Segment Information - Reconciliation of Segment Financial Information to Loss from Operations (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Segment Reporting Information [Line Items]
Contribution margin										$ 607,110	$ 368,529	$ 273,157
Amortization of acquired intangible assets										(80,000)	(9,100)	(3,700)
Corporate costs, such as research and development, corporate general and administrative and other	[1],[2]									(901,443)	(537,591)	(588,430)
Loss from operations		$ (64,437)	$ (82,467)	$ (89,097)	$ (103,753)	$ (86,965)	$ (25,673)	$ (29,424)	$ (51,702)	(339,754)	(193,764)	(374,172)
Operating Segments
Segment Reporting Information [Line Items]
Contribution margin										607,110	368,529	273,157
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Amortization of acquired intangible assets										(80,024)	(9,129)	(3,723)
Stock-based compensation expense										(220,354)	(117,365)	(290,006)
Corporate costs, such as research and development, corporate general and administrative and other										$ (646,486)	$ (435,799)	$ (353,600)

[1] Amounts include amortization of acquired intangible assets as follows (in thousands):

[2] Amounts include stock-based compensation expense as follows (in thousands):