| **Fair Value (Carrying amount and estimated fair value of financial instrument assets and liabilities which are not measured at fair value) (Details) - USD ($) $ in Millions** | Sep. 30, 2024 | Dec. 31, 2023 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Assets**                                                                                                                                                                      |          |          |
| Mortgage loans                                                                                                                                                                  | $ 1,003       | $ 1,035       |
| **Liabilities**                                                                                                                                                                 |          |          |
| Long-term debt                                                                                                                                                                  | 2,972         | 2,481         |
| Carrying Amount                                                                                                                                                                 |          |          |
| **Assets**                                                                                                                                                                      |          |          |
| Mortgage loans                                                                                                                                                                  | 1,003         | 1,035         |
| **Liabilities**                                                                                                                                                                 |          |          |
| Short-term debt                                                                                                                                                                 | 0             | 550           |
| Long-term debt                                                                                                                                                                  | 2,972         | 2,481         |
| Estimated Fair Value                                                                                                                                                            |          |          |
| **Assets**                                                                                                                                                                      |          |          |
| Mortgage loans                                                                                                                                                                  | 988           | 997           |
| **Liabilities**                                                                                                                                                                 |          |          |
| Short-term debt                                                                                                                                                                 | 0             | 546           |
| Long-term debt                                                                                                                                                                  | 2,952         | 2,385         |
| Level 1 | Estimated Fair Value                                                                                                                                                  |          |          |
| **Assets**                                                                                                                                                                      |          |          |
| Mortgage loans                                                                                                                                                                  | 0             | 0             |
| **Liabilities**                                                                                                                                                                 |          |          |
| Short-term debt                                                                                                                                                                 | 0             | 0             |
| Long-term debt                                                                                                                                                                  | 0             | 0             |
| Level 2 | Estimated Fair Value                                                                                                                                                  |          |          |
| **Assets**                                                                                                                                                                      |          |          |
| Mortgage loans                                                                                                                                                                  | 0             | 0             |
| **Liabilities**                                                                                                                                                                 |          |          |
| Short-term debt                                                                                                                                                                 | 0             | 546           |
| Long-term debt                                                                                                                                                                  | 2,952         | 2,385         |
| Level 3 | Estimated Fair Value                                                                                                                                                  |          |          |
| **Assets**                                                                                                                                                                      |          |          |
| Mortgage loans                                                                                                                                                                  | 988           | 997           |
| **Liabilities**                                                                                                                                                                 |          |          |
| Short-term debt                                                                                                                                                                 | 0             | 0             |
| Long-term debt                                                                                                                                                                  | $ 0           | $ 0           |

| X                                                                                                                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - References
No definition available.
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| X                                                                                                                                                                                                                                               |
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| - References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt classified as noncurrent. Excludes lease obligation.
+ References
Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents the amount of short-term debt existing as of the balance sheet date.
+ References
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| X                                                                                                                                                                                       |
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