Current Liabilities - Other Current Liabilities (Details) - USD ($) $ in Thousands	Apr. 02, 2016	Dec. 31, 2015		Apr. 04, 2015	Jun. 28, 2014	Mar. 29, 2014
Accounts Payable and Accrued Liabilities, Current [Abstract]
Salaries and benefits	$ 7,979	$ 6,417
Warranty accrual	1,670	1,586		$ 1,586	$ 1,737	$ 1,501
Advanced billings	1,360	543
Capital lease, current portion	843	831
Other	2,323	2,769
Balance, end of the period	$ 14,175	$ 12,146	[1]

[1] The balance sheet as of December 31, 2015 has been derived from the audited financial statements at that date.