Note 4 - Securities - Available-for-sale Securities in a Continuous Unrealized Loss Position (Details)
$ in Thousands
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Less than 12 Months, Number of Securities 106 70
Less than 12 Months, Fair Value $ 169,634 $ 126,421
Less than 12 Months, Gross Unrealized Losses $ 3,387 $ 1,201
12 Months or Greater, Number of Securities 3 3
12 Months or Greater, Fair Value $ 1,554 $ 1,625
12 Months or Greater, Gross Unrealized Losses $ 121 $ 142
Total, Number of Securities 109 73
Total, Fair Value $ 171,188 $ 128,046
Total, Gross Unrealized Losses $ 3,508 $ 1,343
US Government Agencies Debt Securities [Member]    
Less than 12 Months, Number of Securities 0 0
Less than 12 Months, Fair Value $ 0 $ 0
Less than 12 Months, Gross Unrealized Losses $ 0 $ 0
12 Months or Greater, Number of Securities 0 0
12 Months or Greater, Fair Value $ 0 $ 0
12 Months or Greater, Gross Unrealized Losses $ 0 $ 0
Total, Number of Securities 0 0
Total, Fair Value $ 0 $ 0
Total, Gross Unrealized Losses $ 0 $ 0
US States and Political Subdivisions Debt Securities [Member]    
Less than 12 Months, Number of Securities 82 31
Less than 12 Months, Fair Value $ 88,479 $ 33,022
Less than 12 Months, Gross Unrealized Losses $ 2,303 $ 419
12 Months or Greater, Number of Securities 0 1
12 Months or Greater, Fair Value $ 0 $ 264
12 Months or Greater, Gross Unrealized Losses $ 0 $ 3
Total, Number of Securities 82 32
Total, Fair Value $ 88,479 $ 33,286
Total, Gross Unrealized Losses $ 2,303 $ 422
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Total, Number of Securities 25  
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Residential Mortgage [Member]    
Less than 12 Months, Number of Securities 2 4
Less than 12 Months, Fair Value $ 4,514 $ 5,738
Less than 12 Months, Gross Unrealized Losses $ 40 $ 9
12 Months or Greater, Number of Securities 1 0
12 Months or Greater, Fair Value $ 175 $ 0
12 Months or Greater, Gross Unrealized Losses $ 0
Total, Number of Securities 3 4
Total, Fair Value $ 4,689 $ 5,738
Total, Gross Unrealized Losses $ 40 $ 9
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Commercial Loan [Member]    
Less than 12 Months, Number of Securities 17 16
Less than 12 Months, Fair Value $ 70,146 $ 67,969
Less than 12 Months, Gross Unrealized Losses $ 868 $ 601
12 Months or Greater, Number of Securities 0 0
12 Months or Greater, Fair Value $ 0 $ 0
12 Months or Greater, Gross Unrealized Losses $ 0 $ 0
Total, Number of Securities 17 16
Total, Fair Value $ 70,146 $ 67,969
Total, Gross Unrealized Losses $ 868 $ 601
Collateralized Mortgage Backed Securities [Member]    
Less than 12 Months, Number of Securities 5 7
Less than 12 Months, Fair Value $ 6,495 $ 16,779
Less than 12 Months, Gross Unrealized Losses $ 176 $ 161
12 Months or Greater, Number of Securities
12 Months or Greater, Fair Value
12 Months or Greater, Gross Unrealized Losses
Total, Number of Securities 5 7
Total, Fair Value $ 6,495 $ 16,779
Total, Gross Unrealized Losses $ 176 $ 161
Corporate Debt Securities [Member]    
Less than 12 Months, Number of Securities 0 0
Less than 12 Months, Fair Value $ 0 $ 0
Less than 12 Months, Gross Unrealized Losses $ 0 $ 0
12 Months or Greater, Number of Securities 1 1
12 Months or Greater, Fair Value $ 453 $ 423
12 Months or Greater, Gross Unrealized Losses $ 47 $ 77
Total, Number of Securities 1 1
Total, Fair Value $ 453 $ 423
Total, Gross Unrealized Losses $ 47 $ 77
Negotiable Certificates of Deposit [Member]    
Less than 12 Months, Number of Securities 0 12
Less than 12 Months, Fair Value $ 0 $ 2,913
Less than 12 Months, Gross Unrealized Losses $ 0 $ 11
12 Months or Greater, Number of Securities 0 0
12 Months or Greater, Fair Value $ 0 $ 0
12 Months or Greater, Gross Unrealized Losses $ 0 $ 0
Total, Number of Securities 0 12
Total, Fair Value $ 0 $ 2,913
Total, Gross Unrealized Losses $ 0 $ 11
Equity Securities [Member]    
Less than 12 Months, Number of Securities 0 0
Less than 12 Months, Fair Value $ 0 $ 0
Less than 12 Months, Gross Unrealized Losses $ 0 $ 0
12 Months or Greater, Number of Securities 1 1
12 Months or Greater, Fair Value $ 926 $ 938
12 Months or Greater, Gross Unrealized Losses $ 74 $ 62
Total, Number of Securities 1 1
Total, Fair Value $ 926 $ 938
Total, Gross Unrealized Losses $ 74 $ 62