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Goodwill - Goodwill Reconciliation (Details) - USD ($) $ in Millions | 12 Months Ended
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Sep. 30, 2021 | Sep. 30, 2020
Business Acquisition [Line Items] |  |
Goodwill, foreign currency translation gain (loss) | $ 0.2 | $ 0.1
Chasing Returns Limited |  |
Business Acquisition [Line Items] |  |
Additional goodwill | $ 3.6 |
GIROXX Gmbh |  |
Business Acquisition [Line Items] |  |
Additional goodwill |  | 2.3
UOB Bullion and Futures |  |
Business Acquisition [Line Items] |  |
Additional goodwill |  | $ 1.1

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- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267 + Details
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- Definition Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267 + Details
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