Equity Incentive Plans - 2016 China Stock Appreciation Rights Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 75,776	$ 37,403	$ 21,235
Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Awards granted (in shares)	5,975	3,650	8,000
Exercise price of awards granted (in dollars per share)	$ 129.89	$ 74.92	$ 27.35
Awards vested (in shares)	4,958	14,273	9,302
Stock-based compensation expense	$ 2,100	$ 1,100	$ 200
Cash paid for exercise of SARs	$ 200
SARs exercised (in shares)	2,066
Stock Appreciation Rights (SARs) \| One Year Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
Vesting rights percentage	25.00%
Stock Appreciation Rights (SARs) \| 25 to 36 Months
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	36 months
Vesting rights percentage	75.00%

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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