BRANCH CLOSURES (Details) $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($) item
BRANCH CLOSURES
Number of branches at specified location \| item	3
Deposits of three branch offices to be closed \| $	$ 53

Represents the amount of deposits of branch offices being closed by the entity.

No definition available.

Name:	msfg_DepositsOfBranchesToBeClosed
Namespace Prefix:	msfg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant