Stock-Based Compensation Plan (Summary Of Stock Option Activities) (Details) - $ / shares	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding at beginning of period, Number of Shares	1,420,749	1,263,485
Options outstanding at end of period, Number of Shares	1,189,255	1,426,485
Options exercisable at end of period, Number of Shares	884,817	1,154,844
Options outstanding at beginning of period, Weighted Average Exercise Price	$ 15.67	$ 14.84
Options outstanding at end of period, Weighted Average Exercise Price	18.08	15.67
Options exercisable at end of period, Weighted Average Exercise Price	$ 16.76	$ 14.13
Weighted average remaining term	5 years 1 month 6 days	4 years 9 months 18 days
Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted - employees and directors, Number of Shares	133,000	120,000
Options forfeited - employees, Number of Shares		(5,417)
Options exercised - employees, Number of Shares	(414,494)	(1,583)
Options granted - employees and directors, Weighted Average Exercise Price	$ 21.66	$ 22.09
Options forfeited - employees, Weighted Average Exercise Price		22.55
Options exercised - employees, Weighted Average Exercise Price	$ 11.45	$ 17.77
Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted - employees and directors, Number of Shares	50,000	50,000
Options granted - employees and directors, Weighted Average Exercise Price	$ 21.89	$ 22.09