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, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net income (loss) attributable to common stockholders	$ 61,023	$ 35,679
BASIC:
Weighted average common shares outstanding	44,613,593	42,825,824
Net income per common share - basic	$ 1.37	$ 0.83
DILUTED:
Weighted average common shares outstanding	44,613,593	42,825,824
Stock options	4,546	75,695
Convertible subordinated debentures	0	223,513
Weighed average dilutive common shares outstanding	44,618,139	43,125,032
Net income per common share - diluted	$ 1.37	$ 0.83
Incremental shares excluded since anti-dilutive:
Net share effect of stock options with an exercise price in excess of the average market price for our common shares	305,862	17,415
Common Stock Dividends, Per Share, Declared, Regular	$ 1.1025	$ 1.05