Earnings Per Share (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	2 Months Ended	12 Months Ended	122 Months Ended
Feb. 26, 2021	Dec. 31, 2020	Dec. 31, 2019	Feb. 26, 2021
Earnings Per Share
Common stock repurchased, shares		4,832	3,877
Common stock repurchased, average price per share		$ 431.93	$ 369.55
Common stock repurchased, value		$ 2,087,146	$ 1,432,752
Subsequent event [Member]
Earnings Per Share
Common stock repurchased, shares	1,100			82,100
Common stock repurchased, average price per share	$ 447.49			$ 179.65
Common stock repurchased, value	$ 478,400			$ 14,700,000

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