Fair Value Measurements and Investments (Tables)

6 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

Assets and Liabilities Measured at Fair Value on a Recurring Basis

	Fair Value Measurements Using Inputs Considered as
	Level 1				Level 2
	March 31, 2024		September 30, 2023		March 31, 2024		September 30, 2023
	(in millions)
Assets
Cash equivalents and restricted cash equivalents:
Money market funds	$	9,050	$	13,504	$	—	$	—
U.S. Treasury securities	834		301		—		—
Investment securities:
Marketable equity securities	374		339		—		—
U.S. government-sponsored debt securities	—		—		1,510		1,108
U.S. Treasury securities	5,918		4,316		—		—
Other current and non-current assets:
Money market funds	29		23		—		—
Derivative instruments	—		—		210		293
Total	$	16,205	$	18,483	$	1,720	$	1,401
Liabilities
Accrued compensation and benefits:
Deferred compensation liability	$	223	$	175	$	—	$	—
Accrued and other liabilities:
Derivative instruments	—		—		278		396
Total	$	223	$	175	$	278	$	396

Schedule of Amortized Cost, Unrealized Gains and Losses, and Fair Value of Debt Securities

The amortized cost, unrealized gains and losses and fair value of debt securities were as follows:

	March 31, 2024
	Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
	(in millions)
U.S. government-sponsored debt securities	$	1,511	$	—	$	(1)	$	1,510
U.S. Treasury securities	6,782		4		(34)		6,752
Total	$	8,293	$	4	$	(35)	$	8,262

	September 30, 2023
	Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
	(in millions)
U.S. government-sponsored debt securities	$	1,109	$	1	$	(2)	$	1,108
U.S. Treasury securities	4,697		—		(80)		4,617
Total	$	5,806	$	1	$	(82)	$	5,725

Debt securities with unrealized losses for less than 12 months and 12 months or greater were as follows:

	March 31, 2024
	Less Than 12 Months				12 Months or Greater
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
	(in millions)
U.S. government-sponsored debt securities	$	1,282	$	(1)	$	—	$	—
U.S. Treasury securities	2,789		(6)		1,870		(28)
Total	$	4,071	$	(7)	$	1,870	$	(28)

	September 30, 2023
	Less Than 12 Months				12 Months or Greater
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
	(in millions)
U.S. government-sponsored debt securities	$	412	$	(2)	$	50	$	—
U.S. Treasury securities	1,360		(12)		2,128		(68)
Total	$	1,772	$	(14)	$	2,178	$	(68)

Debt Securities Classified by Contractual Maturity Date

The stated maturities of debt securities were as follows:

	March 31, 2024
	(in millions)
Due within one year	$	5,170
Due after one year through five years	3,092
Total	$	8,262

Schedule of Non-Marketable Equity Securities

The following table summarizes the Company’s non-marketable equity securities held as of period end that were accounted for using the fair value measurement alternative:

	March 31, 2024
	(in millions)
Initial cost basis	$	710
Adjustments:
Upward adjustments	909
Downward adjustments (including impairment)	(445)
Carrying amount	$	1,174

Unrealized gains and losses of the Company’s non-marketable equity securities held as of period end that were accounted for using the fair value measurement alternative were as follows:

	Three Months Ended March 31,				Six Months Ended March 31,
	2024		2023		2024		2023
	(in millions)
Upward adjustments	$	—	$	2	$	9	$	19
Downward adjustments (including impairment)	$	(15)	$	(89)	$	(15)	$	(89)