Share Repurchase Program (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		1 Months Ended	3 Months Ended		6 Months Ended		79 Months Ended
	May 10, 2017	Aug. 07, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Aug. 07, 2017
Share Repurchase Program
Increase in authorized amount	$ 1,000,000
Cumulative authorized amount	$ 8,800,000
Authorization effective period	3 years
Remaining balance under share repurchase program			$ 545,300		$ 545,300
Common stock repurchased, shares			3,475	2,075	5,304	3,306
Common stock repurchased, average price per share			$ 245.26	$ 262.17	$ 253.13	$ 259.14
Common stock repurchased, value			$ 852,226	$ 544,165	$ 1,342,538	$ 856,802
Subsequent event [Member]
Share Repurchase Program
Common stock repurchased, shares		200					62,400
Common stock repurchased, average price per share		$ 207.21					$ 132.00
Common stock repurchased, value		$ 35,000					$ 8,200,000