Fair Value Measurements and Investments (Tables)

6 Months Ended

Mar. 31, 2021

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, 2021		September 30, 2020		March 31, 2021		September 30, 2020
	(in millions)
Assets
Cash equivalents and restricted cash equivalents:
Money market funds	$	13,702	$	12,522	$	—	$	—
U.S. government-sponsored debt securities	—		—		600		1,469
U.S. Treasury securities	450		650		—		—
Investment securities:
Marketable equity securities	191		148		—		—
U.S. government-sponsored debt securities	—		—		901		2,582
U.S. Treasury securities	1,076		1,253		—		—
Other current and non-current assets:
Money market funds	2		—		—		—
Derivative instruments	—		—		424		512
Total	$	15,421	$	14,573	$	1,925	$	4,563
Liabilities
Accrued compensation and benefits:
Deferred compensation liability	$	159	$	135	$	—	$	—
Accrued and other liabilities:
Derivative instruments	—		—		201		181
Total	$	159	$	135	$	201	$	181

Schedule of Non-Marketable Equity Securities

The following table summarizes the total carrying value of the Company’s non-marketable equity securities held as of March 31, 2021 including cumulative unrealized gains and losses:

	March 31, 2021
	(in millions)
Initial cost basis	$	858
Adjustments:
Upward adjustments	355
Downward adjustments (including impairment)	(13)
Carrying amount, end of period	$	1,200

During the three and six months ended March 31, 2021 and 2020, unrealized gains and losses included in the carrying value of the Company’s non-marketable equity securities were as follows:

	Three Months Ended March 31,				Six Months Ended March 31,
	2021		2020		2021		2020
	(in millions)
Upward adjustments	$	129	$	—	$	143	$	9
Downward adjustments (including impairment)	$	—	$	—	$	(2)	$	—