Investments and Fair Value Measurements - Financial Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Apr. 30, 2025	Jan. 31, 2025
Assets
Total assets	$ 4,317,647	$ 3,965,633
Money market funds
Assets
Cash equivalents	1,822,048	1,470,040
U.S. Treasury securities
Assets
Cash equivalents	2,489,005	2,490,097
Deferred compensation investments
Assets
Other assets	6,594	5,496
Level 1
Assets
Total assets	1,828,642	1,475,536
Level 1 \| Money market funds
Assets
Cash equivalents	1,822,048	1,470,040
Level 1 \| U.S. Treasury securities
Assets
Cash equivalents	0	0
Level 1 \| Deferred compensation investments
Assets
Other assets	6,594	5,496
Level 2
Assets
Total assets	2,489,005	2,490,097
Level 2 \| Money market funds
Assets
Cash equivalents	0	0
Level 2 \| U.S. Treasury securities
Assets
Cash equivalents	2,489,005	2,490,097
Level 2 \| Deferred compensation investments
Assets
Other assets	0	0
Level 3
Assets
Total assets	0	0
Level 3 \| Money market funds
Assets
Cash equivalents	0	0
Level 3 \| U.S. Treasury securities
Assets
Cash equivalents	0	0
Level 3 \| Deferred compensation investments
Assets
Other assets	$ 0	$ 0