Long-Duration Insurance Contracts - Balances of and Changes in the LFPB (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2026	Dec. 31, 2025	Dec. 31, 2024
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	$ 1,579.3	$ 1,611.5
Whole Life
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	239.5	229.1
Beginning balance at original discount rate	270.6	263.2
Change in cash flow assumptions		0.0	$ 6.3
Actual variances from expected experience		(0.9)	0.3
Adjusted balance		269.7	269.8
Issuances	2.5	10.7
Interest accruals	2.2	8.4
Net premiums collected	(22.0)	(18.3)
Ending balance at original discount rate	252.4	270.6
Effect of changes in discount rate assumptions	(30.2)	(31.1)
Ending balance	222.2	239.5
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	518.4	504.3
Beginning balance at original discount rate	615.8	631.9	617.4
Changes in cash flow assumptions		0.0	5.9
Actual variances from expected experience		(0.8)	1.0
Adjusted balance		631.1	624.3
Issuances	2.5	10.7
Interest accruals	5.4	21.0
Benefit payments	(23.2)	(24.1)
Ending balance at original discount rate	615.8	631.9
Effect of changes in discount rate assumptions	(119.0)	(113.5)
Ending balance	496.8	518.4
Net liability for future policy benefits	274.4	278.8
Less: Reinsurance recoverable	(56.4)	(57.3)
Net liability for future policy benefits, after reinsurance recoverable	218.0	221.5
Impact of flooring on net liability for future policy benefits	0.0	0.0
Net liability for future policy benefits	218.0	221.5
Term Life
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	245.2	245.9
Beginning balance at original discount rate	259.7	271.2
Change in cash flow assumptions		0.0	(16.5)
Actual variances from expected experience		(1.3)	(3.4)
Adjusted balance		258.4	251.3
Issuances	4.8	23.6
Interest accruals	2.8	11.1
Net premiums collected	(6.1)	(26.3)
Ending balance at original discount rate	259.9	259.7
Effect of changes in discount rate assumptions	(17.1)	(14.5)
Ending balance	242.8	245.2
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	389.3	377.8
Beginning balance at original discount rate	432.5	429.8	433.2
Changes in cash flow assumptions		0.0	(20.7)
Actual variances from expected experience		(0.9)	(4.4)
Adjusted balance		428.9	408.1
Issuances	4.8	23.8
Interest accruals	4.3	17.0
Benefit payments	(5.5)	(19.1)
Ending balance at original discount rate	432.5	429.8
Effect of changes in discount rate assumptions	(46.5)	(40.4)
Ending balance	386.0	389.3
Net liability for future policy benefits	143.2	144.1
Less: Reinsurance recoverable	(20.9)	(20.9)
Net liability for future policy benefits, after reinsurance recoverable	122.3	123.2
Impact of flooring on net liability for future policy benefits	0.0	0.0
Net liability for future policy benefits	122.3	123.2
Experience life
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	67.1	66.6
Beginning balance at original discount rate	64.5	65.4
Change in cash flow assumptions		0.0	0.7
Actual variances from expected experience		(0.5)	1.6
Adjusted balance		64.0	67.7
Issuances	0.0	0.0
Interest accruals	0.9	3.7
Net premiums collected	(1.7)	(6.9)
Ending balance at original discount rate	63.2	64.5
Effect of changes in discount rate assumptions	1.4	2.6
Ending balance	64.6	67.1
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	807.8	813.2
Beginning balance at original discount rate	757.1	763.3	782.8
Changes in cash flow assumptions		0.0	1.7
Actual variances from expected experience		(0.6)	3.4
Adjusted balance		762.7	787.9
Issuances	0.0	0.0
Interest accruals	11.3	45.7
Benefit payments	(16.9)	(70.3)
Ending balance at original discount rate	757.1	763.3
Effect of changes in discount rate assumptions	28.9	44.5
Ending balance	786.0	807.8
Net liability for future policy benefits	721.3	740.8
Less: Reinsurance recoverable	(0.8)	(0.8)
Net liability for future policy benefits, after reinsurance recoverable	720.5	740.0
Impact of flooring on net liability for future policy benefits	0.0	0.0
Net liability for future policy benefits	720.5	740.0
Limited-Pay Whole Life
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	35.0	34.2
Beginning balance at original discount rate	36.5	36.8
Change in cash flow assumptions		0.0	0.4
Actual variances from expected experience		(0.4)	(0.2)
Adjusted balance		36.1	37.0
Issuances	0.5	2.5
Interest accruals	0.4	1.5
Net premiums collected	(1.1)	(4.5)
Ending balance at original discount rate	35.9	36.5
Effect of changes in discount rate assumptions	(1.9)	(1.5)
Ending balance	34.0	35.0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	89.6	86.2
Beginning balance at original discount rate	118.5	118.1	114.3
Changes in cash flow assumptions		0.0	0.2
Actual variances from expected experience		(0.5)	0.0
Adjusted balance		117.6	114.5
Issuances	0.5	2.5
Interest accruals	1.2	4.5
Benefit payments	(0.8)	(3.4)
Ending balance at original discount rate	118.5	118.1
Effect of changes in discount rate assumptions	(30.4)	(28.5)
Ending balance	88.1	89.6
Net liability for future policy benefits	54.1	54.6
Less: Reinsurance recoverable	(1.4)	(1.4)
Net liability for future policy benefits, after reinsurance recoverable	52.7	53.2
Impact of flooring on net liability for future policy benefits	0.0	0.0
Net liability for future policy benefits	52.7	53.2
Supplemental health
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	187.5	179.9
Beginning balance at original discount rate	213.6	214.6
Change in cash flow assumptions		0.0	(2.8)
Actual variances from expected experience		1.7	(2.4)
Adjusted balance		215.3	209.4
Issuances	5.4	22.9
Interest accruals	1.8	7.0
Net premiums collected	(6.8)	(25.7)
Ending balance at original discount rate	215.7	213.6
Effect of changes in discount rate assumptions	(28.5)	(26.1)
Ending balance	187.2	187.5
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	379.0	383.4
Beginning balance at original discount rate	463.9	462.7	482.8
Changes in cash flow assumptions		0.0	(5.3)
Actual variances from expected experience		1.5	(4.7)
Adjusted balance		464.2	472.8
Issuances	5.4	22.9
Interest accruals	3.4	13.9
Benefit payments	(9.1)	(46.9)
Ending balance at original discount rate	463.9	462.7
Effect of changes in discount rate assumptions	(88.9)	(83.7)
Ending balance	375.0	379.0
Net liability for future policy benefits	188.0	191.8
Less: Reinsurance recoverable	(4.8)	(5.1)
Net liability for future policy benefits, after reinsurance recoverable	183.2	186.7
Impact of flooring on net liability for future policy benefits	0.0	0.0
Net liability for future policy benefits	183.2	186.7
Cancer
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	64.4	66.0
Accident
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	17.3	17.9
Disability
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	21.2	21.3
Other
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Net liability for future policy benefits	80.3	81.5
SPIA (life contingent)
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	0.0	0.0
Beginning balance at original discount rate	0.0	0.0
Change in cash flow assumptions		0.0	0.0
Actual variances from expected experience		0.0	0.0
Adjusted balance		0.0	0.0
Issuances	0.2	2.4
Interest accruals	0.0	0.0
Net premiums collected	(0.2)	(2.4)
Ending balance at original discount rate	0.0	0.0
Effect of changes in discount rate assumptions	0.0	0.0
Ending balance	0.0	0.0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	96.0	97.3
Beginning balance at original discount rate	101.7	103.0	107.3
Changes in cash flow assumptions		0.0	0.0
Actual variances from expected experience		(0.2)	0.1
Adjusted balance		102.8	$ 107.4
Issuances	0.2	2.4
Interest accruals	1.0	4.1
Benefit payments	(2.3)	(10.9)
Ending balance at original discount rate	101.7	103.0
Effect of changes in discount rate assumptions	(8.3)	(7.0)
Ending balance	93.4	96.0
Net liability for future policy benefits	93.2	96.0
Less: Reinsurance recoverable	(3.9)	(3.8)
Net liability for future policy benefits, after reinsurance recoverable	89.3	92.2
Impact of flooring on net liability for future policy benefits	0.0	0.0
Net liability for future policy benefits	$ 89.3	$ 92.2