Note 7 - Goodwill and Core Deposit Intangible - Net (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Goodwill	$ 40,196	$ 40,196
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	300
Finite-Lived Intangible Assets, Amortization Expense, Year Two	1,000
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	4,300
Finite-Lived Intangible Assets, Amortization Expense, Year Four	1,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	1,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 1,000
Core Deposits [Member] | Minimum [Member]
Finite-Lived Intangible Asset, Useful Life	12 years
Core Deposits [Member] | Maximum [Member]
Finite-Lived Intangible Asset, Useful Life	13 years
First National Security Company [Member]
Goodwill	$ 25,700
Acquisition of MNB [Member]
Goodwill	14,500
Business Acquisition, Goodwill, Expected Tax Deductible Amount	$ 14,500