Earnings and Dividends Per Share (Summary Of Calculation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to common stockholders	$ 44,595	$ 31,182	$ 77,320	$ 60,866
BASIC:
Weighted Average Number of Shares Outstanding, Basic	38,520,221	37,566,221	38,460,934	37,562,144
DILUTED:
Weighted average common shares outstanding, diluted	38,520,221	37,566,221	38,460,934	37,562,144
Stock options, diluted	41,163	40,896	27,154	54,577
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	0	0	0	9,471
Average dilutive common shares outstanding	38,561,384	37,607,117	38,488,088	37,626,192
Income (Loss) from Continuing Operations, Per Basic Share	$ 1.16	$ 0.83	$ 2.01	$ 1.62
Earnings Per Share, Diluted	$ 1.16	$ 0.83	$ 2.01	$ 1.62
Incremental shares excluded since anti-dilutive:
Stock options with an exercise price in excess of the market price for our common shares	41,163	51,643	23,367	22,401
Common Stock Dividends, Per Share, Declared, Regular	$ 0.90	$ 0.85	$ 1.80	$ 1.70