Share Repurchase Program (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		1 Months Ended	3 Months Ended		64 Months Ended
	Feb. 10, 2016	May. 09, 2016	Mar. 31, 2016	Mar. 31, 2015	May. 09, 2016
Share Repurchase Program
Increase in authorized amount	$ 750,000
Cumulative authorized amount	$ 6,300,000
Authorization effective period	3 years
Remaining balance under share repurchase program			$ 580,600
Common stock repurchased, shares			1,231	650
Common stock repurchased, average price per share			$ 254.02	$ 207.50
Common stock repurchased, value			$ 312,637	$ 134,803
Subsequent event [Member]
Share Repurchase Program
Common stock repurchased, shares		1,700			52,900
Common stock repurchased, average price per share		$ 258.04			$ 109.43
Common stock repurchased, value		$ 436,800			$ 5,800,000