Employee Benefit Plan (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Employee Benefit Plan
Service cost	$ 202,000	$ 184,000	$ 606,000	$ 553,000
Interest cost	105,000	137,000	314,000	411,000
Expected return on plan assets	(18,000)	(201)	(55,000)	(604,000)
Amortization of prior service cost	(3)	(4)	(9)	(12)
Amortization of net loss	55,000	71,000	166,000	212,000
Net periodic pension cost	$ 341,000	$ 187,000	$ 1,022,000	$ 560,000