Postretirement Benefit Plans (Net Funded Status) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in benefit obligations:
Change in benefit obligations: Settlement (gain) loss	$ 3,000	$ 34,000
Change in fair value of plan assets:
Funded status at year end	461,000	183,000
Defined Benefit Postretirement Health And Life Coverage [Member]
Change in benefit obligations:
Benefit obligations	404,000	475,000
Change in benefit obligations: Service cost	3,000	3,000	$ 4,000
Change in benefit obligations: Interest cost	13,000	17,000	17,000
Change in benefit obligations: Change in experience	45,000	(13,000)
Change in benefit obligations: Change in assumptions	27,000	34,000
Change in benefit obligations/fair value of plan assets: Benefit payments	(150,000)	(112,000)
Benefit obligations	342,000	404,000	475,000
Change in fair value of plan assets:
Change in fair value of plan assets: Employer contributions	150,000	112,000
Change in benefit obligations/fair value of plan assets: Benefit payments	(150,000)	(112,000)
Funded status at year end	(342,000)	(404,000)
Director's Retirement Plan [Member]
Change in benefit obligations:
Benefit obligations	1,077,000	1,100,000
Change in benefit obligations: Service cost	49,000	51,000	36,000
Change in benefit obligations: Interest cost	31,000	42,000	38,000
Change in benefit obligations: Actuarial gain (loss)	(7,000)	17,000
Change in benefit obligations: Change in assumptions	65,000	(12,000)
Change in benefit obligations/fair value of plan assets: Benefit payments	(87,000)	(87,000)
Benefit obligations	1,142,000	1,077,000	1,100,000
Change in benefit obligations: Actuarial loss (gain)	7,000	(17,000)
Change in fair value of plan assets:
Change in fair value of plan assets: Employer contributions	87,000	87,000
Change in benefit obligations/fair value of plan assets: Benefit payments	(87,000)	(87,000)
Funded status at year end	(1,142,000)	(1,077,000)
Scottdale Defined Benefit Pension Plan [Member]
Change in benefit obligations:
Benefit obligations	5,587,000	5,163,000
Change in benefit obligations: Service cost	79,000	92,000
Change in benefit obligations: Interest cost	180,000	217,000
Change in benefit obligations: Settlement (gain) loss	(85,000)	(91,000)
Change in benefit obligations: Actuarial gain (loss)	495,000	655,000
Change in benefit obligations/fair value of plan assets: Settlement payments	(769,000)	(363,000)
Change in benefit obligations/fair value of plan assets: Benefit payments	(86,000)	(86,000)
Benefit obligations	5,401,000	5,587,000	5,163,000
Change in benefit obligations: Actuarial loss (gain)	(495,000)	(655,000)
Change in fair value of plan assets:
Fair value of plan assets	5,404,000	4,818,000
Change in fair value of plan assets: Return on plan assets	229,000	498,000
Change in fair value of plan assets: Employer contributions	200,000	600,000
Change in benefit obligations/fair value of plan assets: Benefit payments	(86,000)	(86,000)
Change in fair value of plan assets: Administrative expenses	(39,000)	(63,000)
Change in benefit obligations/fair value of plan assets: Settlement payments	(769,000)	(363,000)
Fair value of plan assets	4,939,000	5,404,000	$ 4,818,000
Funded status at year end	$ (462,000)	$ (183,000)