Earnings Per Common Share (Summary Of Calculation Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share [Abstract]
Net income attributable to common stockholders	$ 34,468	$ 30,814			$ 64,540	$ 105,327
BASIC:
Weighted average common shares outstanding (in shares)	44,339,975	45,850,599			45,236,696	45,668,762
DILUTED:
Weighted average common shares outstanding (in shares)	44,339,975	45,850,599			45,236,696	45,668,762
Stock options (in shares)	62,607	825			24,427	6,391
Convertible senior notes (in shares)	0	0			0	13,938
Weighed average dilutive common shares outstanding (in shares)	44,402,582	45,851,424			45,261,123	45,689,091
Net income per common share - basic (in US dollars per share)	$ 0.78	$ 0.67			$ 1.43	$ 2.31
Net income per common share - diluted (in US dollars per share)	$ 0.78	$ 0.67			$ 1.43	$ 2.31
Incremental anti-dilutive shares excluded:
Net share effect of stock options with an exercise price in excess of the average market price for our common shares (in shares)	390,159	505,459			501,183	308,313
Regular dividends declared per common share (in US dollars per share)	$ 0.90	$ 0.90	$ 1.80	$ 2.0025	$ 2.70	$ 2.9025