Common Share Repurchases (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Apr. 20, 2021
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Number of shares repurchased (in shares)	3,800,000	8,800,000
Cost of shares repurchased	$ 600	$ 1,360
Average cost per share repurchased (in dollars per share)	$ 155.57	$ 153.93
Number of shares acquired to cover tax withholding costs and exercise costs (in shares)	12,181	300,000
Cost of shares acquired to cover tax withholding costs and exercise costs	$ 1	$ 43
Additional share repurchase authorization			$ 5,000
Remaining capacity under share repurchase authorization	$ 4,810	$ 4,810