Long-Term Debt (Additional Information) (Details) - USD ($)		12 Months Ended
	Sep. 02, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Oct. 20, 2015
Debt Instrument [Line Items]
Cross default provision, minimum threshold amount		$ 10,000,000
Loan limit percentage (less than)		10.00%
Cross default provision, minimum debt default amount		$ 75,000,000
Interest expense		43,108,000	$ 37,771,000	$ 39,736,000
Amortization of debt issuance costs		$ 3,300,000	5,700,000	2,000,000
Interest expense, capitalized			$ 200,000	$ 200,000
Unused capacity, commitment fee percentage		0.30%
Syndicated Credit Facility | Credit Facility, September 2, 2014
Debt Instrument [Line Items]
Debt instrument, term	5 years
Credit facility					$ 1,400,000,000
Debt covenant, debt to EBITDAX ratio		4.0
Debt covenant, current assets to current liabilities ratio		1.0
Debt covenant, minimum net present value of proved reserves to consolidated debt, ratio		1.50