Deferred Compensation (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 31, 2023	Oct. 31, 2022	Oct. 31, 2023	Oct. 31, 2022	Jan. 31, 2023
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Costs to obtain a contract	$ 151,000,000		$ 151,000,000		$ 133,000,000
Amortization of costs to obtain a contract	34,000,000	$ 35,000,000	97,000,000	$ 102,000,000
Impairment losses	0	$ 0	0	$ 0
Rabbi Trust
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation liability	90,000,000		90,000,000		86,000,000
Deferred compensation liability, current	7,000,000		7,000,000		7,000,000
Deferred compensation liability, non-current	$ 83,000,000		$ 83,000,000		$ 79,000,000