Long-Term Debt - Additional Information (Details) - USD ($)	Sep. 02, 2014	Jun. 30, 2017	Apr. 21, 2017	Jan. 23, 2017	Dec. 31, 2016	Oct. 25, 2016
Debt Instrument [Line Items]
Gross amount		$ 678,500,000			$ 554,000,000
Cross default provision, threshold amount		10,000,000
Initial borrowing base		$ 1,050,000,000			1,050,000,000
Loan limit percentage (less than)		10.00%
Credit facility cross default provision, threshold amount (more than)		$ 75,000,000
Medium-term Notes | 7.40% Medium-term Notes, Series A, due July 24, 2017
Debt Instrument [Line Items]
Gross amount		$ 0		$ 2,000,000	$ 2,000,000
Stated interest rate		7.40%		7.40%	7.40%
Medium-term Notes | 7.60% Medium-term Notes, Series A, due July 26, 2027
Debt Instrument [Line Items]
Gross amount		$ 0		$ 5,000,000	$ 5,000,000
Stated interest rate		7.60%		7.60%	7.60%
Credit facility
Debt Instrument [Line Items]
Gross amount		$ 131,500,000			$ 0
Initial borrowing base			$ 1,400,000,000			$ 1,050,000,000
Syndicated Credit Facility | Credit Facility, September 2, 2014
Debt Instrument [Line Items]
Term of credit facility	5 years
Debt covenant, debt to EBITDAX ratio (less than or equal to)		4.0
Debt covenant, current assets to current liabilities ratio (greater than or equal to)		1.0
Debt covenant, minimum net present value of proved reserves to consolidated debt, ratio (greater than or equal to)		1.50