Stock Based Compensation (Performance Units Information) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Performance Share Risk Free Rate Assumption	2.47%	2.36%	1.50%
Performance Share Volatility Rate Assumption	16.74%	17.57%	20.00%
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period for recognizing unrecognized compensation cost	1 year 7 months 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares, Outstanding at Beginning of Year	377,541
Shares, Granted	320,078
Shares, Vested	(299,201)
Shares, Canceled	(63,903)
Shares, Outstanding at End of Year	334,515	377,541
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Shares, Outstanding at Beginning of Year, Weighted Average Grant Date Fair Value	$ 51.94
Shares, Granted, Weighted Average Grant Date Fair Value	62.17	$ 54.95	$ 45.02
Shares, Vested, Weighted Average Grant Date Fair Value	54.10
Shares, Cancelled, Weighted Average Grant Date Fair Value	54.52
Shares, Outstanding at End of Year, Weighted Average Grant Date Fair Value	$ 59.30	$ 51.94
Shares, Outstanding at End of Year, Weighted Average Remaining Years Contractual Term	1 year 7 months 6 days
Shares, Outstanding at End of Year, Aggregate Intrinsic Value	$ 19,753,111