Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands					3 Months Ended	9 Months Ended
	Oct. 06, 2017	Aug. 31, 2016	Apr. 29, 2016	Apr. 19, 2016	Sep. 30, 2017	Sep. 30, 2017	Oct. 16, 2018	Sep. 30, 2018
Loss Contingencies [Line Items]
Claims settled	$ 399,000
Bankruptcy claims, undistributed amount returned	1,300
Bankruptcy claims amount of claims settled, make-whole fees	223,800				$ 223,838	$ 223,838
Bankruptcy claims amount of claims settled, postpetition interest	175,200
SPMT | Subsequent Event
Loss Contingencies [Line Items]
Accrued payment							$ 2,000
Indebtedness Claims | Notes holders
Loss Contingencies [Line Items]
Claim reserve account after effective date	$ 400,000
Royalties | ONRR
Loss Contingencies [Line Items]
Bankruptcy claims amount				$ 35,100
Oil Sales Contract | SPMT
Loss Contingencies [Line Items]
Bankruptcy claims amount		$ 16,900
Damage sought			$ 38,600
Accrued payment								$ 2,000
Write off of receivable								$ 700
Oil Sales Contract | SPMT | Subsequent Event
Loss Contingencies [Line Items]
Accrued payment							$ 2,000