Note 11 - Derivatives and Risk Management Activities - Derivative Instrument Gain (Loss) Recorded in Statement of Income (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative Gain (Loss), Net		$ 0
Not Designated as Hedging Instrument [Member] | Mortgage Banking Income [Member] | Best Efforts Forward Loan sales Commitments [Member] | Liability Derivatives [Member]
Derivative Gain (Loss), Net	$ (145,000)
Not Designated as Hedging Instrument [Member] | Mortgage Banking Income [Member] | Mandatory Forward Loan Sales Commitments [Member] | Liability Derivatives [Member]
Derivative Gain (Loss), Net	(87,000)
Not Designated as Hedging Instrument [Member] | Mortgage Banking Income [Member] | Asset Derivatives [Member] | Best Efforts Forward Loan sales Commitments [Member]
Derivative Gain (Loss), Net	(100,000)
Not Designated as Hedging Instrument [Member] | Mortgage Banking Income [Member] | Asset Derivatives [Member] | Mandatory Forward Loan Sales Commitments [Member]
Derivative Gain (Loss), Net	(221,000)
Interest Rate Lock Commitments [Member] | Not Designated as Hedging Instrument [Member] | Mortgage Banking Income [Member] | Liability Derivatives [Member]
Derivative Gain (Loss), Net	48,000
Interest Rate Lock Commitments [Member] | Not Designated as Hedging Instrument [Member] | Mortgage Banking Income [Member] | Asset Derivatives [Member]
Derivative Gain (Loss), Net	$ 392,000