Pension and Supplemental Executive Retirement Plans - Defined Benefit Plan Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Components of net periodic pension cost
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	78	91	234	273
Expected return on plan assets	(118)	(109)	(354)	(327)
Amortization of net actuarial loss	127	105	381	315
Amortization of prior service cost	0	0	0	0
Net periodic benefit cost	87	87	261	261
Contributions paid	$ 0	$ 119	$ 3,835	$ 587