Description of employee stock purchase plan offering period.

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Description of employee stock purchase plan offering period resets.

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

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Aggregate number of common shares reserved for future issuance.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Amount of cost to be recognized for option under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Description of terms of share-based payment arrangement. Includes, but is not limited to, type of award or grantee and reason for issuance.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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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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The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Number of options outstanding, including both vested and non-vested options.

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Percentage of vesting of award under share-based payment arrangement.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Purchase price of common stock expressed as a percentage of its fair value.

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Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			9 Months Ended
	Oct. 31, 2020	Apr. 30, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019	Jan. 31, 2020	Jan. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate intrinsic value of exercised options				$ 25,400	$ 4,500
Aggregate estimated fair value of stock options granted to employees vested				$ 1,900	$ 2,400
Weighted-average grant date fair value of options granted to employees				$ 5.41	$ 8.00
Unrecognized stock-based compensation expense related to stock option	$ 2,500			$ 2,500
Remaining weighted-average period				1 year 7 months 2 days
Stock options outstanding	6,791,725			6,791,725		8,772,585
Unrecognized stock-based compensation expense	$ 3,900			$ 3,900
Share-based compensation expense	37,834		$ 37,758	$ 115,438	$ 106,925
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining weighted-average period				2 years 8 months 8 days
Unrecognized stock-based compensation expense	270,700			$ 270,700
Performance-Based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense related to stock option	$ 1,400			$ 1,400
Remaining weighted-average period				2 years 1 month 2 days
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield				0.00%	0.00%
2015 Equity Incentive Plan \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period				4 years
2015 Equity Incentive Plan \| Performance-Based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options outstanding	1,375,000			1,375,000
2015 Equity Incentive Plan \| Time-Based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period				4 years
2015 Equity Incentive Plan \| Class A Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares common stock reserved for issuance	22,898,009			22,898,009			12,200,000
2015 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of eligible compensation allowed to employees to purchase shares at a discount	15.00%			15.00%
Description of offering period excluding initial offering period				The 2015 ESPP provides for 24-month offering periods beginning March 16 and September 16 of each year, and each offering period consists of four six-month purchase periods.
Purchase price of common stock, percentage				85.00%
Description of offering period resets				the offering period resets and the new lower price becomes the new offering price for a new 24 month offering period.
Unrecognized stock-based compensation expense	$ 38,300			$ 38,300
Dividend yield	0.00%		0.00%	0.00%	0.00%
2015 Employee Stock Purchase Plan \| Class A Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares common stock reserved for issuance	1,288,378			1,288,378			2,500,000
Fiscal 2020 Executive Bonus Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense		$ 1,500
Fiscal 2021 Executive Bonus Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 4,100			$ 4,100
Share-based compensation expense				$ 7,000
Equity incentive compensation description				The Fiscal 2021 Executive Bonus Plan provides opportunities for 100% equity incentive compensation payouts based on our actual achievement of pre-established corporate financial objectives, subject to review and a final approval by our Compensation Committee.
Fiscal 2021 Executive Bonus Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining weighted-average period				1 year
One Year from Vesting Commencement Date \| 2015 Equity Incentive Plan \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage				25.00%
One Year from Vesting Commencement Date \| 2015 Equity Incentive Plan \| Time-Based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage				25.00%
Per Month after One Year of Vesting Commencement Date \| 2015 Equity Incentive Plan \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage				6.25%
Per Month after One Year of Vesting Commencement Date \| 2015 Equity Incentive Plan \| Time-Based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage				2.08%
Per Quarter after One Year Of Vesting Commencement Date \| 2015 Equity Incentive Plan \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage				6.25%