Financing (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Oct. 01, 2016	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	$ 0	(503,000)	$ (502,000)
Percent added to Adjusted LIBOR rate for one month interest period		1.00%
Commitment fees incurred on credit facility		$ 342,000	405,000
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%
Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		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%
Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.40%
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity					$ 120,000,000
Maximum borrowing capacity	$ 120,000,000		120,000,000
Interest rate, increase (decrease)	(100.00%)
Short-term borrowings	$ 0	$ 0	0
Letters of credit outstanding, amount	37,811,000	20,448,000	37,811,000
Line of credit facility, remaining borrowing capacity	$ 82,189,000	$ 99,552,000	$ 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%
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)		2.16%
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%
Eurocurrency Revolving Loans [Member]
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)		3.00%
Term Loan B Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity					$ 460,000,000
Debt instrument, amortization percentage		1.00%
Interest rate, increase (decrease)	(100.00%)
Line of credit facility, interest rate at period end (in hundredths)		4.95%
Test [Member]
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount		$ 26,753,000
Guarantees		$ 17,572,000
Interest Expense [Member]
Line of Credit Facility [Line Items]
Payments of financing costs	$ 1,147,000