Pension Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net periodic benefit cost:
Service cost	$ 325	$ 338
Interest cost	1,623	2,002
Expected return on plan assets	(3,279)	(3,330)
Amortization of net actuarial loss	257	191
Total net periodic benefit	$ (1,074)	$ (799)
Weighted average assumptions used to determine net cost
Discount rate to determine net costs	3.00%	4.05%
Expected return on plan assets	6.50%	7.25%
Employer contributions	$ 1,500	$ 1,500