Other consideration in business acquisition associated with payments related to historical compensation.

No definition available.

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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

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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- Definition

The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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- Definition

Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

+ References

No definition available.

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- Definition

This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

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- Definition

This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

+ References

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- Definition

The amount of identifiable intangible assets recognized as of the acquisition date.

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- Definition

Amount, after accumulated amortization, of debt premium.

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- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Acquisition - Narrative (Details) - USD ($) $ in Millions		2 Months Ended	6 Months Ended	12 Months Ended
Acquisition - Narrative (Details) - USD ($) $ in Millions	Jul. 31, 2020	Sep. 30, 2020	Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Purchase consideration in cash	$ 4,500.0
Business Combination Other Consideration Historical Compensation	200.0
Debt	2,000.0	$ 3,017.1		$ 3,399.4	$ 3,017.1
Definite-lived intangible assets weighted-average remaining useful life				6 years 8 months 12 days
Unamortized debt premium	324.4
Pro Forma Revenue			$ 1,500.8		7,862.0	$ 8,436.0
Pro Forma Net Income			$ 291.4		967.5	$ 886.6
Legg mason, revenue		475.7
Legg mason, net loss		$ (28.7)
Other Intangible Assets [Member]
Business Acquisition [Line Items]
Definite-lived intangibles assets	1,123.2
Definite-lived intangible assets weighted-average remaining useful life				5 years 10 months 24 days
Trade Names [Member]
Business Acquisition [Line Items]
Definite-lived intangibles assets	$ 230.6
Definite-lived intangible assets weighted-average remaining useful life				14 years 6 months
Minimum [Member]
Business Acquisition [Line Items]
Intangible assets, estimated useful lives				3 years
Minimum [Member] \| Other Intangible Assets [Member]
Business Acquisition [Line Items]
Intangible assets, estimated useful lives				5 years
Minimum [Member] \| Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets, estimated useful lives				5 years
Maximum [Member]
Business Acquisition [Line Items]
Intangible assets, estimated useful lives				15 years
Maximum [Member] \| Other Intangible Assets [Member]
Business Acquisition [Line Items]
Intangible assets, estimated useful lives				7 years
Maximum [Member] \| Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets, estimated useful lives				20 years
General, administrative and other expense [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs				$ 6.7	57.4
Compensation and Benefits [Member]
Business Acquisition [Line Items]
Business Combination, Integration Related Costs				$ 13.0	$ 119.6