Restructuring Costs Restructuring Costs Recognized (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period		$ 10.4	$ 1.9	$ 37.9
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		10.4	1.9	36.7
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	1.4
Interest and other income (expense) [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period		0.0	0.0	(0.2)
One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period		4.3	1.0	11.0
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		4.3	1.0	10.9
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	0.1
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
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		1.6	0.5	11.3
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		1.6	0.5	9.8
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	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
Retention Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period		4.5	0.4	15.4
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		4.5	0.4	15.4
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
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
Pension curtailment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred in the period		0.0		(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		$ 0.0		$ (0.2)