Income Taxes, Deferred Tax Assets and Liabilities, Operating Loss Carryovers (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets [Abstract]
Benefit plans			$ 7,665	$ 6,293
Liabilities and reserves			19,291	21,085
Operating loss and credit carryovers	[1]		77,756	82,000
Other			13,228	1,126
Gross deferred tax assets			117,940	110,504
Valuation allowance	[1]		(47,813)	(54,326)
Deferred tax assets			70,127	56,178
Deferred tax liabilities [Abstract]
Property, plant, and equipment			(31,709)	(29,869)
Goodwill			(22,012)	(21,744)
Other			0	(5,192)
Deferred tax liabilities			(53,721)	(56,805)
Net deferred tax assets			16,406
Net deferred tax (liabilities)				(627)
Increase in valuation allowance amount		$ 16,200
Operating Loss Carryforwards [Abstract]
Operating loss carryovers, tax credit			39,300
Deferred tax assets held for sale			100
Deferred tax liabilities, held for sale				$ 600
Undistributed earnings			625,000
Withholding of tax liability			28,300
Foreign [Member]
Operating Loss Carryforwards [Abstract]
Operating loss carryovers			110,000
Operating loss carryovers, subject to expiration			11,800
Operating loss carryovers, not subject to expiration			98,200
State [Member]
Operating Loss Carryforwards [Abstract]
Operating loss carryovers			132,600
Operating loss carryovers, subject to expiration			$ 132,600

[1] In the first quarter of 2019, the Company recognized an increase in its foreign tax credit carryover and corresponding valuation allowance of $16.2 million, related to the finalization of certain tax regulations.