v3.26.3
Fair Value Measurements - Fair Value Measurements - Changes in Unrealized Gains (losses) Included in Net Income (Details) - Recurring Fair Value Measurements - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Changes in Level 3 fair value measurements rollforward, assets and liabilities        
Changes in unrealized gains (losses) included in net income relating to positions still held, net derivative assets (liabilities) $ (33.5) $ 20.1 $ (17.6) $ (10.6)
Investment and universal life contracts        
Changes in Level 3 fair value measurements rollforward, assets and liabilities        
Changes in unrealized gains (losses) included in net income relating to positions still held, liabilities (157.0) (214.3) (674.9) (219.7)
Funds withheld payable embedded derivative        
Changes in Level 3 fair value measurements rollforward, assets and liabilities        
Changes in unrealized gains (losses) included in net income relating to positions still held, liabilities 818.2 (266.0) 891.2 (455.3)
Fixed maturities | Available-for-sale        
Changes in Level 3 fair value measurements rollforward, assets and liabilities        
Changes in unrealized gains (losses) included in net income relating to positions still held, assets (16.8) (14.6) (32.8) 6.3
Corporate debt securities | Available-for-sale        
Changes in Level 3 fair value measurements rollforward, assets and liabilities        
Changes in unrealized gains (losses) included in net income relating to positions still held, assets (15.1) (14.6) (30.8) 6.3
Commercial mortgage-backed securities | Available-for-sale        
Changes in Level 3 fair value measurements rollforward, assets and liabilities        
Changes in unrealized gains (losses) included in net income relating to positions still held, assets (1.7)   (1.7)  
Other debt obligations | Available-for-sale        
Changes in Level 3 fair value measurements rollforward, assets and liabilities        
Changes in unrealized gains (losses) included in net income relating to positions still held, assets     (0.3)  
Fixed maturities, trading        
Changes in Level 3 fair value measurements rollforward, assets and liabilities        
Changes in unrealized gains (losses) included in net income relating to positions still held, assets (6.5) (14.8) (16.2) (14.9)
Other investments        
Changes in Level 3 fair value measurements rollforward, assets and liabilities        
Changes in unrealized gains (losses) included in net income relating to positions still held, assets 0.3 0.4 0.6 4.7
Separate account assets        
Changes in Level 3 fair value measurements rollforward, assets and liabilities        
Changes in unrealized gains (losses) included in net income relating to positions still held, assets $ 2.5 $ 32.4 $ 19.7 $ 24.6