Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
	Jan. 31, 2023 USD ($) segment	Jan. 31, 2022 USD ($)	Jan. 31, 2021 USD ($)
Accounting Policies [Line Items]
Number of reportable segments | segment	3
Cash and cash equivalents	$ 8,625	$ 14,760
Percentage of cash and cash equivalents	62.00%	50.00%
Receivables from transactions with customers, net	$ 3,700	$ 3,400
Depreciation and amortization	10,945	10,658	$ 11,152
Indefinite-lived intangible assets (excluding goodwill)	4,300	4,800
Equity and other securities, changes in fair value	(1,700)	(2,400)	8,600
Trading securities	500	1,000
Membership fee revenue	5,408	4,992	3,918
Advertising expense	4,100	3,900	3,200
Indemnification Agreement
Accounting Policies [Line Items]
Guarantor obligations, current carrying value	600	700
Guarantor obligations, maximum exposure	3,100
Membership Fees
Accounting Policies [Line Items]
Membership fee revenue	2,600	2,200	$ 1,700
Amounts Due from Banks
Accounting Policies [Line Items]
Cash and cash equivalents	2,000	1,700
Nonrepatriable Cash and Cash Equivalents
Accounting Policies [Line Items]
Cash and cash equivalents	$ 2,900	$ 4,300