Shareowners' Deficit Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Changes in Accumulated Other Comprehensive Loss by Component [Roll Forward]
Beginning Balance		$ (173.7)
Remeasurement of benefit obligations		(5.5)		$ 2.8		$ 6.6
Unrealized gain on Investment in CyrusOne, net		0.0		8.3		68.1
Reclassification adjustment to accumulated deficit for stranded other comprehensive income taxes arising from tax reform				0.0
Foreign currency gain (loss)		(6.5)		0.2		(0.1)
Unrealized loss on cash flow hedge arising during the period, net		(4.8)		0.0		0.0
Ending Balance		(175.5)		(173.7)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Changes in Accumulated Other Comprehensive Loss by Component [Roll Forward]
Beginning Balance		(173.1)		(157.6)
Remeasurement of benefit obligations		(5.5)		2.8
Unrealized gain on Investment in CyrusOne, net				0.0
Reclassifications, net	[1]	14.1		13.9
Reclassification adjustment to accumulated deficit for stranded other comprehensive income taxes arising from tax reform	[2]			(32.2)
Foreign currency gain (loss)		0.0		0.0
Unrealized loss on cash flow hedge arising during the period, net		0.0
Ending Balance		(164.5)		(173.1)		(157.6)
Accumulated Net Investment Gain (Loss) Attributable to Parent
Changes in Accumulated Other Comprehensive Loss by Component [Roll Forward]
Beginning Balance		0.0		68.1
Remeasurement of benefit obligations		0.0		0.0
Unrealized gain on Investment in CyrusOne, net	[3]			8.3
Reclassifications, net		0.0		(76.4)	[4]
Reclassification adjustment to accumulated deficit for stranded other comprehensive income taxes arising from tax reform				0.0
Foreign currency gain (loss)		0.0		0.0
Unrealized loss on cash flow hedge arising during the period, net		0.0
Ending Balance		0.0		0.0		68.1
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest [Member]
Changes in Accumulated Other Comprehensive Loss by Component [Roll Forward]
Beginning Balance		0.0		0.0
Remeasurement of benefit obligations		0.0		0.0
Unrealized gain on Investment in CyrusOne, net				0.0
Reclassifications, net		0.9	[5]	0.0
Reclassification adjustment to accumulated deficit for stranded other comprehensive income taxes arising from tax reform				0.0
Foreign currency gain (loss)		0.0		0.0
Unrealized loss on cash flow hedge arising during the period, net	[6]	(4.8)
Ending Balance		(3.9)		0.0		0.0
Accumulated Foreign Currency Adjustment Attributable to Parent
Changes in Accumulated Other Comprehensive Loss by Component [Roll Forward]
Beginning Balance		(0.6)		(0.8)
Remeasurement of benefit obligations		0.0		0.0
Unrealized gain on Investment in CyrusOne, net				0.0
Reclassifications, net		0.0		0.0
Reclassification adjustment to accumulated deficit for stranded other comprehensive income taxes arising from tax reform				0.0
Foreign currency gain (loss)		(6.5)		0.2
Unrealized loss on cash flow hedge arising during the period, net		0.0
Ending Balance		(7.1)		(0.6)		(0.8)
AOCI Attributable to Parent
Changes in Accumulated Other Comprehensive Loss by Component [Roll Forward]
Beginning Balance		(173.7)		(90.3)
Remeasurement of benefit obligations		(5.5)		2.8
Unrealized gain on Investment in CyrusOne, net				8.3
Reclassifications, net		15.0		(62.5)
Reclassification adjustment to accumulated deficit for stranded other comprehensive income taxes arising from tax reform	[7]			(32.2)
Foreign currency gain (loss)		(6.5)		0.2
Unrealized loss on cash flow hedge arising during the period, net		(4.8)
Ending Balance		$ (175.5)		$ (173.7)		$ (90.3)

[1] These reclassifications are included in the other components of net periodic pension and postretirement benefit plans expense and represent amortization of prior service benefit and actuarial loss, net of tax and pension settlement charges, net of tax. The other components of net periodic pension and postretirement benefit plans expense are recorded in "Other components of pension and postretirement benefit plans expense" on the Consolidated Statements of Operations. See Note 11 for further disclosures.

[2] This reclassification adjustment resulted from a change in the corporate tax rate arising from tax legislation enacted in December 2017, commonly referred to as the Tax Cuts and Jobs Act (the "Tax Act"). In February 2018, the FASB issued ASU 2018-02 which allows entities to make a one-time reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from newly enacted corporate tax rates. The Company early adopted the guidance effective December 31, 2017. The amount of the reclassification is calculated on the basis of the difference between the historical and newly enacted tax rates on deferred taxes related to our pension and postretirement benefit plans.

[3] The unrealized gain on Investment in CyrusOne, net of tax, represents changes in the fair value of CyrusOne shares of common stock owned by the Company during the period, before any subsequent sales of those shares.

[4] These reclassifications are reported within "Gain on sale of CyrusOne investment" on the Consolidated Statements of Operations.

[5] These reclassifications are reported within "Interest expense" on the Consolidated Statements of Operations when the hedged transactions impact earnings.

[6] The unrealized loss on cash flow hedge represents the change in the fair value of the derivative instrument that occurred during the period, net of tax. This unrealized loss is recorded in "Other current liabilities" and "Other noncurrent liabilities" on the Consolidated Balance Sheets. See Note 10 for further disclosures.

[7] Per ASU 2018-02, entities can elect to make a one-time reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from newly enacted corporate tax rates under the Tax Cuts and Jobs Act. The Company elected to make the change and recorded the adjustment in 2017.