Investments (Details 12) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Carrying value of non-impaired fixed rate and variable rate mortgage loans by debt service coverage ratio distribution
Total mortgage loans	$ 3,959		$ 4,173
Net carrying value of impaired mortgage loans
Impaired mortgage loans with a valuation allowance	14		77
Total impaired mortgage loans	14		77
Valuation allowance on impaired mortgage loans	9	15
Rollforward of the valuation allowance on impaired mortgage loans
Beginning balance	21	42
Net decrease in valuation allowance	(4)	(26)
Charge offs	(8)	(1)
Ending balance	9	15
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	3,905		4,056
Variable rate mortgage loans	40		40
Total mortgage loans	3,945		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	179		153
Total mortgage loans	179		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	544		560
Total mortgage loans	544		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	1,119		1,167
Variable rate mortgage loans	2		2
Total mortgage loans	1,121		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	2,063		2,176
Variable rate mortgage loans	38		38
Total mortgage loans	2,101		2,214
Mortgage loans
Average carrying value and interest income recognized on impaired mortgage loans
Average balance impaired mortgage loans	$ 46	$ 99