Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Liability	$ 0.0	$ 1.5
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Long-term debt	1,002.6	1,026.2
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Long-term debt	988.5	994.3
Level 2 | Fair Value | Term Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Long-term debt	567.0	575.7
Level 2 | Carrying Value | Term Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Long-term debt	563.5	569.3
Level 2 | Forward Exchange Contracts | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset	0.4	0.9
Derivative Liability	0.0	1.5
Level 2 | Forward Exchange Contracts | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset	0.4	0.9
Derivative Liability	0.0	1.5
Level 1 | Fair Value | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Long-term debt	435.6	450.5
Level 1 | Carrying Value | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Long-term debt	$ 425.0	$ 425.0