Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Consolidated Segment Information [Abstract]
Realized Investment Gains Losses After Tax	$ 7	$ 9	$ 16	$ 37
Shareholders' net income	466	183	1,217	987
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	7,064	5,300	20,729	15,612
Segment income from continuing operations	459	174	1,201	950
Segment Text Detail [Abstract]
Percent International Revenues South Korea	30.00%		29.00%
Percent International Earnings South Korea	55.00%		49.00%
Health Care [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	5,385	3,671	15,788	11,101
Segment income from continuing operations	345	248	919	775
Disability And Life [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	758	698	2,250	2,103
Segment income from continuing operations	60	62	214	232
International [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	938	768	2,717	2,212
Segment income from continuing operations	70	62	215	180
Run Off Reinsurance [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	(37)	138	(90)	114
Segment income from continuing operations	25	(180)	(7)	(189)
Other Operations [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	36	40	114	126
Segment income from continuing operations	22	25	63	68
Corporate [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	(16)	(15)	(50)	(44)
Segment income from continuing operations	$ (63)	$ (43)	$ (203)	$ (116)