Restructuring Costs Restructuring Costs Recognized (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	$ 0.5	$ 6.1	$ 1.9	$ 27.5
Restructuring and Related Cost, Cost Incurred to Date	111.3		111.3
Restructuring Costs, Expected Costs	0.0
General and Administrative Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.5	6.0	1.9	26.3
Net gain (loss) from asset sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.0	0.0	0.0	1.4
Interest and other income (expense) [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.0	0.1	0.0	(0.2)
One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.0	(0.1)	1.0	6.7
Restructuring and Related Cost, Cost Incurred to Date	45.6		45.6
Restructuring Costs, Expected Costs	0.0
One-time Termination Benefits [Member] | General and Administrative Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.0	(0.1)	1.0	6.6
One-time Termination Benefits [Member] | Net gain (loss) from asset sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.0	0.0	0.0	0.1
One-time Termination Benefits [Member] | Interest and other income (expense) [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.0	0.0	0.0	0.0
Lease Termination Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period				0.6
Restructuring and Related Cost, Cost Incurred to Date	1.6		1.6
Restructuring Costs, Expected Costs	0.0
Lease Termination Costs [Member] | General and Administrative Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period				0.6
Lease Termination Costs [Member] | Net gain (loss) from asset sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period				0.0
Lease Termination Costs [Member] | Interest and other income (expense) [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period				0.0
Accelerated Share Based Compensation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.3	1.3	0.5	9.7
Restructuring and Related Cost, Cost Incurred to Date	24.1		24.1
Restructuring Costs, Expected Costs	0.0
Accelerated Share Based Compensation [Member] | General and Administrative Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.3	1.3	0.5	8.2
Accelerated Share Based Compensation [Member] | Net gain (loss) from asset sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.0	0.0	0.0	1.5
Accelerated Share Based Compensation [Member] | Interest and other income (expense) [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.0	0.0	0.0	0.0
Retention Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.2	4.8	0.4	10.9
Restructuring and Related Cost, Cost Incurred to Date	38.7		38.7
Restructuring Costs, Expected Costs	0.0
Retention Expense [Member] | General and Administrative Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.2	4.8	0.4	10.9
Retention Expense [Member] | Net gain (loss) from asset sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.0	0.0	0.0	0.0
Retention Expense [Member] | Interest and other income (expense) [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period	0.0	0.0	0.0	0.0
Pension curtailment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period		0.1		(0.4)
Restructuring and Related Cost, Cost Incurred to Date	1.3		$ 1.3
Restructuring Costs, Expected Costs	$ 0.0
Pension curtailment [Member] | General and Administrative Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period		0.0		0.0
Pension curtailment [Member] | Net gain (loss) from asset sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period		0.0		(0.2)
Pension curtailment [Member] | Interest and other income (expense) [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period		$ 0.1		$ (0.2)