Retirement Plans - Schedule Of Net Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
United States
Defined Benefit Plan Disclosure
Interest cost	$ 56	$ 162	$ 168	$ 486
Expected return on plan assets	(58)	(180)	(173)	(540)
Recognized net actuarial loss	13	31	40	94
Net periodic pension cost	11	13	35	40
United Kingdom
Defined Benefit Plan Disclosure
Interest cost	43	53	129	159
Expected return on plan assets	(59)	(60)	(177)	(180)
Amortization of prior service costs and transition amount	6	10	18	30
Recognized net actuarial loss	63	52	189	156
Net periodic pension cost	$ 53	$ 55	$ 159	$ 165