Stock-Based Compensation Plan (Summary Of Stock Option Activities) (Details) - $ / shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding at beginning of period, Number of Shares	1,189,255	1,420,749
Options outstanding at end of period, Number of Shares	1,189,255	1,066,505
Options exercisable at end of period, Number of Shares	917,729	835,276
Options outstanding at beginning of period, Weighted Average Exercise Price	$ 18.08	$ 15.67
Options outstanding at end of period, Weighted Average Exercise Price	18.08	16.78
Options exercisable at end of period, Weighted Average Exercise Price	$ 16.92	$ 15.31
Options exercisable at end of period, Weighted Average Remaining Contractual Term (in years)	4 years 8 months 12 days	5 years 1 month 6 days
Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercised, Number of Shares		(354,244)
Options exercised, Weighted Average Exercise Price		$ 12.35