Shareholders' Equity (Schedule Of Stock Repurchase Activity) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
$350,000 In Shares Per Calendar Quarter [Member]
Equity, Class of Treasury Stock [Line Items]
Plan Date	Apr. 18, 2016
Expiration	Mar. 31, 2017
Stock repurchase program, authorized amount	$ 350,000
Shares Repurchased		34,048
100,000 Shares [Member]
Equity, Class of Treasury Stock [Line Items]
Plan Date	Oct. 12, 2017
Expiration	Sep. 30, 2018
Shares Authorized	100,000
Shares Repurchased