Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended
	Jan. 31, 2018	Jul. 31, 2018	Jul. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 1,500,000
Additional impairment charges		$ 0
Aggregate amortization expense		$ 889,000	$ 716,000
Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life of intangible assets		5 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life of intangible assets		15 years