Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 33,699	$ 30,654
Weighted average common shares - basic	38,281,000	37,251,000
Equity based awards	280,000	217,000
Weighted average common shares - diluted	38,561,000	37,468,000
Basic Earnings Per Share	$ 0.88	$ 0.82
Diluted Earnings Per Share	$ 0.87	$ 0.82
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	8,439	0