Stockholders' Equity and Stock-Based Compensation - Assumptions Used to Calculate Fair Value of Common Stock Options for Employees and Executive Team Members (Detail) - Service-Based Stock Options [Member]	3 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (years)	6 years 3 months	6 years 3 months
Risk-free interest rate	2.05%	1.54%
Expected volatility	34.10%	35.30%
Expected dividend yield	0.00%	0.00%