Deposits (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deposits [Abstract]
Deposits that meet or exceed FDIC standard deposit insurance limit	$ 335.2	$ 303.6

Deposits that meet or exceed FDIC standard deposit insurance limit.

No definition available.

Name:	mfsf_DepositsThatMeetOrExceedFdicStandardDepositInsuranceLimit
Namespace Prefix:	mfsf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant