Employee Benefit Plans (Schedule Of Stock Options Activity) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2012 years
Employee Benefit Plans [Abstract]
Shares, Outstanding at January 31, 2011	2,881,356
Shares, Granted	12,882
Shares, Exercised	(1,215,028)
Shares, Canceled	(27,810)
Shares, Outstanding at January 31, 2012	1,651,400
Vested and expected to vest at January 31, 2012, Shares	1,638,799
Exercisable at January 31, 2012, Shares	1,296,587
Weighted-average exercise price, Outstanding at January 31, 2011	$ 35.36
Weighted-average exercise price, Granted	$ 48.79
Weighted-average exercise price, Exercised	$ 37.76
Weighted-average exercise price, Canceled	$ 23.95
Weighted-average exercise price, Outstanding at January 31, 2012	$ 33.89
Weighted-average exercise price, Vested and expected to vest at January 31, 2012	$ 33.95
Weighted-average exercise price, Exercisable at January 31, 2012	$ 36.72
Weighted-Average remaining contractual term (in years), Outstanding at January 31, 2012	4.2
Weighted-Average remaining contractual term (in years), Vested and expected to vest at January 31, 2012	4.1
Weighted-Average remaining contractual term (in years), Exercisable at January 31, 2012	3.3
Aggregate intrinsic value, Outstanding	$ 29,783
Aggregate intrinsic value, Vested and expected to vest at January 31, 2012	29,444
Aggregate intrinsic value, Exercisable at January 31, 2012	$ 19,712