Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating leases, future minimum payments due [Abstract]
Operating leases, due in 2018	$ 10,200
Operating leases, due in 2019	8,000
Operating leases, due in 2020	5,500
Operating leases, due in 2021	3,600
Operating leases, due in 2022	2,900
Operating leases, due thereafter	5,200
Rent expense	$ 12,100	$ 12,400	$ 12,300