Note 10 - Borrowed Funds (Details) - USD ($)			12 Months Ended
	Nov. 23, 2014	Mar. 13, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2005	Dec. 31, 2004
Note 10 - Borrowed Funds (Details) [Line Items]
Securities Sold under Agreements to Repurchase			$ 400,000,000	$ 450,000,000
Weighted Average Rate of Securities Sold Under Agreements			3.89%	3.85%
Prepaid Security Sold Under Repurchase Agreement			$ 0	$ 100,000,000
Rate of Prepaid Security Sold Under Repurchase Agreements				3.50%
Prepayment Penalty Security Sold Under Agreements to Repurchase				$ 3,400,000
Debt Instrument, Basis Spread on Variable Rate		3.50%
Advances from Federal Home Loan Banks			$ 275,000,000	$ 425,000,000
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Weighted Average Interest Rate			0.27%	0.27%
Threshold for Deferred Bonus						$ 225,000
Amount of Deferred Bonus Accrued in Other Liabilities		$ 300,000					$ 610,000
Accrued Interest On Deferred Bonus	5.06%	5.02%					7.00%
Debt Instrument Basis Spread on Variable Rate 2	2.75%
Interest Expense, Other			$ 79,000	$ 93,000	$ 77,000
Accrued Bonuses			1,600,000	1,500,000
Mature in March 2018 [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Advances from Federal Home Loan Banks			$ 25,000,000	$ 25,000,000
Federal Home Loan Bank, Advances, Interest Rate			1.13%	1.13%
Non Callable Fixed Rate Securities [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Number of Securities Sold Under Agreements to Repurchase			4	4
Total Floating to Fixed Rate			$ 200,000,000	$ 200,000,000
Debt, Weighted Average Interest Rate			2.78%	2.78%
Floating to Fixed Rate Agreements Totaling $200 Million [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Number of Securities Sold Under Agreements to Repurchase			4
Total Floating to Fixed Rate			$ 200,000,000
Debt, Weighted Average Interest Rate			5.00%
Floating Interest Rate, Range of Time Period			1 year
Securities Sold under Agreements to Repurchase [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Debt, Weighted Average Interest Rate			3.95%	3.92%	3.88%
Investment Securities Pledged As Collateral			$ 430,200,000	$ 516,300,000
Mature in August 2016 [Member] | Non Callable Fixed Rate Securities [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months			50,000,000
Mature in July 2017 [Member] | Non Callable Fixed Rate Securities [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Year Two			50,000,000
Mature in June 2018 [Member] | Non Callable Fixed Rate Securities [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Year Three			50,000,000
Mature in July 2018 [Member] | Non Callable Fixed Rate Securities [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Year Three			$ 50,000,000
Maximum [Member] | Floating to Fixed Rate Agreements Totaling $200 Million [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			5.07%
Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member] | Floating to Fixed Rate Agreements Totaling $200 Million [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Debt Instrument, Basis Spread on Variable Rate			3.40%
Minimum [Member] | Floating to Fixed Rate Agreements Totaling $200 Million [Member]
Note 10 - Borrowed Funds (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			4.89%