Description of offering period.

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Restricted stock weighted average grant date fair value.

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Aggregate number of common shares reserved for future issuance.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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Unrecognized cost of unvested options awarded to employees as compensation.

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No definition available.

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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- Definition

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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- Definition

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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No definition available.

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- Definition

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

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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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- Definition

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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- Definition

Number of share instruments newly issued under a share-based compensation plan.

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- Definition

Percentage of vesting of share-based compensation awards.

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- Definition

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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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- Definition

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

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No definition available.

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- Definition

Number of shares of stock issued during the period pursuant to acquisitions.

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Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Jan. 31, 2015	Jan. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Description of offering period excluding initial offering period	the offering period resets and the new lower price becomes the new offering price for a new 24 month offering period
Aggregate intrinsic value of exercised options	$ 6.6	$ 11.9
Aggregate estimated fair value of stock options granted to employees vested	$ 2.6	$ 5.7
Weighted-average grant date fair value of options granted to employees	$ 6.74	$ 5.25
Unrecognized stock-based compensation expense related to stock option	$ 20.3
Remaining weighted-average period	2 years 9 months 7 days
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining weighted-average period	2 years 11 months 23 days
Unrecognized stock-based compensation expense	$ 193.8
Unvested shares outstanding	13,974,193			11,822,316
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested shares outstanding	2,874			5,842
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%	0.00%
2015 Equity Incentive Plan \| Performance-Based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate estimated fair value of stock options granted to employees vested	$ 3.1
Stock options granted	475,000
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	17,404,178		12,200,000
2015 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares common stock reserved for issuance	2,969,790
Percentage of eligible compensation allowed to employees to purchase shares at a discount	15.00%
Description of offering period excluding initial offering period	Except for the 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%
Unrecognized stock-based compensation expense	$ 9.6
Dividend yield	0.00%	0.00%
2015 Employee Stock Purchase Plan \| Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining weighted-average period	5 months 23 days
Unrecognized stock-based compensation expense	$ 0.5
Issuance of common stock in connection with acquisition (in shares)			344,667
Weighted average grant date fair value, 2015 acquisition			$ 12.96
Unvested shares outstanding	145,737
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			2,500,000
Vesting Commencement Per Year \| 2015 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and restricted stock units vesting percentage	25.00%
Vesting Commencement Per Month
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and restricted stock units vesting percentage	2.08%
Vesting Commencement Per Quarter
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and restricted stock units vesting percentage	6.25%