Note 2 - Business Combinations - Pro Forma Income Statements (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Net interest income $ 26,990 $ 26,717 $ 26,627 $ 25,902 $ 25,429 $ 24,833 $ 25,070 $ 24,795 $ 106,236 $ 100,127 $ 76,828
Net interest income after provision for loan and lease losses                 101,910 95,731 75,944
Non-interest income                 54,039 55,960 48,322
Non-interest expense                 101,745 125,765 81,418
Income before income taxes 14,092 13,720 13,743 12,649 (9,631) 11,580 12,415 11,562 54,204 25,926 42,848
Income taxes 4,684 4,346 4,810 4,328 (3,276) 4,084 4,296 4,068 18,168 9,172 15,005
Net Income $ 9,408 $ 9,374 $ 8,933 $ 8,321 $ (6,355) $ 7,496 $ 8,119 $ 7,494 $ 36,036 $ 16,754 $ 27,843
Weighted-average basic shares outstanding (in shares) [1]                 16,859,623 17,488,325 13,566,239
Dilutive shares (in shares)                 168,499 267,996 294,801
Adjusted weighted-average diluted shares (in shares)                 17,028,122 17,756,321 13,861,040
Basic earnings per common share* (in dollars per share) $ 0.56 [2] $ 0.56 [2] $ 0.53 [2] $ 0.49 [2] $ (0.37) [2] $ 0.43 [2] $ 0.46 [2] $ 0.43 [2] $ 2.14 $ 0.96 $ 2.05
Diluted earnings per common share* (in dollars per share) $ 0.55 [2] $ 0.55 [2] $ 0.52 [2] $ 0.49 [2] $ (0.37) [2] $ 0.42 [2] $ 0.45 [2] $ 0.42 [2] $ 2.12 $ 0.94 $ 2.01
Pro Forma [Member]                      
Net interest income                 $ 106,236 $ 100,127 $ 100,609
Provision for loan and lease losses                 4,326 4,396 2,041
Net interest income after provision for loan and lease losses                 101,910 95,731 98,568
Non-interest income                 54,039 55,960 51,836
Non-interest expense                 101,745 125,765 100,011
Income before income taxes                 54,204 25,926 50,393
Income taxes                 18,168 9,172 17,673
Net Income                 $ 36,036 $ 16,754 $ 32,720
Weighted-average basic shares outstanding (in shares) [3]                 16,859,623 17,488,325 17,444,543
Dilutive shares (in shares) [3]                 168,499 267,996 373,384
Adjusted weighted-average diluted shares (in shares) [3]                 17,028,122 17,756,321 17,817,927
Basic earnings per common share* (in dollars per share) [3]                 $ 2.14 $ 0.96 $ 1.88
Diluted earnings per common share* (in dollars per share) [3]                 $ 2.12 $ 0.94 $ 1.84
[1] excludes restricted stock
[2] Earnings per share is computed independently for each period shown. As a result, the sum of the quarters may not equal the total earnings per share for the year.
[3] Assumes that the shares of CBH common stock outstanding as of December 31, 2014 were outstanding for the full twelve month periods ended December 31, 2013 and 2014, and therefore equal the weighted average shares of common stock outstanding for the twelve months periods ended December 31, 2013 and 2014. The merger conversion of 8,618,629 shares of CBH common stock equals 3,878,304 shares of Corporation common stock (8,618,629 times 0.45, minus 79 fractional shares paid in cash).