Accrued Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Jul. 01, 2014	Dec. 31, 2013
Components of accrued liabilities
Payroll and vacation	$ 16,247	$ 16,634
Accrued payroll taxes	2,688	2,453
Business Combination, Contingent Consideration, Liability, Current	0	10,895
Sales tax payable	4,235	6,379
Other	18,737	14,695
Total Accrued liabilities	$ 41,907	$ 51,056