Aquisitions and Sales of Subsidiaries (Details) (Medicare supplement and critical illness businesses [Member], USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended			9 Months Ended
	Aug. 31, 2012	Sep. 30, 2012		Sep. 30, 2011	Sep. 30, 2012		Sep. 30, 2011
Medicare supplement and critical illness businesses [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale proceeds	$ 307
Expenses	(12)
Net proceeds	295
Assets of businesses sold:
Cash and investments	217
Deferred policy acquisition costs	108
Other assets	31
Total assets	356
Liabilities of businesses sold:
Life, accident and health reserves	209
Other liabilities	7
Total liabilities	216
Net assets of businesses sold	140
Gain on sale of subsidiaries	155
Total revenues		53	[1]	80	212	[1]	244
Total costs and expenses		43	[1]	69	184	[1]	223
Operating earnings before income taxes		$ 10		$ 11	$ 28		$ 21

[1] Reflects revenues and expenses through the end of August 2012.