Marketable and Other Securities - Fair Value of Cash Equivalents and Marketable Debt Securities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Summary of Investment Holdings [Line Items]
Total available-for-sale debt securities with contractual maturities	$ 885
Total cash and cash equivalents	7,820	$ 5,094
Cash and cash equivalents	208	190
Total restricted cash	3,170	2,987
Due in one year or less	885
Due between one and five years	0
Total available-for-sale debt securities with contractual maturities	885
Cash and cash equivalents
Summary of Investment Holdings [Line Items]
Cash and time deposits	3,186	2,793
Total available-for-sale debt securities with contractual maturities	863	124
Total available-for-sale debt securities with contractual maturities	863	124
Cash and cash equivalents | Level 2 | U.S. government and agencies
Summary of Investment Holdings [Line Items]
Total available-for-sale debt securities with contractual maturities	781	0
Total available-for-sale debt securities with contractual maturities	781	0
Cash and cash equivalents | Level 2 | Sovereign debt
Summary of Investment Holdings [Line Items]
Total available-for-sale debt securities with contractual maturities	83	124
Total available-for-sale debt securities with contractual maturities	83	124
Cash and cash equivalents | Level 1
Summary of Investment Holdings [Line Items]
Money market funds	3,770	2,177
Marketable debt securities
Summary of Investment Holdings [Line Items]
Total available-for-sale debt securities with contractual maturities	21	0
Total available-for-sale debt securities with contractual maturities	21	0
Marketable debt securities | Level 2 | U.S. government and agencies
Summary of Investment Holdings [Line Items]
Total available-for-sale debt securities with contractual maturities	21	0
Total available-for-sale debt securities with contractual maturities	21	0
Restricted cash | Level 1
Summary of Investment Holdings [Line Items]
Money market funds	$ 2,962	$ 2,798