Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2014	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 31, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Jun. 28, 2014	Jun. 29, 2013	Sep. 27, 2014	Sep. 28, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
Tax credit carryforwards	$ 2,696,000				$ 3,758,000								$ 2,696,000	$ 3,758,000
Unrecognized tax benefits	2,803,000				2,297,000								2,803,000	2,297,000	1,356,000	2,194,000
Income Tax Expense (Benefit)	(1,122,000)	1,754,000	3,197,000	2,544,000	(2,115,000)	(1,000,000)	2,193,000	(1,071,000)	5,741,000	1,122,000	7,495,000	122,000	6,373,000	(1,993,000)	6,501,000
Effective income tax rate													24.30%	(21.20%)	26.90%
Tax credits for the year													2,400,000	4,500,000
Federal research and development tax credit benefits recognized														2,000,000
Interest expense (benefit) related to uncertain tax positions													0	0	(100,000)
Interest and penalties accrued	100,000				100,000								100,000	100,000	100,000
Unrecognized tax benefits that would impact effective tax rate	1,900,000												1,900,000
Federal
Income Taxes [Line Items]
Tax credit carryforwards	2,700,000												2,700,000
Tax credit carryforwards not recognized due to ASC Subtopic 740-10	1,000,000												1,000,000
State
Income Taxes [Line Items]
Tax credit carryforwards	8,300,000												8,300,000
Tax credit carryforwards not recognized due to ASC Subtopic 740-10	1,000,000												1,000,000
Net operating loss carryforwards	$ 26,600,000												$ 26,600,000