Notes Payable Notes Payable - Forestar Textuals (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Letters of credit, amount outstanding	$ 178.9
Forestar Consolidated [Member]
Debt Instrument [Line Items]
Line of credit, current borrowing capacity	380.0
Line of credit, maximum borrowing capacity	570.0
Letter of Credit, Maximum Borrowing Capacity (in dollars)	$ 100.0
Letter of Credit, Maximum Borrowing Capacity	50.00%
Line of credit, amount outstanding	$ 0.0	$ 0.0
Letters of credit, amount outstanding	36.0
Line of Credit Facility, Remaining Borrowing Capacity	344.0
Authorized Repurchase Of Debt Securities	30.0
Debt Repurchase Authorization Remaining	$ 30.0
Forestar Consolidated [Member] \| Senior Note Member Forty [Member]
Debt Instrument [Line Items]
Senior notes, stated interest rate	3.75%
Maturities of Senior Debt	$ 118.9
Forestar Consolidated [Member] \| Senior Note Member Forty One [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 350.0
Senior notes, stated interest rate	8.00%
Debt Instrument, Maturity Date	Apr. 15, 2024
Forestar Consolidated [Member] \| Senior Note Member Forty Three
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 300.0
Senior notes, stated interest rate	5.00%
Debt Instrument, Maturity Date	Mar. 01, 2028
Debt Instrument, Interest Rate, Effective Percentage	5.20%

The total repurchase amount authorized by an entity's Board of Directors under a debt repurchase plan.

No definition available.

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- Definition

The remaining repurchase amount authorized by an entity's Board of Directors under a debt repurchase plan.

+ References

No definition available.

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- Definition

Maximum borrowing capacity of letter of credit.

+ References

No definition available.

+ Details

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- Definition

Letter of Credit, Maximum Borrowing Capacity (in dollars)

+ References

No definition available.

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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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.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

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- Definition

The cash outflow for the settlement of long-term borrowing, with the highest claim on the assets of the entity in case of bankruptcy or liquidation, as it matures.

+ References

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