Long-Duration Insurance Contracts - Balances of and Changes in the LFPB (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2026	Sep. 30, 2026	Dec. 31, 2025	Jun. 30, 2026	Dec. 31, 2024
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	$ 1,463.3	$ 1,463.3	$ 1,611.5
Whole Life
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	221.4	239.5	229.1
Beginning balance at original discount rate	250.8	270.6	263.2
Change in cash flow assumptions			(2.0)	$ (2.0)	$ 6.3
Actual variances from expected experience			(1.7)	(0.3)	0.3
Adjusted balance			267.0	248.5	269.8
Issuances	2.2	7.5	10.7
Interest accruals	2.1	6.4	8.4
Net premiums collected	(6.4)	(34.6)	(18.3)
Ending balance at original discount rate	246.3	246.3	270.6
Effect of changes in discount rate assumptions	(41.3)	(41.3)	(31.1)
Ending balance	205.1	205.1	239.5
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	501.7	518.4	504.3
Beginning balance at original discount rate	613.7	613.7	631.9	616.5	617.4
Changes in cash flow assumptions			(2.4)	(2.4)	5.9
Actual variances from expected experience			(1.8)	(0.5)	1.0
Adjusted balance			627.6	613.5	624.3
Issuances	2.2	7.5	10.7
Interest accruals	5.4	16.2	21.0
Benefit payments	(7.4)	(37.6)	(24.1)
Ending balance at original discount rate	613.7	613.7	631.9
Effect of changes in discount rate assumptions	(155.1)	(155.1)	(113.5)
Ending balance	458.5	458.5	518.4
Net liability for future policy benefits	253.5	253.5	278.8
Less: Reinsurance recoverable	(52.5)	(52.5)	(57.3)
Net liability for future policy benefits, after reinsurance recoverable	201.0	201.0	221.5
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.0
Net liability for future policy benefits	201.0	201.0	221.5
Term Life
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	244.5	245.2	245.9
Beginning balance at original discount rate	261.3	259.7	271.2
Change in cash flow assumptions			16.7	16.7	(16.5)
Actual variances from expected experience			(3.3)	(1.8)	(3.4)
Adjusted balance			273.2	276.2	251.3
Issuances	5.7	16.0	23.6
Interest accruals	3.0	8.7	11.1
Net premiums collected	(6.7)	(19.6)	(26.3)
Ending balance at original discount rate	278.2	278.2	259.7
Effect of changes in discount rate assumptions	(36.4)	(36.4)	(14.5)
Ending balance	241.8	241.8	245.2
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	393.0	389.3	377.8
Beginning balance at original discount rate	458.5	458.5	429.8	437.4	433.2
Changes in cash flow assumptions			16.8	16.8	(20.7)
Actual variances from expected experience			(3.9)	(3.0)	(4.4)
Adjusted balance			442.7	451.1	408.1
Issuances	5.7	16.2	23.8
Interest accruals	4.6	13.4	17.0
Benefit payments	(3.0)	(13.7)	(19.1)
Ending balance at original discount rate	458.5	458.5	429.8
Effect of changes in discount rate assumptions	(81.4)	(81.4)	(40.4)
Ending balance	377.1	377.1	389.3
Net liability for future policy benefits	135.3	135.3	144.1
Less: Reinsurance recoverable	(20.6)	(20.6)	(20.9)
Net liability for future policy benefits, after reinsurance recoverable	114.7	114.7	123.2
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.0
Net liability for future policy benefits	114.7	114.7	123.2
Experience life
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	63.0	67.1	66.6
Beginning balance at original discount rate	61.6	64.5	65.4
Change in cash flow assumptions			(4.3)	(4.3)	0.7
Actual variances from expected experience			(2.2)	(0.9)	1.6
Adjusted balance			57.9	56.3	67.7
Issuances	0.0	0.0	0.0
Interest accruals	0.8	2.6	3.7
Net premiums collected	(1.5)	(4.9)	(6.9)
Ending balance at original discount rate	55.6	55.6	64.5
Effect of changes in discount rate assumptions	(2.2)	(2.2)	2.6
Ending balance	53.4	53.4	67.1
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	780.9	807.8	813.2
Beginning balance at original discount rate	737.1	737.1	763.3	750.9	782.8
Changes in cash flow assumptions			(7.1)	(7.1)	1.7
Actual variances from expected experience			(2.9)	(1.2)	3.4
Adjusted balance			753.3	742.6	787.9
Issuances	0.0	0.0	0.0
Interest accruals	10.9	33.3	45.7
Benefit payments	(16.4)	(49.4)	(70.3)
Ending balance at original discount rate	737.1	737.1	763.3
Effect of changes in discount rate assumptions	(20.5)	(20.5)	44.5
Ending balance	716.6	716.6	807.8
Net liability for future policy benefits	663.2	663.2	740.8
Less: Reinsurance recoverable	(0.7)	(0.7)	(0.8)
Net liability for future policy benefits, after reinsurance recoverable	662.4	662.4	740.0
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.0
Net liability for future policy benefits	662.4	662.4	740.0
Limited-Pay Whole Life
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	33.7	35.0	34.2
Beginning balance at original discount rate	35.6	36.5	36.8
Change in cash flow assumptions			(0.2)	(0.2)	0.4
Actual variances from expected experience			(0.6)	(0.2)	(0.2)
Adjusted balance			35.7	35.3	37.0
Issuances	0.3	1.4	2.5
Interest accruals	0.4	1.1	1.5
Net premiums collected	(1.1)	(3.3)	(4.5)
Ending balance at original discount rate	34.9	34.9	36.5
Effect of changes in discount rate assumptions	(3.3)	(3.3)	(1.5)
Ending balance	31.5	31.5	35.0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	89.8	89.6	86.2
Beginning balance at original discount rate	119.4	119.4	118.1	119.3	114.3
Changes in cash flow assumptions			(0.2)	(0.2)	0.2
Actual variances from expected experience			(0.7)	(0.3)	0.0
Adjusted balance			117.2	118.8	114.5
Issuances	0.3	1.4	2.5
Interest accruals	1.2	3.5	4.5
Benefit payments	(1.0)	(2.7)	(3.4)
Ending balance at original discount rate	119.4	119.4	118.1
Effect of changes in discount rate assumptions	(38.3)	(38.3)	(28.5)
Ending balance	81.1	81.1	89.6
Net liability for future policy benefits	49.6	49.6	54.6
Less: Reinsurance recoverable	(1.4)	(1.4)	(1.4)
Net liability for future policy benefits, after reinsurance recoverable	48.2	48.2	53.2
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.0
Net liability for future policy benefits	48.2	48.2	53.2
Supplemental health
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	189.0	187.5	179.9
Beginning balance at original discount rate	216.6	213.6	214.6
Change in cash flow assumptions			(9.1)	(9.1)	(2.8)
Actual variances from expected experience			6.7	3.7	(2.4)
Adjusted balance			211.1	211.0	209.4
Issuances	14.3	24.4	22.9
Interest accruals	2.0	5.5	7.0
Net premiums collected	(7.1)	(20.9)	(25.7)
Ending balance at original discount rate	220.1	220.1	213.6
Effect of changes in discount rate assumptions	(34.0)	(34.0)	(26.1)
Ending balance	186.1	186.1	187.5
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	377.6	379.0	383.4
Beginning balance at original discount rate	463.9	463.9	462.7	464.3	482.8
Changes in cash flow assumptions			(13.3)	(13.3)	(5.3)
Actual variances from expected experience			7.2	4.4	(4.7)
Adjusted balance			456.6	455.3	472.8
Issuances	14.3	24.4	22.9
Interest accruals	3.6	10.5	13.9
Benefit payments	(9.3)	(27.6)	(46.9)
Ending balance at original discount rate	463.9	463.9	462.7
Effect of changes in discount rate assumptions	(104.3)	(104.3)	(83.7)
Ending balance	359.6	359.6	379.0
Net liability for future policy benefits	173.5	173.5	191.8
Less: Reinsurance recoverable	(4.7)	(4.7)	(5.1)
Net liability for future policy benefits, after reinsurance recoverable	168.8	168.8	186.7
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.0
Net liability for future policy benefits	168.8	168.8	186.7
Cancer
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	59.8	59.8	66.0
Accident
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	15.5	15.5	17.9
Disability
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	18.7	18.7	21.3
Other
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	74.7	74.7	81.5
SPIA (life contingent)
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	0.0	0.0	0.0
Beginning balance at original discount rate	0.0	0.0	0.0
Change in cash flow assumptions			0.0	0.0	0.0
Actual variances from expected experience			0.0	0.0	0.0
Adjusted balance			0.0	0.0	0.0
Issuances	0.4	0.7	2.4
Interest accruals	0.0	0.0	0.0
Net premiums collected	(0.4)	(0.7)	(2.4)
Ending balance at original discount rate	0.0	0.0	0.0
Effect of changes in discount rate assumptions	0.0	0.0	0.0
Ending balance	0.0	0.0	0.0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	91.5	96.0	97.3
Beginning balance at original discount rate	98.5	98.5	103.0	99.7	107.3
Changes in cash flow assumptions			0.0	0.0	0.0
Actual variances from expected experience			(0.3)	(0.1)	0.1
Adjusted balance			102.7	$ 99.7	$ 107.4
Issuances	0.4	0.7	2.4
Interest accruals	1.0	2.9	4.1
Benefit payments	(2.7)	(7.8)	(10.9)
Ending balance at original discount rate	98.5	98.5	103.0
Effect of changes in discount rate assumptions	(12.8)	(12.8)	(7.0)
Ending balance	85.6	85.6	96.0
Net liability for future policy benefits	85.6	85.6	96.0
Less: Reinsurance recoverable	(3.8)	(3.8)	(3.8)
Net liability for future policy benefits, after reinsurance recoverable	81.9	81.9	92.2
Impact of flooring on net liability for future policy benefits	0.0	0.0	0.0
Net liability for future policy benefits	$ 81.9	$ 81.9	$ 92.2

Liability For Future Policy Benefit, Adjustment Due To Reserve Flooring

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- Definition

Liability For Future Policy Benefit, After Reinsurance, Before Impact Of Flooring

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No definition available.

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- Definition

Amount, before tax, of accumulated other comprehensive income (loss) (AOCI) from (increase) decrease in expected future policy benefit component of liability for future policy benefit from change in discount rate.

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Amount, before tax, of accumulated other comprehensive income (loss) (AOCI) from increase (decrease) in expected net premium component of liability for future policy benefit from change in discount rate.

+ References

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Amount, after effect of reinsurance, of liability for future policy benefit.

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Amount, before effect of reinsurance and after current period update of cash flow assumption, of expected future benefit and expense component for liability for future policy benefit, discounted at original rate.

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Amount, before effect of reinsurance and after current period update of cash flow assumption and discount rate change, of expected future policy benefit and expense component of liability for future policy benefit.

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Amount of cumulative increase (decrease) in expected future policy benefit and expense component for liability of future policy benefit from cash flow assumption change for future cash flows.

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Amount of cumulative increase (decrease) in expected future policy benefit and expense component for liability of future policy benefit from effect of variance from cash flow assumption change for actual experience.

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Amount of interest expense for expected future policy benefit and expense component of liability for future policy benefit.

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- Definition

Amount of increase in expected future policy benefit and expense component of liability for future policy benefit from contract issuance.

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- Definition

Amount, before effect of reinsurance and current period update of cash flow assumption, of expected future policy benefit and expense component of liability for future policy benefit, discounted at original rate.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount, before effect of reinsurance and after current period update of cash flow assumption and discount rate change, of expected net premium component of liability for future policy benefit.

+ References

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Amount of cumulative increase (decrease) in expected net premium component of liability for future policy benefit from cash flow assumption change for future cash flows.

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Amount of interest income for expected net premium component of liability for future policy benefit.

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Amount, before effect of reinsurance and current period update of cash flow assumption, of expected net premium component of liability for future policy benefit, discounted at original rate.

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Amount, before effect of reinsurance, of present value of future benefit to be paid to or on behalf of policyholder and related expense less present value of future net premium receivable under insurance contract.

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