Investments (excluding Consolidated Investment Entities) - Fixed Maturities (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		$ 36,974	$ 35,836
Fixed maturities, available-for-sale, at fair value		42,330	39,663
Securities pledged, amortized costs		677	1,264
U.S. Treasuries
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		1,058	1,074
Gross Unrealized Capital Gains		483	308
Gross Unrealized Capital Losses		0	0
Embedded Derivatives		0	0
Fixed maturities, available-for-sale, at fair value		1,541	1,382
OTTI	$ 0	0
U.S. Government agencies and authorities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		73	74
Gross Unrealized Capital Gains		30	21
Gross Unrealized Capital Losses		0	0
Embedded Derivatives		0	0
Fixed maturities, available-for-sale, at fair value		103	95
OTTI	0	0
State, municipalities and political subdivisions
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		1,171	1,220
Gross Unrealized Capital Gains		183	103
Gross Unrealized Capital Losses		1	0
Embedded Derivatives		0	0
Fixed maturities, available-for-sale, at fair value		1,353	1,323
OTTI	0	0
U.S. corporate public securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		13,051	12,980
Gross Unrealized Capital Gains		2,674	1,977
Gross Unrealized Capital Losses		36	19
Embedded Derivatives		0	0
Fixed maturities, available-for-sale, at fair value		15,689	14,938
OTTI	0	0
U.S. corporate private securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		5,433	5,568
Gross Unrealized Capital Gains		807	488
Gross Unrealized Capital Losses		41	21
Embedded Derivatives		0	0
Fixed maturities, available-for-sale, at fair value		6,199	6,035
OTTI	0	0
Foreign corporate public securities and foreign governments
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		3,989	3,887
Gross Unrealized Capital Gains		598	460
Gross Unrealized Capital Losses		13	6
Embedded Derivatives		0	0
Fixed maturities, available-for-sale, at fair value		4,574	4,341
OTTI	0	0
Foreign corporate private securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		4,354	4,545
Gross Unrealized Capital Gains		409	288
Gross Unrealized Capital Losses		39	2
Embedded Derivatives		0	0
Fixed maturities, available-for-sale, at fair value		4,724	4,831
OTTI	0	0
Residential mortgage-backed
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		5,430	4,999
Gross Unrealized Capital Gains		278	200
Gross Unrealized Capital Losses		34	14
Embedded Derivatives		23	19
Fixed maturities, available-for-sale, at fair value		5,695	5,204
OTTI	5	2
Commercial mortgage-backed securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		4,011	3,402
Gross Unrealized Capital Gains		271	176
Gross Unrealized Capital Losses		78	4
Embedded Derivatives		0	0
Fixed maturities, available-for-sale, at fair value		4,203	3,574
OTTI	0	1
Other asset-backed securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		2,095	2,058
Gross Unrealized Capital Gains		37	22
Gross Unrealized Capital Losses		29	25
Embedded Derivatives		0	0
Fixed maturities, available-for-sale, at fair value		2,090	2,055
OTTI	1	13
Fixed maturities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost		40,665	39,807
Gross Unrealized Capital Gains		5,770	4,043
Gross Unrealized Capital Losses		271	91
Embedded Derivatives		23	19
Fixed maturities, available-for-sale, at fair value		46,171	43,778
OTTI	6	16
Total fixed maturities, less securities pledged, Amortized Cost		39,988	38,543
Total fixed maturities, less securities pledged, Gross Unrealized Capital Gains		5,616	3,889
Total fixed maturities, less securities pledged, Gross Unrealized Capital Losses		267	81
Total fixed maturities, less securities pledged, Fair Value		45,344	42,370
Impaired available-for-sale securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Net unrealized gains on impaired available-for-sale securities	336
Collateral Pledged
Available-for-sale Securities, Including Securities Pledged [Line Items]
Securities pledged		827	1,408
Collateral Pledged | Fixed maturities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Embedded Derivatives		0	0
OTTI	$ 0	0
Securities pledged, amortized costs		677	1,264
Securities pledged, Gross Unrealized Capital Gains		154	154
Securities pledged, Gross Unrealized Capital Losses		4	10
Securities pledged		$ 827	$ 1,408