Pension and Other Post Retirement Benefit Plans - Components of Net Periodic Benefit Cost for Company's Defined Benefit Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
United States
Net periodic benefit cost:
Interest cost	$ 85	$ 127	$ 114
Amortization of prior service cost and actuarial loss	7
Net periodic benefit cost	$ 92	$ 127	$ 114
Assumptions:
Discount rate	2.40%	3.65%	2.95%
German Plan
Net periodic benefit cost:
Interest cost	$ 88	$ 147	$ 147
Expected return on plan assets	(121)	(126)	(130)
Amortization of prior service cost and actuarial loss	124	72	73
Net periodic benefit cost	$ 91	$ 93	$ 90
Assumptions:
Discount rate	1.08%	1.06%	2.04%
Long-term return on assets	2.90%	3.10%	3.40%