Investments - Available-For-Sale Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value	$ 4,766
Short-term investments:
Debt Securities, Available-for-sale [Line Items]
Gross Amortized Cost	3,462	$ 2,552
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(6)	(19)
Estimated Fair Value	3,457	2,533
Short-term investments: | Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Gross Amortized Cost	3,095	2,170
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(2)	(8)
Estimated Fair Value	3,094	2,162
Short-term investments: | Government and agency securities
Debt Securities, Available-for-sale [Line Items]
Gross Amortized Cost	367	382
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4)	(11)
Estimated Fair Value	363	371
Long-term investments:
Debt Securities, Available-for-sale [Line Items]
Gross Amortized Cost	1,311	625
Gross Unrealized Gains	4	0
Gross Unrealized Losses	(6)	(26)
Estimated Fair Value	1,309	599
Long-term investments: | Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Gross Amortized Cost	1,117	338
Gross Unrealized Gains	4	0
Gross Unrealized Losses	(2)	(10)
Estimated Fair Value	1,119	328
Long-term investments: | Government and agency securities
Debt Securities, Available-for-sale [Line Items]
Gross Amortized Cost	194	287
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4)	(16)
Estimated Fair Value	$ 190	$ 271