Fair Value Measurements and Investments (Tables)

3 Months Ended

Dec. 31, 2018

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
	December 31, 2018		September 30, 2018		December 31, 2018		September 30, 2018
	(in millions)
Assets
Cash equivalents and restricted cash:
Money market funds	$	7,063	$	6,252
U.S. government-sponsored debt securities					$	98	$	1,048
Investment securities:
Marketable equity securities	123		113
U.S. government-sponsored debt securities					5,234		5,008
U.S. Treasury securities	2,236		2,508
Other current and non-current assets:
Foreign exchange derivative instruments					113		78
Total	$	9,422	$	8,873	$	5,445	$	6,134
Liabilities
Accrued liabilities:
Foreign exchange derivative instruments					$	28	$	22
Total	$	—	$	—	$	28	$	22