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Fair Value Measurements - The carrying value and fair value of financial instruments (Details) - USD ($) $ in Millions | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Financial assets: |  |
Mortgage loans | $ 975 | $ 791
Long-term debt | 1,820 | 1,475
Level 1 |  |
Financial assets: |  |
Cash and cash equivalents | 1,842 | 1,406
Mortgage loans | 0 | 0
Total financial assets not accounted for at fair value | 1,842 | 1,406
Long-term debt | 0 | 0
Total financial liabilities not accounted for at fair value | 0 | 0
Level 2 |  |
Financial assets: |  |
Cash and cash equivalents | 0 | 0
Mortgage loans | 0 | 0
Total financial assets not accounted for at fair value | 0 | 0
Long-term debt | 1,643 | 1,273
Total financial liabilities not accounted for at fair value | 1,643 | 1,273
Level 3 |  |
Financial assets: |  |
Cash and cash equivalents | 0 | 0
Mortgage loans | 958 | 754
Total financial assets not accounted for at fair value | 958 | 754
Long-term debt | 3 | 3
Total financial liabilities not accounted for at fair value | 3 | 3
Carrying Value |  |
Financial assets: |  |
Cash and cash equivalents | 1,842 | 1,406
Mortgage loans | 975 | 791
Total financial assets not accounted for at fair value | 2,817 | 2,197
Long-term debt | 1,820 | 1,475
Total financial liabilities not accounted for at fair value | 1,820 | 1,475
Fair Value |  |
Financial assets: |  |
Cash and cash equivalents | 1,842 | 1,406
Mortgage loans | 958 | 754
Total financial assets not accounted for at fair value | 2,800 | 2,160
Long-term debt | 1,646 | 1,276
Total financial liabilities not accounted for at fair value | $ 1,646 | $ 1,276

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- Definition Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-11 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-11 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-10 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
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