Employee Benefit Plans (Schedule Of Restricted Stock Units Activity) (Details) (USD $)	12 Months Ended
	Jan. 31, 2012
Employee Benefit Plans [Abstract]
Shares, Outstanding at January 31, 2011	543,841
Shares, Granted	272,949
Shares, Vested	(210,094)
Shares, Canceled	(38,198)
Shares, Outstanding at January 31, 2012	568,498
Weighted-average grant date fair value, Outstanding at January 31, 2011	$ 38.60
Weighted-average grant date fair value, Granted	$ 48.53
Weighted-average grant date fair value, Vested	$ 37.40
Weighted-average grant date fair value, Canceled	$ 41.35
Weighted-average grant date fair value, Outstanding at January 31, 2012	$ 43.74