Consolidated Statements Of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Treasury Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings (Accumulated Deficit) [Member]	Foreign Currency Translation [Member]	Benefit Plan Liabilities [Member]	Cash Flow Hedge - Interest Rate Swap [Member]	Noncontrolling Interest [Member]
Beginning Balance at Dec. 31, 2018	$ 75.9	$ 0.4	$ (6.6)	$ 381.0	$ 14.2	$ (52.8)	$ (264.0)	$ 1.0	$ 2.7
Beginning Balance, shares at Dec. 31, 2018		37,656,000
Beginning Balance Treasury Stock, shares at Dec. 31, 2018			(213,000)
Net income (loss)	82.7				82.4				0.3
Foreign currency translation	4.3					4.2			0.1
Changes in defined benefit pension and other post-retirement benefit plans, net of tax	10.9						10.9
Adoption of accounting principle | ASU 2016-02 [Member]	3.0				3.0
Stock-based compensation expense	3.1			3.1
Stock-based compensation expense, shares		340,000
Purchase of subsidiary shares from noncontrolling interest				(2.9)					2.9
Cash flow hedge - interest rate swap, net of tax	(1.3)							(1.3)
Ending Balance at Dec. 31, 2019	178.6	$ 0.4	$ (6.6)	381.2	99.6	(48.6)	(253.1)	(0.3)	6.0
Ending Balance, shares at Dec. 31, 2019		37,996,000
Ending Balance Treasury Stock, shares at Dec. 31, 2019			(213,000)
Net income (loss)	(65.3)				(65.8)				0.5
Foreign currency translation	1.6					1.6
Changes in defined benefit pension and other post-retirement benefit plans, net of tax	31.3						31.3
Stock-based compensation expense	1.9			1.9
Stock-based compensation expense, shares		334,000
Dividends paid to noncontrolling interest	(0.2)								(0.2)
Cash flow hedge - interest rate swap, net of tax	(2.8)							(2.8)
Ending Balance at Dec. 31, 2020	$ 145.1	$ 0.4	$ (6.6)	383.1	33.8	(47.0)	(221.8)	(3.1)	6.3
Ending Balance, shares at Dec. 31, 2020	38,329,897	38,330,000
Ending Balance Treasury Stock, shares at Dec. 31, 2020	212,500		(213,000)
Net income (loss)	$ 295.4				294.3				1.1
Foreign currency translation	(2.1)					(2.1)
Changes in defined benefit pension and other post-retirement benefit plans, net of tax	107.3						107.3
Share repurchases	(1.8)		$ (1.8)
Share repurchase, shares			(80,000)
Stock-based compensation expense	5.5			5.5
Stock-based compensation expense, shares		357,000
Cash dividends and dividend equivalents	(6.4)				(6.4)
Cash flow hedge - interest rate swap, net of tax	1.6							1.6
Ending Balance at Dec. 31, 2021	$ 544.6	$ 0.4	$ (8.4)	$ 388.6	$ 321.7	$ (49.1)	$ (114.5)	$ (1.5)	$ 7.4
Ending Balance, shares at Dec. 31, 2021	38,687,094	38,687,000
Ending Balance Treasury Stock, shares at Dec. 31, 2021	292,932		(293,000)