Stock Plans: (Compensation Expense and Respective Tax Benefit for Restricted Share Unit Awards) (Details) - Restricted Stock Units (RSUs) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Compensation Expense Related to RSU Awards	$ 175	$ 157	$ 153
Tax Benefit/(Charge) Related to RSU Awards	$ 41	$ 29	$ 26

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S45
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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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