Commitments and Contingencies Lease Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Future Minimum Payments Due, Less than 1 year	$ 1,858
Operating Leases, Future Minimum Payments, 1 year to 3 years	2,829
Operating Leases, Future Minimum Payments, 3 years to 5 years	173
Operating Leases, Future Minimum Payments, More than 5 years	0
Operating Leases, Future Minimum Payments Due	4,860
Operating Leases, Rent Expense, Net	$ 1,100	$ 600	$ 600