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Subsequent Events Subsequent Events (Details)	2 Months Ended	12 Months Ended
	Feb. 28, 2018 MMBTU $ / bbl bbl	Dec. 31, 2017 MMBTU bbl
Crude oil | 2018 Swaps
Subsequent Event [Line Items]
Total notional amount of oil barrels (in bbl)		13,675,000
Crude oil | 2018 Swaps | Subsequent Event
Subsequent Event [Line Items]
Total notional amount of oil barrels (in bbl)	756,000
Average floor price (in dollars per barrel / dollars per btu) | $ / bbl	56.16
Crude oil | 2020 Swaps
Subsequent Event [Line Items]
Total notional amount of oil barrels (in bbl)		279,000
Crude oil | 2020 Swaps | Subsequent Event
Subsequent Event [Line Items]
Total notional amount of oil barrels (in bbl)	217,000
Crude oil | 2019 Swaps
Subsequent Event [Line Items]
Total notional amount of oil barrels (in bbl)		4,091,000
Crude oil | 2019 Swaps | Subsequent Event
Subsequent Event [Line Items]
Total notional amount of oil barrels (in bbl)	2,400,000
Natural gas | 2018 Swaps
Subsequent Event [Line Items]
Total notional amount of natural gas (in MMBtu) | MMBTU		7,665,000
Natural gas | 2018 Swaps | Subsequent Event
Subsequent Event [Line Items]
Average floor price (in dollars per barrel / dollars per btu) | $ / bbl	3.03
Total notional amount of natural gas (in MMBtu) | MMBTU	668,000

X

- Definition

The average floor rate on a group of price risk derivatives such as floors or collars. A payment or receipt is triggered if the market rate falls below the floor rate on the contract.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

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- Definition

Nominal energy measure used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Nominal volume used to calculate payments on a derivative instrument.

+ References

No definition available.

+ Details

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X

- Definition

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.

+ References

No definition available.

+ Details

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X

- Details

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X

- Details

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X

- Details

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X

- Details

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X

- Details

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- Details

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