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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents the amount of deferred compensation liability as of the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	mpaa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of likelihood of future financing, used as an input to measure fair value.

+ References

No definition available.

+ Details

Name:	mpaa_FairValueInputsProbabilityOfFutureFinancing
Namespace Prefix:	mpaa_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Net gain (loss) from the increase (decrease) in fair value of derivative instrument not designated as hedging instrument.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 45

-Subparagraph b(1)(b)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Details

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Period Type:	duration

- Definition

Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

+ References

+ Details

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

- Definition

Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

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Period Type:	duration

- Definition

Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

+ References

+ Details

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

- Definition

Risk-free interest rate assumption used in valuing an instrument.

+ References

+ Details

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

- Details

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Balance Type:	na
Period Type:	duration

- Definition

Amount of gain (loss) recognized in earnings, arising from liabilities measured at fair value on a recurring basis using unobservable inputs (level 3).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Issues that have taken place during the period in relation to liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Settlements that have taken place during the period in relation to liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

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Period Type:	duration

- Definition

This element represents [net] transfers in to and out of liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents a liability measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

+ Details

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- Definition

This element represents the sum of all intangible assets having statutory or estimated useful lives.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 33

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents contracts related to the exchange of different currencies, including foreign currency options, forward (delivery or nondelivery) contracts, and swaps entered into and existing as of the balance sheet date.

+ References

No definition available.

+ Details

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents contracts related to the exchange of different currencies, including foreign currency options, forward (delivery or nondelivery) contracts, and swaps entered into and existing as of the balance sheet date.

+ References

No definition available.

+ Details

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- Definition

This item represents the cumulative amount paid in excess of fair value for acquired assets from one or more business combinations, after to the initial recording thereof.

+ References

+ Details

Name:	us-gaap_GoodwillFairValueDisclosure
Namespace Prefix:	us-gaap_
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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 13

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a, f, g

-Article 7

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=16383099&loc=d3e24584-111560

+ Details

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Balance Type:	debit
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- Details

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Fair Value Measurements (Details) (USD $)	12 Months Ended
Fair Value Measurements (Details) (USD $)	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Change in warrant liability measured at fair value recurring basis using significant unobservable inputs (Level 3) [Rollforward]
Beginning balance	$ 0
Newly issued	1,625,000	0	0
Total (gain) loss included in net loss (gain)	389,000	0	0
Warrants exercised	0
Net transfers in (out) of Level 3	0
Ending balance	2,014,000	0
Forward Foreign Currency Exchange Contracts [Member]
Other liabilities [Abstract]
Net gain (loss) on forward foreign currency exchange contracts	804,000	476,000
Warrant Liability [Member]
Change in warrant liability measured at fair value recurring basis using significant unobservable inputs (Level 3) [Rollforward]
Total (gain) loss included in net loss (gain)	389,000
Cerberus Warrant [Member]
Fair value assumptions of warrants [Abstract]
Risk free interest rate (in hundredths)	0.60%
Expected life	4 years 1 month 24 days
Expected volatility (in hundredths)	43.94%
Dividend yield (in hundredths)	0.00%
Probability of future financing (in hundredths)	0.00%
Supplier Warrant [Member]
Fair value assumptions of warrants [Abstract]
Risk free interest rate (in hundredths)	0.67%
Expected life	4 years 6 months
Expected volatility (in hundredths)	54.66%
Dividend yield (in hundredths)	0.00%
Probability of future financing (in hundredths)	0.00%
Recurring [Member]
Short-Term Investments [Abstract]
Mutual funds	411,000	342,000
Prepaid expenses and other current assets [Abstract]
Forward foreign currency exchange contracts	683,000	0
Other current liabilities [Abstract]
Deferred compensation	411,000	342,000
Forward foreign currency exchange contracts	0	121,000
Other liabilities [Abstract]
Warrant liability	2,014,000	0
Recurring [Member] \| Level 1 [Member]
Short-Term Investments [Abstract]
Mutual funds	411,000	342,000
Prepaid expenses and other current assets [Abstract]
Forward foreign currency exchange contracts	0	0
Other current liabilities [Abstract]
Deferred compensation	411,000	342,000
Forward foreign currency exchange contracts	0	0
Other liabilities [Abstract]
Warrant liability	0	0
Recurring [Member] \| Level 2 [Member]
Short-Term Investments [Abstract]
Mutual funds	0	0
Prepaid expenses and other current assets [Abstract]
Forward foreign currency exchange contracts	683,000	0
Other current liabilities [Abstract]
Deferred compensation	0	0
Forward foreign currency exchange contracts	0	121,000
Other liabilities [Abstract]
Warrant liability	0	0
Recurring [Member] \| Level 3 [Member]
Short-Term Investments [Abstract]
Mutual funds	0	0
Prepaid expenses and other current assets [Abstract]
Forward foreign currency exchange contracts	0	0
Other current liabilities [Abstract]
Deferred compensation	0	0
Forward foreign currency exchange contracts	0	0
Other liabilities [Abstract]
Warrant liability	2,014,000	0
Nonrecurring [Member]
Assets measured at fair value on a nonrecurring basis [Abstract]
Goodwill	0
Intangible assets	0
Nonrecurring [Member] \| Level 1 [Member]
Assets measured at fair value on a nonrecurring basis [Abstract]
Goodwill	0
Intangible assets	0
Nonrecurring [Member] \| Level 2 [Member]
Assets measured at fair value on a nonrecurring basis [Abstract]
Goodwill	0
Intangible assets	0
Nonrecurring [Member] \| Level 3 [Member]
Assets measured at fair value on a nonrecurring basis [Abstract]
Goodwill	0
Intangible assets	$ 0