Contractholder Funds - Guaranteed Minimum Interest Rate (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Excess of crediting rates over GMIR
Total policyholder account value	$ 26,184.4	$ 26,349.6
Retirement and Income Solutions
Excess of crediting rates over GMIR
Total policyholder account value	19,628.4	19,764.4
Workplace savings and retirement solutions | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	10,425.7	10,058.7
Policyholder account value without GMIR	2,050.9	2,096.0
Total policyholder account value	12,476.6	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	1,937.6	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	8,452.9	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	9.0	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	7.7	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	18.5	18.8
Workplace savings and retirement solutions | At GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	34.1	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	0.2	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	7.7	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	7.7	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	18.5	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	528.9	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	4.0	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	524.8	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	6,125.1	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	128.5	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	5,995.9	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	0.7
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	2,772.9	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	1,119.4	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	1,653.0	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	0.5	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	964.7	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	685.5	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	$ 279.2	$ 9.4
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	$ 351.8	$ 368.4
Policyholder account value without GMIR	14.3	13.0
Total policyholder account value	366.1	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	28.9	33.0
Individual variable annuities | 1.01% - 2.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	3.6	3.6
Individual variable annuities | 2.01% - 3.00% | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	319.3	331.8
Individual variable annuities | At GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	351.8	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	28.9	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	3.6	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	$ 319.3	$ 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	$ 6,491.0	$ 6,915.5
Policyholder account value without GMIR	294.7	312.8
Total policyholder account value	6,785.7	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	2,541.1	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	397.1	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	3,386.6	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	166.2	169.7
Individual fixed deferred annuities | At GMIR | Retirement and Income Solutions
Excess of crediting rates over GMIR
Policyholder account value with GMIR	4,076.3	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	402.1	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	121.4	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	3,386.6	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	166.2	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	157.8	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	156.5	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	1.3	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	249.4	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	210.2	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	39.2	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	981.9	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	747.5	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	234.4	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	1,025.6	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	1,024.8	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	$ 0.8	$ 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	$ 6,162.6	$ 6,214.1
Policyholder account value without GMIR	752.8	733.8
Total policyholder account value	6,915.4	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	19.1	19.2
Universal life | 1.01% - 2.00% | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	1,565.4	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	2,735.2	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	1,787.4	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	55.5	55.7
Universal life | At GMIR | Benefits and Protection | Life Insurance
Excess of crediting rates over GMIR
Policyholder account value with GMIR	2,894.1	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	312.4	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	846.9	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	1,695.1	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	39.7	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	924.7	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	1.7	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	881.9	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	30.2	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	10.9	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	1,406.7	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	16.2	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	412.4	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	945.0	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	29.7	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	799.5	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	707.8	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	61.0	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	29.2	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	137.6	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	1.2	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	132.8	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	0.4	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	0.04%	4.00%