Fair Value Measurement (Details) - USD ($) $ in Thousands	Jan. 31, 2025	Jan. 31, 2024
Financial Assets:
Total marketable securities	$ 844,435	$ 818,145
Treasury bills & U.S. government securities
Financial Assets:
Total marketable securities	703,319	641,192
Corporate bonds
Financial Assets:
Total marketable securities	94,025	1,991
Commercial paper
Financial Assets:
Total marketable securities	42,391
Yankee bonds
Financial Assets:
Total marketable securities	4,700
Agency bonds
Financial Assets:
Total marketable securities		174,962
Recurring
Financial Assets:
Total cash equivalents	311,942	509,053
Total marketable securities	844,435	818,145
Other investments carried at fair value	11,879
Total	1,168,256	1,327,198
Recurring | Money market funds
Financial Assets:
Total cash equivalents	311,942	509,053
Recurring | Treasury bills & U.S. government securities
Financial Assets:
Total marketable securities	703,319	641,192
Recurring | Corporate bonds
Financial Assets:
Total marketable securities	94,025	1,991
Recurring | Commercial paper
Financial Assets:
Total marketable securities	42,391
Recurring | Yankee bonds
Financial Assets:
Total marketable securities	4,700
Recurring | Agency bonds
Financial Assets:
Total marketable securities		174,962
Recurring | Level 1
Financial Assets:
Total cash equivalents	311,942	509,053
Total marketable securities	703,319	816,154
Other investments carried at fair value	0
Total	1,015,261	1,325,207
Recurring | Level 1 | Money market funds
Financial Assets:
Total cash equivalents	311,942	509,053
Recurring | Level 1 | Treasury bills & U.S. government securities
Financial Assets:
Total marketable securities	703,319	641,192
Recurring | Level 1 | Corporate bonds
Financial Assets:
Total marketable securities	0	0
Recurring | Level 1 | Commercial paper
Financial Assets:
Total marketable securities	0
Recurring | Level 1 | Yankee bonds
Financial Assets:
Total marketable securities	0
Recurring | Level 1 | Agency bonds
Financial Assets:
Total marketable securities		174,962
Recurring | Level 2
Financial Assets:
Total cash equivalents	0	0
Total marketable securities	141,116	1,991
Other investments carried at fair value	0
Total	141,116	1,991
Recurring | Level 2 | Money market funds
Financial Assets:
Total cash equivalents	0	0
Recurring | Level 2 | Treasury bills & U.S. government securities
Financial Assets:
Total marketable securities	0	0
Recurring | Level 2 | Corporate bonds
Financial Assets:
Total marketable securities	94,025	1,991
Recurring | Level 2 | Commercial paper
Financial Assets:
Total marketable securities	42,391
Recurring | Level 2 | Yankee bonds
Financial Assets:
Total marketable securities	4,700
Recurring | Level 2 | Agency bonds
Financial Assets:
Total marketable securities		0
Recurring | Level 3
Financial Assets:
Total cash equivalents	0	0
Total marketable securities	0	0
Other investments carried at fair value	11,879
Total	11,879	0
Recurring | Level 3 | Money market funds
Financial Assets:
Total cash equivalents	0	0
Recurring | Level 3 | Treasury bills & U.S. government securities
Financial Assets:
Total marketable securities	0	0
Recurring | Level 3 | Corporate bonds
Financial Assets:
Total marketable securities	0	0
Recurring | Level 3 | Commercial paper
Financial Assets:
Total marketable securities	0
Recurring | Level 3 | Yankee bonds
Financial Assets:
Total marketable securities	$ 0
Recurring | Level 3 | Agency bonds
Financial Assets:
Total marketable securities		$ 0