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

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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&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://www.xbrl.org/2003/role/presentationRef
-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=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-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=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-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=6879938&loc=d3e572229-122910

+ Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_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:

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Commitments and Contingencies [Abstract]
Surety bonds	$ 1,200.0
Outstanding letters of credit	77.9
Letter of Credit - Other [Member]
Commitments and Contingencies [Abstract]
Outstanding letters of credit	2.8
Homebuilding [Member]
Commitments and Contingencies [Abstract]
Liabilities for various claims, complaints and other legal actions	$ 453.5	$ 426.4	$ 423.5	$ 451.0
Construction defect portion of loss contingency accrual, percentage	96.00%		95.00%
Expenses related to legal claims	$ 80.6	34.2
Estimated insurance recoveries related to legal claims	82.6	$ 97.5	$ 88.7
Earnest money deposits	201.0
Remaining purchase price of land under option contracts	4,500.0
Homebuilding [Member] \| Line of Credit [Member]
Commitments and Contingencies [Abstract]
Outstanding letters of credit	75.1
Homebuilding [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Commitments and Contingencies [Abstract]
Earnest money deposits	195.2		$ 149.5
Homebuilding [Member] \| Option Contracts Subject to Specific Performance Clauses [Member]
Commitments and Contingencies [Abstract]
Remaining purchase price of land under option contracts	30.1
Homebuilding [Member] \| Cash [Member]
Commitments and Contingencies [Abstract]
Earnest money deposits	196.0
Homebuilding [Member] \| Notes Payable, Other Payables [Member]
Commitments and Contingencies [Abstract]
Earnest money deposits	$ 5.0