Employee Benefit Plans (Summary Of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Exercised (in shares)	(755)	(3,581)	(4,921)	(11,721)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Proceeds from stock option exercises			$ 223	$ 526
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options Outstanding, beginning balance (in shares)			46,251	57,972
Options, Exercised (in shares)			(4,921)	(11,721)
Options Outstanding, ending balance (in shares)	41,330	46,251	41,330	46,251
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted-Average Exercise Price, Outstanding, beginning balance (in dollars per share)			$ 52.74	$ 51.15
Weighted-Average Exercise Price, Exercised (in dollars per share)			45.17	44.87
Weighted-Average Exercise Price, Outstanding, ending balance (in dollars per share)	$ 53.64	$ 52.74	$ 53.64	$ 52.74
Exercisable (shares)	21,459	8,063	21,459	8,063
Exercisable, Weighted average exercise price (US$ per share)	$ 50.45	$ 44.48	$ 50.45	$ 44.48
Proceeds from stock option exercises			$ 223	$ 526
Intrinsic value of stock options exercised			93	368
Stock-based compensation expense associated with stock options			47	$ 92
Unrecognized stock-based compensation expense associated with stock options	$ 37		$ 37
Weighted average period (in years) in which the above amount is expected to be recognized			1 year

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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