Shareholders' Equity - Shares Repurchased and Reissued (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Jan. 31, 2022	Aug. 31, 2020
Share repurchases
Repurchase of common shares	$ 477	$ 484	$ 1,056	$ 1,038
Shares surrendered upon vesting for income tax obligation			0.3	0.3
Income tax obligations paid on vesting date			$ 91	$ 58
Number of shares reacquired through net settlement options			0.2	0.8
Aggregate value of shares reacquired through net settlement options			$ 75	$ 167
Treasury shares reissued for restricted stock award grants, performance share units and issuance of shares vested under advisor deferred compensation plans			0.7	0.4
Share repurchase authorization
Share repurchases
Repurchase of common shares (in shares)			3.2	3.4
Repurchase of common shares			$ 887	$ 813
Stock repurchase program, authorized amount					$ 3,000	$ 2,500
Remaining balance under stock repurchase program	$ 2,500		$ 2,500