Employee Incentive, Retirement, Deferred Compensation, and Career Achievement Plans - Stock-Based Compensation Expense and Related Income Tax Benefit (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	[1]	$ 320	$ 366	$ 254
Income tax benefit on share-based compensation expense		(76)	(88)	(60)
Stock option expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense		33	30	36
Restricted stock unit expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense		262	311	200
Employee stock purchase plan expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense		25	25	18
Share-Based Payment Arrangement, Option Exercised And Restricted Stock Units (RSUs) Vested
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit on share-based compensation expense		$ (31)	$ (51)	$ (93)

[1] Certain prior year amounts have been reclassified to conform to the current year presentation. See Note 1 for additional information.