Goodwill, Other Intangibles, and Property and Equipment (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 3,164	$ 3,119
Goodwill sold	0	(6)
Impact of foreign currency translation	8	(6)
Goodwill, Ending Balance	6,001	3,164
FirstAssist [Member]
Goodwill [Line Items]
Goodwill acquired	7	57
HealthSpring [Member]
Goodwill [Line Items]
Goodwill acquired	2,541	0
Great American Supplemental Benefits Group [Member]
Goodwill [Line Items]
Goodwill acquired	168	0
Finans Emeklilik [Member]
Goodwill [Line Items]
Goodwill acquired	113	0
Global Health Benefits Segment [Member]
Goodwill [Line Items]
Goodwill, Ending Balance	5,700
Global Supplemental Benefits Segment [Member]
Goodwill [Line Items]
Goodwill, Ending Balance	$ 350