Derivative Financial Instruments (Details 4) $ in Millions	Mar. 31, 2017 USD ($) party	Dec. 31, 2016 USD ($) party
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash and securities pledged as collateral by counterparties	$ 4
Securities pledged as collateral to counterparties	$ 4
Credit Derivatives
Number of counter-parties (in Party) | party	6	5
Notional amount	$ 324	$ 312
Credit exposure	5	12
Exposure, net of collateral	2	9
Gross liability fair value of contracts containing credit-risk-contingent features	3	2
Gross asset fair value of contracts containing credit-risk-contingent features and subject to MNAs	(3)	(2)
Maximum amount of additional exposure for contracts with credit-risk-contingent features if all features were triggered concurrently	$ 0	$ 0
A+
Credit Derivatives
Number of counter-parties (in Party) | party	5	5
Notional amount	$ 314	$ 312
Credit exposure	4	12
Exposure, net of collateral	$ 1	$ 9
A
Credit Derivatives
Number of counter-parties (in Party) | party	1	0
Notional amount	$ 10	$ 0
Credit exposure	1	0
Exposure, net of collateral	$ 1	$ 0