Income Taxes Unrecognized Tax Benefits - Annual (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 3,947	$ 0	$ 0
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	1,100
Unrecognized Tax Benefits, Interest on Income Taxes Expense	300
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	1,500
Unrecognized Tax Benefits, Increase Resulting from Acquisition	2,847	0
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	$ 1,100	$ 0