Valuation of debt and equity investments and certain liabilities - Investments at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	$ 3,311	$ 3,200
Short-term investments	1,875	4,380
Long-Term Investments	17	23
Measured at fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	2,957	2,457
Short-term investments	1,875	4,380
Long-Term Investments	11	11
Other measurement basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	0	0
Short-term investments	0	0
Long-Term Investments	6	12
Money market funds | Measured at fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	737	762
Short-term investments	0	0
Long-Term Investments	0	0
Corporate obligations | Measured at fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	738	694
Short-term investments	503	796
Long-Term Investments	0	0
U.S. government and agency securities | Measured at fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	1,432	752
Short-term investments	1,198	3,485
Long-Term Investments	0	0
Non-U.S. government and agency securities | Measured at fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	50	249
Short-term investments	174	99
Long-Term Investments	0	0
Mutual funds | Measured at fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	0	0
Short-term investments	0	0
Long-Term Investments	11	11
Equity-method investments | Other measurement basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	0	0
Short-term investments	0	0
Long-Term Investments	2	8
Nonmarketable investments | Other measurement basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	0	0
Short-term investments	0	0
Long-Term Investments	4	4
Cash on hand | Other measurement basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and Cash Equivalents	354	743
Short-term investments	0	0
Long-Term Investments	$ 0	$ 0