Investments (Details 13) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Total mortgage loans	$ 4,276		$ 4,188
Mortgage loans, non-impaired
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Fixed rate mortgage loans	4,239		4,151
Variable rate mortgage loans	21		21
Total mortgage loans	4,260		4,172
Net carrying value of impaired mortgage loans
Impaired mortgage loans with a valuation allowance	16		16
Impaired mortgage loans without a valuation allowance	0		0
Total impaired mortgage loans	16		16
Valuation allowance on impaired mortgage loans	8	9
Average carrying value and interest income recognized on impaired mortgage loans
Average impaired mortgage loans	16	48
Rollforward of the valuation allowance on impaired mortgage loans
Valuation allowance on impaired mortgage loans, beginning balance	8	21
Net decrease in valuation allowance	0	(4)
Charge offs	0	(8)
Valuation allowance on impaired mortgage loans, ending balance	8	9
Carrying value of past due mortgage loans
Less than 90 days past due	6		0
90 days or greater past due	0		0
Total past due	6		0
Current loans	4,270		4,188
Total mortgage loans	4,276		4,188
Mortgage loans, non-impaired \| Below 1.0
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Fixed rate mortgage loans	93		110
Variable rate mortgage loans	0		0
Total mortgage loans	93		110
Mortgage loans, non-impaired \| 1.0 - 1.25
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Fixed rate mortgage loans	433		424
Variable rate mortgage loans	0		0
Total mortgage loans	433		424
Mortgage loans, non-impaired \| 1.26 - 1.50
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Fixed rate mortgage loans	1,194		1,167
Variable rate mortgage loans	1		1
Total mortgage loans	1,195		1,168
Mortgage loans, non-impaired \| Above 1.50
Carrying value of non-impaired mortgage loans, summarized by debt service coverage ratio distribution
Fixed rate mortgage loans	2,519		2,450
Variable rate mortgage loans	20		20
Total mortgage loans	$ 2,539		$ 2,470

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Financing receivables that are less than 90 days past due.

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Financing receivables that are equal to or greater than 90 days past due.

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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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