Investments (Details) - Investment Information, Equity Securities - USD ($) $ in Millions |
9 Months Ended | 12 Months Ended | |
|---|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2024 |
Dec. 31, 2024 |
|
| Investment disclosure details | |||
| Equity securities, cost | $ 506 | $ 544 | |
| Gross gains | 198 | 154 | |
| Gross losses | 12 | 11 | |
| Equity securities, at fair value | 692 | 687 | |
| Net recognized gains on equity securities still held | 41 | $ 102 | |
| Common stock [Member] | |||
| Investment disclosure details | |||
| Equity securities, cost | 462 | 500 | |
| Gross gains | 193 | 150 | |
| Gross losses | 6 | 11 | |
| Equity securities, at fair value | 649 | 639 | |
| Non-redeemable preferred stock [Member] | |||
| Investment disclosure details | |||
| Equity securities, cost | 44 | 44 | |
| Gross gains | 5 | 4 | |
| Gross losses | 6 | 0 | |
| Equity securities, at fair value | $ 43 | $ 48 | |
| 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 gain (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 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 Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|