Organization and Basis of Presentation (Additional Information) (Details)		3 Months Ended
	Sep. 02, 2014	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Oct. 20, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Line of Credit Facility [Line Items]
Cash			$ 1,272,000		$ 1,852,000	$ 2,523,000
Available for borrowings			1,177,500,000		1,515,000,000
Long-term debt, gross			776,500,000		1,039,000,000
Outstanding long-term debt			$ 776,500,000
Syndicated Credit Facility | Credit Facility, September 2, 2014
Line of Credit Facility [Line Items]
Credit facility				$ 1,400,000,000
Debt instrument, term	5 years
Debt covenant, debt to EBITDAX ratio			4.0
Medium-term Notes and Notes Payable, Other Payables [Member]
Line of Credit Facility [Line Items]
Long-term debt, gross			$ 554,000,000
Credit facility | Credit facility
Line of Credit Facility [Line Items]
Long-term debt, gross			$ 222,500,000		$ 485,000,000
One-time Termination Benefits | Subsequent Event
Line of Credit Facility [Line Items]
Incurred cost in connection with workforce reduction		$ 3,200,000