Financial Instruments- Unrealized Loss Position (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses, less than 12 months	$ (59)	$ (241)
Estimate fair value, less than 12 months	3,414	7,635
Gross unrealized losses, 12 months or more	(289)	(223)
Estimated fair value, 12 months or more	7,702	5,524
Gross unrealized losses, total	(348)	(464)
Estimated fair value, total	11,116	13,159
U.S. treasury bills
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses, less than 12 months	0	0
Estimate fair value, less than 12 months	0	128
Gross unrealized losses, 12 months or more	0	0
Estimated fair value, 12 months or more	0	0
Gross unrealized losses, total	0	0
Estimated fair value, total	0	128
U.S. treasury notes
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses, less than 12 months	(25)	(101)
Estimate fair value, less than 12 months	1,783	3,956
Gross unrealized losses, 12 months or more	(131)	(128)
Estimated fair value, 12 months or more	4,063	3,541
Gross unrealized losses, total	(156)	(229)
Estimated fair value, total	5,846	7,497
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses, less than 12 months	(33)	(138)
Estimate fair value, less than 12 months	1,593	3,505
Gross unrealized losses, 12 months or more	(151)	(88)
Estimated fair value, 12 months or more	3,537	1,890
Gross unrealized losses, total	(184)	(226)
Estimated fair value, total	5,130	5,395
Government debt securities
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses, less than 12 months	(1)	(2)
Estimate fair value, less than 12 months	38	46
Gross unrealized losses, 12 months or more	(7)	(7)
Estimated fair value, 12 months or more	102	93
Gross unrealized losses, total	(8)	(9)
Estimated fair value, total	$ 140	$ 139