Earnings Per Share (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		70 Months Ended
	Nov. 08, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Nov. 08, 2016
Earnings Per Share
Common stock repurchased, shares		367	1,147	3,673	3,784
Common stock repurchased, average price per share		$ 281.04	$ 238.97	$ 261.32	$ 224.39
Common stock repurchased, value		$ 102,941	$ 274,213	$ 959,743	$ 849,145
Subsequent event [Member]
Earnings Per Share
Common stock repurchased, shares	600					55,600
Common stock repurchased, average price per share	$ 269.29					$ 116.76
Common stock repurchased, value	$ 169,900					$ 6,500,000