Leases (Components of Lease Expense) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 26,242	$ 75,531
Short-term and month-to-month lease cost	4,502	14,275
Variable lease cost	5,601	15,563
Sublease income	(5,222)	(14,915)
Total net lease cost	$ 31,123	$ 90,454