Pension - Components of Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Compensation And Retirement Disclosure [Abstract]
Interest cost	$ 82	$ 168	$ 164	$ 336
Expected return on plan assets	(78)	(154)	156	308
Net periodic pension cost	$ 4	$ 14	$ 8	$ 28