Savings Plans, Pension Plans and Other Postretirement Employee Benefits (Narrative) (Details) - USD ($)	1 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer		$ 4,300,000	$ 4,200,000	$ 4,000,000
Accumulated benefit obligation		223,500,000	223,700,000
Funding of pension and other postretirement benefit plans		3,336,000	5,065,000	$ 9,044,000
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments in Level 3		0	$ 0
Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan and other postretirement employee benefit, estimated payments in next fiscal year		$ 4,400,000
Management Deferred Compensation Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Annual incentive plan, employee permitted minimum defer percentage		50.00%
Annual incentive plan, employee permitted maximum defer percentage		90.00%
Management Deferred Compensation Plan [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Basic salary defer percentage		50.00%
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Change in monthly retirement benefit amount		$ 0
Non-cash pretax settlement charge		$ 14,200,000
Discount rate used to measure projected benefit obligations for qualified pension plans		5.55%	5.60%
Pension plan and other postretirement employee benefit, estimated payments in next fiscal year		$ 16,261,000
Pension Plans [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Transfer of outstanding pension benefit obligation related to qualified pension plans to insurance company	$ 75,600,000
Defined Benefit Plan, Funding Status [Extensible Enumeration]	Defined Benefit Plan, Funded Plan [Member]
Discount rate used to measure projected benefit obligations for qualified pension plans			3.95%	3.00%
Pension Plans [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan and other postretirement employee benefit, estimated payments in next fiscal year		$ 2,600,000
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate used to measure projected benefit obligations for qualified pension plans		5.45%	5.55%
Pension plan and other postretirement employee benefit, estimated payments in next fiscal year		$ 1,949,000
Defined Benefit Plan, Assumption Health Care Cost Trend Rate for Next Fiscal Year		4.00%
Other Postretirement Benefit Plans [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension plan and other postretirement employee benefit, estimated payments in next fiscal year		$ 1,900,000
Other Postretirement Benefit Plans [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year		9.00%
Other Postretirement Benefit Plans [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year		10.62%