Pension and Supplemental Executive Retirement Plans - Defined Benefit Plan Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Components of net periodic pension cost
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	78	91	156	182
Expected return on plan assets	(118)	(109)	(236)	(218)
Amortization of net actuarial loss	127	105	254	210
Amortization of prior service cost	0	0	0	0
Net periodic benefit cost	87	87	174	174
Contributions paid	$ 0	$ 119	$ 3,835	$ 468