Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 27, 2015	Sep. 27, 2015	Sep. 28, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010
Significant Accounting Policies [Line Items]
Reporting period		270 days	271 days
Fair value measurements, transfers between Level 1 and Level 2	$ 0	$ 0	$ 0
Original maturity period of cash and cash equivalents		Three months or less
Fair value of cash and cash equivalents based on quoted market prices in active markets Level 1 valuation	0	$ 0
Gain/(Loss) on disposal of discontinued operations, net of tax		(86,000)	(562,000)
Thermax and Raydex [Member]
Significant Accounting Policies [Line Items]
Gain/(Loss) on disposal of discontinued operations, before income tax			(900,000)		$ 211,600,000
Gain/(Loss) on disposal of discontinued operations, net of tax			$ (600,000)		124,700,000
Cash proceeds from the sales of discontinued operations					$ 265,600,000
Trapeze [Member]
Significant Accounting Policies [Line Items]
Sale price for business						$ 152,100,000
Gain/(Loss) on disposal of discontinued operations, before income tax		(200,000)				88,300,000
Gain/(Loss) on disposal of discontinued operations, net of tax		(100,000)				44,800,000
Cash proceeds from the sales of discontinued operations						136,900,000
Amount in escrow as partial security for Company's indemnity obligations under transaction's purchase and sale agreement						$ 15,200,000
Escrow receivable collected		3,500,000		$ 4,200,000
Loss from discontinued operations, net of tax	(200,000)	(200,000)
Standby Letters of Credit [Member]
Significant Accounting Policies [Line Items]
Standby letters of credit, bank guaranties, and surety bonds	7,800,000	7,800,000
Bank Guaranties [Member]
Significant Accounting Policies [Line Items]
Standby letters of credit, bank guaranties, and surety bonds	3,100,000	3,100,000
Surety Bonds [Member]
Significant Accounting Policies [Line Items]
Standby letters of credit, bank guaranties, and surety bonds	$ 1,800,000	$ 1,800,000
First Quarter Fiscal Year 2015 [Member]
Significant Accounting Policies [Line Items]
Reporting period		88 days
Guideline used to determine the end date of first quarter		91 days
Fiscal Second Quarter 2015 [Member]
Significant Accounting Policies [Line Items]
Reporting period		91 days
Fiscal Third Quarter 2015 [Member]
Significant Accounting Policies [Line Items]
Reporting period		91 days