Note 2 - Acquisition (Details) - Assets Acquired and Liabilities Assumed (USD $)	12 Months Ended
	Jun. 13, 2014	Dec. 31, 2014
Consideration paid:
Goodwill		$ 25,717,000
First National Security Company [Member]
Consideration paid:
Goodwill		25,700,000
First National Security Company [Member] | Portion at Other than Fair Value Measurement [Member]
Assets acquired:
Cash and cash equivalents	41,015,000
Federal funds sold	43,025,000
Investment securities available for sale	138,140,000
Other investment securities, at cost	7,480,000
Loans receivable	622,758,000
Allowance for loan losses	(13,179,000)
Loans receivable, net	609,579,000
Accrued interest receivable	2,954,000
Real estate owned - net	69,000
Office properties and equipment, net	33,074,000
Cash surrender value of life insurance	1,935,000
Core deposit intangible	568,000
Deferred tax asset, net	542,000
Prepaid expenses and other assets	2,899,000
Total assets acquired	881,280,000
Liabilities assumed:
Deposits – noninterest bearing	151,331,000
Deposits – interest bearing	611,841,000
Total deposits	763,172,000
Short term borrowings	14,295,000
Other borrowings	27,434,000
Other liabilities	1,802,000
Total liabilities assumed	806,703,000
Net assets acquired	74,577,000
First National Security Company [Member] | Changes Measurement [Member]
Assets acquired:
Loans receivable	(17,294,000)
Allowance for loan losses	13,179,000
Loans receivable, net	(4,115,000)
Office properties and equipment, net	(2,775,000)
Core deposit intangible	7,109,000
Deferred tax asset, net	(51,000)
Prepaid expenses and other assets	362,000
Total assets acquired	530,000
Liabilities assumed:
Deposits – interest bearing	366,000
Total deposits	366,000
Other borrowings	64,000
Total liabilities assumed	430,000
Net assets acquired	100,000
First National Security Company [Member] | Estimate of Fair Value Measurement [Member]
Assets acquired:
Cash and cash equivalents	41,015,000
Federal funds sold	43,025,000
Investment securities available for sale	138,140,000
Other investment securities, at cost	7,480,000
Loans receivable	605,464,000
Loans receivable, net	605,464,000
Accrued interest receivable	2,954,000
Real estate owned - net	69,000
Office properties and equipment, net	30,299,000
Cash surrender value of life insurance	1,935,000
Core deposit intangible	7,677,000
Deferred tax asset, net	491,000
Prepaid expenses and other assets	3,261,000
Total assets acquired	881,810,000
Liabilities assumed:
Deposits – noninterest bearing	151,331,000
Deposits – interest bearing	612,207,000
Total deposits	763,538,000
Short term borrowings	14,295,000
Other borrowings	27,498,000
Other liabilities	1,802,000
Total liabilities assumed	807,133,000
Net assets acquired	74,677,000
Consideration paid:
Cash	50,000,000
Common stock	50,394,000
Total consideration paid	100,394,000
Goodwill	$ 25,717,000