Stockholders' Equity (Schedule Of Deferred Stock Units Transactions) (Details) (Deferred Stock Unit [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding	692,961	613,754	369,133
Issued	56,212	32,462	23,713
Granted	187,490	140,461	282,925
Dividend equivalents	27,532		34,568
Forfeited	(38,855)	(4,505)
Exercised	(187,052)	(89,211)	(96,585)
Outstanding	738,288	692,961	613,754
Stock Price, Dividend equivalent	$ 50.45	$ 30.50	$ 33.32
Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Stock Price, Outstanding	$ 6.16	$ 6.16	$ 5.50
Stock Price, Issued	$ 36.68	$ 33.84	$ 24.53
Stock Price, Granted	$ 45.98	$ 36.58	$ 26.54
Stock Price, Forfeited	$ 26.98
Stock Price, Exercised	$ 19.98	$ 20.20	$ 5.50
Stock Price, Outstanding	$ 6.16	$ 6.16	$ 6.16
Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Stock Price, Outstanding	$ 50.85	$ 33.32	$ 40.68
Stock Price, Issued	$ 51.46	$ 48.53	$ 32.07
Stock Price, Granted	$ 46.95	$ 50.85	$ 30.50
Stock Price, Forfeited	$ 50.89
Stock Price, Exercised	$ 50.89	$ 30.65	$ 40.68
Stock Price, Outstanding	$ 51.46	$ 50.85	$ 33.32