Equity (Common Stock - Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Equity [Abstract]
Treasury Stock, Shares, Acquired					52,857,261	12,806,464
Treasury Stock, Value, Acquired, Cost Method	$ 1,015	$ 80	$ 2,112	$ 500	$ 3,100	$ 580