Goodwill and Purchased Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 23, 2016	Sep. 25, 2015	Sep. 23, 2016	Sep. 25, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization of finite-lived intangibles	$ 1,400	$ 1,600	$ 4,318	$ 4,042
Marchi Thermal Systems Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of finite-lived intangibles		$ 700		$ 1,700
Trade Name [Member] | American Integration Technologies LLC [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			6 years
Trade Name [Member] | American Integration Technologies LLC [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Trade Name [Member] | Marchi Thermal Systems Inc [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			6 years
Trade Name [Member] | Marchi Thermal Systems Inc [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Customer Relationships [Member] | American Integration Technologies LLC [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			6 years
Customer Relationships [Member] | American Integration Technologies LLC [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Customer Relationships [Member] | Marchi Thermal Systems Inc [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Customer Relationships [Member] | Marchi Thermal Systems Inc [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years
Customer Relationships [Member] | Miconex [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Customer Relationships [Member] | Miconex [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years
Intellectual Properties/Know-How [Member] | Marchi Thermal Systems Inc [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Intellectual Properties/Know-How [Member] | Marchi Thermal Systems Inc [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years
Intellectual Properties/Know-How [Member] | Miconex [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			7 years
Intellectual Properties/Know-How [Member] | Miconex [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated economic lives for intangible assets			12 years