Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions |
Jun. 30, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Debt securities, available for sale, allowance for credit losses | $ 0.0 | $ 1.1 |
| Debt securities, available for sale, cost | 4,700.0 | 5,143.8 |
| Debt securities, trading, cost | 125.1 | 187.3 |
| Short-term investments, cost | 54.9 | 95.3 |
| Other long-term investments, cost | 436.2 | 438.2 |
| Related party investments at fair value | $ 218.1 | $ 217.2 |
| Common share, shares issued (in shares) | 116,759,539 | 116,429,057 |
| Common share, shares outstanding (in shares) | 116,759,539 | 116,429,057 |
| Series B preference shares | ||
| Preference shares, par value (in dollars per share) | $ 0.10 | $ 0.10 |
| Preference shares, shares authorized (in shares) | 8,000,000 | 8,000,000 |
| Preference shares, shares issued (in shares) | 8,000,000 | 8,000,000 |
| X | ||||||||||
- Definition Other Long-Term Investments, Cost No definition available.
|
| X | ||||||||||
- Definition Other Long-term investments, Related Parties No definition available.
|
| X | ||||||||||
- Definition Other Short-term Investments, Cost No definition available.
|
| X | ||||||||||
- Definition Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amortized cost excluding accrued interest, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Number of shares issued for nonredeemable preferred shares and preferred shares redeemable solely at option of issuer. Includes, but is not limited to, preferred shares issued, repurchased, and held as treasury shares. Excludes preferred shares classified as debt. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amortized cost of investments in debt securities classified as trading. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Details
|