Organization and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017	Feb. 01, 2019
Summary Of Significant Accounting Policies [Line Items]
Accumulated amortization of intangible asset	$ 7,612,000	$ 3,087,000
Impairment of long-lived assets	0
Goodwill impairment	0	0	$ 0
Impairment losses on investment	0
Accrued warranty	$ 0	$ 1,750,000
Expected dividend yield	0.00%	0.00%	0.00%
ASU 2016-02 [Member] | Minimum [Member] | Subsequent Event [Member]
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets				$ 8,000,000
Lease liabilities				8,000,000
ASU 2016-02 [Member] | Maximum [Member] | Subsequent Event [Member]
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets				10,000,000
Lease liabilities				$ 10,000,000
IPR&D [Member]
Summary Of Significant Accounting Policies [Line Items]
Accumulated amortization of intangible asset	$ 0	$ 0