Financial Instruments - Available-for-sale Marketable Securities (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Marketable Securities [Line Items]
Less than 12 months, fair value	$ 1,907	$ 10,284
Less than 12 months, unrealized losses	(7)	(99)
12 months or greater, fair value	6,448	12,786
12 months or greater, unrealized losses	(123)	(382)
Fair value	8,355	23,070
Unrealized losses	(130)	(481)
U.S. government securities
Marketable Securities [Line Items]
Less than 12 months, fair value	1,208	6,860
Less than 12 months, unrealized losses	(5)	(71)
12 months or greater, fair value	2,767	4,330
12 months or greater, unrealized losses	(56)	(146)
Fair value	3,975	11,190
Unrealized losses	(61)	(217)
U.S. government agency securities
Marketable Securities [Line Items]
Less than 12 months, fair value	129	435
Less than 12 months, unrealized losses	0	(2)
12 months or greater, fair value	622	2,083
12 months or greater, unrealized losses	(5)	(44)
Fair value	751	2,518
Unrealized losses	(5)	(46)
Corporate debt securities
Marketable Securities [Line Items]
Less than 12 months, fair value	570	2,989
Less than 12 months, unrealized losses	(2)	(26)
12 months or greater, fair value	3,059	6,373
12 months or greater, unrealized losses	(62)	(192)
Fair value	3,629	9,362
Unrealized losses	$ (64)	$ (218)