Revenue (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue
Revenue recognized	$ 3,207,638	$ 2,666,528	$ 8,775,720	$ 7,667,010
Loyalty program [Member]
Revenue
Deferred revenue liability	5,000		5,000		$ 4,100
Revenue recognized	$ 3,800	$ 4,000	$ 10,800	$ 11,800