Long-Term Debt and Commitments Related to Letters of Credit Long-Term Debt (Details) - USD ($) $ in Thousands	Jul. 01, 2017	Dec. 31, 2016
Revolving credit facility, noncurrent	$ 102,500	$ 67,000
Senior unsecured notes	24,000	24,000
Term loans	10,252	16,151
Capital leases	2,620	2,343
Long-term debt	139,372	109,494
Less debt issuance costs	263	333
Less current portion	9,813	16,871
Long-term debt, excluding current maturities	129,296	92,290
Swing-line borrowings [Member]
Revolving credit facility, noncurrent	7,500	10,000
London Interbank Offered Rate (LIBOR) [Member]
Revolving credit facility, noncurrent	$ 95,000	$ 57,000