Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Section 50
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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

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

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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- 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
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-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

Percentage of vesting of share-based compensation awards.

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-Publisher FASB
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-SubTopic 10
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Equity Incentive Plans - Restricted Stock (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Mar. 31, 2018	Jan. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 43,955	$ 32,219
Compensation cost, weighted average term	2 years 2 months 12 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award balance (in shares)	20,453,251		1,375,210	17,682,646
Compensation cost, weighted average term	3 years 1 month 6 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 3,500
Unrecognized stock-based compensation expense	$ 36,900
Compensation cost, weighted average term	2 years 10 months 24 days
Restricted Stock \| Performance Vesting Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award balance (in shares)	697,116
Restricted Stock \| Service Vesting Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award balance (in shares)	678,094
Restricted Stock \| Performance Vesting At Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award balance (in shares)	1,933,861
Restricted Stock \| Maximum \| Performance Vesting At Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage	180.00%
Restricted Stock \| Minimum \| Performance Vesting At Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage	0.00%