Benefit Plans - Defined Benefit Plans - Components of Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Supplemental Retirement Plan
Components of net periodic benefit cost:
Service cost	$ 120	$ 123	$ 240	$ 246
Interest cost	190	236	380	467
Amortization of prior service cost	75		100
Amortization of net actuarial loss	136	105	272	190
Net periodic benefit cost	521	464	992	903
Defined Benefit Plan, Assets for Plan Benefits	0		0
Split-Dollar Life Insurance Benefit Plan
Components of net periodic benefit cost:
Interest cost	55	62	110	124	$ 246
Amortization of prior transition obligation	(1)	(15)	(2)	(30)
Net periodic benefit cost	$ 54	$ 47	$ 108	$ 94