Description of offering period.

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Restricted stock weighted average grant date fair value.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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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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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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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.

+ References

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

Percentage of vesting of share-based compensation awards.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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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
-Name Accounting Standards Codification
-Topic 718
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-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

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

+ References

No definition available.

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- Definition

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015	Jan. 31, 2015	Jan. 31, 2016
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			$ 15.4	$ 11.3
Aggregate estimated fair value of stock options granted to employees vested			$ 9.6	$ 9.8
Weighted-average grant date fair value of options granted to employees			$ 5.10	$ 7.56
Unrecognized stock-based compensation expense related to stock option	$ 18.7		$ 18.7
Remaining weighted-average period			2 years 3 months 4 days
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining weighted-average period			2 years 10 months 13 days
Unrecognized stock-based compensation expense	$ 122.3		$ 122.3
Unvested shares outstanding	9,670,955		9,670,955			8,204,968
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining weighted-average period			9 months 18 days
Unvested shares outstanding	11,904		11,904			30,607
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%	0.00%
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	18,203,062		18,203,062		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	3,138,536		3,138,536
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			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 will consist of four six-month purchase periods.
Purchase price of common stock, percentage			85.00%
Unrecognized stock-based compensation expense	$ 11.4		$ 11.4
Dividend yield	0.00%	0.00%	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			1 year 2 months 12 days
Unrecognized stock-based compensation expense	$ 1.4		$ 1.4
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	220,207		220,207
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
Other Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares common stock reserved for issuance	42,137		42,137
Remaining weighted-average period			11 months 1 day
Unrecognized stock-based compensation expense	$ 0.5		$ 0.5
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%