Accumulated Other Comprehensive Income (AOCI) (Schedule of Items Reclassified to Statement of Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax effect	$ (10,040)	$ (12,454)
Effect on net income due to items reclassified from Accumulated Other Comprehensive Income	27,582	9,109
Amortization of prior service credit	(1,119)	(1,114)
Net actuarial loss	1,109	1,244
Total pretax amount reclassified	37,649	20,048
Reclassification out of Accumulated Other Comprehensive Income | Derivative valuation adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Expense/(income) related to interest rate swaps included in Income before taxes	1,476	407
Income tax effect	(381)	(104)
Effect on net income due to items reclassified from Accumulated Other Comprehensive Income	1,095	303
Reclassification out of Accumulated Other Comprehensive Income | Pension and postretirement liability adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax effect	3	(32)
Effect on net income due to items reclassified from Accumulated Other Comprehensive Income	(7)	98
Amortization of prior service credit	(1,119)	(1,114)
Net actuarial loss	1,109	1,244
Total pretax amount reclassified	$ (10)	$ 130