Fair Value Measurement (Details) - USD ($)	Jul. 31, 2022	Jan. 31, 2022
Financial assets:
Total marketable securities	$ 116,584,000	$ 115,940,000
Commercial paper
Financial assets:
Total marketable securities	27,244,000	15,343,000
Corporate bonds
Financial assets:
Total marketable securities	70,073,000	91,432,000
Municipal bonds
Financial assets:
Total marketable securities	19,267,000	9,165,000
Recurring
Financial assets:
Total cash equivalents	1,058,074,000	1,056,555,000
Total marketable securities	116,584,000	115,940,000
Total	1,174,658,000	1,172,495,000
Recurring | Commercial paper
Financial assets:
Total marketable securities	27,244,000	15,343,000
Recurring | Corporate bonds
Financial assets:
Total marketable securities	70,073,000	91,432,000
Recurring | Municipal bonds
Financial assets:
Total marketable securities	19,267,000	9,165,000
Recurring | Money market
Financial assets:
Total cash equivalents	1,058,074,000	1,056,555,000
Recurring | Level 1
Financial assets:
Total cash equivalents	1,058,074,000	1,056,555,000
Total marketable securities	0	0
Total	1,058,074,000	1,056,555,000
Recurring | Level 1 | Commercial paper
Financial assets:
Total marketable securities	0	0
Recurring | Level 1 | Corporate bonds
Financial assets:
Total marketable securities	0	0
Recurring | Level 1 | Municipal bonds
Financial assets:
Total marketable securities	0	0
Recurring | Level 1 | Money market
Financial assets:
Total cash equivalents	1,058,074,000	1,056,555,000
Recurring | Level 2
Financial assets:
Total cash equivalents	0	0
Total marketable securities	116,584,000	115,940,000
Total	116,584,000	115,940,000
Recurring | Level 2 | Commercial paper
Financial assets:
Total marketable securities	27,244,000	15,343,000
Recurring | Level 2 | Corporate bonds
Financial assets:
Total marketable securities	70,073,000	91,432,000
Recurring | Level 2 | Municipal bonds
Financial assets:
Total marketable securities	19,267,000	9,165,000
Recurring | Level 2 | Money market
Financial assets:
Total cash equivalents	0	0
Recurring | Level 3
Financial assets:
Total	$ 0	$ 0