Financial Instruments and Derivatives - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			9 Months Ended	12 Months Ended
	Sep. 28, 2014	Sep. 29, 2013	Sep. 28, 2014	Sep. 29, 2013	Dec. 31, 2013	Sep. 28, 2014 Foreign Currency Forward Contracts	Dec. 31, 2013 Foreign Currency Forward Contracts	Oct. 25, 2013 ZTEC Instruments, Inc.
Financial Instruments and Fair Value [Line Items]
Contingent consideration								$ 2,200,000
Contingent consideration, maximum								5,000,000
Contingent consideration discount rate			5.20%
Changes to fair value of contingent consideration	630,000		630,000
Fair market value of investments with unrealized losses	212,156,000		212,156,000		241,760,000
Fair market value of investments with unrealized losses greater than one year	5,000,000		5,000,000		900,000
Fair market value of investments with unrealized losses less than one year	207,200,000		207,200,000		240,900,000
Notional amount of foreign currency forward contracts						67,900,000	74,800,000
Gains (losses) on foreign currency transactions	(400,000)	(400,000)	900,000	(5,000,000)		(600,000)	200,000
Offsetting foreign exchange contracts	0		0		0
Realized (losses) gains on foreign currency contracts	$ 200,000	$ 0	$ (1,600,000)	$ 4,100,000