Amount before tax of foreign currency transaction realized gain (loss) recognized in the income statement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30690-110894

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109240200&loc=d3e30700-110894

Name:	us-gaap_ForeignCurrencyTransactionGainLossRealized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Financial Instruments and Hedging Activities - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Foreign currency exchange gain	$ (0.8)	$ (1.1)	$ (1.4)
Derivatives Not Designated as Hedges
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Derivative, Notional Amount	$ 189.6	$ 117.1
Derivatives Not Designated as Hedges \| Maximum
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Maturity Period Of Foreign Currency Derivatives	90 days