Variable Interest Entity - Additional Information (Details)	12 Months Ended
Jan. 31, 2017
Variable Interest Entity [Line Items]
Monthly fee percentage on outstanding balance	4.75%

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.

No definition available.

Name:	us-gaap_VariableInterestEntityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration