Taxes - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jul. 01, 2012	Dec. 31, 2012
Tax Credit Carryforward [Line Items]
Increase in liabilities, net of deferred tax benefit, for uncertain tax positions	$ 274,000	$ 918,000
Increase (decrease) in interest and penalties	38,000	76,000
Effective tax rate excluding effect of discrete event	0.00%	19.00%	0.00%
Reserve for income taxes, total	6,255,000	6,255,000		5,216,000
Interest and penalties, gross	1,303,000	1,303,000
Reserve for income taxes to be recorded in additional paid in capital		405,000
Minimum decrease in income tax expense due to release in reserves		1,600,000
Maximum decrease in income tax expense due to release in reserves		1,800,000
Tax years open to examination by various taxing authorities		2008 through 2012
Tax years open to examination by various taxing authorities for other entities		2006 through 2012
Tax years currently under audit by internal revenue service for U.S. federal returns		2010 and 2011
Research and Development Tax Credit [Member]
Tax Credit Carryforward [Line Items]
Reduction in tax expense	$ 555,000	$ 555,000