Derivative Financial Instruments (Details 4) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014 party	Dec. 31, 2013 party
Derivative Financial Instruments
Cash and securities pledged as collateral by counterparties	$ 5
Securities pledged as collateral to counterparties	21
Collateral posted under MNAs, credit-risk-contingent provisions in a liability position	19	14
Collateral posted under MNAs for contracts without credit-risk-contingent liabilities	2
Credit Derivatives
Number of counter-parties	7	8
Notional amount	196	1,648
Credit exposure	3	5
Exposure, net of collateral	1	1
Gross liability fair value of contracts containing credit-risk-contingent features	28	25
Gross asset fair value of contracts containing credit-risk-contingent features and subject to MNAs	(7)	(9)
Collateral posted under MNAs for contracts containing credit-risk-contingent features	(19)	(14)
Maximum amount of additional exposure for contracts with credit-risk-contingent features if all features were triggered concurrently	2	2
A+
Credit Derivatives
Number of counter-parties	1	1
Notional amount	21	22
Credit exposure	1	1
Exposure, net of collateral	1	1
A
Credit Derivatives
Number of counter-parties	4	4
Notional amount	96	1,523
Credit exposure	2	2
A-
Credit Derivatives
Number of counter-parties		1
Notional amount		24
Credit exposure		1
BBB+
Credit Derivatives
Number of counter-parties	1	1
Notional amount	3	3
BBB
Credit Derivatives
Number of counter-parties	1	1
Notional amount	76	76
Credit exposure		$ 1