Pension - Components of Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Compensation And Retirement Disclosure [Abstract]
Service cost		$ 191		$ 572
Interest cost	$ 179	259	$ 514	778
Expected return on plan assets	(164)	(231)	(472)	(692)
Amortization of prior service cost		(25)		(75)
Amortization of actuarial loss		15		44
Net periodic pension cost	$ 15	$ 209	$ 43	$ 627