Summary of Significant Accounting Policies - Earnings per Share (Details) - shares	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted average common shares outstanding - Basic (in shares)	29,142,843	29,094,062	29,013,759	30,796,114
Dilutive effect of stock options, RSUs and PSUs (in shares)	340,638	616,678	0	557,720
Weighted average common shares outstanding - Diluted (in shares)	29,483,481	29,710,740	29,013,759	31,353,834
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)	894,130	660,304	1,225,771	885,554