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
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income (loss) attributable to common stockholders	$ 35,679	$ 38,432
BASIC:
Weighted Average Number of Shares Outstanding, Basic	42,825,824	41,532,154
Earnings Per Share, Basic	$ 0.83	$ 0.93
DILUTED:
Weighted average common shares outstanding, diluted	42,825,824	41,532,154
Stock options, diluted	75,695	44,722
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	223,513	0
Average dilutive common shares outstanding	43,125,032	41,576,876
Earnings Per Share, Diluted	$ 0.83	$ 0.92
Incremental shares excluded since anti-dilutive:
Stock options with an exercise price in excess of the market price for our common shares	17,415	118,639
Common Stock, Dividends, Per Share, Declared	$ 1.05	$ 1.00