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

No definition available.

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Namespace Prefix:	dhi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of Projects

+ References

No definition available.

+ Details

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Namespace Prefix:	dhi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Date when the business acquisition agreement was executed, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

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

- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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- Details

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Subsequent Event (Details) $ in Millions	3 Months Ended	12 Months Ended
Subsequent Event (Details) $ in Millions	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Oct. 05, 2017 Market State Projects
Subsequent Event [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired		$ 4.1	$ 82.2	$ 70.9
Forestar Group [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Business Acquisition, Date of Acquisition Agreement	Oct. 05, 2017
Business Acquisition, Percentage of Voting Interests Acquired					75.00%
Payments to Acquire Businesses, Net of Cash Acquired	$ 558.3
Number Of Housing Construction Markets \| Market					14
Number of States in which Entity Operates \| State					10
Number of Projects \| Projects					44