Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Cost	$ 2,286,765		$ 2,286,765		$ 2,232,129
Accumulated depreciation	(1,428,491)		(1,428,491)		(1,389,811)
Total	858,274		858,274		842,318
Depreciation expense	33,365	$ 33,031	67,920	$ 65,219
Land [Member]
Property, Plant and Equipment [Line Items]
Cost	57,857		57,857		56,583
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Cost	541,860		541,860		527,192
Machinery, equipment and other [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 1,687,048		$ 1,687,048		$ 1,648,354