Stockholders' Equity - Schedule of Weighted-Average Assumptions Used to Estimate Grant Date Fair Value of Options Granted (Parenthetical) (Detail) - shares	3 Months Ended	9 Months Ended
	Oct. 31, 2018	Oct. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock options, granted	0	175,000