Income Taxes Unrecognized Tax Benefits (Table Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Current income tax benefit	$ 628	$ 87	$ 6
Unrecognized tax benefits - beginning of year	1,367	1,274	0
Gross additions - current year tax positions	0	0
Gross additions - prior year tax positions	93	1,274
Gross reductions - prior year tax positions	0	0
Gross reductions - settlements with taxing authorities	0	0
Impact due to expiration of statute of limitations	0	0
Deferred income tax (benefit) expense	(18,389)	(9,807)	87
Income tax benefit	$ (17,761)	$ (9,720)	$ 93