Financing (Narrative) (Details) - USD ($)	3 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Sep. 29, 2018
Line of Credit Facility [Line Items]
Percent added to Adjusted LIBOR rate for one month interest period	1.00%
Commitment fees incurred on credit facility	$ 72,000	$ 79,000
Annual excess cash flow percentage per credit agreement	50.00%
Net cash proceed percentage per credit agreement	100.00%
Alternate base rate
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	2.25%
Minimum
Line of Credit Facility [Line Items]
Line of credit facility, commitment fees payable, percent	0.25%
Minimum | Alternate base rate
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	1.75%
Maximum
Line of Credit Facility [Line Items]
Line of credit facility, commitment fees payable, percent	0.40%
Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	$ 150,000,000
Maximum borrowing capacity	150,000,000		$ 120,000,000
Debt issuance costs	541,000
Short-term borrowings	80,391,000		0
Letters of credit outstanding, amount	20,221,000		20,448,000
Line of credit facility, remaining borrowing capacity	$ 49,388,000		$ 99,552,000
Revolving credit facility | London interbank offered rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
Term loan B facility
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	$ 460,000,000
Principal amount, amortization percentage	1.00%		1.00%
Weighted average interest rate	5.57%
Eurocurrency term loans
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	3.25%
Eurocurrency term loans | London interbank offered rate (LIBOR)
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	2.46%
Eurocurrency term loans | Minimum | London interbank offered rate (LIBOR)
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	0.75%
Eurocurrency borrowing | London interbank offered rate (LIBOR)
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	3.00%