Note 2 - Acquisitions - Assets Acquired and Liabilities Assumed (Details) - USD ($)	Oct. 01, 2015	Jun. 13, 2014	Dec. 31, 2016	Dec. 31, 2015
Consideration paid:
Goodwill			$ 40,196,000	$ 40,196,000
Acquisition of MNB [Member]
Consideration paid:
Cash	$ 28,000,000
Total consideration paid	70,000,000
Goodwill	14,500,000		$ 14,500,000
Acquisition of MNB [Member] | Portion at Other than Fair Value Measurement [Member]
Assets acquired:
Cash and cash equivalents	14,069,000
Federal funds sold	51,000
Investment securities available for sale	42,677,000
Other investment securities, at cost	2,001,000
Loans receivable	375,521,000
Allowance for loan losses	(5,839,000)
Loans receivable, net	369,682,000
Accrued interest receivable	1,484,000
Real estate owned - net	97,000
Office properties and equipment, net	11,484,000
Cash surrender value of life insurance	6,202,000
Core deposit intangible	0
Deferred tax asset, net	0
Prepaid expenses and other assets	597,000
Total assets acquired	448,344,000
Liabilities assumed:
Deposits – noninterest bearing	56,187,000
Deposits – interest bearing	314,275,000
Total deposits	370,462,000
Short term borrowings	21,137,000
Other borrowings	0
Other liabilities	20,190,000
Total liabilities assumed	411,789,000
Net assets acquired	36,555,000
Acquisition of MNB [Member] | Changes Measurement [Member]
Assets acquired:
Cash and cash equivalents	0
Federal funds sold	0
Investment securities available for sale	88,000
Other investment securities, at cost	0
Loans receivable	(10,517,000)
Allowance for loan losses	5,839,000
Loans receivable, net	(4,678,000)
Accrued interest receivable	0
Real estate owned - net	0
Office properties and equipment, net	1,796,000
Cash surrender value of life insurance	0
Core deposit intangible	4,760,000
Deferred tax asset, net	144,000
Prepaid expenses and other assets	0
Total assets acquired	2,110,000
Liabilities assumed:
Deposits – noninterest bearing	0
Deposits – interest bearing	187,000
Total deposits	187,000
Short term borrowings	0
Other borrowings	0
Other liabilities	857,000
Total liabilities assumed	1,044,000
Net assets acquired	1,066,000
Acquisition of MNB [Member] | Estimate of Fair Value Measurement [Member]
Assets acquired:
Cash and cash equivalents	14,069,000
Federal funds sold	51,000
Investment securities available for sale	42,765,000
Other investment securities, at cost	2,001,000
Loans receivable	365,004,000
Allowance for loan losses	0
Loans receivable, net	365,004,000
Accrued interest receivable	1,484,000
Real estate owned - net	97,000
Office properties and equipment, net	13,280,000
Cash surrender value of life insurance	6,202,000
Core deposit intangible	4,760,000
Deferred tax asset, net	144,000
Prepaid expenses and other assets	597,000
Total assets acquired	450,454,000
Liabilities assumed:
Deposits – noninterest bearing	56,187,000
Deposits – interest bearing	314,462,000
Total deposits	370,649,000
Short term borrowings	21,137,000
Other borrowings	0
Other liabilities	21,047,000
Total liabilities assumed	412,833,000
Net assets acquired	37,621,000
Consideration paid:
Cash	10,100,000
Common stock	42,000,000
Total consideration paid	52,100,000
Goodwill	$ 14,479,000
First National Security Company Acquisition [Member]
Consideration paid:
Cash		$ 74,000,000
Total consideration paid		124,400,000
Goodwill		25,700,000
First National Security Company Acquisition [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 Acquisition [Member] | Changes Measurement [Member]
Assets acquired:
Cash and cash equivalents		0
Federal funds sold		0
Investment securities available for sale		0
Other investment securities, at cost		0
Loans receivable		(17,294,000)
Allowance for loan losses		13,179,000
Loans receivable, net		(4,115,000)
Accrued interest receivable		0
Real estate owned - net		0
Office properties and equipment, net		(2,775,000)
Cash surrender value of life insurance		0
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 – noninterest bearing		0
Deposits – interest bearing		366,000
Total deposits		366,000
Short term borrowings		0
Other borrowings		64,000
Other liabilities		0
Total liabilities assumed		430,000
Net assets acquired		100,000
First National Security Company Acquisition [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
Allowance for loan losses		0
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