Pension Plans and Other Postretirement Benefits (Details-2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Amortization of:
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Transition Asset (Obligation), Statement of Income or Comprehensive Income [Extensible Enumeration]	Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Nonoperating Income (Expense)
Pension Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 2,892	$ 5,064	$ 5,730
Interest cost	17,319	11,161	9,109
Expected return on assets	(25,248)	(31,391)	(29,487)
Amortization of:
Transition obligation	0	0	0
Prior service (credit) cost	0	(20)	(124)
Actuarial loss	1,760	2,416	6,646
Net periodic benefit cost (credit)	(3,277)	(12,770)	(8,126)
Postretirement Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	780	1,293	1,448
Interest cost	3,308	1,940	1,549
Expected return on assets	(2,595)	(3,365)	(3,277)
Amortization of:
Transition obligation	3	3	3
Prior service (credit) cost	0	(297)	(1,518)
Actuarial loss	(190)	145	493
Net periodic benefit cost (credit)	$ 1,306	$ (281)	$ (1,302)