Investments and Fair Value Measurements - Amortized Cost to Fair Value Reconciliation (Details) - USD ($) $ in Thousands	Jul. 31, 2023	Jan. 31, 2023
Debt Securities, Available-for-sale
Cash and cash equivalents, amortized cost	$ 1,523,462	$ 690,587
Investments, amortized cost	1,037,348	1,381,666
Investments, unrealized gains	2	3
Investments, unrealized losses	(960)	(5,616)
Investments, fair value	1,036,390	1,376,053
Investments, Current | U.S. Government and Agency Securities
Debt Securities, Available-for-sale
Investments, amortized cost	354,006	1,125,700
Investments, unrealized gains	0	1
Investments, unrealized losses	(282)	(4,546)
Investments, fair value	353,724	1,121,155
Investments, Current | Corporate Bonds
Debt Securities, Available-for-sale
Investments, amortized cost	38,995	54,173
Investments, unrealized gains	2	2
Investments, unrealized losses	(62)	(342)
Investments, fair value	38,935	53,833
Investments, Current | Commercial Paper
Debt Securities, Available-for-sale
Investments, amortized cost	533,461	142,061
Investments, unrealized gains	0	0
Investments, unrealized losses	(594)	(702)
Investments, fair value	532,867	141,359
Commercial Paper
Debt Securities, Available-for-sale
Cash and cash equivalents, amortized cost	103,888
Cash and cash equivalents, unrealized gains	0
Cash and cash equivalents, unrealized losses	(22)
Cash and cash equivalents, fair value	103,866
U.S. Government and Agency Securities
Debt Securities, Available-for-sale
Cash and cash equivalents, amortized cost	6,998	59,732
Cash and cash equivalents, unrealized gains	0	0
Cash and cash equivalents, unrealized losses	0	(26)
Cash and cash equivalents, fair value	$ 6,998	$ 59,706