Share Based Compensation - Outstanding stock units (Details) - Director	12 Months Ended
	Jan. 31, 2020 $ / shares shares
Number of stock units
Outstanding, beginning of period (in shares) | shares	105,225
Granted (in shares) | shares	19,528
Deferred retainers (in shares) | shares	2,872
Dividends (in shares) | shares	1,788
Outstanding, end of period (in shares) | shares	129,413
Weighted average price
Outstanding, beginning of period (in usd per share) | $ / shares	$ 22.67
Granted (in usd per share) | $ / shares	34.82
Deferred retainers (in usd per share) | $ / shares	34.82
Dividends (in usd per share) | $ / shares	35.66
Outstanding, end of period (in usd per share) | $ / shares	$ 24.95