Realignment and Efficiency Plan (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Realignment And Efficiency Rollforward Table [Line Items]
Balance, January 1,	$ 71
Third quarter 2012 charge		77
Less: Payments	9
Balance, March 31,	62
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
Less: Payments	8
Balance, March 31,	59
Real estate [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Balance, January 1,	4
Less: Payments	1
Balance, March 31,	$ 3