Realignment and Efficiency Plan (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2013	Jun. 30, 2012
Realignment And Efficiency Rollforward Table [Line Items]
Balance, January 1,		$ 71	$ 71
Third quarter 2012 charge				77
Less: Payments	16	9
Balance, March 31,	46		46
Caption that Includes Restructuring Charges			Other operating expenses
After Tax [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Third quarter 2012 charge				50
Employee Severance [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Balance, January 1,		67	67
Less: Payments	16	8
Balance, March 31,	43		43
Real estate [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Balance, January 1,		4	4
Less: Payments		1
Balance, March 31,	$ 3		$ 3