The maximum leverage ratio required by the debt agreement.

No definition available.

Name:	mdc_DebtInstrumentCovenantMaximumLeverageRatio
Namespace Prefix:	mdc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The minimum common stock outstanding ownership percentage required by the debt agreement.

+ References

No definition available.

+ Details

Name:	mdc_DebtInstrumentCovenantMinimumCommonStockOutstandingOwnershipPercentage
Namespace Prefix:	mdc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line of Credit Facility, Leverage Ratio

+ References

No definition available.

+ Details

Name:	mdc_LineOfCreditFacilityLeverageRatio
Namespace Prefix:	mdc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The maximum amount the borrowing capacity of the facility may increase under certain conditions.

+ References

No definition available.

+ Details

Name:	mdc_LineOfCreditFacilityMaximumIncreaseToBorrowingCapacity
Namespace Prefix:	mdc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility subject to receipt of additional commitments from existing or additional lenders and, in the case of additional lenders, the consent of the co-administrative agents.

+ References

No definition available.

+ Details

Name:	mdc_LineOfCreditFacilityPotentialMaximumBorrowingCapacitySubjectToAdditionalCommitments
Namespace Prefix:	mdc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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

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.

+ 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
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: 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=6876686&loc=d3e534808-122878

Reference 3: 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(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- 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

+ Details

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

- Definition

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

+ References

+ Details

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

- Definition

Carrying value as of the balance sheet date of the outstanding short-term borrowings under a revolving line of credit used by mortgage bankers to finance the origination or purchase of loans.

+ 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(13))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=mdc_BorrowingBaseIsRequiredMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_FederalFundsEffectiveSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=mdc_SpecifiedEurocurrencyRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_CreditFacilityAxis=mdc_MortgageRepurchaseFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_WarehouseAgreementBorrowingsMember
Namespace Prefix:
Data Type:	na
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Note 18 - Lines of Credit (Details Textual) - USD ($) $ in Millions	Sep. 29, 2017	Nov. 01, 2018	Sep. 30, 2018	Aug. 09, 2018	Jun. 26, 2018	Jun. 25, 2018	Dec. 31, 2017	Dec. 27, 2017	Dec. 26, 2017	Sep. 28, 2017
Letters of Credit Outstanding, Amount			$ 71.4
Maximum [Member] \| Borrowing Base is Required [Member]
Line of Credit Facility, Leverage Ratio	55.00%
Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 700.0	$ 1,000.0								$ 550.0
Line of Credit Facility, Potential Maximum Borrowing Capacity, Subject to Additional Commitments	$ 1,250.0	$ 1,500.0
Debt Instrument, Interest Rate, Stated Percentage	0.00%
Debt Instrument, Covenant, Maximum Leverage Ratio	55.00%
Debt Instrument, Covenant, Minimum Common Stock Outstanding Ownership, Percentage			50.00%
Long-term Line of Credit, Total			$ 15.0				$ 15.0
Line of Credit Facility, Remaining Borrowing Capacity			655.2
Revolving Credit Facility [Member] \| Federal Funds Effective Swap Rate [Member]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Revolving Credit Facility [Member] \| Specified Eurocurrency Rate [Member]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Standby Letters of Credit [Member]
Letters of Credit Outstanding, Amount			29.8				32.0
Mortgage Repurchase Facility [Member] \| Warehouse Agreement Borrowings [Member]
Line of Credit Facility, Maximum Borrowing Capacity				$ 75.0	$ 100.0			$ 115.0	$ 75.0
Line of Credit Facility, Maximum Increase to Borrowing Capacity				$ 75.0		$ 75.0
Warehouse Agreement Borrowings, Total			$ 90.8				$ 112.3