Summary of Significant Accounting Policies - Earnings per Share (Details) - shares	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted average common shares outstanding - Basic (in shares)	29,070,607	31,442,909	28,948,216	31,660,320
Dilutive effect of stock options, RSUs and PSUs (in shares)	69,939	515,795	0	537,704
Weighted average common shares outstanding - Diluted (in shares)	29,140,546	31,958,704	28,948,216	32,198,024
Restricted Stock Units And Phantom Share Units [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted average number of stock options and restricted stock units not included in the calculation of the dilutive effect of stock options and restricted stock units (in shares)	1,116,730	927,969	1,479,599	892,098