Earnings Per Share ("EPS") (Earnings Per Share Basic And Diluted) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2014	Jul. 31, 2013
Earnings Per Share [Abstract]
Net income	$ 39,328	$ 14,695	$ 52,795	$ 32,455
Weighted average shares, basic	38,244	38,043	38,191	37,976
Equity-based awards, Weighted average shares	124	137	151	201
Weighted average shares, diluted	38,368	38,180	38,342	38,177
Basic (in USD per share)	$ 1.03	$ 0.39	$ 1.38	$ 0.85
Diluted (in USD per share)	$ 1.03	$ 0.38	$ 1.38	$ 0.85