Fair Value of Assets and Liabilities - Fair Value Measurements (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
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	99.2	$ 136.7
Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Total	110.4	149.4
Fair value liabilities measured on recurring basis
Total	9.5	12.0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Total	108.3	146.5
Fair value liabilities measured on recurring basis
Total	9.1	9.8
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Total	2.1	2.9
Fair value liabilities measured on recurring basis
Total	0.4	2.2
Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Foreign exchange forward contracts	2.1	2.9
Fair value liabilities measured on recurring basis
Derivative Liability	0.0	1.0
Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Foreign exchange forward contracts	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
Foreign exchange forward contracts	2.1	2.9
Fair value liabilities measured on recurring basis
Derivative Liability	0.0	1.0
Interest rate swaps | Fair Value, Measurements, Recurring [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	0.4	1.2
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
Interest rate swaps | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value liabilities measured on recurring basis
Derivative Liability	0.4	1.2
Certificates of deposit | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Investments, Fair Value Disclosure	99.2	136.7
Certificates of deposit | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Investments, Fair Value Disclosure	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	9.1	9.8
Fair value liabilities measured on recurring basis
Deferred compensation	9.1	9.8
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	9.1	9.8
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