Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	Oct. 31, 2021	Jul. 31, 2021	Apr. 30, 2021	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of accounting change	$ (662,905)	$ (673,724)	$ 268,364	$ 5,033	$ (21,804)	$ (48,151)	$ (63,041)	$ (82,858)
Temporary equity, convertible senior notes	0			4,714
Convertible senior notes, net	1,135,684			937,729
Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of accounting change	1,105,186	1,023,893	946,760	935,403	859,602	786,951	722,426	668,232
Additional Paid-In Capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of accounting change	(1,770,635)	$ (1,699,150)	$ (680,413)	(932,332)	$ (883,002)	$ (836,293)	$ (785,730)	(752,127)
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of accounting change				256,746				227
Temporary equity, convertible senior notes	4,700
Convertible senior notes, net	261,500
Cumulative Effect, Period of Adoption, Adjustment | Accumulated Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of accounting change	(52,600)			(52,635)				$ 227
Cumulative Effect, Period of Adoption, Adjustment | Additional Paid-In Capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of accounting change	$ (309,400)			$ 309,381