Contractholder Funds - Guaranteed Minimum Interest Rate (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Excess of crediting rates over GMIR
Total policyholder account value	$ 25,488.8	$ 26,349.6
Retirement and Income Solutions
Excess of crediting rates over GMIR
Total policyholder account value	18,957.1	19,764.4
Workplace savings and retirement solutions | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	10,567.6	10,058.7
Policyholder account value without GMIR	2,003.6	2,096.0
Total policyholder account value	12,571.2	12,154.7	$ 10,996.2
Workplace savings and retirement solutions | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,461.4	1,890.3
Workplace savings and retirement solutions | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	8,146.4	8,126.5
Workplace savings and retirement solutions | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	934.2	15.3
Workplace savings and retirement solutions | 3.01% - 4.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	7.6	7.8
Workplace savings and retirement solutions | 4.01% and above | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	18.0	18.8
Workplace savings and retirement solutions | At GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	436.2	45.6
Workplace savings and retirement solutions | At GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR		3.9
Workplace savings and retirement solutions | At GMIR | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	410.6	15.1
Workplace savings and retirement solutions | At GMIR | 3.01% - 4.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	7.6	7.8
Workplace savings and retirement solutions | At GMIR | 4.01% and above | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	18.0	18.8
Workplace savings and retirement solutions | Up to 0.50% above GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	5,523.4	574.8
Workplace savings and retirement solutions | Up to 0.50% above GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	3.7	24.8
Workplace savings and retirement solutions | Up to 0.50% above GMIR | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	5,519.6	549.9
Workplace savings and retirement solutions | Up to 0.50% above GMIR | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	0.1	0.1
Workplace savings and retirement solutions | 0.51% to 1.00% above GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,278.6	7,279.1
Workplace savings and retirement solutions | 0.51% to 1.00% above GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	105.4	1,188.9
Workplace savings and retirement solutions | 0.51% to 1.00% above GMIR | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,172.4	6,090.2
Workplace savings and retirement solutions | 0.51% to 1.00% above GMIR | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	0.8
Workplace savings and retirement solutions | 1.01% to 2.00% above GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,074.2	1,784.9
Workplace savings and retirement solutions | 1.01% to 2.00% above GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,048.5	307.8
Workplace savings and retirement solutions | 1.01% to 2.00% above GMIR | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR		1,477.0
Workplace savings and retirement solutions | 1.01% to 2.00% above GMIR | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	25.7	0.1
Workplace savings and retirement solutions | 2.01% or more above GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	2,255.2	374.3
Workplace savings and retirement solutions | 2.01% or more above GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	303.8	364.9
Workplace savings and retirement solutions | 2.01% or more above GMIR | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,454.4	$ 9.4
Workplace savings and retirement solutions | 2.01% or more above GMIR | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	$ 497.0
Workplace savings and retirement solutions | Minimum | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	1.01%	1.01%
Workplace savings and retirement solutions | Minimum | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	2.01%	2.01%
Workplace savings and retirement solutions | Minimum | 3.01% - 4.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	3.01%	3.01%
Workplace savings and retirement solutions | Minimum | 4.01% and above | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	4.01%	4.01%
Workplace savings and retirement solutions | Maximum | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	1.00%	1.00%
Workplace savings and retirement solutions | Maximum | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	2.00%	2.00%
Workplace savings and retirement solutions | Maximum | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	3.00%	3.00%
Workplace savings and retirement solutions | Maximum | 3.01% - 4.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	4.00%	4.00%
Individual variable annuities | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	$ 324.6	$ 368.4
Policyholder account value without GMIR	112.0	13.0
Total policyholder account value	436.6	381.4	380.9
Individual variable annuities | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	25.8	33.0
Individual variable annuities | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	5.7	3.6
Individual variable annuities | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	293.1	331.8
Individual variable annuities | At GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	324.6	368.4
Individual variable annuities | At GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	25.8	33.0
Individual variable annuities | At GMIR | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	5.7	3.6
Individual variable annuities | At GMIR | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	$ 293.1	$ 331.8
Individual variable annuities | Minimum | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	1.01%	1.01%
Individual variable annuities | Minimum | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	2.01%	2.01%
Individual variable annuities | Minimum | 3.01% - 4.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	3.01%	3.01%
Individual variable annuities | Minimum | 4.01% and above | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	4.01%	4.01%
Individual variable annuities | Maximum | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	1.00%	1.00%
Individual variable annuities | Maximum | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	2.00%	2.00%
Individual variable annuities | Maximum | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	3.00%	3.00%
Individual variable annuities | Maximum | 3.01% - 4.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	4.00%	4.00%
Individual fixed deferred annuities | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	$ 5,695.7	$ 6,915.5
Policyholder account value without GMIR	253.6	312.8
Total policyholder account value	5,949.3	7,228.3	9,646.3
Individual fixed deferred annuities | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	2,104.0	2,696.5
Individual fixed deferred annuities | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	364.1	432.2
Individual fixed deferred annuities | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	3,066.7	3,617.1
Individual fixed deferred annuities | 3.01% - 4.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	160.9	169.7
Individual fixed deferred annuities | At GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	3,671.6	4,353.0
Individual fixed deferred annuities | At GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	336.6	426.4
Individual fixed deferred annuities | At GMIR | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	107.4	139.8
Individual fixed deferred annuities | At GMIR | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	3,066.7	3,617.1
Individual fixed deferred annuities | At GMIR | 3.01% - 4.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	160.9	169.7
Individual fixed deferred annuities | Up to 0.50% above GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	135.4	163.1
Individual fixed deferred annuities | Up to 0.50% above GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	134.4	161.7
Individual fixed deferred annuities | Up to 0.50% above GMIR | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1.0	1.4
Individual fixed deferred annuities | 0.51% to 1.00% above GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	174.2	276.1
Individual fixed deferred annuities | 0.51% to 1.00% above GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	144.4	236.2
Individual fixed deferred annuities | 0.51% to 1.00% above GMIR | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	29.8	39.9
Individual fixed deferred annuities | 1.01% to 2.00% above GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	712.8	1,129.7
Individual fixed deferred annuities | 1.01% to 2.00% above GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	488.1	879.2
Individual fixed deferred annuities | 1.01% to 2.00% above GMIR | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	224.7	250.5
Individual fixed deferred annuities | 2.01% or more above GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,001.7	993.6
Individual fixed deferred annuities | 2.01% or more above GMIR | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,000.5	993.0
Individual fixed deferred annuities | 2.01% or more above GMIR | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	$ 1.2	$ 0.6
Individual fixed deferred annuities | Minimum | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	1.01%	1.01%
Individual fixed deferred annuities | Minimum | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	2.01%	2.01%
Individual fixed deferred annuities | Minimum | 3.01% - 4.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	3.01%	3.01%
Individual fixed deferred annuities | Minimum | 4.01% and above | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	4.01%	4.01%
Individual fixed deferred annuities | Maximum | Up to 1.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	1.00%	1.00%
Individual fixed deferred annuities | Maximum | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	2.00%	2.00%
Individual fixed deferred annuities | Maximum | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	3.00%	3.00%
Individual fixed deferred annuities | Maximum | 3.01% - 4.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
GMIR	4.00%	4.00%
Universal life | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	$ 6,081.8	$ 6,214.1
Policyholder account value without GMIR	806.3	733.8
Total policyholder account value	6,888.1	6,947.9	$ 6,962.5
Universal life | Up to 1.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	18.9	19.2
Universal life | 1.01% - 2.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,591.2	1,573.2
Universal life | 2.01% - 3.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	2,635.3	2,780.9
Universal life | 3.01% - 4.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,781.7	1,785.1
Universal life | 4.01% and above | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	54.7	55.7
Universal life | At GMIR | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	2,745.7	2,921.1
Universal life | At GMIR | 1.01% - 2.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	300.0	315.7
Universal life | At GMIR | 2.01% - 3.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	750.7	865.9
Universal life | At GMIR | 3.01% - 4.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,657.3	1,698.9
Universal life | At GMIR | 4.01% and above | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	37.7	40.6
Universal life | Up to 0.50% above GMIR | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	748.2	1,005.5
Universal life | Up to 0.50% above GMIR | Up to 1.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	0.5	8.4
Universal life | Up to 0.50% above GMIR | 2.01% - 3.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	686.9	951.2
Universal life | Up to 0.50% above GMIR | 3.01% - 4.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	48.7	35.8
Universal life | Up to 0.50% above GMIR | 4.01% and above | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	12.1	10.1
Universal life | 0.51% to 1.00% above GMIR | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,327.0	1,345.9
Universal life | 0.51% to 1.00% above GMIR | Up to 1.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	16.7	10.1
Universal life | 0.51% to 1.00% above GMIR | 1.01% - 2.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	412.8	407.0
Universal life | 0.51% to 1.00% above GMIR | 2.01% - 3.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	850.5	903.5
Universal life | 0.51% to 1.00% above GMIR | 3.01% - 4.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	43.6	21.9
Universal life | 0.51% to 1.00% above GMIR | 4.01% and above | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	3.4	3.4
Universal life | 1.01% to 2.00% above GMIR | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	849.8	782.3
Universal life | 1.01% to 2.00% above GMIR | 1.01% - 2.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	472.8	695.5
Universal life | 1.01% to 2.00% above GMIR | 2.01% - 3.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	346.6	59.9
Universal life | 1.01% to 2.00% above GMIR | 3.01% - 4.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	28.9	25.3
Universal life | 1.01% to 2.00% above GMIR | 4.01% and above | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1.5	1.6
Universal life | 2.01% or more above GMIR | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	411.1	159.3
Universal life | 2.01% or more above GMIR | Up to 1.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1.7	0.7
Universal life | 2.01% or more above GMIR | 1.01% - 2.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	405.6	155.0
Universal life | 2.01% or more above GMIR | 2.01% - 3.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	0.6	0.4
Universal life | 2.01% or more above GMIR | 3.01% - 4.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	$ 3.2	$ 3.2
Universal life | Minimum | 1.01% - 2.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
GMIR	1.01%	1.01%
Universal life | Minimum | 2.01% - 3.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
GMIR	2.01%	2.01%
Universal life | Minimum | 3.01% - 4.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
GMIR	3.01%	3.01%
Universal life | Minimum | 4.01% and above | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
GMIR	4.01%	4.01%
Universal life | Maximum | Up to 1.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
GMIR	1.00%	1.00%
Universal life | Maximum | 1.01% - 2.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
GMIR	2.00%	2.00%
Universal life | Maximum | 2.01% - 3.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
GMIR	3.00%	3.00%
Universal life | Maximum | 3.01% - 4.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
GMIR	4.00%	4.00%