Income Taxes (Schedule of Unrecognized Tax Benefits Roll Forward) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits – January 1	$ 1,476	$ 2,412	$ 1,736
Gross increases – tax positions in prior periods	44	100	87
Gross decreases – tax positions in prior periods	(581)	(1,418)	(410)
Gross increases – current period tax positions	136	344	1,208
Settlements	109	39	206
Unrecognized tax benefits – December 31	$ 966	1,476	2,412
Statute Lapse			$ (3)
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions		$ (1)