Leases (Lessee Components of Lease Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Property leases
Operating lease expense	$ 134	$ 128	$ 273	$ 313
Variable lease expense	112	20	166	56
Total property lease expense	246	148	439	369
Minimum annual guaranteed rent in excess of concession fees, net	$ (3)	$ 30	$ 16	$ 30