Capital Stock And Share-Based Compensation (Schedule Of Non-Vested Stock Award Activity) (Details) (Non-Vested Stock Units [Member], USD $)	12 Months Ended
	Dec. 31, 2011
Non-Vested Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Non-vested Beginning Balance	46,894
Weighted average grant date fair Value, Non-vested Beginning Balance	$ 37.65
Shares, Granted	31,390
Weighted average grant date fair Value, Granted	$ 27.40
Shares, Vested	(49,856)
Weighted average grant date fair Value, Vested	$ 37.04
Shares, Canceled, forfeited or expired
Weighted average grant date fair Value, Canceled, forfeited or expired
Shares, Non-vested Ending Balance	28,428
Weighted average grant date fair Value, Non-vested Ending Balance	$ 27.40