Investment Securities - Common Equity Securities and Other Long Term Investments (Details) - USD ($) $ in Millions |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2025 |
Dec. 31, 2024 |
|
| Common equity securities | ||
| Cost or Amortized Cost | $ 353.7 | $ 537.0 |
| Gross Unrealized Gains | 81.3 | 120.4 |
| Gross Unrealized Losses | 0.0 | 0.0 |
| Net Foreign Currency Gains (Losses) | 0.0 | (7.4) |
| Carrying Value | 435.0 | 650.0 |
| Other long-term investments | ||
| Cost or Amortized Cost | 1,818.5 | 1,748.7 |
| Gross Unrealized Gains | 624.3 | 546.4 |
| Gross Unrealized Losses | (126.0) | (116.7) |
| Net Foreign Currency Gains (Losses) | (9.7) | (28.2) |
| Carrying Value | 2,307.1 | 2,150.2 |
| MediaAlpha | ||
| Investment in MediaAlpha | ||
| Cost or Amortized Cost | 59.2 | 59.2 |
| Gross Unrealized Gains | 136.3 | 142.4 |
| Gross Unrealized Losses | 0.0 | 0.0 |
| Net Foreign Currency Gains (Losses) | 0.0 | 0.0 |
| Carrying Value | $ 195.5 | $ 201.6 |
| X | ||||||||||
- Definition This element represents the aggregate cost of investments accounted for under the equity method of accounting. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of unrealized gain on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of unrealized loss on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of long-term investments classified as other. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Equity Method Investment, Net Foreign Currency Gain (Loss) No definition available.
|
| X | ||||||||||
- Definition Equity Method Investment, Unrealized Gain No definition available.
|
| X | ||||||||||
- Definition Equity Method Investment, Unrealized Loss No definition available.
|
| X | ||||||||||
- Definition Equity Method Investments No definition available.
|
| X | ||||||||||
- Definition Equity Securities, FN-NI, Net Foreign Currency Gain (Loss) No definition available.
|
| X | ||||||||||
- Definition Other Long-Term Investments No definition available.
|
| X | ||||||||||
- Definition Other Long-Term Investments, Cost No definition available.
|
| X | ||||||||||
- Definition Other Long-Term Investments, Net Foreign Currency Gain (Loss) No definition available.
|
| X | ||||||||||
- Definition Other Long-Term Investments, Unrealized Gain No definition available.
|
| X | ||||||||||
- Definition Other Long-Term Investments, Unrealized Loss No definition available.
|
| X | ||||||||||
- Details
|