Income Taxes - Summary of Differences Between Effective Tax Rate and Federal Statutory Rate (Details)	12 Months Ended
Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	34.00%	34.00%	34.00%
State tax, net of federal benefit	2.60%	2.70%	2.70%
Change in valuation allowance	(36.20%)	(32.00%)	(35.40%)
Stock-based compensation	(2.70%)	(6.30%)	(0.40%)
Other non-deductible items	(1.80%)	(0.40%)	(1.06%)
Foreign rate differential	(1.40%)	(0.40%)	(0.24%)
Tax credits	3.20%	1.70%
Total	(2.30%)	(0.70%)	(0.40%)

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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