Long-Term Debt and Commitments Related to Letters of Credit Long-Term Debt (Details) - USD ($) $ in Thousands	Sep. 26, 2020	Dec. 31, 2019
Revolving credit facility, noncurrent	$ 30,000	$ 62,000
Term loans	34,907	24,076
Long-term debt	139,907	167,076
Less debt issuance costs	291	420
Less current portion	33,065	23,302
Long-term debt, excluding current maturities	106,551	143,354
Swing-line borrowings [Member]
Revolving credit facility, noncurrent	18,000	10,000
London Interbank Offered Rate (LIBOR) [Member]
Revolving credit facility, noncurrent	12,000	52,000
Unsecured debt [Member]
Senior unsecured notes	75,000	81,000
5.09% Senior unsecured notes [Member]
Senior unsecured notes	0	6,000
3.99% Senior unsecured notes [Member]
Senior unsecured notes	50,000	50,000
4.00% Senior unsecured notes [Member]
Senior unsecured notes	$ 25,000	$ 25,000

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying value as of the balance sheet date of all notes and loans payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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