Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

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- Definition

Future Obligations Under Cost Sharing Agreements

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- Definition

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

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- 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))

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- Definition

Average fixed price related to the group of price risk swap derivatives.

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- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

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- Definition

Total amount of product committed to be supplied under existing contracts or agreements.

+ References

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

-Publisher SEC

-Name Regulation S-K (SK)

-Number 229

-Section 1207

-Paragraph (a)

-Subparagraph (2)

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Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

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Subsequent Events (Details)	1 Months Ended	9 Months Ended
Subsequent Events (Details)	Oct. 31, 2015 USD ($)	Sep. 30, 2015 USD ($) MBbls	Nov. 05, 2015 MBbls	Oct. 30, 2015 MBbls $ / bbl	Oct. 06, 2015 USD ($)	Oct. 05, 2015 USD ($)	Oct. 01, 2015 USD ($)	Apr. 13, 2015 USD ($)	Apr. 12, 2015 USD ($)	Dec. 31, 2012
Subsequent Event [Line Items]
Future obligations under cost sharing agreements \| $		$ 2,300,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Average swap price (in dollars per barrel) \| $ / bbl				52.19
Future obligations under cost sharing agreements \| $	$ 4,900,000
Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Line of credit facility maximum increase to aggregate commitments \| $								$ 1,700,000,000	$ 2,000,000,000
Revolving Credit Facility [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Line of credit facility maximum increase to aggregate commitments \| $					$ 1,525,000,000.0	$ 1,700,000,000
2015 Swaps [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Derivative, notional amount of oil (barrels)				120
2016 Swaps [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Derivative, notional amount of oil (barrels)				3,139
2017 Swaps [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Derivative, notional amount of oil (barrels)				1,615
2018 Swaps [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Derivative, notional amount of oil (barrels)				124
2019 Notes [Member] \| Senior Unsecured Debt [Member]
Subsequent Event [Line Items]
Stated interest rate										7.25%
2021 Notes [Member] \| Senior Unsecured Debt [Member]
Subsequent Event [Line Items]
Stated interest rate										6.50%
2023 Notes [Member] \| Senior Unsecured Debt [Member]
Subsequent Event [Line Items]
Stated interest rate										6.875%
Drilling contracts [Member]
Subsequent Event [Line Items]
Payments upon early contract termination \| $		$ 5,300,000					$ 7,100,000
Williston Basin Project [Member] \| Long Term Commitments [Member] \| Crude oil [Member]
Subsequent Event [Line Items]
Minimum quantity of delivery		29,200
Williston Basin Project [Member] \| Long Term Commitments [Member] \| Crude oil [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Minimum quantity of delivery			7,100