Fair Value Measurements and Investments (Tables)

6 Months Ended

Mar. 31, 2017

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, 2017		September 30, 2016		March 31, 2017		September 30, 2016
	(in millions)
Assets
Cash equivalents and restricted cash:
Money market funds	$	4,594	$	4,537
U.S. government-sponsored debt securities					$	132	$	196
Investment securities, trading:
Equity securities	78		71
Investment securities, available-for-sale:
U.S. government-sponsored debt securities					3,039		4,699
U.S. Treasury securities	1,102		2,178
Equity securities	78		53
Corporate debt securities					80		249
Prepaid and other current assets:
Foreign exchange derivative instruments					52		50
Other assets:
Foreign exchange derivative instruments					—		6
Total	$	5,852	$	6,839	$	3,303	$	5,200
Liabilities
Accrued liabilities:
Foreign exchange derivative instruments					$	83	$	116
Other liabilities:
Foreign exchange derivative instruments					—		20
Total	$	—	$	—	$	83	$	136

Schedule of Long-term Debt Instruments

The following table presents the carrying amount and estimated fair value of the Company’s debt in order of maturity:

	March 31, 2017				September 30, 2016
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
	(in millions)
1.20% Senior Notes due December 2017	$	1,748	$	1,748	$	1,746	$	1,754
2.20% Senior Notes due December 2020	2,989		3,009		2,988		3,077
2.80% Senior Notes due December 2022	2,239		2,270		2,238		2,359
3.15% Senior Notes due December 2025	3,966		4,014		3,964		4,225
4.15% Senior Notes due December 2035	1,485		1,569		1,485		1,698
4.30% Senior Notes due December 2045	3,461		3,673		3,461		4,045
Total	$	15,888	$	16,283	$	15,882	$	17,158