Schedule of Fair Value of Assets and Liabilities (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2022	Dec. 25, 2021
American & Foreign Power Company, Inc. 5% debentures, due 2030
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long term debt, interest rate	5.00%	5.00%
Carrying Amount | Long-Term Debt | New Facilities loans Under Third Amended Credit Agreement due 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, due date	2025	2025
Carrying Amount | Long-Term Debt | Revenue bonds, due in varying amounts periodically through 2029
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, due date	2029	2029
Carrying Amount | Long-Term Debt | American & Foreign Power Company, Inc. 5% debentures, due 2030
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, due date	2030	2030
Long term debt, interest rate	5.00%	5.00%
Fair Value | Long-Term Debt | New Facilities loans Under Third Amended Credit Agreement due 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, due date	2025	2025
Fair Value | Long-Term Debt | Revenue bonds, due in varying amounts periodically through 2029
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, due date	2029	2029
Fair Value | Long-Term Debt | American & Foreign Power Company, Inc. 5% debentures, due 2030
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, due date	2030	2030
Long term debt, interest rate	5.00%	5.00%