Reinsurance - Transactions (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jul. 17, 2020	Jul. 01, 2020	Jun. 01, 2020	Dec. 31, 2019
Effects of Reinsurance [Line Items]
Equity Securities without Readily Determinable Fair Value, Amount	$ 433
Liabilities	173,971				$ 132,734
Assets	191,088				146,875
Interest sensitive contract liabilities	(141,207)				(102,745)
Funds withheld at interest	$ 48,593				$ 15,181
MassMutual [Member]
Effects of Reinsurance [Line Items]
Funds withheld at interest			$ 5,021
Reinsurance Agreement
Effects of Reinsurance [Line Items]
Equity Securities without Readily Determinable Fair Value, Amount		$ 500
Liabilities				$ 27,439
Assets				28,805
Interest sensitive contract liabilities				$ (1,366)