Leases Assets and Liabilities, Lessee (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating Lease, Right-of-Use Asset	$ 38,365	$ 0	[1]
Operating Lease, Liability, Current	7,966	$ 0
Operating Lease, Liability, Noncurrent	30,640
Operating Lease, Liability	$ 38,606
Operating Lease, Weighted Average Remaining Lease Term	6 years
Operating Lease, Weighted Average Discount Rate, Percent	5.57%

[1] December 31, 2018 balances were derived from audited consolidated financial statements.