Pension Plans (Plan Assets for Qualified Pension Plan) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value plan assets before accrued income		$ 541,733	$ 762,186
Total carrying value		$ 544,642	764,009
Liquidity		61.30%
Maximize return		38.70%
Qualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		$ 544,642	$ 764,009	$ 766,921
Expected return on plan assets		5.70%	6.00%
Managers’ securities holdings percentage maximum limit of total market value		7.50%
Quoted prices  in active markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value plan assets before accrued income		$ 113,660	$ 112,089
Total carrying value		113,767	112,056
Significant  other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value plan assets before accrued income		250,179	233,075
Total carrying value		252,981	234,931
Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value plan assets before accrued income		0	0
Defined benefit plan, fair value of plan assets, accrued income		0	0
Total carrying value		0	0
Not Subject to Leveling [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value plan assets before accrued income		177,894	417,022
Total carrying value		177,894	417,022
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		14,168	19,033
Cash and cash equivalents | Quoted prices  in active markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		14,168	19,033
Cash and cash equivalents | Significant  other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Cash and cash equivalents | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Cash and cash equivalents | Not Subject to Leveling [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Derivative
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		145	2,014
Derivative | Significant  other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		145	2,014
Futures contracts - liabilities
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		(1,283)	(372)
Futures contracts - liabilities | Significant  other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		(1,283)	(372)
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		251,317	231,433
Fixed income securities | Quoted prices  in active markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Fixed income securities | Significant  other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		251,317	231,433
Fixed income securities | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Fixed income securities | Not Subject to Leveling [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		73,042	72,834
Mutual funds | Quoted prices  in active markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		73,042	72,834
Mutual funds | Significant  other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Mutual funds | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Mutual funds | Not Subject to Leveling [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Common trust funds
Defined Benefit Plan Disclosure [Line Items]
Total carrying value	[1]	177,894	417,022
Common trust funds | Quoted prices  in active markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Common trust funds | Significant  other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Common trust funds | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Common trust funds | Not Subject to Leveling [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		177,894	417,022
Corporate stock
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		26,450	20,222
Corporate stock | Quoted prices  in active markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		26,450	20,222
Corporate stock | Significant  other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Corporate stock | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Corporate stock | Not Subject to Leveling [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Other Income
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		2,909	1,823
Other Income | Quoted prices  in active markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		107	(33)
Other Income | Significant  other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		2,802	1,856
Other Income | Not Subject to Leveling [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Assets | Futures contracts - liabilities | Quoted prices  in active markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Assets | Futures contracts - liabilities | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Assets | Futures contracts - liabilities | Not Subject to Leveling [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Liability | Futures contracts - liabilities | Quoted prices  in active markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Liability | Futures contracts - liabilities | Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		0	0
Liability | Futures contracts - liabilities | Not Subject to Leveling [Member]
Defined Benefit Plan Disclosure [Line Items]
Total carrying value		$ 0	$ 0

[1] 1) In accordance with ASU 2015-07, Fair Value Measurement (Topic 820), certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented for the total pension plan assets.