Equity Incentive Plans (Summary Of Exercisable Options) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Y
Options outstanding (in shares)	752,056
Weighted avg. life remaining (in years)	4.1
Weighted avg. exercise price	$ 36.60
Aggregate intrinsic value	$ 9,294
$18.18 - 19.99 [Member]
Exercise price range, lower limit	$ 18.18
Exercise price range, upper limit	$ 19.99
Options outstanding (in shares)	149,923
Weighted avg. life remaining (in years)	6.9
20.00 - 29.99 [Member]
Exercise price range, lower limit	$ 20.00
Exercise price range, upper limit	$ 29.99
Options outstanding (in shares)	172,304
Weighted avg. life remaining (in years)	0.9
30.00 - 39.99 [Member]
Exercise price range, lower limit	$ 30.00
Exercise price range, upper limit	$ 39.99
Options outstanding (in shares)	77,705
Weighted avg. life remaining (in years)	2.9
40.00 - 49.99 [Member]
Exercise price range, lower limit	$ 40.00
Exercise price range, upper limit	$ 49.99
Options outstanding (in shares)	240,771
Weighted avg. life remaining (in years)	4.7
50.00 - 59.99 [Member]
Exercise price range, lower limit	$ 50.00
Exercise price range, upper limit	$ 59.99
Options outstanding (in shares)	10,000
Weighted avg. life remaining (in years)	6.1
60.00 - 65.50 [Member]
Exercise price range, lower limit	$ 60.00
Exercise price range, upper limit	$ 65.50
Options outstanding (in shares)	101,353
Weighted avg. life remaining (in years)	4.8