Leases - Finance Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Finance Leases:
Gross cost	$ 6,706	$ 5,951
Accumulated depreciation	(2,465)	(1,671)
Operating lease right-of-use assets	4,241	$ 4,280
Other current liabilities	503
Other liabilities	1,173
Total finance lease liabilities	1,676
Finance Leases
Finance Leases:
Gross cost	2,557
Accumulated depreciation	(763)
Operating lease right-of-use assets	$ 1,794
Financial position	us-gaap:OtherLiabilitiesCurrent
Financial position	us-gaap:OtherLiabilitiesNoncurrent