Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Earnings Per Share [Abstract]
Net income	$ 33,373	$ 51,277
Weighted average common shares - basic	35,127,000	36,822,000
Equity based awards	243,000	214,000
Weighted average common shares - diluted	35,370,000	37,036,000
Basic	$ 0.95	$ 1.39
Diluted	$ 0.94	$ 1.38
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	200,383	0