Stock-Based Compensation (Summary Of Restricted Stock And Restricted Stock Units Granted) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010		Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock, Shares	173,553	121,923		115,060
Restricted stock units, Shares forfeited		2,013
Restricted stock units, Forfeited shares price per share		$ 29.84
Restricted stock units outstanding	42,938	29,872		14,426
Executives Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock, Shares	167,250	112,500		113,250
Restricted stock, Price per share	44.39	$ 30.87		15.67
Restricted stock, Aggregate value	7,424	$ 3,473		1,774
Percent vested	0.00%	20.00%		40.00%
Directors Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock, Shares	6,303	9,423		1,810
Restricted stock, Price per share	40.45	$ 30.85		29.93
Restricted stock, Aggregate value	255	291		54
Percent vested	100.00%	100.00%		100.00%
Directors Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock, Shares	13,063	15,443	[1]	9,831
Restricted stock, Price per share	40.49	$ 29.95		29.76
Restricted stock, Aggregate value	529	$ 463		293
Percent vested	100.00%	100.00%		100.00%

[1] 2,013 shares at $29.84 per share were later forfeited in 2010.