Investments (Details 13) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Total mortgage loans	$ 3,686	$ 4,173
Net carrying value of impaired mortgage loans
Impaired mortgage loans with a valuation allowance	16	77
Impaired mortgage loans without a valuation allowance	0	0
Total impaired mortgage loans	16	77
Valuation allowance on impaired mortgage loans	8	21	42
Rollforward of the valuation allowance on impaired mortgage loans
Beginning balance	21	42	63
Net decrease in valuation allowance	(5)	(11)	(5)
Charge offs	(8)	(8)	(16)
Mortgage loans classified as held for sale	0	(2)	0
Ending balance	8	21	42
Non-impaired mortgage loans
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Fixed rate mortgage loans	3,669	4,056
Variable rate mortgage loans	1	40
Total mortgage loans	3,670	4,096
Non-impaired mortgage loans \| Below 1.0
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Fixed rate mortgage loans	110	153
Variable rate mortgage loans	0	0
Total mortgage loans	110	153
Non-impaired mortgage loans \| 1.0 - 1.25
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Fixed rate mortgage loans	387	560
Variable rate mortgage loans	0	0
Total mortgage loans	387	560
Non-impaired mortgage loans \| 1.26 - 1.50
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Fixed rate mortgage loans	1,118	1,167
Variable rate mortgage loans	1	2
Total mortgage loans	1,119	1,169
Non-impaired mortgage loans \| Above 1.50
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Fixed rate mortgage loans	2,054	2,176
Variable rate mortgage loans	0	38
Total mortgage loans	2,054	2,214
Mortgage loans
Average carrying value and interest income recognized on impaired mortgage loans
Average balance impaired mortgage loans	$ 26	$ 86	$ 202

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A valuation allowance for financing receivables that are expected to be uncollectible.

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The amount of financing receivables reclassified to held for sale during the reporting period.

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

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Total increases or decreases in allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs.

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