Investments (Details Textuals 15) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other investment portfolio gains (losses)	$ 95
Other investment portfolio gains (losses)	35	(52)
Securities and mortgage loans [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other investment portfolio gains (losses)	(102)
Impairments [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other investment portfolio gains (losses)	7
Mitsui Sumitomo MetLife Insurance Co., LTD. ("MSI MetLife") [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other investment portfolio gains (losses)		$ 80