STOCK BASED COMPENSATION - Performance Measures and Additional Disclosures (Details)	Jun. 30, 2013
Restricted stock \| Directors
Additional disclosures
Quarterly vesting percentage of stock awards	25.00%

Represents the vesting percentage of stock awards vesting quarterly on May 1, August 1, and November 1, 2015, and February 1, 2016.

No definition available.

Name:	msfg_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardQuarterlyVestingRightsPercentage
Namespace Prefix:	msfg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant