Significant Accounting Policies - Additional Information (Details) - ASU 2016-09 $ in Millions	12 Months Ended
Jan. 31, 2017 USD ($)
Significant Accounting Policies [Line Items]
Cumulative-effect decrease in accumulated deficit	$ 6.7
Valuation allowance against deferred tax assets	$ 6.7

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

Name:	us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant