Leases (Future Minimum Finance Lease Payments) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Commitments [Abstract]
Remainder of 2019	$ 4,539
2020	5,157
2021	3,871
2022	2,314
2023	1,020
Thereafter	43
Total future minimum lease payments	16,944
less: imputed interest	(303)
Total finance lease liability	16,641
less: finance lease liability - current	(5,729)
Total finance lease liability - non current	$ 10,912	$ 10,146