Fair Value of Assets and Liabilities - Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 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	49.7	$ 39.9
Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Restricted Cash and Cash Equivalents	116.1	0.0
Total	222.3	59.7
Fair value liabilities measured on recurring basis
Total	15.6	10.8
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Restricted Cash and Cash Equivalents	116.1	0.0
Total	173.9	49.2
Fair value liabilities measured on recurring basis
Total	8.1	9.3
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Restricted Cash and Cash Equivalents	0.0	0.0
Total	48.4	10.5
Fair value liabilities measured on recurring basis
Total	7.5	1.5
Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Foreign currency option contracts	4.9	3.5
Fair value liabilities measured on recurring basis
Derivative Liability	7.5	1.5
Foreign exchange forward contracts | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Foreign currency option 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 currency option contracts	4.9	3.5
Fair value liabilities measured on recurring basis
Derivative Liability	7.5	1.5
Foreign currency option contract | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Foreign currency option contracts	43.5	7.0
Foreign currency option contract | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets measured on recurring basis
Foreign currency option contracts	0.0	0.0
Foreign currency option contract | Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets measured on recurring basis
Foreign currency option contracts	43.5	7.0
Certificates of deposit | Fair Value, Measurements, Recurring [Member]
Fair value assets measured on recurring basis
Fair value of investment assets	49.7	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	8.1	9.3
Fair value liabilities measured on recurring basis
Deferred compensation	8.1	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	8.1	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