Managed Investment Entities - Narrative (Details) $ in Millions	1 Months Ended		9 Months Ended
	Mar. 31, 2017 USD ($)	May 31, 2016 USD ($)	Sep. 30, 2017 USD ($) collateralizedloanobligation	Sep. 30, 2016 USD ($)	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			60.90%
Number of collateralized loan obligation entities | collateralizedloanobligation			15
Face amount of managed investment entities liabilities purchased by subsidiaries after issuance date			$ 58	$ 19
Amount paid by subsidiaries to purchase managed investment entities liabilities after issuance date			58	15
Proceeds received by subsidiaries related to sales and redemptions of managed investment entities liabilities			$ 86	69
Number of collateralized loan obligation entities substantially liquidated, during the period | collateralizedloanobligation			2
Difference between aggregate unpaid principal balance and fair value of CLOs' fixed maturity investments			$ 66		$ 75
Difference between aggregate unpaid principal balance and carrying value of CLOs' debt			135		159
Carrying amount of CLO loans in default			5		1
Aggregate unpaid principal balance of CLO loans in default			19		10
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Aggregate fair value of investment in collateralized loan obligations			261	$ 245	$ 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			$ 197