Commitments and Contingencies - Additional Information (Details) MMBoe in Millions		12 Months Ended
	Nov. 04, 2015 a	Dec. 31, 2008 gal	Mar. 31, 2018 MMBoe
Sylacauga, Talladega County, Alabama
Long-term Purchase Commitment [Line Items]
Gallons of wastewater transported | gal		3,000
Crude Oil and Natural Gas
Long-term Purchase Commitment [Line Items]
Delivery commitments (MMBOE) | MMBoe			2.4
Endeavor Energy Resources | Pending Litigation
Long-term Purchase Commitment [Line Items]
Number of acres with cloud on the title | a	10,000