Convertible Senior Notes - Schedule of Components of Convertible Senior Notes (Details) - USD ($) $ in Thousands	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2018
Liability:
Net carrying amount	$ 1,614,257	$ 897,525
0.375% Convertible Senior Notes Due 2026
Liability:
Principal	1,380,000	1,380,000
Unamortized debt discount and issuance costs	(408,467)	(482,475)
Net carrying amount	971,533	897,525
Carrying amount of the equity component	501,053	501,053
0.125% Convertible Senior Notes Due 2025
Liability:
Principal	804,990	804,999
Unamortized debt discount and issuance costs	(162,266)	(203,638)
Net carrying amount	642,724	601,361
Carrying amount of the equity component	246,966	246,966
0.375% Convertible Senior Notes Due 2023
Liability:
Principal	1,752	8,832	$ 230,000
Unamortized debt discount and issuance costs	(113)	(1,125)
Net carrying amount	1,639	7,707
Carrying amount of the equity component	$ 460	$ 1,560