Investments (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 securities	Dec. 31, 2010	Dec. 31, 2009
Investments [Abstract]
Residential MBS with shorter durations being transferred from Fixed Maturities AFS		$ 6,800,000,000
Net unrealized appreciation (depreciation) included in OCI	48,000,000	193,000,000
Net unrealized depreciation included in AOCI	155,000,000	99,000,000
Percentage of mortgage-backed securities represented by investments in US government agency bonds	84.00%	79.00%
Portion of gross unrealized loss represented by united states treasury and agency obligations	15,000,000
Company assumed recovery rate	25.00%
Moodys historical mean recovery rate	41.00%
Credit losses recognized in net income for corporate securities	9,000,000	14,000,000	59,000,000
Credit losses in net income relating to mortgage-backed securities	11,000,000	32,000,000	56,000,000
Number of fixed maturities in an unrealized loss position	3,873
Limited partnerships number	59
Trading securities - mutual funds	162,000,000
Trading securities - equity securities	24,000,000	28,000,000
Trading securities - fixed maturities	8,000,000	9,000,000
Total number of fixed maturities	22,198
Largest single unrealized loss in the fixed maturities	9,000,000
Number of equity securities in an unrealized loss position	77
Total number of equity securities	179
Largest single unrealized loss in the equity securities	32,000,000
Restricted assets in fixed maturities and short-term investments	14,900,000,000	13,000,000,000
Restricted assets in cash	$ 179,000,000	$ 104,000,000