Accounts Receivable, Net and Supplemental Balance-Sheet Information (Details) - USD ($) $ in Thousands	Jul. 04, 2015	Dec. 31, 2014
Accounts receivable, net
Accounts receivable	$ 108,997	$ 98,657
Receivables under contractual arrangements	24,274	15,362
Accounts receivable, gross	133,271	114,019
Less allowances for doubtful accounts	2,776	2,421
Accounts receivable, net	130,495	111,598
Other current assets
Refundable income taxes	3,462	2,122
Prepaid expenses	8,572	14,088
Note receivable	0	4,319
Other	9,528	9,686
Total	21,562	30,215
Accrued expenses
Employee compensation	15,053	19,195
Accrued compensated absences	8,794	8,034
Self-insured medical claims	560	2,722
Customer advances, deposits	438	2,030
Taxes, other than income	2,358	2,054
Other	1,490	890
Total	28,693	34,925
Other current liabilities
Other current liabilities	$ 25,430	$ 31,288