Acquisitions - Allocation of Acquired Intangible Assets and Related Estimates of Useful Lives (Detail) - Electro Scientific Industries Inc [Member] - USD ($) $ in Thousands			9 Months Ended
	Sep. 30, 2019	Feb. 01, 2019	Sep. 30, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, purchase price		$ 316,200
Completed Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, purchase price			$ 274,000
Completed Technology [Member] \| Lasers Products [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, purchase price		$ 255,700
Estimated useful life of finite-lived intangible assets		12 years
Completed Technology [Member] \| Non Laser Products [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, purchase price		$ 18,300
Estimated useful life of finite-lived intangible assets		10 years
Trademarks and Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, purchase price		$ 14,400
Estimated useful life of finite-lived intangible assets		7 years
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, purchase price	$ 25,400	$ 25,400
Estimated useful life of finite-lived intangible assets		10 years
Backlog [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired intangible assets, purchase price		$ 2,400
Estimated useful life of finite-lived intangible assets		1 year