Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 31, 2012	Sep. 29, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
Federal tax credit carryforwards	$ 3,290,000				$ 2,454,000				$ 3,290,000	$ 2,454,000
State tax credit carryforwards	5,900,000								5,900,000
State net operating loss	24,400,000								24,400,000
Income tax expense (benefit)	(2,476,000)	(86,000)	2,097,000	(1,228,000)	3,183,000	894,000	271,000	1,230,000	(1,693,000)	5,578,000	(4,742,000)
Effective income tax rate									(22.10%)	25.30%	(9.10%)
Tax credits for the year					2,200,000				4,500,000	2,200,000
Interest expense (benefit) related to uncertain tax positions									0	(100,000)	100,000
Interest and penalties accrued	100,000				100,000				100,000	100,000
Unrecognized tax benefits	2,597,000				1,656,000				2,597,000	1,656,000	2,194,000
Unrecognized tax benefits, reductions									200,000
La Barge
Income Taxes [Line Items]
Income tax expense (benefit)							(1,600,000)
Federal Research and Development
Income Taxes [Line Items]
Income tax expense (benefit)				(2,000,000)
Federal Tax Credit Carryforward
Income Taxes [Line Items]
Federal tax credit carryforwards	$ 3,300,000								$ 3,300,000