Employee Benefit Plans - Summary of Changes in Projected Benefit Obligations and Plan Assets, and Ending Balances of Defined Benefit Plans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Change in projected benefit obligations:
Service cost	$ 1.0	$ 0.8
Interest cost	0.4	0.5
Change in plan assets:
Fair value of plan assets, beginning of year	11.1
Fair value of plan assets, end of year	12.9	11.1
Newport Corporation
Change in projected benefit obligations:
Projected benefit obligations, beginning of year	30.1	24.9
Assumed in ESI Merger		3.5
Service cost	1.0	0.8
Interest cost	0.4	0.5
Contributions by plan participants	0.7
Plan amendments	(0.2)
Actuarial loss	3.0	2.1
Benefits paid	(1.2)	(1.5)
Currency translation adjustments	2.4	(0.2)
Projected benefit obligations, end of year	36.2	30.1
Change in plan assets:
Fair value of plan assets, beginning of year	11.1	7.8
Assumed in ESI Merger		1.3
Company contributions	1.1	1.8
Gain on plan assets	0.6	0.6
Benefits paid	(0.5)	(0.5)
Currency translation adjustments	0.6	0.1
Fair value of plan assets, end of year	12.9	11.1
Net underfunded status	$ (23.3)	$ (19.0)