Revenues (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Revenue from External Customer [Line Items]
Other	$ 0.2	$ 1.0	$ 0.4	$ 1.3
Revenue, Net (Deprecated 2018-01-31)	159.1	65.3	406.4	103.8
Real Estate [Member] \| Residential Real Estate [Member]
Revenue from External Customer [Line Items]
Residential lot sales	156.4	49.3	373.5	84.0
Land [Member] \| Residential Real Estate [Member]
Revenue from External Customer [Line Items]
Residential lot sales	0.0	0.0	30.0	0.0
Land [Member] \| Commercial Real Estate [Member]
Revenue from External Customer [Line Items]
Residential lot sales	$ 2.5	$ 15.0	$ 2.5	$ 18.5

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.

No definition available.

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Amount of other revenue (expense) derived from real estate investments partnerships.

+ References

No definition available.

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Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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