Share Repurchase Program (Schedule Of Shares Repurchased) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Proceeds from (Repurchase of) Equity [Abstract]
Shares repurchased	9,301	5,698
Average price per share	$ 233.57	$ 264.21
Total investment	$ 2,172,437	$ 1,505,371