Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 55,400	$ 33,699
Weighted average common shares - basic	37,011,000	38,281,000
Equity based awards	236,000	280,000
Weighted average common shares - diluted	37,247,000	38,561,000
Basic Earnings Per Share	$ 1.50	$ 0.88
Diluted Earnings Per Share	$ 1.49	$ 0.87
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	322	8,439