Basis of Presentation and Significant Accounting Policies - Narrative (Details) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2025 USD ($) $ / shares	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($) plan segment $ / shares shares	Dec. 31, 2024 USD ($) investment	Dec. 31, 2023 USD ($)	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of reportable segments (in segments) | segment			4
Net income			$ 162.1	$ 102.8	$ 45.0
Net investment income			$ 464.3	$ 445.7	444.8
Number of limited partnership investments | investment				2
Amortization of acquisition costs for property and casualty contracts, first term			6 months
Amortization of acquisition costs for property and casualty contracts, second term			12 months
Amortization of acquisition costs for supplemental and group benefits			6 years
Purchase price	$ 128.1		$ 128.1
Amortization in 2026	14.2		14.2
Amortization in 2027	14.1		14.1
Amortization in 2028	14.1		14.1
Amortization in 2029	13.9		13.9
Amortization in 2030	14.0		$ 14.0
Purchase of FHLB activity-based common stock as percentage of borrowing, required			4.50%
Purchase of FHLB activity-based common stock as percentage of borrowing, percentage, authorized			15.00%			25.00%
Repayment of FHLB funding agreements			$ 509.5	$ 270.0	189.5
FHLB advances	$ 1,039.5		1,039.5	989.5
Share-based compensation expense			$ 8.7	7.8	7.5
Weighted average fair value of nonvested options outstanding (in usd per share) | $ / shares	$ 8.80		$ 8.80
Unrecognized share-based compensation expense, nonvested options	$ 2.3		$ 2.3
Plan cash contributions	3.0
Pre-tax settlement charge	7.1
Antidilutive securities exclude from EPS computation (in shares) | shares			420,553
Minimum exercise price (in usd per share) | $ / shares			$ 35.39
Maximum exercise price (in usd per share) | $ / shares			$ 42.95
Qualified Plan | 401(k) plan assets | Pension Plan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Employer matching contribution as percent of employees' gross pay			3.00%
Percentage of employer match			5.00%
Vesting period for Company contributions			5 years
Nonqualified Plan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of retirement plans | plan			2
Employee stock option
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Share-based compensation expense			$ 1.5	1.6	1.4
Restricted Stock Units (RSUs) [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Unrecognized share-based compensation expense, equity instruments other than options	$ 10.1		10.1
HMLIC and NTA
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds from FHLB funding agreements			559.5
Repayment of FHLB funding agreements			$ 509.5
Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Purchase of FHLB activity-based common stock as percentage of borrowing, required			2.00%
Real estate property | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Property, plant and equipment, useful life	20 years		20 years
Real estate property | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Property, plant and equipment, useful life	45 years		45 years
Lease hold improvements and other property and equipment | Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Property, plant and equipment, useful life	3 years		3 years
Lease hold improvements and other property and equipment | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Property, plant and equipment, useful life	10 years		10 years
Value of business acquired
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Purchase price	$ 54.5		$ 54.5
Amortization in 2026	4.7		4.7
Amortization in 2027	4.4		4.4
Amortization in 2028	4.1		4.1
Amortization in 2029	3.9		3.9
Amortization in 2030	3.6		3.6
Value of distribution acquired | NTA
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Purchase price	30.3		30.3
Amortization in 2026	2.9		2.9
Amortization in 2027	2.9		2.9
Amortization in 2028	2.9		2.9
Amortization in 2029	2.9		2.9
Amortization in 2030	2.9		2.9
Value of agency relationships | NTA
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Amortization in 2026	1.0		1.0
Amortization in 2027	0.9		0.9
Amortization in 2028	0.8		0.8
Amortization in 2029	0.6		0.6
Amortization in 2030	0.5		0.5
Value of agency relationship	4.6		4.6
Value of customer relationships | Benefit Consultants Group Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Purchase price	38.3		38.3
Amortization in 2026	5.5		5.5
Amortization in 2027	5.9		5.9
Amortization in 2028	6.3		6.3
Amortization in 2029	6.5		6.5
Amortization in 2030	6.9		6.9
Voya Commercial Mortgage Loan Fund
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Equity method investments, fair value disclosure	$ 234.2		234.2	241.6
Life & Retirement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Net income			56.8	56.3	71.5
Supplemental & Group Benefits
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Net income			$ 45.0	60.4	54.9
Revision of Prior Period, Error Correction, Adjustment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Net income		$ (8.1)		$ (4.4)	$ (1.3)
Net investment income		(10.2)
Revision of Prior Period, Error Correction, Adjustment | Life & Retirement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Net income		(5.3)
Revision of Prior Period, Error Correction, Adjustment | Supplemental & Group Benefits
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Net income		$ (2.8)