Commitments and Contingencies (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, Next Twelve Months	$ 4,178
Operating Leases, Future Minimum Payments, Due in Two Years	2,034
Operating Leases, Future Minimum Payments, Due in Three Years	1,164
Operating Leases, Future Minimum Payments, Due in Four Years	627
Operating Leases, Future Minimum Payments, Due in Five Years and Thereafter	272
Operating Leases, Future Minimum Payments Due	8,275
Guarantee obligations
Operating Leases, Rent Expense	$ 2,400	$ 2,300	$ 1,400