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, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net income (loss) attributable to common stockholders	$ 39,183		$ 44,368		$ 74,513	$ 105,392
BASIC:
Weighted average common shares outstanding	45,850,599		44,650,002		45,577,843	44,631,797
Net income per common share - basic	$ 0.85		$ 0.99		$ 1.63	$ 2.36
DILUTED:
Weighted average common shares outstanding	45,850,599		44,650,002		45,577,843	44,631,797
Stock options	7,475		0		9,174	2,273
Convertible subordinated debentures	0		0		20,907	0
Weighed average dilutive common shares outstanding	45,858,074		44,650,002		45,607,924	44,634,070
Net income per common share - diluted	$ 0.85		$ 0.99		$ 1.63	$ 2.36
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	290,998		610,367		248,223	439,962
Common Stock, Dividends, Per Share, Declared	$ 0.90	$ 1.1025	$ 1.1025	$ 1.1025	$ 2.0025	$ 2.205