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		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to common stockholders	$ 33,032	$ 33,600	$ 110,352	$ 94,466
BASIC:
Weighted Average Number of Shares Outstanding, Basic	39,283,919	37,566,221	38,735,262	37,563,503
DILUTED:
Weighted average common shares outstanding, diluted	39,283,919	37,566,221	38,735,262	37,563,503
Stock options, diluted	93,437	16,920	49,248	42,024
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	274,544	0	91,515	6,314
Average dilutive common shares outstanding	39,651,900	37,583,141	38,876,025	37,611,841
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.84	$ 0.89	$ 2.85	$ 2.51
Earnings Per Share, Diluted	$ 0.83	$ 0.89	$ 2.84	$ 2.51
Incremental shares excluded since anti-dilutive:
Stock options with an exercise price in excess of the market price for our common shares	0	107,993	8,490	42,052
Common Stock Dividends, Per Share, Declared, Regular	$ 0.90	$ 0.85	$ 2.70	$ 2.55