Debt (Narrative) (Details) (USD $)							1 Months Ended		9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Aug. 31, 2012 2.85% Note [Member]	Aug. 31, 2012 4.25% Note [Member]	May 02, 2013 Senior Notes [Member] 2.95% Note [Member]	May 02, 2013 Senior Notes [Member] 4.50% Note [Member]	Sep. 30, 2013 Revolving Credit Facility [Member]	Aug. 19, 2013 Revolving Credit Facility [Member] Option	Sep. 30, 2013 Change of Control and Loss of Investment Grade Rating [Member]
Debt Instrument [Line Items]
Short-term borrowings	$ 0	$ 0
Credit agreement							3,000,000,000	3,000,000,000
Term of credit agreement							5 years
Number of extension options								2
Extension option, term								1 year
Debt principal amount			$ 1,900,000,000	$ 900,000,000	$ 350,000,000	$ 650,000,000
Interest rate			2.85%	4.25%	2.95%	4.50%
Required purchase price as percentage of aggregate principal amount									101.00%