Investments (excluding Consolidated Investment Entities) - Fixed Maturities (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	$ 36,209	$ 35,836
Fixed maturities, available-for-sale, at fair value	40,938	39,663
Securities pledged, amortized costs	950	1,264
U.S. Treasuries
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	1,049	1,074
Gross Unrealized Capital Gains	495	308
Gross Unrealized Capital Losses	0	0
Embedded Derivatives	0	0
Fixed maturities, available-for-sale, at fair value	1,544	1,382
OTTI	0	0
U.S. Government agencies and authorities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	74	74
Gross Unrealized Capital Gains	29	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	1,206	1,220
Gross Unrealized Capital Gains	163	103
Gross Unrealized Capital Losses	1	0
Embedded Derivatives	0	0
Fixed maturities, available-for-sale, at fair value	1,368	1,323
OTTI	0	0
U.S. corporate public securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	12,592	12,980
Gross Unrealized Capital Gains	2,497	1,977
Gross Unrealized Capital Losses	47	19
Embedded Derivatives	0	0
Fixed maturities, available-for-sale, at fair value	15,042	14,938
OTTI	0	0
U.S. corporate private securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	5,545	5,568
Gross Unrealized Capital Gains	716	488
Gross Unrealized Capital Losses	42	21
Embedded Derivatives	0	0
Fixed maturities, available-for-sale, at fair value	6,219	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	3,844	3,887
Gross Unrealized Capital Gains	532	460
Gross Unrealized Capital Losses	16	6
Embedded Derivatives	0	0
Fixed maturities, available-for-sale, at fair value	4,360	4,341
OTTI	0	0
Foreign corporate private securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	4,381	4,545
Gross Unrealized Capital Gains	315	288
Gross Unrealized Capital Losses	40	2
Embedded Derivatives	0	0
Fixed maturities, available-for-sale, at fair value	4,653	4,831
OTTI	3	0
Residential mortgage-backed
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	5,681	4,999
Gross Unrealized Capital Gains	284	200
Gross Unrealized Capital Losses	44	14
Embedded Derivatives	27	19
Fixed maturities, available-for-sale, at fair value	5,946	5,204
OTTI	2	5
Commercial mortgage-backed securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	3,763	3,402
Gross Unrealized Capital Gains	251	176
Gross Unrealized Capital Losses	167	4
Embedded Derivatives	0	0
Fixed maturities, available-for-sale, at fair value	3,847	3,574
OTTI	0	0
Other asset-backed securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	2,122	2,058
Gross Unrealized Capital Gains	26	22
Gross Unrealized Capital Losses	60	25
Embedded Derivatives	0	0
Fixed maturities, available-for-sale, at fair value	2,076	2,055
OTTI	12	1
Fixed maturities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	40,257	39,807
Gross Unrealized Capital Gains	5,308	4,043
Gross Unrealized Capital Losses	417	91
Embedded Derivatives	27	19
Fixed maturities, available-for-sale, at fair value	45,158	43,778
OTTI	17	6
Total fixed maturities, less securities pledged, Amortized Cost	39,307	38,543
Total fixed maturities, less securities pledged, Gross Unrealized Capital Gains	5,125	3,889
Total fixed maturities, less securities pledged, Gross Unrealized Capital Losses	406	81
Total fixed maturities, less securities pledged, Fair Value	44,036	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	1,122	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	950	1,264
Securities pledged, Gross Unrealized Capital Gains	183	154
Securities pledged, Gross Unrealized Capital Losses	11	10
Securities pledged	$ 1,122	$ 1,408