Income Taxes - Effective Tax Rate Reconciliation After ASU Adoption (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2026	Jan. 31, 2025	Jan. 31, 2024
Amount
US federal statutory tax rate	$ 508,680	$ 276,270	$ 174,785
State and local income tax, net of federal income tax effect	39,700	56,336	37,137
Other foreign jurisdictions		141	2,943
Foreign-derived intangible income deduction	(42,360)	(56,630)	(63,571)
Other effect of cross-border tax laws	(2,705)
Stock-based compensation	25,274	58,770	96,936
Research and development tax credits	(34,347)	(49,813)	(39,226)
Changes in valuation allowance	5,503	(7,765)	(14,109)
Changes in unrecognized tax benefits	16,065	7,478	2,674
Other	3,905	(1,576)	(10,570)
Non-deductible compensation		15,757	10,639
Total provision for income taxes	$ 522,137	$ 305,346	$ 194,850
Percent
US federal statutory tax rate	21.00%
State and local income tax, net of federal income tax effect	1.60%
Foreign-derived intangible income deduction	(1.70%)
Other effect of cross-border tax laws	(0.10%)
Stock-based compensation	1.00%
Research and development tax credits	(1.40%)
Changes in valuation allowance	0.20%
Changes in unrecognized tax benefits	0.70%
Other	0.20%
Effective tax rate	21.60%	23.20%	23.40%
Excess tax benefit on stock-based compensation for awards vested and exercised	$ 36,800
Other foreign jurisdictions
Amount
Other foreign jurisdictions	$ 2,422
Percent
Other foreign jurisdictions	0.10%