Investments - Loans by Debt Service Coverage Ratio (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		$ 4,233	$ 4,694
>1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Loans Receivable, Debt Service Coverage Ratio, Minimum	150.00%	150.00%
Mortgage loans, before Allowance for Credit Loss		$ 3,060	3,480
>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%
Mortgage loans, before Allowance for Credit Loss		$ 377	684
>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%
Mortgage loans, before Allowance for Credit Loss		$ 449	320
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%
Mortgage loans, before Allowance for Credit Loss		$ 347	210
Commercial mortgage loans secured by land or construction loans
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		0	0
Year of Origination 2021
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		670
Year of Origination 2021 | >1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		556
Year of Origination 2021 | >1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		23
Year of Origination 2021 | >1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		34
Year of Origination 2021 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		57
Year of Origination 2021 | Commercial mortgage loans secured by land or construction loans
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		0
Year of Origination 2020
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		385	409
Year of Origination 2020 | >1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		342	298
Year of Origination 2020 | >1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		15	93
Year of Origination 2020 | >1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		23	18
Year of Origination 2020 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		5	0
Year of Origination 2020 | Commercial mortgage loans secured by land or construction loans
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		0	0
Year of Origination 2019
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		356	481
Year of Origination 2019 | >1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		206	319
Year of Origination 2019 | >1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		43	77
Year of Origination 2019 | >1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		84	36
Year of Origination 2019 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		23	49
Year of Origination 2019 | Commercial mortgage loans secured by land or construction loans
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		0	0
Year of Origination 2018
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		173	288
Year of Origination 2018 | >1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		96	102
Year of Origination 2018 | >1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		3	79
Year of Origination 2018 | >1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		49	60
Year of Origination 2018 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		25	47
Year of Origination 2018 | Commercial mortgage loans secured by land or construction loans
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		0	0
Year of Origination 2017
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		748	861
Year of Origination 2017 | >1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		355	494
Year of Origination 2017 | >1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		139	204
Year of Origination 2017 | >1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		93	103
Year of Origination 2017 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		161	60
Year of Origination 2017 | Commercial mortgage loans secured by land or construction loans
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		0	0
Year of Origination 2016
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		518	675
Year of Origination 2016 | >1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		440	591
Year of Origination 2016 | >1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		17	53
Year of Origination 2016 | >1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		44	31
Year of Origination 2016 | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		17	0
Year of Origination 2016 | Commercial mortgage loans secured by land or construction loans
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		0	0
Year of Origination 2015 and prior
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		1,383	1,980
Year of Origination 2015 and prior | >1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		1,065	1,676
Year of Origination 2015 and prior | >1.25x - 1.5x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		137	178
Year of Origination 2015 and prior | >1.0x - 1.25x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		122	72
Year of Origination 2015 and prior | Less than 1.0x
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		59	54
Year of Origination 2015 and prior | Commercial mortgage loans secured by land or construction loans
Schedule of Loans by Debt Service Coverage Ratio [Line Items]
Mortgage loans, before Allowance for Credit Loss		$ 0	$ 0