Financial Instruments and Derivatives - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended					6 Months Ended	12 Months Ended
	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013	Dec. 31, 2013	Oct. 25, 2013 ZTEC Instruments, Inc.	Oct. 25, 2013 ZTEC Instruments, Inc. Maximum	Jun. 29, 2014 Foreign Currency Forward Contracts	Dec. 31, 2013 Foreign Currency Forward Contracts
Financial Instruments and Fair Value [Line Items]
Available-for-sale securities, realized gain	$ 400,000	$ 100,000	$ 700,000	$ 300,000
Available-for-sale securities, realized losses	0	0	0	0
Contingent consideration						2,200,000	5,000,000
Contingent consideration discount rate			5.20%
Changes to fair value of contingent consideration			0
Fair market value of investments with unrealized losses	104,322,000		104,322,000		241,760,000
Fair market value of investments with unrealized losses greater than one year	6,900,000		6,900,000		900,000
Fair market value of investments with unrealized losses less than one year	97,400,000		97,400,000		240,900,000
Notional amount of foreign currency forward contracts								69,400,000	74,800,000
Gains (losses) on foreign currency transactions	700,000	(1,800,000)	1,300,000	(4,600,000)				(300,000)	200,000
Offsetting foreign exchange contracts	0		0		0
Realized (losses) gains on foreign currency contracts	$ (1,100,000)	$ 1,800,000	$ (1,900,000)	$ 4,100,000