Note 20 - Subsequent Events - Summary of Estimated Fair Value of Assets and Liabilities Acquired (Details) - USD ($)
Jan. 01, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Goodwill   $ 50,771,000 $ 50,686,000 $ 28,834,000
Acquisition of Private Bancshares [Member] | Subsequent Event [Member]        
Cash and cash equivalents $ 17,793,000      
Investment securities 9,973,000      
Mortgage loans held-for-sale 24,628,000      
Loans 260,577,000      
Allowance for loan losses      
Net loans 260,577,000      
Premises and equipment, net 463,000      
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill 2,979,000      
Bank-owned life insurance 3,294,000      
Other real estate and repossessions      
Other assets 4,514,000      
Total assets 324,221,000      
Non-interest bearing deposits 135,822,000      
Interest-bearing deposits 150,391,000      
Total deposits 286,213,000      
Repurchase liability 2,201,000      
Other liabilities 4,079,000      
Total liabilities 292,493,000      
Net identifiable assets acquired over liabilities assumed 31,728,000      
Goodwill 47,809,000      
Net assets acquired over liabilities assumed $ 79,537,000      
Shares of common stock issued (in shares) 1,809,189      
Estimated value per share of the Company's stock (in dollars per share) $ 37.15      
Fair value of Company stock issued $ 67,211,000      
Cash paid for shares and in lieu of fractional shares 8,322,000      
Value of assumed stock options 4,004,000      
Fair value of total consideration transferred 79,537,000      
Acquisition of Private Bancshares [Member] | Subsequent Event [Member] | Measured by Acquired Company [Member]        
Cash and cash equivalents 17,793,000      
Investment securities 10,001,000      
Mortgage loans held-for-sale 24,628,000      
Loans 266,750,000      
Allowance for loan losses 3,306,000      
Net loans 263,444,000      
Premises and equipment, net 558,000      
Bank-owned life insurance 3,294,000      
Other real estate and repossessions      
Other assets 2,744,000      
Total assets 322,462,000      
Non-interest bearing deposits 135,822,000      
Interest-bearing deposits 150,260,000      
Total deposits 286,082,000      
Repurchase liability 2,201,000      
Other liabilities 3,906,000      
Total liabilities 292,189,000      
Net identifiable assets acquired over liabilities assumed 30,273,000      
Net assets acquired over liabilities assumed 30,273,000      
Acquisition of Private Bancshares [Member] | Subsequent Event [Member] | Fair Value Adjustments [Member]        
Cash and cash equivalents      
Investment securities [1] (28,000)      
Mortgage loans held-for-sale      
Loans [2] (6,173,000)      
Allowance for loan losses [3] (3,306,000)      
Net loans (2,867,000)      
Premises and equipment, net [4] (95,000)      
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill [5] 2,979,000      
Bank-owned life insurance      
Other real estate and repossessions      
Other assets [6] 1,770,000      
Total assets 1,759,000      
Non-interest bearing deposits      
Interest-bearing deposits 131,000      
Total deposits 131,000      
Repurchase liability      
Other liabilities [7] 173,000      
Total liabilities 304,000      
Net identifiable assets acquired over liabilities assumed 1,455,000      
Goodwill 47,809,000      
Net assets acquired over liabilities assumed $ 49,264,000      
[1] Adjustment reflects fair value adjustments of the available-for-sale portfolio at acquisition date.
[2] Adjustment reflects the fair value adjustments based on the Company's evaluation of the acquired loan portfolio.
[3] Adjustment reflects the elimination of Private Bancshares’s allowance for loan losses.
[4] Adjustment reflects the write-off of certain fixed assets.
[5] Adjustment reflects the recording of core deposit intangible asset.
[6] Adjustment to record the deferred tax asset created by purchase adjustments.
[7] Adjustment to reflect unrecorded liabilities.