Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary Of Significant Accounting Polices [Line Items]
Depreciation, depletion and amortization	$ 114,534	$ 102,487	$ 104,298
Impairment of oil and natural gas properties	0	6,775	249,569
Amortization expense for debt issue costs	900	900	900
Oil and Natural Gas Properties
Summary Of Significant Accounting Polices [Line Items]
Depreciation, depletion and amortization	114,300	102,400	102,700
Proved Oil And Gas Properties [Member]
Summary Of Significant Accounting Polices [Line Items]
Impairment of oil and natural gas properties	0	4,900	127,800
Unproved Oil And Natural Gas Properties
Summary Of Significant Accounting Polices [Line Items]
Impairment of oil and natural gas properties	0	1,900	121,800
Other Property and Equipment
Summary Of Significant Accounting Polices [Line Items]
Depreciation, depletion and amortization	$ 200	$ 100	$ 1,600
Other Property and Equipment | Minimum
Summary Of Significant Accounting Polices [Line Items]
Other property and equipment, expected useful lives	3 years
Other Property and Equipment | Maximum
Summary Of Significant Accounting Polices [Line Items]
Other property and equipment, expected useful lives	7 years