Balance Sheet - Additional Information (Detail)	9 Months Ended	12 Months Ended
Oct. 31, 2019 USD ($) customer	Jan. 31, 2019 USD ($) customer
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of customers due \| customer	2	3
Contracts receivable	$ 1,500,000	$ 3,000,000
Contracts receivable, noncurrent		$ 712,000
Contracts receivable, interest rate	4.30%	3.60%
Impairment of long-lived assets	$ 0	$ 0

The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

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