Stock Based Compensation (Stock Option Activity) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Beginning of Year	3,272,300
Options, Exercised	326,900
Options, End of Year	2,945,400
Options, Exercisable at End of Year	2,750,325
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options, Beginning of Year, Weighted Average Exercise Price	$ 32.78
Options, Exercised, Weighted Average Exercise Price	$ 20.10
Options, End of Year, Weighted Average Exercise Price	$ 34.19
Options, Exercisable at End of Year, Weighted Average Exercise Price	$ 34.24
Options, Outstanding at December 31, 2012, Weighted Average Remaining Years Contractual Term	5 years 3 months 18 days
Options, Exercisable at December 31, 2012, Weighted Average Remaining Years Contractual Term	5 years 2 months 12 days
Options, Outstanding at December 31, 2012, Aggregate Intrinsic Value	$ 1,509,670
Options, Exercisable at December 31, 2012, Aggregate Intrinsic Value	$ 1,506,268