Note 7 - Fair Value of Financial Instruments - Fair Values of Financial Instruments (Details) - USD ($)	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Reported Value Measurement [Member] | Interest Rate Lock Commitments [Member]
Financial assets:
Derivative asset	$ 1,027,000
Financial liabilities:
Derivative liability	9,000
Reported Value Measurement [Member] | Best Efforts Forward Loan sales Commitments [Member]
Financial liabilities:
Derivative liability	377,000
Reported Value Measurement [Member] | Mandatory Forward Loan Sales Commitments [Member]
Financial liabilities:
Derivative liability	294,000
Reported Value Measurement [Member]
Financial assets:
Cash and cash equivalents	150,041,000		$ 27,139,000
Investment securities available for sale, at fair value	299,385,000		284,795,000
Investment securities held to maturity, at fair value	220,470,000		172,277,000
Restricted stock	1,366,000		3,059,000
Loans held for sale	29,715,000		3,653,000
Loans receivable, net	936,088,000		866,066,000
SBA servicing assets	5,297,000		4,886,000
Accrued interest receivable	4,588,000		4,216,000
Financial liabilities:
Demand, savings and money market	1,473,105,000		1,181,720,000
Time	109,127,000		67,578,000
Subordinated debt	22,476,000		22,476,000
Accrued interest payable	339,000		245,000
Short-term borrowings			47,000,000
Off-Balance Sheet Data
Commitments to extend credit
Standby letters-of-credit
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Lock Commitments [Member]
Financial assets:
Derivative asset
Financial liabilities:
Derivative liability
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Best Efforts Forward Loan sales Commitments [Member]
Financial liabilities:
Derivative liability
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Mandatory Forward Loan Sales Commitments [Member]
Financial liabilities:
Derivative liability
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets:
Cash and cash equivalents	150,041,000		27,139,000
Investment securities available for sale, at fair value
Investment securities held to maturity, at fair value
Restricted stock
Loans held for sale
Loans receivable, net
SBA servicing assets
Accrued interest receivable
Financial liabilities:
Demand, savings and money market
Time
Subordinated debt
Accrued interest payable
Short-term borrowings
Off-Balance Sheet Data
Commitments to extend credit
Standby letters-of-credit
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Lock Commitments [Member]
Financial assets:
Derivative asset	1,027,000
Financial liabilities:
Derivative liability	9,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Best Efforts Forward Loan sales Commitments [Member]
Financial liabilities:
Derivative liability	377,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Mandatory Forward Loan Sales Commitments [Member]
Financial liabilities:
Derivative liability	294,000
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets:
Cash and cash equivalents
Investment securities available for sale, at fair value	294,761,000		280,078,000
Investment securities held to maturity, at fair value	223,247,000		171,845,000
Restricted stock	1,366,000		3,059,000
Loans held for sale	26,865,000
Loans receivable, net
SBA servicing assets
Accrued interest receivable	4,588,000		4,216,000
Financial liabilities:
Demand, savings and money market	1,473,105,000		1,181,720,000
Time	109,172,000		67,422,000
Subordinated debt
Accrued interest payable	339,000		245,000
Short-term borrowings			47,000,000
Off-Balance Sheet Data
Commitments to extend credit
Standby letters-of-credit
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Lock Commitments [Member]
Financial assets:
Derivative asset
Financial liabilities:
Derivative liability
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Best Efforts Forward Loan sales Commitments [Member]
Financial liabilities:
Derivative liability
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Mandatory Forward Loan Sales Commitments [Member]
Financial liabilities:
Derivative liability
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets:
Cash and cash equivalents
Investment securities available for sale, at fair value	4,624,000		4,717,000
Investment securities held to maturity, at fair value
Restricted stock
Loans held for sale	2,850,000		3,831,000
Loans receivable, net	917,242,000		849,578,000
SBA servicing assets	5,297,000		4,886,000
Accrued interest receivable
Financial liabilities:
Demand, savings and money market
Time
Subordinated debt	18,257,000		18,972,000
Accrued interest payable
Short-term borrowings
Off-Balance Sheet Data
Commitments to extend credit
Standby letters-of-credit
Estimate of Fair Value Measurement [Member] | Interest Rate Lock Commitments [Member]
Financial assets:
Derivative asset	1,027,000
Financial liabilities:
Derivative liability	9,000
Estimate of Fair Value Measurement [Member] | Best Efforts Forward Loan sales Commitments [Member]
Financial liabilities:
Derivative liability	377,000
Estimate of Fair Value Measurement [Member] | Mandatory Forward Loan Sales Commitments [Member]
Financial liabilities:
Derivative liability	294,000
Estimate of Fair Value Measurement [Member]
Financial assets:
Cash and cash equivalents	150,041,000		27,139,000
Investment securities available for sale, at fair value	299,385,000		284,795,000
Investment securities held to maturity, at fair value	223,247,000		171,845,000
Restricted stock	1,366,000		3,059,000
Loans held for sale	29,715,000		3,831,000
Loans receivable, net	917,242,000		849,578,000
SBA servicing assets	5,297,000		4,886,000
Accrued interest receivable	4,588,000		4,216,000
Financial liabilities:
Demand, savings and money market	1,473,105,000		1,181,720,000
Time	109,172,000		67,422,000
Subordinated debt	18,257,000		18,972,000
Accrued interest payable	339,000		245,000
Short-term borrowings			47,000,000
Off-Balance Sheet Data
Commitments to extend credit
Standby letters-of-credit
Investment securities available for sale, at fair value	299,385,000		284,795,000
Investment securities held to maturity, at fair value	223,247,000		171,845,000
SBA servicing assets	$ 5,297,000	$ 5,118,000	$ 4,886,000	$ 4,174,000	$ 4,319,000	$ 4,099,000