Employee Benefit Plans (Summary Of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Exercised (in shares)	(2,650)	(5,638)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Proceeds from stock option exercises	$ 122	$ 252
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)	(2,650)	(5,638)
Options Outstanding, ending balance (in shares)	43,601	52,334
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)	46.06	44.74
Weighted-Average Exercise Price, Outstanding, ending balance (in dollars per share)	$ 53.15	$ 51.84
Exercisable (shares)	23,730	14,146
Exercisable, Weighted average exercise price (US$ per share)	$ 49.84	$ 44.70
Proceeds from stock option exercises	$ 122	$ 252
Intrinsic value of stock options exercised	44	177
Stock-based compensation expense associated with stock options	22	$ 37
Unrecognized stock-based compensation expense associated with stock options	$ 63
Weighted average period (in years) in which the above amount is expected to be recognized	1 year 4 months 24 days

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

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