Subsequent Events (Details) (USD $)	3 Months Ended			12 Months Ended			2 Months Ended
	Sep. 30, 2012	Jun. 30, 2012	Sep. 30, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Feb. 27, 2014 Subsequent event
Subsequent events
Number of shares repurchased		3,100,000		7,340,682	3,062,283	6,515,849	1,200,000
Purchase of treasury stock value		$ 500,000,000		$ 1,449,300,000	$ 500,000,000	$ 1,000,200,000	$ 294,900,000
Share repurchase authorized	3,000,000,000		1,500,000,000
Total shares repurchased under program							8,500,000
Aggregate expenditure for repurchased stock							$ 1,700,000,000