Accounts Receivable, Net and Supplemental Balance-Sheet Information (Details) - USD ($) $ in Thousands	Jul. 01, 2017	Dec. 31, 2016
Accounts receivable, net
Accounts receivable	$ 126,751	$ 128,202
Receivables under contractual arrangements	34,293	21,541
Accounts receivable, gross	161,044	149,743
Less allowances for doubtful accounts	3,489	3,609
Accounts receivable, net	157,555	146,134
Other current assets
Refundable income taxes	94	548
Prepaid expense	9,251	14,493
Other	299	1,315
Total	9,644	16,356
Accrued expenses
Employee compensation	14,189	18,438
Accrued compensated absences	9,663	9,215
Self-insured medical claims	5,428	2,961
Income tax payable	3,744	953
Customer advances, deposits	756	2,997
Taxes, other than income	2,431	2,166
Other	1,411	929
Total	37,622	37,659
Other current liabilities
Long-term debt	9,813	16,871
Total	$ 33,071	$ 39,963