v3.26.1
Investments - Narrative (Details) - USD ($)
 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]      
Mortgage- and Asset-backed Securities Not Due at a Single Maturity Date $ 1,633,500,000    
Financing Receivable, Accrued Interest, before Allowance for Credit Loss 73,500,000   $ 75,300,000
Equity securities, FV-NI, unrealized gain (loss) $ (2,700,000) $ (100,000)  
Percentage of Equity Method Limited Liability Investments reported with a lag 4.10%    
Percentage of Equity Method Limited Liability Investments reported with a One Month Lag 0.80%    
Equity Securities at Modified Cost $ 18,600,000   21,700,000
Equity securities without readily determinable fair value, impairment loss, cumulative amount 1,300,000   3,200,000
Equity Securities      
Debt Securities, Available-for-sale [Line Items]      
Other Asset Impairment Charges 0    
Investments in Fixed Maturities      
Debt Securities, Available-for-sale [Line Items]      
Other Receivables 3,000,000.0   1,600,000
Other liabilities 4,200,000   42,700,000
Debt securities, available-for-sale, unrealized loss position, accumulated loss 763,800,000   733,100,000
Government National Mortgage Association Certificates and Obligations (GNMA)      
Debt Securities, Available-for-sale [Line Items]      
Mortgage- and Asset-backed Securities Not Due at a Single Maturity Date 453,300,000    
Federal National Mortgage Association Certificates and Obligations (FNMA)      
Debt Securities, Available-for-sale [Line Items]      
Mortgage- and Asset-backed Securities Not Due at a Single Maturity Date 41,700,000    
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC)      
Debt Securities, Available-for-sale [Line Items]      
Mortgage- and Asset-backed Securities Not Due at a Single Maturity Date 21,100,000    
Other Non-Governmental Issuers      
Debt Securities, Available-for-sale [Line Items]      
Mortgage- and Asset-backed Securities Not Due at a Single Maturity Date 1,117,400,000    
Equity Securities      
Debt Securities, Available-for-sale [Line Items]      
Other Receivables 0   200,000
Other liabilities 0   0
Equity Method Investments      
Debt Securities, Available-for-sale [Line Items]      
Other Receivables 900,000   0
Other liabilities 0   0
Consolidated Entity, Excluding VIE      
Debt Securities, Available-for-sale [Line Items]      
Other Receivables 181,800,000   184,700,000
Equity Securities, FV-NI, Current 309,600,000   306,400,000
Equity Method Limited Liability Investments 183,000,000.0   176,000,000.0
Loans to Policyholders 279,400,000   279,900,000
Variable Interest Entity, Not Primary Beneficiary | Equity Method Limited Liability Investments      
Debt Securities, Available-for-sale [Line Items]      
Outstanding commitments to fund equity method limited liability investments 107,300,000    
Investment grade | Investments in Fixed Maturities      
Debt Securities, Available-for-sale [Line Items]      
Debt securities, available-for-sale, unrealized loss position, accumulated loss 752,200,000   719,600,000
Non-investment-grade | Investments in Fixed Maturities      
Debt Securities, Available-for-sale [Line Items]      
Debt securities, available-for-sale, unrealized loss position, accumulated loss $ 11,600,000   $ 13,600,000
Percentage of unrealized loss position to amortized cost basis of available for sale security average 2.40%   3.30%