Share Repurchase Program (Schedule Of Shares Repurchased) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Proceeds from (Repurchase of) Equity [Abstract]
Shares repurchased	932	2,743	4,695	8,047
Average price per share	$ 306.22	$ 200.70	$ 266.48	$ 235.26
Total investment	$ 285,183	$ 550,530	$ 1,251,013	$ 1,893,068

Number of shares that have been repurchased and retired during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration