Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Consolidated Segment Information [Abstract]
Realized Investment Gains Losses After Tax	$ (3)	$ 11	$ 9	$ 28
Shareholders' net income	380	391	751	804
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	7,178	5,206	13,665	10,312
Segment income from continuing operations	383	380	742	776
Segment Text Detail [Abstract]
Percent International Revenues South Korea	29.00%		29.00%
Percent International Earnings South Korea	55.00%		46.00%
Health Care Segment [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	5,466	3,711	10,403	7,430
Segment income from continuing operations	332	280	574	527
Disability And Life Segment [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	749	717	1,492	1,405
Segment income from continuing operations	89	88	154	170
International Segment [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	904	740	1,779	1,444
Segment income from continuing operations	65	57	145	118
Run Off Reinsurance Segment [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	37	10	(53)	(24)
Segment income from continuing operations	(62)	(22)	(32)	(9)
Other Operations Segment [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	39	42	78	86
Segment income from continuing operations	21	20	41	43
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Premiums and fees, Mail order pharmacy revenues and Other revenues	(17)	(14)	(34)	(29)
Segment income from continuing operations	$ (62)	$ (43)	$ (140)	$ (73)