Accounts Receivable Discount Programs (Details) (USD $)	3 Months Ended
Jun. 30, 2013	Jun. 30, 2012
Accounts Receivable Discount Programs [Abstract]
Receivables discounted	$ 44,208,000	$ 45,972,000
Weighted average days	332 days	337 days
Annualized weighted average discount rate (in hundredths)	2.40%	2.70%
Amount of discount as interest expense	$ 978,000	$ 1,181,000

Represents the weighted average number of days these discount arrangements have allowed the Company to accelerate collection of discounted accounts receivable balances during the period.

No definition available.

Name:	mpaa_DiscountedAccountsReceivableWeightedAverageDaysForAcceleratedCollection
Namespace Prefix:	mpaa_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration