Schedule I - Condensed Financial Information of Registrant (Parent Company) - Narrative (Details) - Parent Company	12 Months Ended
Sep. 30, 2018 USD ($)
Guarantee Obligations
Surety bonds indemnified	$ 70,300,000
Maximum amount authorized to guarantee obligations to suppliers and customers	500,000,000
Current carrying value	$ 448,500,000

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12069-110248

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant