v3.25.2
Long-Duration Insurance Contracts - Account Balances by Guaranteed Minimum Interest Rates (Details)
$ in Millions
Jun. 30, 2025
USD ($)
Dec. 31, 2024
USD ($)
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 5,076.4 $ 5,100.3
Less than 2%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 769.6 $ 797.6
Less than 2% | Maximum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, guaranteed minimum credit rating 2.00% 2.00%
Equal to 2% but less than 3%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 504.8 $ 449.4
Equal to 2% but less than 3% | Minimum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, guaranteed minimum credit rating 2.00% 2.00%
Equal to 2% but less than 3% | Maximum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, guaranteed minimum credit rating 3.00% 3.00%
Equal to 3% but less than 4%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 638.5 $ 653.4
Equal to 3% but less than 4% | Minimum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, guaranteed minimum credit rating 3.00% 3.00%
Equal to 3% but less than 4% | Maximum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, guaranteed minimum credit rating 4.00% 4.00%
Equal to 4% but less than 5%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 2,575.8 $ 2,600.0
Equal to 4% but less than 5% | Minimum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, guaranteed minimum credit rating 4.00% 4.00%
Equal to 4% but less than 5% | Maximum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, guaranteed minimum credit rating 5.00% 5.00%
5% or higher    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 80.4 $ 81.8
5% or higher | Minimum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, guaranteed minimum credit rating 5.00% 5.00%
Policyholder account balance with a guaranteed minimum crediting rate    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 4,569.1 $ 4,582.2
At Guaranteed Minimum | Less than 2%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 9.4 15.9
At Guaranteed Minimum | Equal to 2% but less than 3%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 81.2 94.5
At Guaranteed Minimum | Equal to 3% but less than 4%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 562.4 545.6
At Guaranteed Minimum | Equal to 4% but less than 5%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 2,575.8 2,600.0
At Guaranteed Minimum | 5% or higher    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 80.4 81.8
At Guaranteed Minimum | Policyholder account balance with a guaranteed minimum crediting rate    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 3,309.2 $ 3,337.8
1-50 Basis Points Above | Minimum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, above guaranteed minimum crediting rate 0.0001 0.0001
1-50 Basis Points Above | Maximum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, above guaranteed minimum crediting rate 0.0050 0.0050
1-50 Basis Points Above | Less than 2%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 12.8 $ 77.3
1-50 Basis Points Above | Equal to 2% but less than 3%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 149.9 122.2
1-50 Basis Points Above | Equal to 3% but less than 4%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 9.7 43.3
1-50 Basis Points Above | Equal to 4% but less than 5%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 0.0 0.0
1-50 Basis Points Above | 5% or higher    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 0.0 0.0
1-50 Basis Points Above | Policyholder account balance with a guaranteed minimum crediting rate    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 172.4 $ 242.8
51-150 Basis Points Above | Minimum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, above guaranteed minimum crediting rate 0.0051 0.0051
51-150 Basis Points Above | Maximum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, above guaranteed minimum crediting rate 0.0150 0.0150
51-150 Basis Points Above | Less than 2%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 367.2 $ 400.4
51-150 Basis Points Above | Equal to 2% but less than 3%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 109.4 97.9
51-150 Basis Points Above | Equal to 3% but less than 4%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 14.0 13.3
51-150 Basis Points Above | Equal to 4% but less than 5%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 0.0 0.0
51-150 Basis Points Above | 5% or higher    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 0.0 0.0
51-150 Basis Points Above | Policyholder account balance with a guaranteed minimum crediting rate    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 490.6 $ 511.6
Greater Than 150 Basis Points Above | Minimum    
Policyholder Account Balance [Line Items]    
Policyholder account balance, above guaranteed minimum crediting rate 0.0150 0.0150
Greater Than 150 Basis Points Above | Less than 2%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 380.2 $ 304.0
Greater Than 150 Basis Points Above | Equal to 2% but less than 3%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 164.3 134.8
Greater Than 150 Basis Points Above | Equal to 3% but less than 4%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 52.4 51.2
Greater Than 150 Basis Points Above | Equal to 4% but less than 5%    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 0.0 0.0
Greater Than 150 Basis Points Above | 5% or higher    
Policyholder Account Balance [Line Items]    
Policyholders' account balances 0.0 0.0
Greater Than 150 Basis Points Above | Policyholder account balance with a guaranteed minimum crediting rate    
Policyholder Account Balance [Line Items]    
Policyholders' account balances $ 596.9 $ 490.0