Basis of Presentation and Preparation - Revenue Recognition and Contract Costs (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Oct. 02, 2016 USD ($)	Jun. 26, 2016 USD ($)	Mar. 27, 2016 USD ($)	Dec. 27, 2015 USD ($)	Sep. 27, 2015 USD ($)	Jun. 28, 2015 USD ($)	Mar. 29, 2015 USD ($)	Dec. 28, 2014 USD ($)	Oct. 02, 2016 USD ($) item	Sep. 27, 2015 USD ($)	Sep. 28, 2014 USD ($)
Revenue recognition and contract costs
Unfavorable operating income adjustments	$ (47,190)	$ (39,085)	$ (16,650)	$ (32,930)	$ 20,047	$ (40,721)	$ (30,398)	$ (36,612)	$ (135,855)	$ (87,684)	$ (153,833)
Liability for anticipated losses	6,700				$ 10,500				6,700	10,500
Estimated cost to complete the related contracts	$ 23,600								$ 23,600
Number of types of contracts under which revenue is recognized | item									3
Number of types of fixed-price contracts | item									2
Contracts accounted for under the percentage-of-completion method of accounting
Revenue recognition and contract costs
Unfavorable operating income adjustments									$ 2,300	$ 8,900	$ 35,900