Income Taxes - Income Tax Benefit (Provision) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current benefit (provision):
Federal	$ (779)	$ (89)	$ (9,429)
State	(532)	138	(1,783)
Foreign	(786)	(31)	(61)
Total current	(2,097)	18	(11,273)
Deferred benefit (provision):
Federal	(25,919)	7,612	973
State	(345)	342	189
Foreign	109	0	0
Total deferred	(26,155)	7,954	1,162
Total benefit (provision)	$ (28,252)	$ 7,972	$ (10,111)