Earnings and Dividends Per Share (Summary Of Calculation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Income from continuing operations attributable to common stockholders	$ 14,828	$ 17,217
Discontinued operations	915	1,133
Net income attributable to common stockholders	$ 15,743	$ 18,350
Weighted Average Number of Shares Outstanding, Basic	27,876,176	27,776,104
Income from continuing operations per common share, basic	$ 0.53	$ 0.62
Discontinued operations per common share, basic	$ 0.03	$ 0.04
Net income per common share attributable to common stockholders	$ 0.56	$ 0.66
Weighted average common shares outstanding, diluted	27,876,176	27,776,104
Stock options, diluted	35,408	27,118
Average dilutive common shares outstanding	27,911,584	27,803,222
Income from continuing operations per common share	$ 0.53	$ 0.62
Discontinued operations per common share	$ 0.03	$ 0.04
Net income per common share attributable to common stockholders	$ 0.56	$ 0.66
Stock options with an exercise price in excess of the market price for our common shares	11,964	11,681
Common Stock, Dividends, Per Share, Declared	$ 0.695	$ 0.65