Note 3 - Mergers and Acquisitions - (Details Textual) $ / shares in Units, $ in Thousands	Mar. 31, 2015 USD ($) $ / shares	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Goodwill		$ 6,824	$ 6,824
American Gateway Financial Corporation [Member]
Number of Branches	10
Business Acquisition, Cash Conversion Ratio Per Share | $ / shares	$ 10
Business Acquisition, Exchange Ratio	11.88
Business Combination, Consideration Transferred	$ 47,900
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	371,500
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	143,200
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities	108,400
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	98,500
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	2,800
Goodwill	6,800
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	330,500
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits	283,300
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Federal Home Loan Bank Borrowings	41,200
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Securities Sold under Agreements to Repurchase	$ 4,300