Common and Preferred Shares - Common Shares (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Equity [Abstract]
Common shares, authorized (in shares)	3,600	3,600	3,600
Schedule Of Stock By Class [Roll Forward]
Shares issued and outstanding at beginning of year (in shares)	743	761	805
Repurchases of common shares (in shares)	(22)	(20)	(46)
Net shares issued for RSUs and stock option exercises (in shares)	2	2	2
Shares issued and outstanding as of December 31 (in shares)	723	743	761
Shares reserved for issuance under employee stock and employee benefit plans (in shares)	16