Shareholders' Equity - Shares Repurchased and Reissued (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jan. 31, 2022	Aug. 31, 2020	Feb. 28, 2019
Share repurchases
Repurchase of common shares	$ 2,095	$ 2,222	$ 1,647
Stock repurchase program, authorized amount				$ 3,000	$ 2,500	$ 2,500
Remaining balance under stock repurchase program	$ 1,600
Shares surrendered upon vesting for income tax obligation (in shares)	0.3	0.3	0.3
Income tax obligations paid on vesting date	$ 99	$ 69	$ 52
Shares reacquired through net settlement of options (in shares)	0.5	1.3	1.5
Aggregate value of shares reacquired through net settlement of options	$ 145	$ 306	$ 263
Treasury shares reissued for restricted stock award grants, performance share units and issuance of shares vested under advisor deferred compensation plans (in shares)	0.8	0.4	0.5
Share repurchase authorization
Share repurchases
Repurchase of common shares (in shares)	6.6	7.1	8.4
Repurchase of common shares	$ 1,900	$ 1,800	$ 1,300