Investments (excluding Consolidated Investment Entities) - Fixed Maturities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	$ 35,836	$ 36,268
Securities pledged, Amortized Cost	1,264	1,436
Fixed maturities, including securities pledged	39,663	36,897
U.S. Treasuries
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	1,074	1,228
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	308	196
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	0	1
Embedded Derivatives	0	0
Fixed maturities, including securities pledged	1,382	1,423
OTTI	0	0
U.S. Government agencies and authorities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	74	62
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	21	12
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	0	0
Embedded Derivatives	0	0
Fixed maturities, including securities pledged	95	74
OTTI	0	0
State, municipalities, and political subdivisions
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	1,220	1,241
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	103	25
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	0	16
Embedded Derivatives	0	0
Fixed maturities, including securities pledged	1,323	1,250
OTTI	0	0
U.S. corporate public securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	12,980	14,455
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	1,977	721
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	19	300
Embedded Derivatives	0	0
Fixed maturities, including securities pledged	14,938	14,876
OTTI	0	0
U.S. corporate private securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	5,568	5,499
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	488	134
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	21	142
Embedded Derivatives	0	0
Fixed maturities, including securities pledged	6,035	5,491
OTTI	0	0
Foreign corporate public securities and foreign governments
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	3,887	4,139
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	460	125
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	6	129
Embedded Derivatives	0	0
Fixed maturities, including securities pledged	4,341	4,135
OTTI	0	0
Foreign corporate private securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	4,545	4,705
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	288	66
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	2	131
Embedded Derivatives	0	0
Fixed maturities, including securities pledged	4,831	4,640
OTTI	0	0
Residential mortgage-backed securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	4,999	4,143
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	200	170
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	14	47
Embedded Derivatives	19	16
Fixed maturities, including securities pledged	5,204	4,282
OTTI	5	7
Commercial mortgage-backed securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	3,402	2,777
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	176	27
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	4	41
Embedded Derivatives	0	0
Fixed maturities, including securities pledged	3,574	2,763
OTTI	0	0
Other asset-backed securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	2,058	1,688
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	22	10
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	25	40
Embedded Derivatives	0	0
Fixed maturities, including securities pledged	2,055	1,658
OTTI	1	2
Fixed maturities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, including securities pledged, Amortized Cost Basis	39,807	39,937
Total fixed maturities, less securities pledged, Amortized Cost	38,543	38,501
Fixed maturities, including securities pledged, Gross Unrealized Capital Gains	4,043	1,486
Total fixed maturities, less securities pledged, Gross Unrealized Capital Gains	3,889	1,411
Fixed maturities, including securities pledged,Gross Unrealized Capital Losses	91	847
Total fixed maturities, less securities pledged, Gross Unrealized Capital Losses	81	798
Embedded Derivatives	19	16
Fixed maturities, including securities pledged	43,778	40,592
Total fixed maturities, less securities pledged, Fair Value	42,370	39,130
OTTI	6	9
Impaired
Available-for-sale Securities, Including Securities Pledged [Line Items]
Net unrealized gains on impaired available-for-sale securities	336	234
Collateral pledged
Available-for-sale Securities, Including Securities Pledged [Line Items]
Securities pledged	1,408	1,462
Collateral pledged | Fixed maturities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Securities pledged, Amortized Cost	1,264	1,436
Securities pledged, Gross Unrealized Capital Gains	154	75
Securities pledged, Gross Unrealized Capital Losses	10	49
Embedded Derivatives	0	0
Securities pledged	1,408	1,462
OTTI	$ 0	$ 0