Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2016 USD ($)	Jul. 01, 2016 USD ($)	Sep. 30, 2016 USD ($) reporting_unit	Oct. 02, 2015 USD ($) reporting_unit	Sep. 26, 2014 USD ($) reporting_unit	Apr. 02, 1999 company
Significant Accounting Policies [Line Items]
Business separation costs	$ 11.5	$ 5.4	$ 16.9	$ 0.0	$ 0.0
Number of publicly traded companies | company						3
Number of publicly traded companies distributed to stockholders | company						2
Foreign currency gain (loss) before tax			1.6	(2.0)	(0.5)
Carrying value of equity investments in privately-held companies	49.3		49.3	49.7
Impairment					$ 7.7
Equity investments under cost method	18.7		$ 18.7	$ 15.0
Number of reporting units tested for impairment of goodwill | reporting_unit			4	4	4
Warranty period			12 months
Costs incurred and revenues recognized in excess of customer billings	111.6		$ 111.6	$ 79.1
Customer billings in excess of costs incurred and revenue recognized	13.7		13.7	53.8
Deferred tax liabilties	$ (26.6)		$ (26.6)	(31.8)
New Accounting Pronouncement, Early Adoption, Effect
Significant Accounting Policies [Line Items]
Decrease in current deferred tax assets				132.1
Decrease in current deferred tax liabilities				6.3
Deferred tax assets				110.0
Deferred tax liabilties				$ 15.8
Minimum
Significant Accounting Policies [Line Items]
Finite-lived intangible asset, useful life (in years)			2 years
Maximum
Significant Accounting Policies [Line Items]
Finite-lived intangible asset, useful life (in years)			10 years
Land Improvements
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life (in years)			15 years
Building | Minimum
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life (in years)			20 years
Building | Maximum
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life (in years)			30 years
Machinery and Equipment | Minimum
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life (in years)			3 years
Machinery and Equipment | Maximum
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life (in years)			7 years