Current Liabilities - Other Current Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011		Jul. 02, 2011	Apr. 02, 2011	Dec. 31, 2010
Accounts Payable and Accrued Liabilities, Current [Abstract]
Salaries and benefits	$ 8,950		$ 10,023
Warranty accrual	2,795	2,165	2,398		2,674	2,424	2,111
Accrued taxes-other	979		1,729
Capital lease, current portion	89		176
Advanced billing	1,821		5,809
Other	2,568		2,238
Balance, end of the period	$ 17,202		$ 22,373	[1]

[1] The Balance Sheet as of December 31, 2011 has been derived from the audited financial statements at that date.