Note 3 - Securities (Details Textual) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Payments to Acquire Available-for-sale Securities			$ 133,524	$ 37,854
Individual Stockholders Equity Maximum Percentage			10.00%
Available-for-sale Securities Pledged as Collateral	$ 266,100		$ 266,100		$ 271,300
Proceeds from Sale of Available-for-sale Securities	54,500	$ 0	130,972	32,588
Available-for-sale Securities, Gross Realized Gains	400		1,400	960
Available-for-sale Securities, Gross Realized Losses	$ 24		$ 67	$ 0
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	82		82		109
Federal Home Loan Bank Stock	$ 2,450		$ 2,450		$ 3,311
Federal Home Loan Bank of Pittsburgh [Member]
Federal Home Loan Bank Stock	2,500		2,500		3,300
Impairment on Federal Reserve Bank of Philadelphia Stock	$ 0		0		$ 0
Corporate Debt Securities [Member]
Payments to Acquire Available-for-sale Securities			$ 2,000
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions					1
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	49		49		82
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	31		31
Asset-backed Securities [Member]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1		1		0
Equity Securities [Member]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1		1		1
Equity Security Without Readily Determinable Fair Value [Member]
Other Investment, Ownership Percentage	4.90%		4.90%
Other than Temporary Impairment Losses, Investments	$ 0
Subordinated Note 1 Previously Recorded in Loan Portfolio [Member]
Transfer to Investments	1,000
Mandatory Redeemable Preferred Stock Previously Recorded in Loan Portfolio [Member]
Transfer to Investments	1,000
Reclassified Recorded Investment from Loans Receivable to Available-for-sale Securities [Member | December 31, 2015 [Member]
Prior Period Reclassification Adjustment	3,000
Increase to Available-for-sale Securities [Member] | December 31, 2015 [Member]
Prior Period Reclassification and Valuation Adjustment	$ 3,300
Prior Period Reclassification and Valuation Adjustment, Percentage	1.29%
Increase to Available-for-sale Securities [Member] | December 31, 2016 [Member]
Prior Period Reclassification and Valuation Adjustment	$ 3,300
Prior Period Reclassification and Valuation Adjustment, Percentage	1.22%
Decrease to Loans Receivable, Net of Allowance for Loan and Lease Losses [Member] | December 31, 2015 [Member]
Prior Period Reclassification and Valuation Adjustment	$ 3,000
Prior Period Reclassification and Valuation Adjustment, Percentage	0.41%
Decrease to Loans Receivable, Net of Allowance for Loan and Lease Losses [Member] | December 31, 2016 [Member]
Prior Period Reclassification and Valuation Adjustment	$ 3,000
Prior Period Reclassification and Valuation Adjustment, Percentage	0.41%
Increases to Total Capital, Specifically Accumulated Other Comprehensive Income, Net of Income Taxes [Member] | December 31, 2015 [Member]
Prior Period Reclassification and Valuation Adjustment	$ 178
Prior Period Reclassification and Valuation Adjustment, Percentage	0.21%
Increases to Total Capital, Specifically Accumulated Other Comprehensive Income, Net of Income Taxes [Member] | December 31, 2016 [Member]
Prior Period Reclassification and Valuation Adjustment	$ 224
Prior Period Reclassification and Valuation Adjustment, Percentage	0.25%
Decrease to Net Deferred Tax Assets [Member] | December 31, 2015 [Member]
Prior Period Reclassification and Valuation Adjustment	$ 91
Prior Period Reclassification and Valuation Adjustment, Percentage	0.32%
Decrease to Net Deferred Tax Assets [Member] | December 31, 2016 [Member]
Prior Period Reclassification and Valuation Adjustment	$ 115
Prior Period Reclassification and Valuation Adjustment, Percentage	0.43%
Subordinated Note 2 Previously Recorded in Loan Portfolio [Member]
Transfer to Investments	$ 1,000