Derivative Financial Instruments (Details 4) $ in Millions	Jun. 30, 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	3
Collateral already posted, without credit-risk-contingent features	1
Credit Derivatives
Gross liability fair value of contracts containing credit-risk-contingent features	7	$ 2
Gross asset fair value of contracts containing credit-risk-contingent features and subject to MNAs	(2)	(2)
Collateral posted under MNAs for contracts containing credit-risk-contingent features	(2)	0
Maximum amount of additional exposure for contracts with credit-risk-contingent features if all features were triggered concurrently	$ 3	$ 0
A+
Credit Derivatives
Number of counter-parties (in Party) | party	4	5
Notional amount	$ 250	$ 312
Credit exposure	4	12
Exposure, net of collateral	$ 0	$ 9