Benefit Plans - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Components of net periodic benefit cost
Service cost	$ 132	$ 98
Interest cost	60	59
Expected return on assets	(122)	(117)
Amortization of prior service cost and net loss	45	13
Pension expense	$ 115	$ 53