Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended
Feb. 28, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Accumulated other comprehensive income (loss)				$ (190,500)	$ (106,399)
Other comprehensive loss before reclassifications				(7,527)	(37,035)
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income	$ (19,331)			4,047	5,628
Net current-period other comprehensive (loss) income		$ 4,698	$ (61,920)	(3,480)	(31,407)
Accumulated other comprehensive income (loss)		(193,980)	(157,137)	(193,980)	(157,137)
Gains and Losses on Cash Flow Hedges
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Accumulated other comprehensive income (loss)				834	72
Other comprehensive loss before reclassifications				(2,038)	79
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income	0			245	732
Net current-period other comprehensive (loss) income				(1,793)	811
Accumulated other comprehensive income (loss)		(959)	883	(959)	883
Pension and Other Postretirement Benefit Items
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Accumulated other comprehensive income (loss)				(138,690)	(103,844)
Other comprehensive loss before reclassifications				(265)	1,293
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income	(19,331)			3,802	4,896
Net current-period other comprehensive (loss) income				3,537	6,189
Accumulated other comprehensive income (loss)		(135,153)	(116,986)	(135,153)	(116,986)
Foreign Currency Items
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Accumulated other comprehensive income (loss)				(52,644)	(2,627)
Other comprehensive loss before reclassifications				(5,224)	(38,407)
Amounts reclassified from accumulated other comprehensive income to the consolidated statements of income	$ 0			0	0
Net current-period other comprehensive (loss) income				(5,224)	(38,407)
Accumulated other comprehensive income (loss)		$ (57,868)	$ (41,034)	$ (57,868)	$ (41,034)

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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