Managed Investment Entities - Narrative (Details) $ in Millions	1 Months Ended			6 Months Ended
	Apr. 30, 2017 collateralizedloanobligation	Mar. 31, 2017 USD ($)	May 31, 2016 USD ($)	Jun. 30, 2017 USD ($) collateralizedloanobligation	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Variable Interest Entity [Line Items]
Percentage of investment of most subordinate debt tranche, Minimum				15.00%
Percentage of investment of most subordinate debt tranche, Maximum				64.40%
Number of collateralized loan obligation entities | collateralizedloanobligation				16
Face amount of managed investment entities liabilities purchased by subsidiaries after issuance date				$ 29	$ 13
Amount paid by subsidiaries to purchase managed investment entities liabilities after issuance date				29	12
Proceeds received by subsidiaries related to sales and redemptions of managed investment entities liabilities				64	69
Number of collateralized loan obligation entities substantially liquidated, during the period | collateralizedloanobligation	1
Difference between aggregate unpaid principal balance and fair value of CLOs' fixed maturity investments				60		$ 75
Difference between aggregate unpaid principal balance and carrying value of CLOs' debt				135		159
Carrying amount of CLO loans in default				1		1
Aggregate unpaid principal balance of CLO loans in default				8		10
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Aggregate fair value of investment in collateralized loan obligations				188	$ 218	$ 216
New Collateralized Loan Obligation Entities
Variable Interest Entity [Line Items]
Face value of liabilities issued by managed investment entities on issuance date		$ 408	$ 406
Face amount of managed investment entities liabilities purchased by subsidiaries at issuance date		$ 24	$ 36
Subordinated Debt Obligations | Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Aggregate fair value of investment in collateralized loan obligations				$ 142