The number of markets the entity operates in as of the balance sheet date.

No definition available.

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- Definition

Number of Projects

+ References

No definition available.

+ Details

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- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
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-Name Accounting Standards Codification
-Topic 280
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-Section 50
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-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

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- Definition

The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2443-110228

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- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

+ Details

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

+ Details

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- Definition

The number of states the entity operates in as of the balance sheet date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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Period Type:	instant

- Definition

The cash inflow from sale of buildings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585

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- Definition

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.

+ References

No definition available.

+ Details

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- Details

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- Details

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Segment Information - Narrative (Details) $ in Millions	3 Months Ended			6 Months Ended
Segment Information - Narrative (Details) $ in Millions	Mar. 31, 2020 USD ($) OperatingDivisions Segments Market State Projects	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2020 USD ($) Market State Projects	Mar. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)
Segment Reporting Information [Line Items]
Proceeds from Sale of Buildings				$ 129.8	$ 83.8
Gain (Loss) on Sale of Properties	$ 28.5		$ 29.3	59.5	31.3
Total assets	17,130.0			17,130.0		$ 15,606.6
Other Segments [Member]
Segment Reporting Information [Line Items]
Gain (Loss) on Sale of Properties	28.2		29.3	59.4	29.3
Total assets	$ 333.4			$ 333.4		317.9
Home Building [Member]
Segment Reporting Information [Line Items]
Number of housing construction markets \| Market	89			89
Number of housing construction states \| State	29			29
Number of home building operating divisions \| OperatingDivisions	52
Number of homebuilding reporting segments \| Segments	6
Gain (Loss) on Sale of Properties	$ 0.0		0.0	$ 0.0	2.0
Total assets	$ 13,598.5			$ 13,598.5		12,715.9
Forestar Group [Member]
Segment Reporting Information [Line Items]
Number of housing construction markets \| Market	50			50
Number of housing construction states \| State	21			21
Gain (Loss) on Sale of Properties	$ 0.3		$ 0.0	$ 0.1	$ 0.9
Total assets	1,675.6			1,675.6		1,455.7
Multifamily [Member] \| Other Segments [Member]
Segment Reporting Information [Line Items]
Proceeds from Sale of Buildings	67.0	$ 61.5
Gain (Loss) on Sale of Properties	28.2	$ 31.2
Total assets	$ 202.8			$ 202.8		$ 204.0
Asset under Construction [Member] \| Multifamily [Member] \| Other Segments [Member]
Segment Reporting Information [Line Items]
Number of Projects \| Projects	3			3
Assets Leased to Others [Member] \| Multifamily [Member] \| Other Segments [Member]
Segment Reporting Information [Line Items]
Number of Projects \| Projects	1			1