Financing (Narrative) (Details)	3 Months Ended			9 Months Ended
	Jun. 27, 2020 USD ($)	Sep. 28, 2019 USD ($)	Jun. 29, 2019 USD ($)	Jun. 27, 2020 USD ($)	Jun. 29, 2019 USD ($)	Jul. 30, 2020	Dec. 28, 2019 USD ($)
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	$ 66,000		$ 52,000	$ 257,000	$ 176,000
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%			2.25%
Minimum
Line of Credit Facility [Line Items]
Line of credit facility, commitment fees payable, percent				0.20%
Minimum | Alternate base rate
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	1.75%			1.75%
Maximum
Line of Credit Facility [Line Items]
Line of credit facility, commitment fees payable, percent				0.35%
Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	$ 200,000,000			$ 200,000,000
Maximum borrowing capacity	200,000,000	$ 150,000,000		200,000,000			$ 200,000,000
Debt issuance costs	$ 577,000			$ 577,000
Weighted average interest rate	4.25%			4.25%
Revolving Credit Facility outstanding borrowings	$ 85,576,000	0		$ 85,576,000
Letters of credit outstanding, amount	24,961,000	21,173,000		24,961,000
Line of credit facility, remaining borrowing capacity	89,463,000	128,827,000		$ 89,463,000
Revolving credit facility | London interbank offered rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on variable rate				0.50%
Letter of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 60,000,000					$ 50,000,000
Term loan B facility
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	$ 460,000,000			$ 460,000,000
Principal amount, amortization percentage	1.00%	1.00%		1.00%
Weighted average interest rate	4.72%			4.72%
Eurocurrency term loans
Line of Credit Facility [Line Items]
Effective interest rate applicable to outstanding credit facility (in hundredths)	3.25%			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)	0.75%			0.75%
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%			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)	2.75%			2.75%
Unsecured Debt
Line of Credit Facility [Line Items]
Interest rate, percentage	5.75%			5.75%
5.750% Senior Unsecured Notes Due 2027 | Unsecured Debt
Line of Credit Facility [Line Items]
Principal amount		$ 350,000,000
Interest rate, percentage		5.75%
Proceeds from debt, net of issuance costs		$ 343,352,000
Repurchase percentage of principal amount due to change of control		101.00%
Repurchase percentage of principal amount due to sale of assets		100.00%
Subsequent Event | Revolving credit facility
Line of Credit Facility [Line Items]
Maximum coverage ratio						6.0
Interest coverage ratio						3.0