Fair Value Measurements - Schedule of Financial Assets and Liabilities (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Oct. 31, 2025	Jan. 31, 2025
Short-term investments:
Total financial assets	$ 1,721,974	$ 1,999,032
Level 1
Short-term investments:
Total financial assets	1,721,974	1,999,032
Level 2
Short-term investments:
Total financial assets	0	0
Level 3
Short-term investments:
Total financial assets	0	0
U.S. government treasury securities
Short-term investments:
Short-term investments:	1,471,669	1,846,444
U.S. government treasury securities | Level 1
Short-term investments:
Short-term investments:	1,471,669	1,846,444
U.S. government treasury securities | Level 2
Short-term investments:
Short-term investments:	0	0
U.S. government treasury securities | Level 3
Short-term investments:
Short-term investments:	0	0
Money market funds
Cash and cash equivalents:
Cash and cash equivalents:	250,305	152,588
Money market funds | Level 1
Cash and cash equivalents:
Cash and cash equivalents:	250,305	152,588
Money market funds | Level 2
Cash and cash equivalents:
Cash and cash equivalents:	0	0
Money market funds | Level 3
Cash and cash equivalents:
Cash and cash equivalents:	$ 0	$ 0