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, 2025	Dec. 31, 2024
Assets
Mortgage loans	$ 1,055	$ 1,019
Liabilities
Long-term debt	2,970	2,973
Carrying Amount
Assets
Mortgage loans	1,055	1,019
Liabilities
Short-term debt	500	0
Long-term debt	2,970	2,973
Estimated Fair Value
Assets
Mortgage loans	1,047	987
Liabilities
Short-term debt	500	0
Long-term debt	2,959	2,885
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	500	0
Long-term debt	2,959	2,885
Level 3 \| Estimated Fair Value
Assets
Mortgage loans	1,047	987
Liabilities
Short-term debt	0	0
Long-term debt	$ 0	$ 0

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.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-28

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-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 3: http://www.xbrl.org/2009/role/commonPracticeRef
-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 4: http://www.xbrl.org/2009/role/commonPracticeRef
-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 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

Name:	us-gaap_ShorttermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant