Current Liabilities - Other Current Liabilities (Details) - USD ($) $ in Thousands	Apr. 01, 2017	Dec. 31, 2016		Apr. 02, 2016	Jun. 28, 2014	Mar. 29, 2014
Accounts Payable and Accrued Liabilities, Current [Abstract]
Salaries and benefits	$ 9,319	$ 11,494
Warranty accrual	2,126	1,884		$ 1,884	$ 1,670	$ 1,586
Advanced billings	535	583
Capital lease, current portion	289	504
Other	1,538	3,563
Balance, end of the period	$ 13,807	$ 18,028	[1]

[1] The balance sheet as of December 31, 2016 has been derived from the audited financial statements at that date.