Fair Value Measurements - Marketable Securities (Details) - U.S. government treasury securities - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Apr. 30, 2025	Jan. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized cost, due withen one year	$ 1,028,664	$ 968,748
Amortized cost, due after one year and withen three years	759,066	876,154
Amortized cost, total	1,787,730	1,844,902
Unrealized loss, due withen one year	1,602	944
Due after one year and within three years	6,797	598
Total short-term investments	8,399	1,542
Short-term investments	1,030,266	969,692
Marketable securities, non-current	765,863	876,752
Total short-term investments	$ 1,796,129	$ 1,846,444