Realignment and Efficiency Plan (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Realignment And Efficiency Rollforward Table [Line Items]
Third quarter 2012 charge	$ 77
less: Fourth quarter 2012 payments	6
Balance, December 31,	71
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]
Third quarter 2012 charge	72
less: Fourth quarter 2012 payments	5
Balance, December 31,	67
Real estate and mortgage loans, including pooled separate accounts [Member]
Realignment And Efficiency Rollforward Table [Line Items]
Third quarter 2012 charge	5
less: Fourth quarter 2012 payments	1
Balance, December 31,	$ 4