Fair Value of Assets and Liabilities - Fair Value Measurements (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Transfers Between Levels Amount	$ 0.0	$ 0.0
Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Total	15.9		$ 20.9
Fair value liabilities measured on recurring basis
Total	16.1		11.4
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Total	12.8		16.2
Fair value liabilities measured on recurring basis
Total	6.0		6.2
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Total	3.1		4.7
Fair value liabilities measured on recurring basis
Total	10.1		5.2
Short-term investments | Certificates of deposit | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Fair value of investment assets	6.8		10.0
Short-term investments | Certificates of deposit | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Fair value of investment assets	6.8		10.0
Short-term investments | Certificates of deposit | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Fair value of investment assets	0.0		0.0
Securities and other investments | Interest rate swaps | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Derivative Asset	0.0		0.1
Securities and other investments | Interest rate swaps | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Derivative Asset	0.0		0.0
Securities and other investments | Interest rate swaps | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Derivative Asset	0.0		0.1
Securities and other investments | Assets held in rabbi trusts [Member] | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Assets held in rabbi trusts	6.0		6.2
Securities and other investments | Assets held in rabbi trusts [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Assets held in rabbi trusts	6.0		6.2
Securities and other investments | Assets held in rabbi trusts [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Assets held in rabbi trusts	0.0		0.0
Other current assets | Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Derivative Asset	3.1		2.9
Other current assets | Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Derivative Asset	0.0		0.0
Other current assets | Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Derivative Asset	3.1		2.9
Other current assets | Interest rate swaps | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Derivative Asset	0.0		1.7
Other current assets | Interest rate swaps | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Derivative Asset	0.0		0.0
Other current assets | Interest rate swaps | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Derivative Asset	0.0		1.7
Other current liabilities | Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	4.1		2.9
Other current liabilities | Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	0.0		0.0
Other current liabilities | Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	4.1		2.9
Other liabilities | Fair Value, Measurements, Recurring [Member]
Fair value liabilities measured on recurring basis
Deferred compensation	6.0		6.2
Other liabilities | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value liabilities measured on recurring basis
Deferred compensation	6.0		6.2
Other liabilities | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value liabilities measured on recurring basis
Deferred compensation	0.0		0.0
Other liabilities | Interest rate swaps | Fair Value, Measurements, Recurring [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	6.0		2.3
Other liabilities | Interest rate swaps | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	0.0		0.0
Other liabilities | Interest rate swaps | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	$ 6.0		$ 2.3