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Identifiable Intangible Assets Narrative (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life |  |  | 12 years
Amortization | $ 28.2 | $ 28.2 | $ 27.0
Goodwill | $ 115.1 | 99.8 | 95.7
Software and Software Development Costs [Member] |  |  |
Finite-Lived Intangible Asset, Useful Life | 6 years |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life | 1 year 9 months 18 days |  |
Amortization | $ 3.3 |  |
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months | 3.5 |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Two | 2.7 |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Three | 2.1 |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Four | 1.1 |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Five | $ 0.5 |  |
Customer Relationships [Member] |  |  |
Finite-Lived Intangible Asset, Useful Life | 4 years 4 months 24 days |  |
Technology-Based Intangible Assets [Member] |  |  |
Finite-Lived Intangible Asset, Useful Life | 4 years 6 months |  |
Business Combination-Related Identifiable Intangible [Member] |  |  |
Amortization | $ 25.2 | $ 24.9 | $ 23.7
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months | 25.4 |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Two | 24.8 |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Three | 24.8 |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Four | 5.2 |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Five | $ 4.4 |  |

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- Definition Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
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- Definition The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 + Details
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