Fair Value Measurement - Additional Information (Details)	3 Months Ended
Apr. 30, 2016 USD ($)
Fair Value Disclosures [Abstract]
Transfers into or out of the Level 3 category	$ 0

Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

No definition available.

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration