Note 15 - Fair Value Measurements and Disclosures - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)
Dec. 31, 2016
Dec. 31, 2015
Investment securities available-for-sale $ 73,380,000 $ 53,405,000
Fair Value, Measurements, Recurring [Member]    
Investment securities available-for-sale 73,380,000 53,405,000
Mortgage loans held-for-sale 15,373,000  
Derivative assets 427,000 258,000
Derivative liabilities 366,000 518,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]    
Investment securities available-for-sale
Mortgage loans held-for-sale  
Derivative assets
Derivative liabilities
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]    
Investment securities available-for-sale 73,380,000 53,405,000
Mortgage loans held-for-sale 15,373,000  
Derivative assets 427,000 258,000
Derivative liabilities 366,000 518,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]    
Investment securities available-for-sale
Mortgage loans held-for-sale  
Derivative assets
Derivative liabilities
US Government Agencies Debt Securities [Member]    
Investment securities available-for-sale 3,617,000  
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Investment securities available-for-sale 3,617,000  
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]    
Investment securities available-for-sale  
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]    
Investment securities available-for-sale 3,617,000  
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]    
Investment securities available-for-sale  
Collateralized Mortgage Backed Securities [Member]    
Investment securities available-for-sale 39,148,000 48,726,000
Collateralized Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Investment securities available-for-sale 39,148,000 48,726,000
Collateralized Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]    
Investment securities available-for-sale
Collateralized Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]    
Investment securities available-for-sale 39,148,000 48,726,000
Collateralized Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]    
Investment securities available-for-sale
US States and Political Subdivisions Debt Securities [Member]    
Investment securities available-for-sale 4,523,000 4,679,000
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Investment securities available-for-sale 4,523,000 4,679,000
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]    
Investment securities available-for-sale
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]    
Investment securities available-for-sale 4,523,000 4,679,000
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]    
Investment securities available-for-sale
Asset-backed Securities [Member]    
Investment securities available-for-sale 26,092,000  
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Investment securities available-for-sale 26,092,000  
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]    
Investment securities available-for-sale  
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]    
Investment securities available-for-sale 26,092,000  
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]    
Investment securities available-for-sale