Note 15 - Fair Value Measurements and Fair Values of Financial Instruments - Financial Assets Measured at on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investment securities available for sale, at fair value	$ 464,430	$ 369,739
Mortgages Held-for-sale, Fair Value Disclosure	43,375	23,911
SBA Servicing Assets	5,243	5,352	$ 4,886	$ 4,099
Collateralized Mortgage Obligations [Member]
Investment securities available for sale, at fair value	320,241	224,765
Agency Mortgage-backed Securities [Member]
Investment securities available for sale, at fair value	54,866	36,710
US States and Political Subdivisions Debt Securities [Member]
Investment securities available for sale, at fair value	15,100	26,547
Corporate Debt Securities [Member]
Investment securities available for sale, at fair value	60,282	64,748
Asset-backed Securities [Member]
Investment securities available for sale, at fair value	13,452	15,149
Collateralized Debt Obligations [Member]
Investment securities available for sale, at fair value	489	1,820
Fair Value, Measurements, Recurring [Member]
Investment securities available for sale, at fair value	464,430	369,739
Mortgages Held-for-sale, Fair Value Disclosure	43,375	23,911
SBA Servicing Assets	5,243	5,352
Fair Value, Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member]
Derivative Asset	363	439
Derivative Liability	1	55
Fair Value, Measurements, Recurring [Member] | Best Efforts Forward Loan sales Commitments [Member]
Derivative Asset	5	103
Derivative Liability	93	125
Fair Value, Measurements, Recurring [Member] | Mandatory Forward Loan Sales Commitments [Member]
Derivative Asset	19	229
Derivative Liability	195	38
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Mortgages Held-for-sale, Fair Value Disclosure
SBA Servicing Assets
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Lock Commitments [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Best Efforts Forward Loan sales Commitments [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Mandatory Forward Loan Sales Commitments [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	460,855	364,948
Mortgages Held-for-sale, Fair Value Disclosure	43,375	23,911
SBA Servicing Assets
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Lock Commitments [Member]
Derivative Asset	363	439
Derivative Liability	1	55
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Best Efforts Forward Loan sales Commitments [Member]
Derivative Asset	5	103
Derivative Liability	93	125
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mandatory Forward Loan Sales Commitments [Member]
Derivative Asset	19	229
Derivative Liability	195	38
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value	3,575	4,791
Mortgages Held-for-sale, Fair Value Disclosure
SBA Servicing Assets	5,243	5,352
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Lock Commitments [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Best Efforts Forward Loan sales Commitments [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mandatory Forward Loan Sales Commitments [Member]
Derivative Asset
Derivative Liability
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member]
Investment securities available for sale, at fair value	320,241	224,765
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	320,241	224,765
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | Agency Mortgage-backed Securities [Member]
Investment securities available for sale, at fair value	54,866	36,710
Fair Value, Measurements, Recurring [Member] | Agency Mortgage-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | Agency Mortgage-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	54,866	36,710
Fair Value, Measurements, Recurring [Member] | Agency Mortgage-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Investment securities available for sale, at fair value	15,100	26,547
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	15,100	26,547
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Investment securities available for sale, at fair value	60,282	64,748
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	57,196	61,777
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value	3,086	2,971
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member]
Investment securities available for sale, at fair value	13,452	15,149
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value	13,452	15,149
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | Collateralized Debt Obligations [Member]
Investment securities available for sale, at fair value	489	1,820
Fair Value, Measurements, Recurring [Member] | Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale, at fair value
Fair Value, Measurements, Recurring [Member] | Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale, at fair value	$ 489	$ 1,820