Share Repurchase Program (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands			1 Months Ended	3 Months Ended		9 Months Ended		118 Months Ended
	Oct. 28, 2020	Feb. 05, 2020	Nov. 06, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Nov. 06, 2020
Share Repurchase Program
Increase in authorized amount		$ 1,000,000
Authorization effective period		3 years
Remaining balance under share repurchase program				$ 474,700		$ 474,700
Common stock repurchased, shares				965	1,025	2,634	3,585
Common stock repurchased, average price per share				$ 458.70	$ 377.85	$ 415.28	$ 364.84
Common stock repurchased, value				$ 442,962	$ 387,255	$ 1,093,973	$ 1,307,947
Subsequent event [Member]
Share Repurchase Program
Increase in authorized amount	$ 1,000,000
Cumulative authorized amount	$ 14,800,000
Authorization effective period	3 years
Common stock repurchased, shares			1,000					79,800
Common stock repurchased, average price per share			$ 454.15					$ 172.09
Common stock repurchased, value			$ 465,300					$ 13,700,000