Fair Value of Assets and Liabilities - Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Document Period End Date	Mar. 31, 2017
Fair Value Transfers Between Levels Amount	$ 0.0
Fair value assets measured on recurring basis
Short-term investments	77.7	$ 64.1
Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Total	102.6	88.2
Fair value liabilities measured on recurring basis
Total	27.5	23.1
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Total	86.6	72.6
Fair value liabilities measured on recurring basis
Total	8.9	8.5
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Total	16.0	15.6
Fair value liabilities measured on recurring basis
Total	18.6	14.6
Short-term investments | Certificates of deposit | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Fair value of investment assets	77.7	64.1
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
Short-term investments | Certificates of deposit | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Short-term investments	77.7	64.1
Securities and other investments | Interest rate swaps | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Derivative Asset	8.6	8.4
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	8.6	8.4
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	8.9	8.5
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	2.9	7.2
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	2.9	7.2
Other current assets | Currency Swap [Member] | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Derivative Asset	2.8	0.0
Other current assets | Currency Swap [Member] | 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 | Currency Swap [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Derivative Asset	2.8	0.0
Other assets | Currency Swap [Member] | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Derivative Asset	1.7	0.0
Other assets | Currency Swap [Member] | 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 assets | Currency Swap [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Derivative Asset	1.7	0.0
Other current liabilities | Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	7.5	7.7
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	7.5	7.7
Other current liabilities | Interest rate swaps | Fair Value, Measurements, Recurring [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	6.6	6.9
Other current 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 current liabilities | Interest rate swaps | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	6.6	6.9
Other current liabilities | Currency Swap [Member] | Fair Value, Measurements, Recurring [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	2.8	0.0
Other current liabilities | Currency Swap [Member] | 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 | Currency Swap [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	2.8	0.0
Other liabilities | Currency Swap [Member] | Fair Value, Measurements, Recurring [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	1.7	0.0
Other liabilities | Currency Swap [Member] | 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 | Currency Swap [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	1.7	0.0
Other liabilities | Assets held in rabbi trusts [Member] | Fair Value, Measurements, Recurring [Member]
Fair value liabilities measured on recurring basis
Deferred compensation	8.9	8.5
Other liabilities | Assets held in rabbi trusts [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Fair value of investment assets	8.9	8.5
Other liabilities | Assets held in rabbi trusts [Member] | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value liabilities measured on recurring basis
Deferred compensation	$ 0.0	$ 0.0