Investments Investments - Allowance for Credit Losses Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	$ 104
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	9	$ 59
Debt Securities, Available-for-sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase	2	1
Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	(6)	(1)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	2	2
Investments, excluding investments in Related Party
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	103
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	9
Debt Securities, Available-for-sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase	2
Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	(5)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	2
U.S. government and agencies | Investments, excluding investments in Related Party
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	0
U.S. state, municipal and political subdivisions | Investments, excluding investments in Related Party
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	0
Foreign governments | Investments, excluding investments in Related Party
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	0
Corporate | Investments, excluding investments in Related Party
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	6
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	2	15
Debt Securities, Available-for-sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase	0	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	(2)	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	2	0
CLO | Investments, excluding investments in Related Party
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	1
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	(1)
ABS | Investments, excluding investments in Related Party
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	6
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	5	5
Debt Securities, Available-for-sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase	0	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	0	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	0	0
CMBS | Investments, excluding investments in Related Party
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	10
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	2	4
Debt Securities, Available-for-sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase	0	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	0	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	2	0
RMBS | Investments, excluding investments in Related Party
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	80
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0	35
Debt Securities, Available-for-sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase	2	1
Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	(3)	(1)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	(1)	$ 2
Related Party
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	1
Related Party | Corporate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	0
Related Party | CLO
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	1
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase	0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold	(1)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal)	0
Related Party | ABS
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Beginning Balance	$ 0