v3.26.3
Fair Value Measurements - Quantitative Information for Level 3 Measurements (Details) - Recurring Fair Value Measurements
$ in Millions
Sep. 30, 2026
USD ($)
Dec. 31, 2025
USD ($)
Unobservable inputs    
Assets measured at fair value $ 274,689.0 $ 276,234.1
Liabilities measured at fair value 366.6 602.9
Fair value hierarchy Level 3    
Unobservable inputs    
Assets measured at fair value 5,648.1 5,893.1
Liabilities measured at fair value 1,026.2 1,149.5
Fair value hierarchy Level 3 | Investment and universal life contracts    
Unobservable inputs    
Liabilities measured at fair value $ (2,432.6) $ (1,410.2)
Embedded derivative, Valuation technique Discounted cash flow Discounted cash flow
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long duration interest rate | Minimum    
Unobservable inputs    
Embedded derivative, Input 0.043 0.035
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long duration interest rate | Maximum    
Unobservable inputs    
Embedded derivative, Input 0.057 0.048
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long duration interest rate | Weighted average input    
Unobservable inputs    
Embedded derivative, Input 0.056 0.048
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long-term equity market volatility | Minimum    
Unobservable inputs    
Embedded derivative, Input 0.16 0.161
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long-term equity market volatility | Maximum    
Unobservable inputs    
Embedded derivative, Input 0.302 0.334
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Long-term equity market volatility | Weighted average input    
Unobservable inputs    
Embedded derivative, Input 0.199 0.218
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Non-performance risk | Minimum    
Unobservable inputs    
Embedded derivative, Input 0.005 0.005
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Non-performance risk | Maximum    
Unobservable inputs    
Embedded derivative, Input 0.011 0.011
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Non-performance risk | Weighted average input    
Unobservable inputs    
Embedded derivative, Input 0.01 0.009
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Lapse rate | Minimum    
Unobservable inputs    
Embedded derivative, Input 0 0
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Lapse rate | Maximum    
Unobservable inputs    
Embedded derivative, Input 0.77 0.55
Fair value hierarchy Level 3 | Investment and universal life contracts | Discounted cash flow | Lapse rate | Weighted average input    
Unobservable inputs    
Embedded derivative, Input 0.087 0.08
Fair value hierarchy Level 3 | Fixed maturities | Trading    
Unobservable inputs    
Assets measured at fair value $ 207.1 $ 257.6
Fixed maturities, trading, Valuation technique Discounted cash flow Discounted cash flow
Fair value hierarchy Level 3 | Fixed maturities | Trading | Discounted cash flow | Discount rate | Minimum    
Unobservable inputs    
Fixed maturities, trading, Input 0.09 0.085
Fair value hierarchy Level 3 | Fixed maturities | Trading | Discounted cash flow | Discount rate | Maximum    
Unobservable inputs    
Fixed maturities, trading, Input 0.107 0.13
Fair value hierarchy Level 3 | Fixed maturities | Trading | Discounted cash flow | Discount rate | Weighted average input    
Unobservable inputs    
Fixed maturities, trading, Input 0.09 0.09
Fair value hierarchy Level 3 | Fixed maturities | Trading | Discounted cash flow | Earnings before interest, taxes, depreciation and amortization multiple    
Unobservable inputs    
Fixed maturities, trading, Input   0.9
Fair value hierarchy Level 3 | Fixed maturities | Trading | Discounted cash flow | Earnings before interest, taxes, depreciation and amortization multiple | Minimum    
Unobservable inputs    
Fixed maturities, trading, Input 0.8  
Fair value hierarchy Level 3 | Fixed maturities | Trading | Discounted cash flow | Earnings before interest, taxes, depreciation and amortization multiple | Maximum    
Unobservable inputs    
Fixed maturities, trading, Input 0.9  
Fair value hierarchy Level 3 | Fixed maturities | Trading | Discounted cash flow | Earnings before interest, taxes, depreciation and amortization multiple | Weighted average input    
Unobservable inputs    
Fixed maturities, trading, Input 0.9 0.9
Fair value hierarchy Level 3 | Fixed maturities | Trading | Discounted cash flow | Comparability adjustment | Minimum    
Unobservable inputs    
Fixed maturities, trading, Input (0.0120) (0.0088)
Fair value hierarchy Level 3 | Fixed maturities | Trading | Discounted cash flow | Comparability adjustment | Maximum    
Unobservable inputs    
Fixed maturities, trading, Input 0.0532 0.2047
Fair value hierarchy Level 3 | Fixed maturities | Trading | Discounted cash flow | Comparability adjustment | Weighted average input    
Unobservable inputs    
Fixed maturities, trading, Input 0.0066 0.0114
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale    
Unobservable inputs    
Assets measured at fair value $ 1,955.6 $ 2,017.3
Fixed maturities, available-for-sale, Valuation technique Discounted cash flow Discounted cash flow
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Discount rate | Minimum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.043 0.027
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Discount rate | Maximum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.147 0.131
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Discount rate | Weighted average input    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.08 0.08
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Earnings before interest, taxes, depreciation and amortization multiple    
Unobservable inputs    
Fixed maturities, available-for-sale, Input   0.9
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Earnings before interest, taxes, depreciation and amortization multiple | Minimum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.8  
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Earnings before interest, taxes, depreciation and amortization multiple | Maximum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 1.7  
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Earnings before interest, taxes, depreciation and amortization multiple | Weighted average input    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 1 0.9
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Illiquidity premium | Minimum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.0030 0.0030
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Illiquidity premium | Maximum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.0771 0.0771
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Illiquidity premium | Weighted average input    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.0149 0.0146
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Comparability adjustment | Minimum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input (0.0120) (0.0120)
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Comparability adjustment | Maximum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.0571 0.3462
Fair value hierarchy Level 3 | Corporate debt securities | Available-for-sale | Discounted cash flow | Comparability adjustment | Weighted average input    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.0062 0.0122
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale    
Unobservable inputs    
Assets measured at fair value $ 1,475.5 $ 1,745.4
Fixed maturities, available-for-sale, Valuation technique Discounted cash flow Discounted cash flow
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Discount rate | Minimum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.048 0.034
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Discount rate | Maximum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.093 0.086
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Discount rate | Weighted average input    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.057 0.042
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Illiquidity premium | Minimum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input (0.0083) (0.0083)
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Illiquidity premium | Maximum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.0415 0.0415
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Illiquidity premium | Weighted average input    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.0163 0.0179
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Comparability adjustment | Minimum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input (0.0058) (0.0010)
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Comparability adjustment | Maximum    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.0323 0.0285
Fair value hierarchy Level 3 | Other debt obligations | Available-for-sale | Discounted cash flow | Comparability adjustment | Weighted average input    
Unobservable inputs    
Fixed maturities, available-for-sale, Input 0.0071 0.0066
Fair value hierarchy Level 3 | Other investments    
Unobservable inputs    
Assets measured at fair value $ 62.0 $ 167.1
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Discount rate | Minimum    
Unobservable inputs    
Other investments, Input 0.115 0.12
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Discount rate | Maximum    
Unobservable inputs    
Other investments, Input 0.135 0.135
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Discount rate | Weighted average input    
Unobservable inputs    
Other investments, Input 0.124 0.122
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Probability of default | Minimum    
Unobservable inputs    
Other investments, Input 0.06 0.06
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Probability of default | Maximum    
Unobservable inputs    
Other investments, Input 0.10 0.10
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Probability of default | Weighted average input    
Unobservable inputs    
Other investments, Input 0.084 0.08
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Potential loss severity | Minimum    
Unobservable inputs    
Other investments, Input 0.87 0.87
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Potential loss severity | Maximum    
Unobservable inputs    
Other investments, Input 1 1
Fair value hierarchy Level 3 | Other investments | Discounted cash flow | Potential loss severity | Weighted average input    
Unobservable inputs    
Other investments, Input 0.918 0.929
Fair value hierarchy Level 3 | Separate account assets    
Unobservable inputs    
Assets measured at fair value $ 765.6 $ 742.5
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Discount rate | Minimum    
Unobservable inputs    
Separate account assets, Input 0.068 0.068
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Discount rate | Maximum    
Unobservable inputs    
Separate account assets, Input 0.10 0.093
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Discount rate | Weighted average input    
Unobservable inputs    
Separate account assets, Input 0.074 0.073
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Terminal capitalization rate | Minimum    
Unobservable inputs    
Separate account assets, Input 0.055 0.055
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Terminal capitalization rate | Maximum    
Unobservable inputs    
Separate account assets, Input 0.08 0.08
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Terminal capitalization rate | Weighted average input    
Unobservable inputs    
Separate account assets, Input 0.06 0.06
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Average market rent growth rate | Minimum    
Unobservable inputs    
Separate account assets, Input 0.02 0.02
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Average market rent growth rate | Maximum    
Unobservable inputs    
Separate account assets, Input 0.033 0.033
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate | Average market rent growth rate | Weighted average input    
Unobservable inputs    
Separate account assets, Input 0.027 0.027
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Loan to value | Minimum    
Unobservable inputs    
Separate account assets, Input 0.463 0.472
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Loan to value | Maximum    
Unobservable inputs    
Separate account assets, Input 0.655 0.693
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Loan to value | Weighted average input    
Unobservable inputs    
Separate account assets, Input 0.52 0.527
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Market interest rate | Minimum    
Unobservable inputs    
Separate account assets, Input 0.053 0.053
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Market interest rate | Maximum    
Unobservable inputs    
Separate account assets, Input 0.071 0.064
Fair value hierarchy Level 3 | Separate account assets | Discounted cash flow, real estate debt | Market interest rate | Weighted average input    
Unobservable inputs    
Separate account assets, Input 0.059 0.058