Note 2 - Acquisitions (Details Textual) $ in Thousands	May 15, 2017 USD ($) shares	Sep. 09, 2016 USD ($) shares	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Goodwill			$ 375,731	$ 348,505
Hardeman County Investment Company, Inc. [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	799,970
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	$ 42,600
Payments to Acquire Businesses, Gross	$ 30,000
Number of Bank Branches	10
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 462,893
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans	251,649
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Total Deposits	388,976
Goodwill	$ 29,402
Citizens National Bank [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares		835,741
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned		$ 41,300
Payments to Acquire Businesses, Gross		$ 35,000
Number of Bank Branches		9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		$ 585,149
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans		340,850
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Total Deposits		509,857
Goodwill		23,376
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Acquired Not Covered by FDIC Loss Share		$ 340,900