Pension - Components of Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Compensation And Retirement Disclosure [Abstract]
Service cost		$ 189		$ 381
Interest cost	$ 168	259	$ 336	519
Expected return on plan assets	(154)	(229)	(308)	(461)
Amortization of prior service cost		(25)		(50)
Amortization of actuarial loss		14		29
Net periodic pension cost	$ 14	$ 208	$ 28	$ 418