Commitments and Contingencies (Details) - USD ($) $ in Thousands			12 Months Ended
		Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 16, 2013
Operating leases
Operating Leases, Rent Expense, Net		$ 302	$ 6,000	$ 6,000	$ 5,000
Operating Leases, Future Minimum Payments Due
Operating leases, future minimum payments due	[1]		9,377
Operating leases, future minimum payments due, current	[1]		3,710
Operating leases, future minimum payments, due in two years	[1]		2,234
Operating leases, future minimum payments, due in three years	[1]		1,279
Operating leases, future minimum payments, due in four years	[1]		1,175
Operating leases, future minimum payments, due in five years	[1]		979
Operating leases, future minimum payments, due after fifth year	[1]		0
Recorded Unconditional Purchase Obligation and Operating Leases, Future Minimum Payments Due
Unrecorded unconditional purchase obligation and operating leases, future minimum payments due			158,800
Unrecorded unconditional purchase obligation and operating leases, future minimum payments due, current			39,598
Unrecorded unconditional purchase obligation and operating leases, future minimum payments due in second year			35,651
Unrecorded unconditional purchase obligation and operating leases, future minimum payments due in third year			25,251
Unrecorded unconditional purchase obligation and operating leases, future minimum payments due in fourth year			23,703
Unrecorded unconditional purchase obligation and operating leases, future minimum payments due in fifth year			20,102
Unrecorded unconditional purchase obligation and operating leases, future minimum payments due after fifth year			14,495
Other commitments
Unrecorded Unconditional Purchase Obligation Payment Schedule
Unrecorded unconditional purchase obligation due	[2]		2,442
Unrecorded unconditional purchase obligation due, current	[2]		2,442
Unrecorded unconditional purchase obligation due in second year	[2]		0
Unrecorded unconditional purchase obligation due in third year	[2]		0
Unrecorded unconditional purchase obligation due in fourth year	[2]		0
Unrecorded unconditional purchase obligation due in fifth year	[2]		0
Unrecorded unconditional purchase obligation due after fifth year	[2]		0
Firm natural gas transportation contracts
Unrecorded Unconditional Purchase Obligation Payment Schedule
Unrecorded unconditional purchase obligation due	[3]		146,981
Unrecorded unconditional purchase obligation due, current	[3]		33,446
Unrecorded unconditional purchase obligation due in second year	[3]		33,417
Unrecorded unconditional purchase obligation due in third year	[3]		23,972
Unrecorded unconditional purchase obligation due in fourth year	[3]		22,528
Unrecorded unconditional purchase obligation due in fifth year	[3]		19,123
Unrecorded unconditional purchase obligation due after fifth year	[3]		$ 14,495

[1] Operating leases relate primarily to obligations associated with the Company’s office facilities, rail cars and vehicles.

[2] Other commitments relate primarily to cogeneration facility management services and equipment rental obligations.

[3] The Company enters into certain firm commitments to transport natural gas production to market and to transport natural gas for use in the Company’s cogeneration and conventional steam generation facilities. The remaining terms of these contracts range from approximately two to eight years and require a minimum monthly charge regardless of whether the contracted capacity is used or not