Fair Value of Assets and Liabilities - Fair Value Measurements (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Transfers Between Levels Amount	$ 0.0
Fair value assets measured on recurring basis
Short-term investments	39.9	$ 39.9
Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Total	55.5	59.7
Fair value liabilities measured on recurring basis
Total	14.4	10.8
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Total	48.2	49.2
Fair value liabilities measured on recurring basis
Total	8.3	9.3
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Total	7.3	10.5
Fair value liabilities measured on recurring basis
Total	6.1	1.5
Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Derivative Asset	7.3	3.5
Fair value liabilities measured on recurring basis
Derivative Liability	6.1	1.5
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
Fair value liabilities measured on recurring basis
Derivative Liability	0.0	0.0
Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Derivative Asset	7.3	3.5
Fair value liabilities measured on recurring basis
Derivative Liability	6.1	1.5
Foreign currency option contract | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Derivative Asset	0.0	7.0
Foreign currency option contract | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Derivative Asset	0.0	0.0
Foreign currency option contract | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Derivative Asset	0.0	7.0
Certificates of deposit | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Fair value of investment assets	39.9	39.9
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
Assets held in rabbi trusts [Member] | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Assets held in rabbi trusts	8.3	9.3
Fair value liabilities measured on recurring basis
Deferred compensation	8.3	9.3
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	8.3	9.3
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
Fair value liabilities measured on recurring basis
Deferred compensation	0.0	$ 0.0
Not Designated as Hedging Instrument [Member] | Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	$ 0.0