Leases Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Operating lease cost	$ 569	$ 1,117
Short-term lease cost	4,167	10,386
Total lease cost	$ 4,736	$ 11,503