Employee Benefit Plans (Summary Of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Options
Options Outstanding, beginning balance	41,330	46,251	57,972
Options, Granted	0	0	0
Exercise of stock options	(14,603)	(4,921)	(11,721)
Options, Forfeited	0	0	0
Options Outstanding, ending balance	26,727	41,330	46,251
Weighted-Average Exercise Price
Weighted-Average Exercise Price, Outstanding, beginning balance	$ 53.64	$ 52.74	$ 51.15
Weighted-Average Exercise Price, Granted	0	0	0
Weighted-Average Exercise Price, Exercised	47.43	45.17	44.87
Weighted-Average Exercise Price, Forfeited	0	0	0
Weighted-Average Exercise Price, Outstanding, ending balance	$ 57.04	$ 53.64	$ 52.74
Options, Exercisable at end of year	20,848	21,459	8,063
Weighted-Average Exercise Price, Exercisable at end of year	$ 54.42	$ 50.45	$ 44.48
Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares	5,879	19,871	38,188	55,275
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares	13,992	18,317	17,087
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares	0	0	0
Weighted-Average Exercise Price
Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price	$ 66.32	$ 56.97	$ 54.42	$ 51.40
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	0	0	0
Weighted-Average Exercise Price, Vested during the year	53.22	51.66	44.65
Weighted-Average Exercise Price, Forfeited during the year	$ 0	$ 0	$ 0
Proceeds from stock option exercises	$ 691	$ 223	$ 526
Intrinsic value of stock options exercised	474	93	368
Stock-based compensation expense associated with stock options	22	60	119
Income tax benefit recognized related to stock-based compensation	2	$ 5	$ 12
Unrecognized stock-based compensation expense	$ 2
Weighted average period in which the above amount is expected to be recognized	2 months 12 days