Supplemental financial information - Treasury Stock (Details) - shares shares in Millions	3 Months Ended
Sep. 30, 2026	Jun. 30, 2026	Mar. 31, 2026
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, beginning (in shares)			834
Balance, ending (in shares)	827
Treasury Common Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Balance, beginning (in shares)	828	831	834
Repurchases (in shares)	0	0	1
Shares issued for stock compensation (in shares)	(1)	(3)	(4)
Balance, ending (in shares)	827	828	831

Number, after forfeiture, of shares or units issued under share-based payment arrangement. Excludes shares or units issued under employee stock ownership plan (ESOP).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details

- Definition

Number of shares that have been repurchased during the period and are being held in treasury.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section S50
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-URI https://asc.fasb.org/1943274/2147480070/505-10-S50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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+ Details