Additional Balance Sheet Details (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Receivables [Abstract]
Trade accounts receivable, net	$ 40,146	$ 45,407
Commodity derivatives settlement receivables	25,994	59,755
Federal income tax receivable, net	0	37,652
Other receivables	20,953	14,141
Total	$ 87,093	$ 156,955