Leases (Summary of Total Lease Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases
Operating lease cost	$ 84,065	$ 80,767	$ 250,721	$ 239,672
Short-term operating lease cost	1,617	1,103	4,342	4,707
Variable operating lease cost	20,630	19,538	61,739	56,801
Sublease income	(1,235)	(1,062)	(3,597)	(2,995)
Total lease cost	$ 105,077	$ 100,346	$ 313,205	$ 298,185