Stock-Based Compensation - Employee Stock Purchase Plan (Details) - Employee Stock Purchase Plan - shares	3 Months Ended
	Apr. 30, 2017	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)		1,500,000
Number of shares authorized, annual increase		2,500,000
Number of shares authorized, annual increase, percentage of outstanding shares at the end of prior fiscal year		1.00%
Number of shares purchased under plan (in shares)	0