Leases Components of Operating Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Leases [Abstract]
Operating lease cost	$ 544	$ 427	$ 1,067	$ 825
Variable lease cost	155	130	295	258
Total operating lease cost	$ 699	$ 557	$ 1,362	$ 1,083