Revolving Line of Credit - Chronology of Total Commitment Under Revolving Credit Facility with Associated Rate Options in Effect (Parenthetical) (Detail)	6 Months Ended
Jun. 30, 2013
Debt Disclosure [Abstract]
The base rate established by the Agent	1.00%
Federal funds	0.50%
Base rate	The "base rate" is the highest of the prime rate established by the Agent, or one-month LIBOR plus 1%, or the federal funds effective rate plus 0.5%.

Line of credit basis spread on London interbank offered rate.

No definition available.

Name:	mfi_LineOfCreditBasisSpreadOnLondonInterbankOfferedRate
Namespace Prefix:	mfi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant