Accounts Receivable Discount Programs (Details) (USD $)	6 Months Ended
Sep. 30, 2014	Sep. 30, 2013
Accounts Receivable Discount Programs [Abstract]
Receivables discounted	$ 136,326,000	$ 100,076,000
Weighted average days	336 days	335 days
Annualized weighted average discount rate (in hundredths)	2.00%	2.40%
Amount of discount as interest expense	$ 2,542,000	$ 2,188,000

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