Leases (Operating Lease Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Leases [Abstract]
Long-term fixed lease expense	$ 9,821	$ 13,500	$ 19,328	$ 27,000
Long-term variable lease expense	505		1,330
Short-term lease expense	4,628		10,001
Total operating lease expense	$ 14,954		$ 30,659