Retirement Plans and Other Post-Retirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 61	$ 0	$ 153
Interest cost	266	318	789	919
Amortization of prior service cost/(credit)	12	12	36	35
Amortization of actuarial loss (gains)	199	164	597	485
Total net periodic benefit expense/(income)	477	555	1,422	1,592
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	8	8	22	22
Interest cost	31	46	95	138
Amortization of prior service cost/(credit)	(58)	(115)	(175)	(347)
Amortization of actuarial loss (gains)	11	(209)	35	(626)
Total net periodic benefit expense/(income)	$ (8)	$ (270)	$ (23)	$ (813)