Leases (Schedule of Lease Costs) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Finance lease amortization expense	$ 1,150
Finance lease interest expense	113
Operating lease expense	16,089
Short-term lease expense	35,735
Variable lease expense	923
Total lease expense	$ 54,010