Stock-Based Compensation - Restricted Stock Units Granted (Parenthetical) (Detail) (Restricted Stock Units (RSUs) [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of unvested RSUs	$ 1.1

Share based compensation arrangement by share based payment award equity instruments other than option nonvested fair value.

No definition available.

Name:	mfi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionNonvestedFairValue
Namespace Prefix:	mfi_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant