Income Taxes - Provision (benefit) for income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current Income Tax Expense (Benefit):
Federal	$ (4)	$ 334	$ 69
State	132	686	2,038
Foreign	65	0	(5,184)
Current income tax provision (benefit)	193	1,020	(3,077)
Deferred Income Tax Expense (Benefit):
Federal	80,586	10,241	(90,827)
State	1,119	526	(1,600)
Foreign	(1,993)	(1,494)	5,564
Deferred income tax provision (benefit)	79,712	9,273	(86,863)
Tax provision (benefit):
Federal	80,582	10,575	(90,758)
State	1,251	1,212	438
Foreign	(1,928)	(1,494)	380
Income tax provision (benefit)	$ 79,905	$ 10,293	$ (89,940)