Derivative Financial Instruments and Off-balance sheet Financial Instruments (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2014 party	Dec. 31, 2013 party
Derivative Financial Instruments and Off-balance sheet Financial Instruments
Cash and securities pledged as collateral by counterparties		$ 4
Securities pledged as collateral to counterparties		7
Collateral posted under MNAs, credit-risk-contingent provisions in a liability position		7	14
Credit Derivatives
Number of counter- parties		7	8
Notional amount		323	1,648
Credit exposure		5	5
Exposure, net of collateral		2	1
Gross liability fair value of contracts containing credit-risk-contingent features		11	25
Gross asset fair value of contracts containing credit-risk-contingent features and subject to MNAs		(2)	(9)
Collateral posted under MNAs for contracts containing credit-risk-contingent features		(7)	(14)
Maximum amount of additional exposure for contracts with credit-risk-contingent features if all features were triggered concurrently		2	2
A plus
Credit Derivatives
Number of counter- parties		1	1
Notional amount		164	22
Credit exposure		2	1
Exposure, net of collateral		1	1
A
Credit Derivatives
Number of counter- parties		3	4
Notional amount		88	1,523
Credit exposure		3	2
Exposure, net of collateral		1	0
A-
Credit Derivatives
Number of counter- parties		1	1
Notional amount		8	24
Credit exposure		0	1
Exposure, net of collateral		0	0
BBB plus
Credit Derivatives
Number of counter- parties		1	1
Notional amount		11	3
Credit exposure		0	0
Exposure, net of collateral		0	0
BBB
Credit Derivatives
Number of counter- parties		1	1
Notional amount		52	76
Credit exposure		0	1
Exposure, net of collateral		0	0
Net investment income
Credit Derivatives
Derivatives not designated as accounting hedging instruments, total gain (loss) recognized in net income on derivatives	(3)
Interest rate contracts | Net investment income
Credit Derivatives
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	$ 3