Notes Payable Notes Payable - Forestar Textuals (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Jun. 30, 2019	Sep. 30, 2019
Debt Instrument [Line Items]
Letters of credit, amount outstanding		$ 171.7
Forestar Group [Member]
Debt Instrument [Line Items]
Repayments of Long-term Lines of Credit		85.0
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 Facility, Remaining Borrowing Capacity		$ 339.6
Proceeds from Lines of Credit		85.0
Forestar Group [Member] \| Senior Note Member Forty [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 118.9
Senior notes, stated interest rate		3.75%
Forestar Group [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
Debt Instrument, Interest Rate, Effective Percentage	8.50%
Forestar Group [Member] \| Revolving credit facility [Member]
Debt Instrument [Line Items]
Letters of credit, amount outstanding		$ 29.7

Maximum borrowing capacity of letter of credit.

No definition available.

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- Definition

Letter of Credit, Maximum Borrowing Capacity (in dollars)

+ References

No definition available.

+ Details

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Namespace Prefix:	dhi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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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-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

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Balance Type:	credit
Period Type:	instant

- 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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-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

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

+ References

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

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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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

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Period Type:	duration

- 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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Balance Type:	credit
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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 210
-SubTopic 10
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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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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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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

+ References

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-Publisher FASB
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- Definition

The cash outflow for the settlement of obligation drawn from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

+ References

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-Publisher FASB
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