Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
	Jan. 31, 2022 USD ($) segment	Jan. 31, 2021 USD ($)	Jan. 31, 2020 USD ($)
Accounting Policies [Line Items]
Number of reportable segments | segment	3
Cash and cash equivalents	$ 14,760	$ 17,741
Percentage of cash and cash equivalents	50.00%	40.00%
Receivables from transactions with customers, net	$ 3,400	$ 2,700
Liabilities for sale	21	12,734
Depreciation and amortization	10,658	11,152	$ 10,987
Indefinite-lived intangible assets (excluding goodwill)	4,800	4,900
Impairment of intangible assets (excluding goodwill)			700
Trading securities	1,000
Membership fee revenue	4,992	3,918	4,038
Advertising expense	3,900	3,200	3,700
Indemnification Agreement
Accounting Policies [Line Items]
Guarantor obligations, current carrying value	700	600
Guarantor obligations, maximum exposure	3,500
Membership Fees [Member]
Accounting Policies [Line Items]
Membership fee revenue	2,200	1,700	$ 1,500
Amounts Due from Banks [Member]
Accounting Policies [Line Items]
Cash and cash equivalents	1,700	4,100
Nonrepatriable Cash and Cash Equivalents [Member]
Accounting Policies [Line Items]
Cash and cash equivalents	4,300	2,800
Prepaid Expenses and Other [Member]
Accounting Policies [Line Items]
Assets held for sale	19,200
Accrued Liabilities [Member]
Accounting Policies [Line Items]
Liabilities for sale	12,700
Long-term Debt [Member] | Net Investment Hedging [Member]
Accounting Policies [Line Items]
Nonderivative hedging instruments		$ 3,300
Flipkart [Member] | Nonrepatriable Cash and Cash Equivalents - Flipkart [Member]
Accounting Policies [Line Items]
Cash and cash equivalents	$ 2,200