Investments - Net Investment Income (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Net Investment Income [Line Items]
Total net investment income	$ 464.3	$ 445.7	$ 444.8
Investment portfolio
Net Investment Income [Line Items]
Investment expenses	(12.1)	(13.3)	(12.1)
Total net investment income	366.2	344.3	339.9
Investment portfolio \| Voya Commercial Mortgage Loan Fund
Net Investment Income [Line Items]
Total net investment income	13.3	19.2
Deposit asset on reinsurance
Net Investment Income [Line Items]
Total net investment income	98.1	101.4	104.9
Fixed maturity securities \| Investment portfolio
Net Investment Income [Line Items]
Investment income	275.6	287.0	269.2
Equity securities \| Investment portfolio
Net Investment Income [Line Items]
Investment income	3.6	5.2	6.5
Limited partnership interests \| Investment portfolio
Net Investment Income [Line Items]
Investment income	76.5	44.8	59.1
Short-term and other investments \| Investment portfolio
Net Investment Income [Line Items]
Investment income	$ 22.6	$ 20.6	$ 17.2

Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

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Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

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