Commitments and contingencies.

No definition available.

Name:	dhi_CommitmentsAndContingenciesAbstract
Namespace Prefix:	dhi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The portion of the total reserve for legal claims that relates to the entity's construction defect matters, expressed as a percentage.

+ References

No definition available.

+ Details

Name:	dhi_ConstructionDefectPortionOfLossContingencyAccrual
Namespace Prefix:	dhi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

A deposit made by a purchaser of real estate to evidence good faith. It is customary for a buyer to give the seller earnest money at the time a sales contract is signed. The earnest money generally is credited to the down payment at closing, which is applied at closing as a component of payment against the purchase price.

+ References

No definition available.

+ Details

Name:	us-gaap_EarnestMoneyDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The increase (decrease) during the reporting period in the amount of deposits given by the reporting entity to a seller which shows that the prospective buyer is serious about purchasing a property.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

+ Details

Name:	us-gaap_IncreaseDecreaseInEarnestMoneyDepositsOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) of consideration paid in advance for other costs that provide economic benefits in future periods.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInPrepaidExpensesOther
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount due in settlement of a claim for reimbursement from an insurance company when the Company has suffered a loss covered under an insurance policy.

+ References

No definition available.

+ Details

Name:	us-gaap_InsuranceSettlementsReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

+ Details

Name:	us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.

+ References

No definition available.

+ Details

Name:	us-gaap_PurchaseObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The noncurrent portion of the carrying value as of the balance sheet date of a type of municipal bond typically used to fund a development project. Also called special assessment limited liability bond, special district bond, special purpose bond, special tax bond and community development obligation. Interest owed to lenders is paid by taxes levied on the community benefiting from the particular bond-funded project. For example, if a bond of this sort was issued to pay for sidewalks to be repaved in a certain community, an additional tax would be levied on homeowners in the area benefiting from this project.

+ 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
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(2))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_SpecialAssessmentBondNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=dhi_HomeBuildingConsolidatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=dhi_ForestarConsolidatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=dhi_HomeBuildingMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=us-gaap_PerformanceGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dhi_TypesOfDepositsAxis=us-gaap_CashMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dhi_TypesOfDepositsAxis=us-gaap_NotesPayableOtherPayablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=dhi_ForestarGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020	Sep. 30, 2019
Commitments and Contingencies [Abstract]
Liabilities for various claims, complaints and other legal actions	$ 524.4	$ 442.2	$ 524.4	$ 442.2	$ 473.8	$ 434.7
Construction defect portion of loss contingency accrual, percentage	99.00%		99.00%		99.00%
Expenses related to legal claims			$ 37.3	26.6
Estimated insurance recoveries related to legal claims	$ 90.5	76.6	90.5	76.6	$ 81.2
Surety bonds	2,100.0		2,100.0
Outstanding letters of credit	189.6		189.6
Home Building Consolidated
Commitments and Contingencies [Abstract]
Outstanding letters of credit	143.6		143.6
Forestar Group [Member]
Commitments and Contingencies [Abstract]
Outstanding letters of credit	46.0		46.0
HomeBuildingMember
Commitments and Contingencies [Abstract]
Earnest money deposits	873.9		873.9
Remaining purchase price of land under option contracts	13,500.0		13,500.0
HomeBuildingMember \| Option Contracts Subject to Specific Performance Clauses [Member]
Commitments and Contingencies [Abstract]
Remaining purchase price of land under option contracts	80.5		80.5
HomeBuildingMember \| Cash [Member]
Commitments and Contingencies [Abstract]
Earnest money deposits	798.6		798.6
HomeBuildingMember \| Notes Payable, Other Payables [Member]
Commitments and Contingencies [Abstract]
Earnest money deposits	75.3		75.3
Forestar Group [Member]
Commitments and Contingencies [Abstract]
Earnest money deposits	139.6		139.6
Remaining purchase price of land under option contracts	1,500.0		1,500.0
Increase (Decrease) in Earnest Money Deposits Outstanding	8.0	5.5	24.2	16.2
Increase (Decrease) in Prepaid Expenses, Other	7.3	$ 8.2	28.2	$ 13.3
Forestar Group [Member] \| Option Contracts Subject to Specific Performance Clauses [Member]
Commitments and Contingencies [Abstract]
Remaining purchase price of land under option contracts	$ 41.5		$ 41.5