Note 10 - Fair Value of Financial Instruments - Fair Value Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets	$ 890,976	$ 867,731
Liabilities	37,576	37,345
Fair Value, Inputs, Level 1 [Member]
Assets
Liabilities
Fair Value, Inputs, Level 2 [Member]
Assets	883,582	860,370
Liabilities	3,040	3,386
Fair Value, Inputs, Level 3 [Member]
Assets	7,394	7,361
Liabilities	34,536	33,959
Collateralized Mortgage Backed Securities [Member]
Assets	537,905	516,476
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets	537,905	516,476
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Other Securities [Member]
Assets	346,238	344,905
Other Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Other Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets	338,844	337,544
Other Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets	7,394	7,361
Interest Rate Swap [Member]
Assets	6,833	6,350
Liabilities	3,040	3,386
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Liabilities
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Assets	6,833	6,350
Liabilities	3,040	3,386
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Liabilities
Borrowed Funds [Member]
Liabilities	34,536	33,959
Borrowed Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities
Borrowed Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities
Borrowed Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities	$ 34,536	$ 33,959