Current Liabilities - Other Current Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 29, 2014	Dec. 31, 2013		Mar. 30, 2013	Dec. 31, 2012
Accounts Payable and Accrued Liabilities, Current [Abstract]
Salaries and benefits	$ 6,144	$ 8,771
Warranty accrual	1,055	1,142		2,047	2,273
Advanced billings	1,467	2,522
Other	2,838	2,660
Balance, end of the period	$ 11,504	$ 15,095	[1]

[1] The balance sheet as of December 31, 2013 has been derived from the audited financial statements at that date.