Financing (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Oct. 01, 2016	Oct. 03, 2015	Jul. 05, 2016
Line of Credit Facility [Line Items]
Payments of Financing Costs	$ 1,770,000
Debt issuance costs	623,000	$ 623,000
Debt issuance costs incurred during noncash transaction	$ 503,000	$ (503,000)	$ (502,000)	$ 0
Percent added to Adjusted LIBOR rate for one month interest period		1.00%
Commitment fees incurred on credit facility		$ 405,000	271,000
Annual excess cash flow percentage		50.00%
Net cash proceed percentage		100.00%
Alternate Base Rate [Member]
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	2.25%	2.25%
Minimum [Member]
Line of Credit Facility [Line Items]
Line of credit facility, commitment fees payable, percent		0.25%
Minimum [Member] | Alternate Base Rate [Member]
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	1.75%	1.75%
Maximum [Member]
Line of Credit Facility [Line Items]
Line of credit facility, commitment fees payable, percent		0.40%
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)		(100.00%)
Line of credit facility, borrowing capacity					$ 120,000,000
Maximum borrowing capacity			$ 120,000,000
Short-term borrowings	$ 0	$ 0
Letters of credit outstanding, amount	37,811,000	37,811,000
Line of credit facility, remaining borrowing capacity	$ 82,189,000	$ 82,189,000
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Debt interest rate spread		1.00%
Eurocurrency Term Loans [Member]
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	3.25%	3.25%
Eurocurrency Term Loans [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	1.24%	1.24%
Eurocurrency Term Loans [Member] | Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	0.75%	0.75%
Eurocurrency Revolving Loans [Member]
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	4.00%	4.00%
Term Loan B Facility [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)		(100.00%)
Line of credit facility, borrowing capacity					$ 460,000,000
Line of credit facility, interest rate at period end (in hundredths)	4.96%	4.96%
Test [Member]
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount	$ 47,086,000	$ 47,086,000
Guarantees	22,800,000	$ 22,800,000
Interest Expense [Member]
Line of Credit Facility [Line Items]
Payments of Financing Costs	$ 1,147,000