Commitments (Details)			12 Months Ended
		Feb. 17, 2016 USD ($) MMcf MMBbls	Dec. 31, 2015 USD ($) MMcf MMBbls	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Commitments and Contingencies
Contractual Obligation, Due in Next Twelve Months	[1]		$ 132,747,000
Contractual Obligation, Due in Second Year	[1]		128,074,000
Contractual Obligation, Due in Third Year	[1]		131,489,000
Contractual Obligation, Due in Fourth Year	[1]		142,161,000
Contractual Obligation, Due in Fifth Year	[1]		141,854,000
Contractual Obligation, Due after Fifth Year	[1]		288,113,000
Contractual Obligation	[1]		964,438,000
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals			3,500,000
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Next Twelve Months			831,000
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Due in Two Years			953,000
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Due in Three Years			978,000
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Due in Four Years			741,000
Operating Leases, Rent Expense			$ 6,100,000	$ 6,500,000	$ 5,700,000
Natural Gas Transportation Commitment [Member]
Commitments and Contingencies
Oil and Gas Delivery Commitments and Contracts, Remaining Contractual Volume | MMcf			2,277,000
Oil and Gas Delivery Commitments and Contracts, Remaining Contractual Volume, Volumes Not Subject To Deficiency Fee | MMcf			1,059,000
Crude Oil Transportation Commitment [Member]
Commitments and Contingencies
Oil and Gas Delivery Commitments and Contracts, Remaining Contractual Volume | MMBbls			36
Subsequent Event [Member] | Natural Gas Transportation Commitment [Member]
Commitments and Contingencies
Oil and Gas Delivery Commitments and Contracts, Decrease in Remaining Contractual Volume | MMcf		829,000
Oil and Gas Delivery Commitments and Contracts, Remaining Contractual Volume | MMcf		310,000
Subsequent Event [Member] | Crude Oil Transportation Commitment [Member]
Commitments and Contingencies
Oil and Gas Delivery Commitments and Contracts, Remaining Contractual Volume | MMBbls		41
Drilling Rig Leasing Contracts [Member]
Commitments and Contingencies
Contractual Obligation			$ 35,300,000
Early Termination Penalty For Rig Contract Cancellation			26,000,000
Gain (Loss) on Contract Termination			(13,700,000)
Gas gathering and Oil and Gas Through-put Commitments [Member]
Commitments and Contingencies
Contractual Obligation			864,000,000
Gas gathering and Oil and Gas Through-put Commitments [Member] | Subsequent Event [Member]
Commitments and Contingencies
Contractual Obligation		$ 360,800,000
Decrease in Contractual Obligation		$ 118,200,000
Office Space Leases [Member]
Commitments and Contingencies
Contractual Obligation			59,400,000
Other miscellaneous contracts and leases [Member]
Commitments and Contingencies
Contractual Obligation			$ 5,700,000

[1] During the third quarter of 2015, the Company vacated its office space in Tulsa, Oklahoma. These amounts include lease payments for the Tulsa office, net of sublease income. The Company expects to receive $3.5 million of sublease income as follows: $831,000 in 2016, $953,000 in 2017, $978,000 in 2018, and $741,000 in 2019.