Other Comprehensive Income (Loss) - Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other (income) expense - net									$ 5,627	$ 1,759	$ (3,985)
Interest expense									44,746	44,341	44,134
Total before tax									(470,340)	(532,903)	(528,939)
Provision for income taxes									92,562	107,382	118,366
Total net of tax	$ (101,068)	$ (103,848)	$ (70,864)	$ (101,998)	$ (96,850)	$ (105,194)	$ (113,209)	$ (110,268)	(377,778)	(425,521)	(410,573)
Reclassification out of Accumulated Other Comprehensive Income | Retirement Benefits Adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax									2,876	2,810	2,938
Provision for income taxes									(106)	(944)	(701)
Total net of tax									2,770	1,866	2,237
Reclassification out of Accumulated Other Comprehensive Income | Amortization/recognition of settlement loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other (income) expense - net									2,909	2,858	3,246
Reclassification out of Accumulated Other Comprehensive Income | Recognition of settlement loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other (income) expense - net									(33)	(48)	(308)
Reclassification out of Accumulated Other Comprehensive Income | Cumulative Unrealized Gain (Loss)  on Derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									6,021	6,327	6,475
Total before tax									6,021	6,327	6,475
Provision for income taxes									(1,369)	(1,445)	(1,469)
Total net of tax									$ 4,652	$ 4,882	$ 5,006