Note 1 - Summary of Significant Accounting Policies (Details) (USD $)	0 Months Ended	12 Months Ended
	Jun. 01, 2014	Dec. 31, 2014	Dec. 31, 2013
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Entity Incorporation, Date of Incorporation		Jul. 15, 1997
Entity Incorporation Date of Operations		Dec. 15, 1997
Business Acquisition, Effective Date of Acquisition	Jun. 01, 2014
Number of Operating Segments		1
Loans and Leases Receivable, Deferred Income		$ 1,100,000	$ 500,000
Interest Income on Commercial and Mortgage Loans, Discontinued Period		90 days
Maximum Delinquency Period for Consumer and Credit Card Loans to be Charged-off		120 days
Repossessed Assets		2,000,000	2,900,000
Building Improvements [Member] | Minimum [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life		5 years
Building Improvements [Member] | Maximum [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life		33 years
Furniture and Fixtures [Member] | Minimum [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life		3 years
Furniture and Fixtures [Member] | Maximum [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life		7 years
Core Deposits [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years
Firstbank Corporation [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	1,452,880,000
Business Combination, Branches Acquired	46
Mercantile Real Estate [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Business Initiation Date of Company		Jul. 21, 2003