Investments - Investments - Available-for-Sale Securities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	$ 41,317	$ 41,561
Allowance for credit losses, fixed maturity, AFS	(19)	(23)	$ (12)	$ 0
Gross Unrealized Gains, fixed maturities, available-for-sale	2,450	3,560
Gross Unrealized Losses, fixed maturities, available-for-sale	(141)	(63)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	43,607	45,035
ABS
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	1,405	1,525
Allowance for credit losses, fixed maturity, AFS	0	0
Gross Unrealized Gains, fixed maturities, available-for-sale	30	39
Gross Unrealized Losses, fixed maturities, available-for-sale	0	0
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	1,435	1,564
CLOs
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	3,040	2,780
Allowance for credit losses, fixed maturity, AFS	0	0
Gross Unrealized Gains, fixed maturities, available-for-sale	10	7
Gross Unrealized Losses, fixed maturities, available-for-sale	(1)	(7)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	3,049	2,780
CMBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	3,979	4,219
Allowance for credit losses, fixed maturity, AFS	0	0
Gross Unrealized Gains, fixed maturities, available-for-sale	206	286
Gross Unrealized Losses, fixed maturities, available-for-sale	(18)	(21)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	4,167	4,484
Corporate
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	18,385	18,401
Allowance for credit losses, fixed maturity, AFS	(19)	(23)	$ (12)	$ 0
Gross Unrealized Gains, fixed maturities, available-for-sale	1,216	1,926
Gross Unrealized Losses, fixed maturities, available-for-sale	(87)	(31)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	19,495	20,273
Foreign Govt./Govt. Agencies
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	825	842
Allowance for credit losses, fixed maturity, AFS	0	0
Gross Unrealized Gains, fixed maturities, available-for-sale	47	77
Gross Unrealized Losses, fixed maturities, available-for-sale	(4)	0
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	868	919
Municipal
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	8,471	8,564
Allowance for credit losses, fixed maturity, AFS	0	0
Gross Unrealized Gains, fixed maturities, available-for-sale	762	940
Gross Unrealized Losses, fixed maturities, available-for-sale	(19)	(1)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	9,214	9,503
RMBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	3,924	3,966
Allowance for credit losses, fixed maturity, AFS	0	0
Gross Unrealized Gains, fixed maturities, available-for-sale	110	144
Gross Unrealized Losses, fixed maturities, available-for-sale	(9)	(3)
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	4,025	4,107
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, available-for-sale, at fair value, amortized cost	1,288	1,264
Allowance for credit losses, fixed maturity, AFS	0	0
Gross Unrealized Gains, fixed maturities, available-for-sale	69	141
Gross Unrealized Losses, fixed maturities, available-for-sale	(3)	0
Fixed maturities, available-for-sale, at fair value (amortized cost of $54,478 and $53,805)	$ 1,354	$ 1,405

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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