Leases Lease Related Expenses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Finance lease expense:
Amortization of finance lease assets	$ 262	$ 523
Interest on finance lease liabilities	107	216
Operating lease expense	2,162	4,317
Variable lease expense	196	331
Short-term lease expense	6	22
Sublease income	(185)	(428)
Total lease expense	$ 2,548	$ 4,981