Investments (excluding Consolidated Investment Entities) - Loans by Property Type (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Investment Holdings [Line Items]
Commercial mortgage loans	$ 6,904	$ 6,879
Year of Origination 2020
Investment Holdings [Line Items]
Commercial mortgage loans	298	0
Year of Origination 2020 | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	49	0
Year of Origination 2020 | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	8	0
Year of Origination 2020 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	117	0
Year of Origination 2020 | Office
Investment Holdings [Line Items]
Commercial mortgage loans	124	0
Year of Origination 2020 | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	0	0
Year of Origination 2020 | Other
Investment Holdings [Line Items]
Commercial mortgage loans	0	0
Year of Origination 2020 | Mixed Use
Investment Holdings [Line Items]
Commercial mortgage loans	0	0
Year of Origination 2020 | Total
Investment Holdings [Line Items]
Commercial mortgage loans	298	0
Year of Origination 2019
Investment Holdings [Line Items]
Commercial mortgage loans	714	723
Year of Origination 2019 | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	55	55
Year of Origination 2019 | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	129	130
Year of Origination 2019 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	391	400
Year of Origination 2019 | Office
Investment Holdings [Line Items]
Commercial mortgage loans	105	105
Year of Origination 2019 | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	34	32
Year of Origination 2019 | Other
Investment Holdings [Line Items]
Commercial mortgage loans	0	0
Year of Origination 2019 | Mixed Use
Investment Holdings [Line Items]
Commercial mortgage loans	0	0
Year of Origination 2019 | Total
Investment Holdings [Line Items]
Commercial mortgage loans	714	722
Year of Origination 2018
Investment Holdings [Line Items]
Commercial mortgage loans	460	513
Year of Origination 2018 | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	78	83
Year of Origination 2018 | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	111	122
Year of Origination 2018 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	206	221
Year of Origination 2018 | Office
Investment Holdings [Line Items]
Commercial mortgage loans	25	46
Year of Origination 2018 | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	4	4
Year of Origination 2018 | Other
Investment Holdings [Line Items]
Commercial mortgage loans	36	36
Year of Origination 2018 | Mixed Use
Investment Holdings [Line Items]
Commercial mortgage loans	0	0
Year of Origination 2018 | Total
Investment Holdings [Line Items]
Commercial mortgage loans	460	512
Year of Origination 2017
Investment Holdings [Line Items]
Commercial mortgage loans	1,118	1,160
Year of Origination 2017 | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	140	142
Year of Origination 2017 | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	520	557
Year of Origination 2017 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	266	268
Year of Origination 2017 | Office
Investment Holdings [Line Items]
Commercial mortgage loans	188	190
Year of Origination 2017 | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	4	4
Year of Origination 2017 | Other
Investment Holdings [Line Items]
Commercial mortgage loans	0	0
Year of Origination 2017 | Mixed Use
Investment Holdings [Line Items]
Commercial mortgage loans	0	0
Year of Origination 2017 | Total
Investment Holdings [Line Items]
Commercial mortgage loans	1,118	1,161
Year of Origination 2016
Investment Holdings [Line Items]
Commercial mortgage loans	961	972
Year of Origination 2016 | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	177	179
Year of Origination 2016 | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	307	312
Year of Origination 2016 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	262	263
Year of Origination 2016 | Office
Investment Holdings [Line Items]
Commercial mortgage loans	191	192
Year of Origination 2016 | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	10	10
Year of Origination 2016 | Other
Investment Holdings [Line Items]
Commercial mortgage loans	9	10
Year of Origination 2016 | Mixed Use
Investment Holdings [Line Items]
Commercial mortgage loans	5	6
Year of Origination 2016 | Total
Investment Holdings [Line Items]
Commercial mortgage loans	961	972
Year of Origination 2015
Investment Holdings [Line Items]
Commercial mortgage loans	746	804
Year of Origination 2015 | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	165	198
Year of Origination 2015 | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	282	285
Year of Origination 2015 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	129	133
Year of Origination 2015 | Office
Investment Holdings [Line Items]
Commercial mortgage loans	78	90
Year of Origination 2015 | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	24	30
Year of Origination 2015 | Other
Investment Holdings [Line Items]
Commercial mortgage loans	68	69
Year of Origination 2015 | Mixed Use
Investment Holdings [Line Items]
Commercial mortgage loans	0	0
Year of Origination 2015 | Total
Investment Holdings [Line Items]
Commercial mortgage loans	746	805
Year of Origination 2014 and prior
Investment Holdings [Line Items]
Commercial mortgage loans	2,607	2,707
Year of Origination 2014 and prior | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	1,179	1,216
Year of Origination 2014 and prior | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	221	230
Year of Origination 2014 and prior | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	480	512
Year of Origination 2014 and prior | Office
Investment Holdings [Line Items]
Commercial mortgage loans	366	376
Year of Origination 2014 and prior | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	101	108
Year of Origination 2014 and prior | Other
Investment Holdings [Line Items]
Commercial mortgage loans	205	209
Year of Origination 2014 and prior | Mixed Use
Investment Holdings [Line Items]
Commercial mortgage loans	55	56
Year of Origination 2014 and prior | Total
Investment Holdings [Line Items]
Commercial mortgage loans	2,607	2,707
Total | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	1,843	1,873
Total | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	1,578	1,636
Total | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	1,851	1,797
Total | Office
Investment Holdings [Line Items]
Commercial mortgage loans	1,077	999
Total | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	177	188
Total | Other
Investment Holdings [Line Items]
Commercial mortgage loans	318	324
Total | Mixed Use
Investment Holdings [Line Items]
Commercial mortgage loans	60	62
Total | Total
Investment Holdings [Line Items]
Commercial mortgage loans	$ 6,904	$ 6,879