Derivative Financial Instruments (Details 4) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014 counterparties	Dec. 31, 2013 counterparties
Derivative Financial Instruments
Cash and securities pledged as collateral by counterparties	$ 10
Securities pledged as collateral to counterparties	20
Collateral posted under MNAs, credit-risk-contingent provisions in a liability position	16	14
Collateral posted under MNAs for contracts without credit-risk-contingent liabilities	4
Credit Derivatives
Number of counter-parties	10	9
Notional amount	434	1,783
Credit exposure	16	15
Exposure, net of collateral	8	3
Gross liability fair value of contracts containing credit-risk-contingent features	29	28
Gross asset fair value of contracts containing credit-risk-contingent features and subject to MNAs	(8)	(11)
Collateral posted under MNAs for contracts containing credit-risk-contingent features	(16)	(14)
Maximum amount of additional exposure for contracts with credit-risk-contingent features if all features were triggered concurrently	5	3
A+
Credit Derivatives
Number of counter-parties	2	1
Notional amount	101	22
Credit exposure	3	1
Exposure, net of collateral	3	1
A
Credit Derivatives
Number of counter-parties	5	5
Notional amount	121	1,628
Credit exposure	6	9
Exposure, net of collateral	1	2
A-
Credit Derivatives
Number of counter-parties	1	1
Notional amount	85	24
Credit exposure	3	1
Exposure, net of collateral	3
BBB+
Credit Derivatives
Number of counter-parties	1	1
Notional amount	65	33
Credit exposure	4	3
Exposure, net of collateral	1
BBB
Credit Derivatives
Number of counter-parties	1	1
Notional amount	62	76
Credit exposure		$ 1