Note 6 - Fair Value Measurements (Details) - Aggregate Fair Value of Securities in Unrealized Loss Positions (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Note 6 - Fair Value Measurements (Details) - Aggregate Fair Value of Securities in Unrealized Loss Positions [Line Items]
Number of Securities in Loss Position	91	79
Aggregate Loss Position	$ (2,195)	$ (1,143)
Aggregate Fair Value of Securities in a Loss Position	94,478	60,614
Debt Securities [Member]
Note 6 - Fair Value Measurements (Details) - Aggregate Fair Value of Securities in Unrealized Loss Positions [Line Items]
Number of Securities in Loss Position	82	72
Aggregate Loss Position	(294)	(430)
Aggregate Fair Value of Securities in a Loss Position	17,758	46,440
Equity Securities [Member]
Note 6 - Fair Value Measurements (Details) - Aggregate Fair Value of Securities in Unrealized Loss Positions [Line Items]
Number of Securities in Loss Position	9	7
Aggregate Loss Position	(1,901)	(713)
Aggregate Fair Value of Securities in a Loss Position	$ 76,720	$ 14,174

Name:	mdc_Note6FairValueMeasurementsDetailsAggregateFairValueofSecuritiesinUnrealizedLossPositionsLineItems
Namespace Prefix:	mdc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

+ Details

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

- Definition

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

+ Details

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

- Definition

Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (b)(3)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

+ Details

Name:	us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant