Inventories - Components of Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018
Inventory
Total inventories	$ 215.1	$ 318.2	$ 253.2
Non-utility LPG and natural gas
Inventory
Total inventories	141.6	231.7	177.0
Gas Utility natural gas
Inventory
Total inventories	15.5	37.3	18.6
Materials, supplies and other
Inventory
Total inventories	$ 58.0	$ 49.2	$ 57.6

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=116846819&loc=d3e3927-108312

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	debit
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