Earnings Per Share (Narrative) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended		34 Months Ended
	Nov. 08, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Nov. 08, 2013
Earnings Per Share
Shares repurchased	700	1,534	6,359	6,548	12,647	39,300
Average price per share	$ 124.72	$ 120.71	$ 84.76	$ 104.93	$ 89.62	$ 81.23
Total investment	$ 83,400	$ 185,226	$ 538,972	$ 687,064	$ 1,133,328	$ 3,200,000