Postretirement Benefit Plans - Weighted-Average Asset Allocation By Investment Category (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Riverview Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Estimated Fair Value	$ 6,895,000	$ 6,720,000	$ 8,984,000
Percentage of Total Assets	100.00%	100.00%
Riverview Defined Benefit Plan | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Estimated Fair Value	$ 48,000	$ 69,000
Percentage of Total Assets	0.70%	1.00%
Riverview Defined Benefit Plan | Mutual fund - equity
Defined Benefit Plan Disclosure [Line Items]
Estimated Fair Value	$ 2,499,000	$ 2,411,000
Percentage of Total Assets	36.20%	35.90%
Riverview Defined Benefit Plan | Common / collective trusts equity
Defined Benefit Plan Disclosure [Line Items]
Estimated Fair Value	$ 310,000	$ 334,000
Percentage of Total Assets	4.50%	5.00%
Riverview Defined Benefit Plan | Mutual fund / EFTs - fixed income
Defined Benefit Plan Disclosure [Line Items]
Estimated Fair Value	$ 4,038,000	$ 3,906,000
Percentage of Total Assets	58.60%	58.10%
Scottdale Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Estimated Fair Value	$ 3,468,000	$ 4,722,000	$ 5,302,000
Percentage of Total Assets	100.00%	100.00%
Scottdale Defined Benefit Pension Plan | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Estimated Fair Value	$ 90,000	$ 108,000
Percentage of Total Assets	2.60%	2.30%
Scottdale Defined Benefit Pension Plan | Corporate debt securities
Defined Benefit Plan Disclosure [Line Items]
Estimated Fair Value	$ 1,192,000	$ 1,841,000
Percentage of Total Assets	34.40%	39.00%
Scottdale Defined Benefit Pension Plan | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Estimated Fair Value	$ 2,186,000	$ 2,773,000
Percentage of Total Assets	63.00%	58.70%