Derivative Financial Instruments (Details 4) $ in Millions	Mar. 31, 2016 USD ($) party	Dec. 31, 2015 USD ($) party
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash and securities pledged as collateral by counterparties	$ 9
Securities pledged as collateral to counterparties	$ 8
Credit Derivatives
Number of counter-parties (in Party) | party	7	9
Notional amount	$ 166	$ 312
Credit exposure	8	14
Exposure, net of collateral	3	6
Gross liability fair value of contracts containing credit-risk-contingent features	14	9
Gross asset fair value of contracts containing credit-risk-contingent features and subject to MNAs	(1)	(1)
Collateral posted under MNAs for contracts containing credit-risk-contingent features	(8)	(7)
Maximum amount of additional exposure for contracts with credit-risk-contingent features if all features were triggered concurrently	$ 5	$ 1
A+
Credit Derivatives
Number of counter-parties (in Party) | party	1	1
Notional amount	$ 71	$ 82
Credit exposure	3	5
Exposure, net of collateral	$ 0	$ 0
A
Credit Derivatives
Number of counter-parties (in Party) | party	4	5
Notional amount	$ 63	$ 178
Credit exposure	2	6
Exposure, net of collateral	$ 0	$ 6
A-
Credit Derivatives
Number of counter-parties (in Party) | party	1	1
Notional amount	$ 16	$ 16
Credit exposure	3	3
Exposure, net of collateral	$ 3	$ 0
BBB+
Credit Derivatives
Number of counter-parties (in Party) | party	1	2
Notional amount	$ 16	$ 36
Credit exposure	0	0
Exposure, net of collateral	$ 0	$ 0