Employer Sponsored Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Components of employer benefit cost
Service cost	$ 40	$ 30
Interest cost	430	982
Expected return on assets	(533)	(872)
Amortization of actuarial loss	2	278
Net periodic benefit cost	(61)	418
Settlement loss	385	0
Total employer benefit plan cost	$ 324	$ 418