Share Repurchase Program (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands			2 Months Ended	12 Months Ended		110 Months Ended
	Feb. 05, 2020	May 31, 2019	Feb. 28, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 28, 2020
Share Repurchase Program
Increase in authorized amount		$ 1,000,000
Authorization effective period		3 years
Remaining balance under share repurchase program				$ 568,700
Common stock repurchased, shares				3,877	6,061
Common stock repurchased, average price per share				$ 369.55	$ 282.80
Common stock repurchased, value				$ 1,432,752	$ 1,713,953
Subsequent event [Member]
Share Repurchase Program
Increase in authorized amount	$ 1,000,000
Cumulative authorized amount	$ 13,800,000
Authorization effective period	3 years
Common stock repurchased, shares			900			77,100
Common stock repurchased, average price per share			$ 400.78			$ 162.72
Common stock repurchased, value			$ 363,400			$ 12,500,000