Pension and Other Postretirement Plans (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) benefit_plan	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) benefit_plan	Jun. 30, 2019 USD ($)	Dec. 31, 2007
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of non-qualified defined benefit pension plans | benefit_plan	3		3
Number of healthcare plans | benefit_plan	2		2
Defined Benefit Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Vesting percentage in accrued benefits from plan freeze					100.00%
Service cost	$ 27	$ 24	$ 54	$ 48
Interest cost	169	210	337	420
Expected return on plan assets	(316)	(272)	(631)	(544)
Amortization of prior service cost	0	0	0	0
Amortization of net loss	145	165	290	330
Net periodic benefit cost	25	127	50	254
Minimum required contribution	0		0
Planned contributions remaining	800		800
Company contributions to plan			200
Chairman and President Non-Qualified Defined Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	303	126	605	251
Interest cost	337	256	675	512
Amortization of prior service cost	15	15	30	30
Amortization of net loss	1,445	348	2,890	696
Net periodic benefit cost	2,100	745	4,200	1,489
Company contributions to plan			900
Company expected contributions to plans in fiscal year	2,000		2,000
Defined Benefit Postretirement Healthcare Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	42	50	83	99
Amortization of prior service cost	0	13	0	26
Amortization of net loss	39	61	79	122
Net periodic benefit cost	$ 81	$ 124	$ 162	$ 247
Minimum | Chairman and President Non-Qualified Defined Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Aggregate average annual participant salary increase			10.00%