Long-Duration Insurance Contracts - Deferred Policy Acquisition Costs, Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of period	$ 347.2
Amortization expense	(124.5)	$ (111.1)	$ (101.2)
Balance, end of period	358.2	347.2
Whole Life
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of period	23.8	22.3	20.9
Capitalizations	2.5	3.0	2.7
Amortization expense	(1.1)	(1.3)	(1.2)
Experience adjustment	(0.3)	(0.2)	(0.1)
Balance, end of period	24.9	23.8	22.3
Term Life
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of period	34.2	32.6	30.0
Capitalizations	4.5	5.1	5.8
Amortization expense	(3.1)	(3.5)	(3.1)
Experience adjustment	(0.1)	0.0	(0.1)
Balance, end of period	35.5	34.2	32.6
Experience Life
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of period	5.5	5.7	5.8
Capitalizations	0.2	0.2	0.3
Amortization expense	(0.4)	(0.4)	(0.4)
Experience adjustment	(0.1)	0.0	0.0
Balance, end of period	5.2	5.5	5.7
Limited-Pay Whole Life
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of period	8.0	7.4	6.7
Capitalizations	0.7	1.1	1.1
Amortization expense	(0.3)	(0.4)	(0.3)
Experience adjustment	(0.1)	(0.1)	(0.1)
Balance, end of period	8.3	8.0	7.4
Indexed Universal Life
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of period	19.2	16.8	15.4
Capitalizations	4.7	3.6	2.5
Amortization expense	(1.0)	(1.1)	(1.0)
Experience adjustment	(0.1)	(0.1)	(0.1)
Balance, end of period	22.8	19.2	16.8
Supplemental Health
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of period	10.6	8.2	6.2
Capitalizations	4.7	3.4	2.9
Amortization expense	(1.2)	(0.8)	(0.6)
Experience adjustment	(0.4)	(0.2)	(0.3)
Balance, end of period	13.7	10.6	8.2
Total Annuities
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of period	211.4	214.0	221.1
Capitalizations	14.4	15.8	15.0
Amortization expense	(16.0)	(16.2)	(14.7)
Experience adjustment	(2.1)	(2.2)	(7.4)
Balance, end of period	$ 207.7	$ 211.4	$ 214.0