Acquisitions and Sales of Subsidiaries (Details Textual) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Aug. 31, 2012 company	Dec. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of undisclosed insurance companies sold	4
Percentage of interest acquired in a subsidiary		28.00%
Purchase of interest not already owned in a subsidiary		$ 17
Medicare supplement and critical illness businesses [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale proceeds	326	326
Pretax gain on sale of subsidiaries	170	170
Small annuity and supplemental insurance company [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale proceeds		$ 7