Retirement Plans - Schedule Of Net Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
United States
Defined Benefit Plan Disclosure
Interest cost	$ 56	$ 162	$ 112	$ 324
Expected return on plan assets	(58)	(180)	(115)	(360)
Recognized net actuarial loss	13	31	27	63
Net periodic pension cost	11	13	24	27
United Kingdom
Defined Benefit Plan Disclosure
Interest cost	43	54	86	108
Expected return on plan assets	(58)	(61)	(116)	(122)
Amortization of prior service costs and transition amount	6	11	12	22
Recognized net actuarial loss	63	53	126	106
Net periodic pension cost	$ 54	$ 57	$ 108	$ 114