Investments OTTI (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended				9 Months Ended				3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended				9 Months Ended				3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2012 securities	Sep. 30, 2011 securities	Sep. 30, 2012 securities	Sep. 30, 2011 securities	Sep. 30, 2012 U.S. corporate securities securities	Sep. 30, 2011 U.S. corporate securities securities	Sep. 30, 2012 U.S. corporate securities securities	Sep. 30, 2011 U.S. corporate securities securities	Sep. 30, 2012 Foreign securities		Sep. 30, 2011 Foreign securities		Sep. 30, 2012 Foreign securities		Sep. 30, 2011 Foreign securities		Sep. 30, 2012 Residential mortgage-backed securities securities	Sep. 30, 2011 Residential mortgage-backed securities securities	Sep. 30, 2012 Residential mortgage-backed securities securities	Sep. 30, 2011 Residential mortgage-backed securities securities	Sep. 30, 2012 Commercial mortgage-backed securities securities	Sep. 30, 2011 Commercial mortgage-backed securities securities	Sep. 30, 2012 Commercial mortgage-backed securities securities	Sep. 30, 2011 Commercial mortgage-backed securities securities	Sep. 30, 2012 Other asset-backed securities securities	Sep. 30, 2011 Other asset-backed securities securities	Sep. 30, 2012 Other asset-backed securities securities	Sep. 30, 2011 Other asset-backed securities securities	Sep. 30, 2012 Mortgage loans on real estate securities	Sep. 30, 2011 Mortgage loans on real estate securities	Sep. 30, 2012 Mortgage loans on real estate securities	Sep. 30, 2011 Mortgage loans on real estate securities	Sep. 30, 2012 Fixed maturities	Dec. 31, 2011 Fixed maturities	Sep. 30, 2012 Credit related impairment	Sep. 30, 2011 Credit related impairment	Sep. 30, 2012 Credit related impairment	Sep. 30, 2011 Credit related impairment	Sep. 30, 2012 Intent related impairment securities	Sep. 30, 2011 Intent related impairment securities	Sep. 30, 2012 Intent related impairment securities	Sep. 30, 2011 Intent related impairment securities	Sep. 30, 2012 Intent related impairment U.S. corporate securities securities	Sep. 30, 2011 Intent related impairment U.S. corporate securities securities	Sep. 30, 2012 Intent related impairment U.S. corporate securities securities	Sep. 30, 2011 Intent related impairment U.S. corporate securities securities	Sep. 30, 2012 Intent related impairment Foreign securities		Sep. 30, 2011 Intent related impairment Foreign securities		Sep. 30, 2012 Intent related impairment Foreign securities		Sep. 30, 2011 Intent related impairment Foreign securities		Sep. 30, 2012 Intent related impairment Residential mortgage-backed securities securities	Sep. 30, 2011 Intent related impairment Residential mortgage-backed securities securities	Sep. 30, 2012 Intent related impairment Residential mortgage-backed securities securities	Sep. 30, 2011 Intent related impairment Residential mortgage-backed securities securities	Sep. 30, 2012 Intent related impairment Commercial mortgage-backed securities securities	Sep. 30, 2011 Intent related impairment Commercial mortgage-backed securities securities	Sep. 30, 2012 Intent related impairment Commercial mortgage-backed securities securities	Sep. 30, 2011 Intent related impairment Commercial mortgage-backed securities securities	Sep. 30, 2012 Intent related impairment Other asset-backed securities securities	Sep. 30, 2011 Intent related impairment Other asset-backed securities securities	Sep. 30, 2012 Intent related impairment Other asset-backed securities securities	Sep. 30, 2011 Intent related impairment Other asset-backed securities securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Impairment	$ 3,300,000	$ 51,900,000	$ 9,200,000	$ 137,800,000	$ 1,300,000	$ 1,700,000	$ 1,800,000	$ 4,800,000	$ 0	[1]	$ 12,800,000	[1]	$ 700,000	[1]	$ 16,800,000	[1]	$ 2,000,000	$ 4,100,000	$ 4,700,000	$ 7,000,000	$ 0	$ 19,300,000	$ 1,700,000	$ 29,700,000	$ 0	$ 9,400,000	$ 300,000	$ 72,600,000	$ 0	$ 4,600,000	$ 0	$ 6,900,000
No. of Securities	30	89	55	159	1	4	2	6	0	[1]	13	[1]	3	[1]	22	[1]	29	50	46	56	0	11	1	12	0	8	3	58	0	3	0	5							0	36	6	98	0	4	1	6	0	[1]	11	[1]	3	[1]	19	[1]	0	3	0	4	0	11	1	12	0	7	1	57
Write-downs related to credit impairments																																			3,300,000	11,400,000	6,300,000	20,900,000																	0	100,000
Write-downs related to intent impairments	0	40,500,000	2,900,000	116,900,000	0	1,700,000	400,000	4,800,000	0	[1]	11,300,000	[1]	700,000	[1]	13,700,000	[1]			0	100,000	0	19,300,000	1,700,000	28,500,000	0	8,100,000	100,000	69,800,000
Fair value of fixed maturities with OTTI																																	$ 2,300,000,000	$ 2,100,000,000

[1] Primarily U.S. dollar denominated.