Equity Income from Unconsolidated Subsidiaries - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Equity income from unconsolidated subsidiaries	$ 385,000	$ 1,274,000	$ 827,000	$ 1,479,000
LTM [Member]
Schedule of Equity Method Investments [Line Items]
Share of members' equity of unconsolidated subsidiary	33.33%		33.33%
Equity income from unconsolidated subsidiaries	400,000	1,300,000	800,000	1,500,000
Receivables or unbilled revenues from unconsolidated subsidiary	0		0		0
Revenue from subcontract agreement	$ 100,000	$ 200,000	$ 100,000	$ 300,000