Segment Information (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and other revenues	$ 27,931	$ 20,657	$ 19,948
Segment Information Text Details [Abstract]
Income Loss From Continuing Operations Before Income Taxes Foreign Percentage	8.00%	10.00%	9.00%
South Korean Percentage Of International Segment's Revenues	54.00%
South Korean Percentage Of International Segment's Earnings	90.00%
United States [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and other revenues	25,217	18,522	18,326
South Korea [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and other revenues	1,076	909	717
All Other Foreign [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and other revenues	1,638	1,226	905
Medical [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and other revenues	20,973	14,443	14,134
Disability [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and other revenues	1,413	1,268	1,167
Life Accident And Health [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and other revenues	3,680	3,117	2,834
Mail Order Pharmacy [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and other revenues	1,623	1,447	1,420
Other Products [Member]
Segment Reporting Information [Line Items]
Premiums and fees, mail order pharmacy revenues and other revenues	$ 242	$ 382	$ 393