Segments - Revenue Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue
Revenue	$ 18,745	$ 18,123	$ 36,474	$ 35,694
Business Segments
Revenue
Revenue	20,351	19,655	39,615	38,677
Other revenue
Revenue
Other - divested businesses	0	13	1	32
Other revenue	5	37	27	81
Internal transactions
Revenue
Revenue	$ (1,611)	$ (1,582)	$ (3,168)	$ (3,096)