Earnings Per Share ("EPS") (Earnings Per Share Basic And Diluted) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Earnings Per Share [Abstract]
Net income	$ 41,700	$ 37,716	$ 94,495	$ 70,171
Weighted average shares, basic	38,253	38,060	38,212	38,004
Equity-based awards, Weighted average shares	180	168	164	202
Weighted average shares, diluted	38,433	38,228	38,376	38,206
Basic (in USD per share)	$ 1.09	$ 0.99	$ 2.47	$ 1.85
Diluted (in USD per share)	$ 1.09	$ 0.99	$ 2.46	$ 1.84