Fair Value Measurements and Investments - Amortized Cost, Unrealized Gains and Losses, and Fair Value of Available-for-sale Securities (Detail) $ in Millions	Sep. 30, 2022 USD ($)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 5,395
Gross Unrealized Gains	0
Gross Unrealized Losses	(134)
Fair Value	5,261
Fair Value	3,915
Gross Unrealized Losses	(134)
U.S. government-sponsored debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	458
Gross Unrealized Gains	0
Gross Unrealized Losses	(1)
Fair Value	457
Fair Value	408
Gross Unrealized Losses	(1)
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,937
Gross Unrealized Gains	0
Gross Unrealized Losses	(133)
Fair Value	4,804
Fair Value	3,507
Gross Unrealized Losses	$ (133)

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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Amount, before tax, of unrealized loss 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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Amortized cost of 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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Amount of 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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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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