Investments - Loans by Debt Service Coverage Ratio (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2023	Sep. 30, 2022	Dec. 31, 2022
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	$ 4,148		$ 4,227
Loans and Leases Receivable, Debt Service Coverage, Benchmark Ratio	100.00%
Greater than 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Loans Receivable, Debt Service Coverage Ratio, Minimum	150.00%	150.00%
Commercial mortgage loans	$ 2,454		2,524
1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Loans Receivable, Debt Service Coverage Ratio, Minimum	125.00%	125.00%
Loans Receivable, Debt Service Coverage Ratio, Maximum	150.00%	150.00%
Commercial mortgage loans	$ 495		514
1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Loans Receivable, Debt Service Coverage Ratio, Minimum	100.00%	100.00%
Loans Receivable, Debt Service Coverage Ratio, Maximum	125.00%	125.00%
Commercial mortgage loans	$ 547		699
Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Loans Receivable, Debt Service Coverage Ratio, Maximum	100.00%	100.00%
Commercial mortgage loans	$ 652		490
Year of Origination 2020
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	284		302
Year of Origination 2020 | Greater than 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	199		211
Year of Origination 2020 | 1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	21		9
Year of Origination 2020 | 1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	5		10
Year of Origination 2020 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	59		72
Year of Origination 2019
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	257		259
Year of Origination 2019 | Greater than 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	160		161
Year of Origination 2019 | 1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	35		40
Year of Origination 2019 | 1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	57		53
Year of Origination 2019 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	5		5
Year of Origination 2018
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	158		160
Year of Origination 2018 | Greater than 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	87		93
Year of Origination 2018 | 1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	21		21
Year of Origination 2018 | 1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	50		46
Year of Origination 2018 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	0		0
Year of Origination 2017
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	2,221		2,285
Year of Origination 2017 | Greater than 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	1,522		1,569
Year of Origination 2017 | 1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	326		331
Year of Origination 2017 | 1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	170		171
Year of Origination 2017 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	203		214
Year of Origination 2021
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	625		665
Year of Origination 2021 | Greater than 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	209		212
Year of Origination 2021 | 1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	18		24
Year of Origination 2021 | 1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	94		248
Year of Origination 2021 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	304		181
Year of Origination 2022
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	565		556
Year of Origination 2022 | Greater than 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	243		278
Year of Origination 2022 | 1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	70		89
Year of Origination 2022 | 1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	171		171
Year of Origination 2022 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	81		$ 18
Year of Origination 2023
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	38
Year of Origination 2023 | Greater than 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	34
Year of Origination 2023 | 1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	4
Year of Origination 2023 | 1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	0
Year of Origination 2023 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Commercial mortgage loans	$ 0