LOANS, Credit Quality Indicators and Aging (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Age Analysis of Past Due Loans by Class of Loans [Abstract]
30-59 Days Past Due	$ 10,267	$ 9,677
60-89 Days Past Due	1,858	2,627
Greater than 90 Days Past Due	5,954	4,297
Total Past Due	18,079	16,601
Current	1,266,352	1,120,953
Total Loans	1,284,431msl_TotalLoanReceivables	1,137,554msl_TotalLoanReceivables
Recorded Investment > 90 days and Accruing	187	178
Credit Risk Profile [Abstract]
Loans	1,284,431	1,137,554
Percentage of Total Loans (in hundredths)	100.00%msl_PercentageOfTotalLoans	100.00%msl_PercentageOfTotalLoans
Commercial, Financial and Agricultural [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
30-59 Days Past Due	2,179	4,350
60-89 Days Past Due	654	208
Greater than 90 Days Past Due	2,556	1,256
Total Past Due	5,389	5,814
Current	461,758	398,162
Total Loans	467,147	403,976
Recorded Investment > 90 days and Accruing	26	26
Credit Risk Profile [Abstract]
Loans	467,147	403,976
Commercial Real Estate Construction [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
30-59 Days Past Due	15	36
60-89 Days Past Due	0	0
Greater than 90 Days Past Due	105	63
Total Past Due	120	99
Current	43,390	64,794
Total Loans	43,510	64,893
Recorded Investment > 90 days and Accruing	97	0
Credit Risk Profile [Abstract]
Loans	43,510	64,893
Commercial Real Estate - Other [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
30-59 Days Past Due	4,989	1,230
60-89 Days Past Due	270	1,447
Greater than 90 Days Past Due	2,464	2,395
Total Past Due	7,723	5,072
Current	459,449	392,063
Total Loans	467,172	397,135
Recorded Investment > 90 days and Accruing	0	141
Credit Risk Profile [Abstract]
Loans	467,172	397,135
Commercial Total [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	100.00%	100.00%
Residential - Construction [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
30-59 Days Past Due	431	149
60-89 Days Past Due	0	0
Greater than 90 Days Past Due	0	0
Total Past Due	431	149
Current	24,636	17,649
Total Loans	25,067	17,798
Recorded Investment > 90 days and Accruing	0	0
Credit Risk Profile [Abstract]
Loans	25,067	17,798
Residential - Prime [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
30-59 Days Past Due	1,843	2,984
60-89 Days Past Due	523	870
Greater than 90 Days Past Due	704	307
Total Past Due	3,070	4,161
Current	151,532	142,680
Total Loans	154,602	146,841
Recorded Investment > 90 days and Accruing	0	0
Credit Risk Profile [Abstract]
Loans	154,602	146,841
Residential - Subprime [Member]
Credit Risk Profile [Abstract]
Loans	0	0
Residential Total [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	100.00%	100.00%
Consumer - Credit Card [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
30-59 Days Past Due	5	36
60-89 Days Past Due	19	0
Greater than 90 Days Past Due	18	7
Total Past Due	42	43
Current	5,970	6,163
Total Loans	6,012	6,206
Recorded Investment > 90 days and Accruing	18	7
Credit Risk Profile [Abstract]
Loans	6,012	6,206
Consumer - Other [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
30-59 Days Past Due	671	767
60-89 Days Past Due	392	102
Greater than 90 Days Past Due	107	269
Total Past Due	1,170	1,138
Current	112,146	90,115
Total Loans	113,316	91,253
Recorded Investment > 90 days and Accruing	46	4
Credit Risk Profile [Abstract]
Loans	113,316	91,253
Lease Financing Receivable [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
Greater than 90 Days Past Due	0	0
Total Past Due	0	0
Current	4,857	5,542
Total Loans	4,857	5,542
Recorded Investment > 90 days and Accruing	0	0
Credit Risk Profile [Abstract]
Loans	4,857	5,542
Other Loans [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
30-59 Days Past Due	134	125
60-89 Days Past Due	0	0
Greater than 90 Days Past Due	0	0
Total Past Due	134	125
Current	2,614	3,785
Total Loans	2,748	3,910
Recorded Investment > 90 days and Accruing	0	0
Credit Risk Profile [Abstract]
Loans	2,748	3,910
Pass [Member] \| Commercial, Financial and Agricultural [Member]
Credit Risk Profile [Abstract]
Loans	456,221	397,513
Pass [Member] \| Commercial Real Estate Construction [Member]
Credit Risk Profile [Abstract]
Loans	43,320	63,577
Pass [Member] \| Commercial Real Estate - Other [Member]
Credit Risk Profile [Abstract]
Loans	440,281	371,618
Pass [Member] \| Commercial Total [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	96.11%	96.15%
Pass [Member] \| Residential - Construction [Member]
Credit Risk Profile [Abstract]
Loans	25,067	17,798
Pass [Member] \| Residential - Prime [Member]
Credit Risk Profile [Abstract]
Loans	150,664	143,790
Pass [Member] \| Residential - Subprime [Member]
Credit Risk Profile [Abstract]
Loans	0	0
Pass [Member] \| Residential Total [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	97.81%	98.15%
Special Mention [Member] \| Commercial, Financial and Agricultural [Member]
Credit Risk Profile [Abstract]
Loans	4,861	2,962
Special Mention [Member] \| Commercial Real Estate Construction [Member]
Credit Risk Profile [Abstract]
Loans	132	49
Special Mention [Member] \| Commercial Real Estate - Other [Member]
Credit Risk Profile [Abstract]
Loans	7,120	8,781
Special Mention [Member] \| Commercial Total [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	1.24%	1.36%
Special Mention [Member] \| Residential - Construction [Member]
Credit Risk Profile [Abstract]
Loans	0	0
Special Mention [Member] \| Residential - Prime [Member]
Credit Risk Profile [Abstract]
Loans	1,184	548
Special Mention [Member] \| Residential - Subprime [Member]
Credit Risk Profile [Abstract]
Loans	0	0
Special Mention [Member] \| Residential Total [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	0.66%	0.33%
Substandard [Member] \| Commercial, Financial and Agricultural [Member]
Credit Risk Profile [Abstract]
Loans	5,541	3,272
Substandard [Member] \| Commercial Real Estate Construction [Member]
Credit Risk Profile [Abstract]
Loans	58	1,267
Substandard [Member] \| Commercial Real Estate - Other [Member]
Credit Risk Profile [Abstract]
Loans	19,771	16,736
Substandard [Member] \| Commercial Total [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	2.60%	2.46%
Substandard [Member] \| Residential - Construction [Member]
Credit Risk Profile [Abstract]
Loans	0	0
Substandard [Member] \| Residential - Prime [Member]
Credit Risk Profile [Abstract]
Loans	2,754	2,503
Substandard [Member] \| Residential - Subprime [Member]
Credit Risk Profile [Abstract]
Loans	0	0
Substandard [Member] \| Residential Total [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	1.53%	1.52%
Doubtful [Member] \| Commercial, Financial and Agricultural [Member]
Credit Risk Profile [Abstract]
Loans	524	229
Doubtful [Member] \| Commercial Real Estate Construction [Member]
Credit Risk Profile [Abstract]
Loans	0	0
Doubtful [Member] \| Commercial Real Estate - Other [Member]
Credit Risk Profile [Abstract]
Loans	0	0
Doubtful [Member] \| Commercial Total [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	0.05%	0.03%
Performing [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	99.65%	99.73%
Performing [Member] \| Consumer - Credit Card [Member]
Credit Risk Profile [Abstract]
Loans	5,995	6,196
Performing [Member] \| Consumer - Other [Member]
Credit Risk Profile [Abstract]
Loans	112,893	90,978
Performing [Member] \| Lease Financing Receivable [Member]
Credit Risk Profile [Abstract]
Loans	4,857	5,542
Performing [Member] \| Other Loans [Member]
Credit Risk Profile [Abstract]
Loans	2,748	3,910
Nonperforming [Member]
Credit Risk Profile [Abstract]
Percentage of Total Loans (in hundredths)	0.35%	0.27%
Nonperforming [Member] \| Consumer - Credit Card [Member]
Credit Risk Profile [Abstract]
Loans	17	10
Nonperforming [Member] \| Consumer - Other [Member]
Credit Risk Profile [Abstract]
Loans	423	275
Nonperforming [Member] \| Lease Financing Receivable [Member]
Credit Risk Profile [Abstract]
Loans	0	0
Nonperforming [Member] \| Other Loans [Member]
Credit Risk Profile [Abstract]
Loans	$ 0	$ 0

Name:	msl_CreditRiskProfileAbstract
Namespace Prefix:	msl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Reflects the percentage derived from dividing classifications of loans by total loans within that category.

+ References

No definition available.

+ Details

Name:	msl_PercentageOfTotalLoans
Namespace Prefix:	msl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

No definition available.

+ Details

Name:	msl_TotalLoanReceivables
Namespace Prefix:	msl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivables that are less than 60 days past due but more than 29 days past due.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7A

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Financing receivables that are less than 90 days past due but more than 59 days past due.

+ References

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant