Investments (excluding Consolidated Investment Entities) - Loans by Property Type (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Investment Holdings [Line Items]
Commercial mortgage loans	$ 6,817	$ 6,879
Year of Origination 2020
Investment Holdings [Line Items]
Commercial mortgage loans	332	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	30	0
Year of Origination 2020 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	121	0
Year of Origination 2020 | Office
Investment Holdings [Line Items]
Commercial mortgage loans	132	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	332	0
Year of Origination 2019
Investment Holdings [Line Items]
Commercial mortgage loans	696	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	112	130
Year of Origination 2019 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	394	400
Year of Origination 2019 | Office
Investment Holdings [Line Items]
Commercial mortgage loans	100	105
Year of Origination 2019 | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	35	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	696	722
Year of Origination 2018
Investment Holdings [Line Items]
Commercial mortgage loans	445	513
Year of Origination 2018 | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	77	83
Year of Origination 2018 | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	110	122
Year of Origination 2018 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	193	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	445	512
Year of Origination 2017
Investment Holdings [Line Items]
Commercial mortgage loans	1,100	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	512	557
Year of Origination 2017 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	265	268
Year of Origination 2017 | Office
Investment Holdings [Line Items]
Commercial mortgage loans	179	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	1,100	1,161
Year of Origination 2016
Investment Holdings [Line Items]
Commercial mortgage loans	953	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	304	312
Year of Origination 2016 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	260	263
Year of Origination 2016 | Office
Investment Holdings [Line Items]
Commercial mortgage loans	188	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	953	972
Year of Origination 2015
Investment Holdings [Line Items]
Commercial mortgage loans	740	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	280	285
Year of Origination 2015 | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	127	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	23	30
Year of Origination 2015 | Other
Investment Holdings [Line Items]
Commercial mortgage loans	67	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	740	805
Year of Origination 2014 and prior
Investment Holdings [Line Items]
Commercial mortgage loans	2,551	2,707
Year of Origination 2014 and prior | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	1,149	1,216
Year of Origination 2014 and prior | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	217	230
Year of Origination 2014 and prior | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	469	512
Year of Origination 2014 and prior | Office
Investment Holdings [Line Items]
Commercial mortgage loans	361	376
Year of Origination 2014 and prior | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	97	108
Year of Origination 2014 and prior | Other
Investment Holdings [Line Items]
Commercial mortgage loans	203	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	2,551	2,707
Total | Retail
Investment Holdings [Line Items]
Commercial mortgage loans	1,812	1,873
Total | Industrial
Investment Holdings [Line Items]
Commercial mortgage loans	1,565	1,636
Total | Apartments
Investment Holdings [Line Items]
Commercial mortgage loans	1,829	1,797
Total | Office
Investment Holdings [Line Items]
Commercial mortgage loans	1,063	999
Total | Hotel/Motel
Investment Holdings [Line Items]
Commercial mortgage loans	173	188
Total | Other
Investment Holdings [Line Items]
Commercial mortgage loans	315	324
Total | Mixed Use
Investment Holdings [Line Items]
Commercial mortgage loans	60	62
Total | Total
Investment Holdings [Line Items]
Commercial mortgage loans	$ 6,817	$ 6,879