Cash, Cash Equivalents, Restricted Cash and Investments - Schedule of Fair Value of Assets Measured on Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	$ 141	$ 221
Total investments	893	1,238
U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	518	766
U.S. Treasury securities \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	518	766
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	39
Commercial paper \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	39
Corporate bonds and notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	375	433
Corporate bonds and notes \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	375	433
Bank deposits \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	8	1
Money market funds \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	130	220
U.S. Treasury securities \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash and cash equivalents	$ 3	$ 0