Investments - Summary of Investments (Detail) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 7,552	$ 7,576
Gross Unrealized Gains	29	18
Gross Unrealized Losses	(18)	(25)
Estimated Fair Value	7,563	7,569
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	254	336
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	254	336
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,265	4,966
Gross Unrealized Gains	24	15
Gross Unrealized Losses	(1)	(5)
Estimated Fair Value	5,288	4,976
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	48	67
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	48	67
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,882	2,103
Gross Unrealized Gains	5	3
Gross Unrealized Losses	(1)	(2)
Estimated Fair Value	1,886	2,104
Mortgage-backed and asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	103	104
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(16)	(18)
Estimated Fair Value	$ 87	$ 86

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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