Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Summary of Significant Accounting Policies [Line Items]
Depreciation and amortization expense	$ 406	$ 452	$ 417
Shipping expense	$ 365	$ 401	$ 351
Minimum
Summary of Significant Accounting Policies [Line Items]
Maturity period of short-term investments at the time of purchase	3 months
Minimum | Core and Developed Technology
Summary of Significant Accounting Policies [Line Items]
Finite-lived intangible assets, useful life	15 years
Minimum | Patents, Trademarks, and Other
Summary of Significant Accounting Policies [Line Items]
Finite-lived intangible assets, useful life	1 year
Minimum | Buildings
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	20 years
Minimum | Machinery and Equipment
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	4 years
Minimum | Leasehold Improvements
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	1 year
Maximum
Summary of Significant Accounting Policies [Line Items]
Maturity period of short-term investments at the time of purchase	1 year
Maximum | Core and Developed Technology
Summary of Significant Accounting Policies [Line Items]
Finite-lived intangible assets, useful life	20 years
Maximum | Patents, Trademarks, and Other
Summary of Significant Accounting Policies [Line Items]
Finite-lived intangible assets, useful life	40 years
Maximum | Buildings
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	45 years
Maximum | Machinery and Equipment
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	13 years
Maximum | Leasehold Improvements
Summary of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	12 years