Marketable Securities - Narrative (Details)	3 Months Ended		9 Months Ended
	Oct. 31, 2025 USD ($) security	Oct. 31, 2024 USD ($)	Oct. 31, 2025 USD ($) security	Oct. 31, 2024 USD ($)	Jan. 31, 2025 USD ($) security
Investments, Debt and Equity Securities [Abstract]
Investment income, interest	$ 4,600,000	$ 5,600,000	$ 15,500,000	$ 20,900,000
Debt securities in an unrealized loss position | security	34		34		40
Unleased loss position	$ 94,000,000		$ 94,000,000		$ 140,000,000
Expected credit losses	$ 0		$ 0		$ 0