Stockholders' Deficit (Details) (USD $)	1 Months Ended		3 Months Ended	6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Mar. 31, 2012	Jun. 30, 2012	Jun. 30, 2011
Stockholders' Deficit
Additional stock repurchases authorized			$ 6,000,000,000
Remaining authorization under share repurchase program				4,221,000,000
Total cost of repurchased shares				2,645,000,000	2,901,000,000
Average price per share (in dollars per share)				$ 46.30	$ 45.94
Number of shares repurchased and retired				57,111,828	63,131,934
Amount paid for stock repurchases	$ 60,000,000	$ 56,000,000		$ 2,612,000,000	$ 2,913,000,000