Note 3 - Investment Securities - Investment Securities With Unrealized Losses Not Recognized In Income (Details) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Less than 12 Months Fair Value $ 341,755 $ 218,898
Less than 12 Months Unrealized Losses 7,036 1,399
12 Months or More Fair Value 13,429 56,994
12 Months or More Unrealized Losses 656 1,833
Total Fair Value 355,184 275,892
Total Unrealized Losses 7,692 3,232
US Government-sponsored Enterprises Debt Securities [Member]    
Less than 12 Months Fair Value 51,657 57,927
Less than 12 Months Unrealized Losses 460 275
12 Months or More Fair Value 21,576
12 Months or More Unrealized Losses 263
Total Fair Value 51,657 79,503
Total Unrealized Losses 460 538
US States and Political Subdivisions Debt Securities [Member]    
Less than 12 Months Fair Value 91,728 30,426
Less than 12 Months Unrealized Losses 2,526 123
12 Months or More Fair Value 1,999 8,276
12 Months or More Unrealized Losses 10 90
Total Fair Value 93,727 38,702
Total Unrealized Losses 2,536 213
Residential Mortgage Backed Securities [Member]    
Less than 12 Months Fair Value 154,397 118,978
Less than 12 Months Unrealized Losses 2,485 851
12 Months or More Fair Value 5,841 21,723
12 Months or More Unrealized Losses 202 638
Total Fair Value 160,238 140,701
Total Unrealized Losses 2,687 1,489
Commercial Mortgage Backed Securities [Member]    
Less than 12 Months Fair Value 43,309 10,882
Less than 12 Months Unrealized Losses 1,557 123
12 Months or More Fair Value 0
12 Months or More Unrealized Losses 0
Total Fair Value 43,309 10,882
Total Unrealized Losses 1,557 123
Corporate Debt Securities [Member]    
Less than 12 Months Fair Value 536 204
Less than 12 Months Unrealized Losses 6 6
12 Months or More Fair Value 5,476 5,155
12 Months or More Unrealized Losses 435 794
Total Fair Value 6,012 5,359
Total Unrealized Losses 441 800
Mutual Funds and Equity Securities [Member]    
Less than 12 Months Fair Value 128 481
Less than 12 Months Unrealized Losses 2 21
12 Months or More Fair Value 113 264
12 Months or More Unrealized Losses 9 48
Total Fair Value 241 745
Total Unrealized Losses $ 11 $ 69