Accounts Receivable, Net and Supplemental Balance-Sheet Information (Details) (USD $) In Thousands, unless otherwise specified	Apr. 04, 2015	Dec. 31, 2014
Accounts receivable, net
Accounts receivable	$ 88,697	$ 98,657
Receivables under contractual arrangements	20,426	15,362
Accounts receivable, gross	109,123	114,019
Less allowances for doubtful accounts	2,649	2,421
Accounts receivable, net	106,474	111,598
Other current assets
Total	26,749	30,215
Accrued expenses
Employee compensation	10,114	19,195
Accrued compensated absences	8,528	8,034
Self-insured medical claims	1,142	2,722
Customer advances, deposits	314	2,030
Taxes, other than income	2,692	2,054
Other	745	890
Total	23,535	34,925
Other current liabilities
Current portion of long-term debt	5,346	8,281
Other current liabilities	$ 28,346	$ 31,288