Investments - Securities Posted as Collateral (Details) - USD ($) $ in Millions |
Jun. 30, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Securities Posted as Collateral | ||
| Mortgage loans | $ 20,663.6 | $ 20,484.2 |
| Pledged as collateral | ||
| Securities Posted as Collateral | ||
| Fixed maturities available-for-sale and trading securities posted as collateral for a reinsurance arrangement, derivative credit support annex (collateral) agreements, Futures Commission Merchant agreements, a lending arrangement and an obligation under funding agreements with Federal Home Loan Bank of Des Moines | 3,794.0 | 3,636.7 |
| Pledged as collateral | Funding agreements with Federal Home Loan Bank | ||
| Securities Posted as Collateral | ||
| Mortgage loans | 6,901.3 | 6,748.8 |
| Pledged as collateral with right to be sold or repledged | ||
| Securities Posted as Collateral | ||
| Securities posted as collateral eligible to be sold or repledged | $ 503.9 | $ 206.0 |