Capital Transactions (Details) (USD $)	1 Months Ended			4 Months Ended	5 Months Ended	6 Months Ended		9 Months Ended			12 Months Ended					1 Months Ended	12 Months Ended		1 Months Ended		12 Months Ended
	Feb. 02, 2012	Feb. 03, 2011	Feb. 10, 2010	May 16, 2012	Jun. 01, 2012	Jun. 30, 2011	Jun. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Jan. 31, 2010 Share Repurchase Program	Dec. 31, 2012 Share Repurchase Program	Dec. 31, 2009 Share Repurchase Program	Jan. 31, 2012 New Share Repurchase Program	Jan. 31, 2011 New Share Repurchase Program	Dec. 31, 2012 New Share Repurchase Program	Dec. 31, 2011 New Share Repurchase Program	Dec. 31, 2010 New Share Repurchase Program
Share Repurchase Program [Line Items]
Stock repurchase program, dollar amount authorized	$ 1,000,000,000	$ 1,500,000,000	$ 1,000,000,000							$ 250,000,000				$ 1,250,000,000	$ 1,000,000,000
Cost of common stock repurchased under the stock repurchase program											315,000,000	692,000,000	959,000,000					1,109,000,000			54,000,000	670,000,000	944,000,000
Shares of common stock repurchased																	26,000,000	101,000,000			4,000,000	59,000,000	84,000,000
Shares of common stock agreed to be repurchase but not yet settled as of the end of the period																1,300,000			1,000,000	1,800,000
Cost of common stock agreed to be repurchase but not yet settled as of the end of the period																15,000,000			12,000,000	22,000,000
Cash dividend payment				$ 201,000,000	$ 3,000,000	$ 192,000,000	$ 187,000,000	$ 2,000,000	$ 2,000,000		$ 204,000,000	$ 194,000,000	$ 189,000,000