Note 7 - Fair Value Measurements (Details Textual) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other-than-temporary Impairment Loss, Debt Securities, Portion Recognized in Earnings, Total	$ 0	$ 300,000	$ 1,400,000
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Mortgage	17,800,000	33,400,000
Loans Receivable Held-for-sale, Mortgage, Unpaid Principal Balance	$ 143,900,000	133,800,000
Minimum [Member]
Short Term Borrowings Maturity Period	30 days
Fair Value, Inputs, Level 2 [Member] \| Under Commitment to Sell [Member]
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Mortgage	$ 130,800,000	103,500,000
Fair Value, Inputs, Level 2 [Member] \| Not Under Commitment to Sell [Member]
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Mortgage	$ 18,500,000	$ 34,600,000

Amount of unpaid principal balance of mortgage loan receivables held for sale.

No definition available.

Name:	mdc_LoansReceivableHeldForSaleMortgageUnpaidPrincipalBalance
Namespace Prefix:	mdc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of days from date of origination to date of sale of loan.

+ References

No definition available.

+ Details

Name:	mdc_ShortTermBorrowingsMaturityPeriod
Namespace Prefix:	mdc_
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Balance Type:	na
Period Type:	duration

- Definition

Amount, after allowance for bad debt, of mortgage loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

+ Details

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

- Definition

Amount of other-than-temporary impairment (OTTI) on investment in debt security, recognized in earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=109979856&loc=SL6284422-111562

+ Details

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- Details

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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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Namespace Prefix:
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- Details

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