Realignment and Efficiency Plan (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Sep. 30, 2013
Realignment And Efficiency Rollforward Table [Line Items]
Balance, January 1, 2013			$ 71		$ 71
Third quarter 2012 charge				77
Less: Payments	15	16	9
Balance, September 30, 2013	31				31
Caption that Includes Restructuring Charges					Other operating expenses
After Tax [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Third quarter 2012 charge				50
Global Health Benefits Segment [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Third quarter 2012 charge				65
Global Health Benefits Segment [Member] | After Tax [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Third quarter 2012 charge				42
Global Supplemental Benefits Segment [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Third quarter 2012 charge				9
Global Supplemental Benefits Segment [Member] | After Tax [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Third quarter 2012 charge				6
Group Disability And Life Segment [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Third quarter 2012 charge				3
Group Disability And Life Segment [Member] | After Tax [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Third quarter 2012 charge				2
Employee Severance [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Balance, January 1, 2013			67		67
Less: Payments	15	16	8
Balance, September 30, 2013	28				28
Real estate [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Balance, January 1, 2013			4		4
Less: Payments	0	0	1
Balance, September 30, 2013	$ 3				$ 3