Statement of Consolidated Shareholders' Deficit - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Capital Surplus	Accumulated Deficit	Accumulated Other Comprehensive Loss	Treasury Stock, At Cost
Beginning balance at Dec. 31, 2017	$ (353.5)	$ 0.0	$ 0.3	$ 2,323.3	$ (2,228.6)	$ (355.8)	$ (92.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	0.2	0.0		0.2
Net income (loss)	(14.6)	0.0			(14.6)
Amortization of prior net losses	3.8	0.0				3.8
Amortization of prior net service credit	(0.1)	0.0				(0.1)
Foreign currency translation adjustments	(1.7)	0.0				(1.7)
Ending balance at Mar. 31, 2018	(365.9)	0.0	0.3	2,323.5	(2,243.2)	(353.8)	(92.7)
Beginning balance at Dec. 31, 2017	(353.5)	0.0	0.3	2,323.3	(2,228.6)	(355.8)	(92.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	20.2
Amortization of prior net losses	14.6
Amortization of prior net service credit	(0.4)
Settlement adjustment	10.9
Net actuarial loss	1.0
Foreign currency translation adjustments	(2.6)
Ending balance at Dec. 31, 2018	(305.5)	0.0	0.3	2,327.6	(2,208.4)	(332.3)	(92.7)
Beginning balance at Mar. 31, 2018	(365.9)	0.0	0.3	2,323.5	(2,243.2)	(353.8)	(92.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	3.1	0.0		3.1
Net income (loss)	14.4	0.0			14.4
Amortization of prior net losses	3.8	0.0				3.8
Amortization of prior net service credit	(0.1)	0.0				(0.1)
Foreign currency translation adjustments	0.6	0.0				0.6
Ending balance at Jun. 30, 2018	(344.1)	0.0	0.3	2,326.6	(2,228.8)	(349.5)	(92.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	0.2	0.0		0.2
Net income (loss)	2.9	0.0			2.9
Amortization of prior net losses	3.5	0.0				3.5
Amortization of prior net service credit	(0.1)	0.0				(0.1)
Settlement adjustment	7.2	0.0				7.2
Net actuarial loss	0.7	0.0				0.7
Foreign currency translation adjustments	0.9	0.0				0.9
Ending balance at Sep. 30, 2018	(328.8)	0.0	0.3	2,326.8	(2,225.9)	(337.3)	(92.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	0.8	0.0		0.8
Net income (loss)	17.5	0.0			17.5
Amortization of prior net losses	3.5	0.0				3.5
Amortization of prior net service credit	(0.1)	0.0				(0.1)
Settlement adjustment	3.7	0.0				3.7
Net actuarial loss	0.3	0.0				0.3
Foreign currency translation adjustments	(2.4)	0.0				(2.4)
Ending balance at Dec. 31, 2018	(305.5)	0.0	0.3	2,327.6	(2,208.4)	(332.3)	(92.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	1.6	0.0		1.6
Net income (loss)	(49.1)	0.0			(49.1)
Amortization of prior net losses	3.2	0.0				3.2
Amortization of prior net service credit	(0.1)	0.0				(0.1)
Foreign currency translation adjustments	0.4	0.0				0.4
Ending balance at Mar. 31, 2019	(349.5)	0.0	0.3	2,329.2	(2,257.5)	(328.8)	(92.7)
Beginning balance at Dec. 31, 2018	(305.5)	0.0	0.3	2,327.6	(2,208.4)	(332.3)	(92.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(104.0)
Amortization of prior net losses	12.9
Amortization of prior net service credit	(0.4)
Settlement adjustment	1.8
Net actuarial loss	(51.7)
Foreign currency translation adjustments	0.4
Ending balance at Dec. 31, 2019	(441.2)	0.0	0.3	2,332.9	(2,312.4)	(369.3)	(92.7)
Beginning balance at Mar. 31, 2019	(349.5)	0.0	0.3	2,329.2	(2,257.5)	(328.8)	(92.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	1.0	0.0		1.0
Net income (loss)	(23.6)	0.0			(23.6)
Amortization of prior net losses	1.6	0.0				1.6
Amortization of prior net service credit	(0.1)	0.0				(0.1)
Foreign currency translation adjustments	0.5	0.0				0.5
Ending balance at Jun. 30, 2019	(370.1)	0.0	0.3	2,330.2	(2,281.1)	(326.8)	(92.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	1.8	0.0		1.8
Net income (loss)	(16.0)	0.0			(16.0)
Amortization of prior net losses	2.5	0.0				2.5
Amortization of prior net service credit	(0.1)	0.0				(0.1)
Settlement adjustment	1.7	0.0				1.7
Net actuarial loss	0.3	0.0				0.3
Foreign currency translation adjustments	(0.8)	0.0				(0.8)
Ending balance at Sep. 30, 2019	(380.7)	0.0	0.3	2,332.0	(2,297.1)	(323.2)	(92.7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-based compensation	0.9	0.0		0.9
Net income (loss)	(15.3)	0.0			(15.3)
Amortization of prior net losses	5.6	0.0				5.6
Amortization of prior net service credit	(0.1)	0.0				(0.1)
Settlement adjustment	0.1	0.0				0.1
Net actuarial loss	(52.0)	0.0				(52.0)
Foreign currency translation adjustments	0.3	0.0				0.3
Ending balance at Dec. 31, 2019	$ (441.2)	$ 0.0	$ 0.3	$ 2,332.9	$ (2,312.4)	$ (369.3)	$ (92.7)