Derivative Financial Instruments (Details 4) $ in Millions	Sep. 30, 2015 USD ($) party	Dec. 31, 2014 USD ($) party
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash and securities pledged as collateral by counterparties	$ 13
Securities pledged as collateral to counterparties	$ 7
Credit Derivatives
Number of counter-parties (in Party) | party	8	7
Notional amount	$ 313	$ 323
Credit exposure	15	5
Exposure, net of collateral	3	2
Gross liability fair value of contracts containing credit-risk-contingent features	9	11
Gross asset fair value of contracts containing credit-risk-contingent features and subject to MNAs	0	(2)
Collateral posted under MNAs for contracts containing credit-risk-contingent features	(7)	(7)
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 (in Party) | party	1	1
Notional amount	$ 95	$ 164
Credit exposure	5	2
Exposure, net of collateral	$ 1	$ 1
A
Credit Derivatives
Number of counter-parties (in Party) | party	5	3
Notional amount	$ 177	$ 88
Credit exposure	8	3
Exposure, net of collateral	$ 2	$ 1
A-
Credit Derivatives
Number of counter-parties (in Party) | party	2	1
Notional amount	$ 41	$ 8
Credit exposure	2	0
Exposure, net of collateral	$ 0	$ 0
BBB+
Credit Derivatives
Number of counter-parties (in Party) | party	0	1
Notional amount	$ 0	$ 11
Credit exposure	0	0
Exposure, net of collateral	$ 0	$ 0
BBB
Credit Derivatives
Number of counter-parties (in Party) | party	0	1
Notional amount	$ 0	$ 52
Credit exposure	0	0
Exposure, net of collateral	$ 0	$ 0