Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value (Details) - Recurring - USD ($) $ in Thousands	Jan. 31, 2026	Jan. 31, 2025
Short-term investments:
Total financial assets	$ 1,685,388	$ 1,999,032
Level 1
Short-term investments:
Total financial assets	1,685,388	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:
U.S. government treasury securities	1,303,701	1,846,444
U.S. government treasury securities | Level 1
Short-term investments:
U.S. government treasury securities	1,303,701	1,846,444
U.S. government treasury securities | Level 2
Short-term investments:
U.S. government treasury securities	0	0
U.S. government treasury securities | Level 3
Short-term investments:
U.S. government treasury securities	0	0
Money market funds
Cash and cash equivalents:
Money market funds	381,687	152,588
Money market funds | Level 1
Cash and cash equivalents:
Money market funds	381,687	152,588
Money market funds | Level 2
Cash and cash equivalents:
Money market funds	0	0
Money market funds | Level 3
Cash and cash equivalents:
Money market funds	$ 0	$ 0