Note 15 - Fair Value Measurements and Fair Value of Financial Instruments - Financial Assets Measured at on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Total, available for sale, fair value	$ 321,014		$ 464,430
SBA Servicing Assets	4,785		5,243	$ 5,352	$ 4,886
Collateralized Mortgage Obligations [Member]
Total, available for sale, fair value	196,259		320,241
Agency Mortgage-backed Securities [Member]
Total, available for sale, fair value	38,499		54,866
US States and Political Subdivisions Debt Securities [Member]
Total, available for sale, fair value	20,639		15,100
Corporate Debt Securities [Member]
Total, available for sale, fair value	59,274		60,282
Asset-backed Securities [Member]
Total, available for sale, fair value	6,343		13,452
Collateralized Debt Obligations [Member]
Total, available for sale, fair value			489
Fair Value, Measurements, Recurring [Member]
Total, available for sale, fair value	321,014		464,430
Mortgages Held-for-sale, Fair Value Disclosure	20,887		43,375
SBA Servicing Assets	4,785		5,243
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total, available for sale, fair value
Mortgages Held-for-sale, Fair Value Disclosure
SBA Servicing Assets
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total, available for sale, fair value	317,945		460,855
Mortgages Held-for-sale, Fair Value Disclosure	20,887		43,375
SBA Servicing Assets
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total, available for sale, fair value	3,069		3,575
Mortgages Held-for-sale, Fair Value Disclosure
SBA Servicing Assets	4,785		5,243
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member]
Total, available for sale, fair value	196,259		320,241
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Total, available for sale, fair value	196,259		320,241
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | Agency Mortgage-backed Securities [Member]
Total, available for sale, fair value	38,499		54,866
Fair Value, Measurements, Recurring [Member] | Agency Mortgage-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | Agency Mortgage-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total, available for sale, fair value	38,499		54,866
Fair Value, Measurements, Recurring [Member] | Agency Mortgage-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Total, available for sale, fair value	20,639		15,100
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total, available for sale, fair value	20,639		15,100
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Total, available for sale, fair value	59,274		60,282
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total, available for sale, fair value	56,205		57,196
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total, available for sale, fair value	3,069		3,086
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member]
Total, available for sale, fair value	6,343		13,452
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Total, available for sale, fair value	6,343		13,452
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member]
Derivative Asset	410		363
Derivative Liability			1
Fair Value, Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative Asset	410		363
Derivative Liability			1
Fair Value, Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Best Efforts Forward Loan sales Commitments [Member]
Derivative Asset	5		5
Derivative Liability	138		93
Fair Value, Measurements, Recurring [Member] | Best Efforts Forward Loan sales Commitments [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Best Efforts Forward Loan sales Commitments [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative Asset	5		5
Derivative Liability	138		93
Fair Value, Measurements, Recurring [Member] | Best Efforts Forward Loan sales Commitments [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Mandatory Forward Loan Sales Commitments [Member]
Derivative Asset	10		19
Derivative Liability	230		195
Fair Value, Measurements, Recurring [Member] | Mandatory Forward Loan Sales Commitments [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Mandatory Forward Loan Sales Commitments [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative Asset	10		19
Derivative Liability	230		195
Fair Value, Measurements, Recurring [Member] | Mandatory Forward Loan Sales Commitments [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Collateralized Debt Obligations [Member]
Total, available for sale, fair value		$ 489
Fair Value, Measurements, Recurring [Member] | Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Total, available for sale, fair value
Fair Value, Measurements, Recurring [Member] | Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Total, available for sale, fair value		$ 489