Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Total net rent expense	$ 13,900	$ 9,000	$ 12,200
Net Operating Leases
2017	9,862
2018	6,660
2019	5,082
2020	4,275
2021	2,906
Thereafter	2,097
Total minimum payments	30,882
Other Contractual Obligations
2017	766
2018	0
2019	0
2020	0
2021	0
Thereafter	0
Total minimum payments	$ 766