [Member] \| Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal debt amount			400,000,000.0
Stated interest rate			6.50%
2023 Notes [Member] \| Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal debt amount			$ 400,000,000.0
Stated interest rate			6.875%