Share Repurchase Program (Schedule of Shares Repurchased) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Share Repurchase Program
Shares repurchased	4,832	3,877
Average price per share	$ 431.93	$ 369.55
Total investment	$ 2,087,146	$ 1,432,752

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

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration