Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 3,726	$ 3,170	$ 2,567
Cost of equipment held pursuant to capital leases	14,820	14,809
Accumulated amortization	12,566	9,012
Assets Held under Capital Leases [Member]
Property, Plant and Equipment [Line Items]
Accumulated amortization	$ 9,266	$ 6,808