Managed Investment Entities - Narrative (Details) $ in Millions	1 Months Ended	3 Months Ended
	Mar. 31, 2018 USD ($) collateralizedloanobligation	Mar. 31, 2019 USD ($) collateralizedloanobligation	Mar. 31, 2018 USD ($) collateralizedloanobligation	Dec. 31, 2018 USD ($)
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		11
Number of collateralized loan obligation entities formed during the period | collateralizedloanobligation	1
Proceeds received by subsidiaries related to sales and redemptions of managed investment entities liabilities			$ 17
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		$ 144		$ 232
Difference between aggregate unpaid principal balance and carrying value of CLOs' debt		145		241
Carrying amount of CLO loans in default		0		0
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Aggregate fair value of investment in collateralized loan obligations	$ 221	193	$ 221	$ 188
New Collateralized Loan Obligation Entities
Variable Interest Entity [Line Items]
Face value of liabilities issued by managed investment entities on issuance date	463
Face amount of managed investment entities liabilities purchased by subsidiaries at issuance date	$ 31
Subordinated Debt Obligations | Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Aggregate fair value of investment in collateralized loan obligations		130
Maximum
Variable Interest Entity [Line Items]
Proceeds received by subsidiaries related to sales and redemptions of managed investment entities liabilities		$ 1