Employee Benefit Plans (Summary Of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Exercised (in shares)	(1,516)	(2,502)	(4,166)	(8,140)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Proceeds from stock option exercises			$ 189	$ 365
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)			(4,166)	(8,140)
Options Outstanding, ending balance (in shares)	42,085	49,832	42,085	49,832
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)			45.44	44.85
Weighted-Average Exercise Price, Outstanding, ending balance (in dollars per share)	$ 53.47	$ 52.18	$ 53.47	$ 52.18
Exercisable (shares)	22,214	11,644	22,214	11,644
Exercisable, Weighted average exercise price (US$ per share)	$ 50.22	$ 44.62	$ 50.22	$ 44.62
Proceeds from stock option exercises			$ 189	$ 365
Intrinsic value of stock options exercised			77	263
Stock-based compensation expense associated with stock options			34	$ 64
Unrecognized stock-based compensation expense associated with stock options	$ 50		$ 50
Weighted average period (in years) in which the above amount is expected to be recognized			1 year 2 months 12 days