Intangible and Other Assets Net (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2013	Dec. 31, 2012
Schedule of Intangible Assets Disclosure [Line Items]
Internet domain names	$ 14,613	$ 14,910
Less accumulated amortization	(14,393)	(14,590)
Internet domain names, net	220	320
Registration fees, net	68	9
Other	281	282
Total intangibles and other assets, net	$ 569	$ 611

Domain names assets accumulated amortization.

No definition available.

Name:	mchx_DomainNamesAssetsAccumulatedAmortization
Namespace Prefix:	mchx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before amortization of domain assets with a finite life.

+ References

No definition available.

+ Details

Name:	mchx_DomainNamesAssetsGross
Namespace Prefix:	mchx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount after amortization of domain assets with a finite life.

+ References

No definition available.

+ Details

Name:	mchx_DomainNamesAssetsNet
Namespace Prefix:	mchx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Registration fees net.

+ References

No definition available.

+ Details

Name:	mchx_RegistrationFees
Namespace Prefix:	mchx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	mchx_ScheduleOfIntangibleAssetsDisclosureLineItems
Namespace Prefix:	mchx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate carrying amounts, as of the balance sheet date, of assets not separately disclosed in the balance sheet.

+ 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 210.5-02.17)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 10

-Article 7

+ Details

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

- Definition

Aggregate carrying amount, as of the balance sheet date, of noncurrent assets not separately disclosed in the balance sheet. Noncurrent assets are expected to be realized or consumed after one year (or the normal operating cycle, if longer).

+ References

+ Details

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