Note 13 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Securities available-for-sale	$ 1,309,853	$ 1,242,509
Equity securities	29,261	25,098
Assets, fair value disclosure	1,344,234	1,275,998
Liabilities, fair value disclosure	6,384	3,312
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	149,240	124,751
Equity securities	29,261	25,098
Assets, fair value disclosure	178,501	149,849
Liabilities, fair value disclosure
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	1,160,613	1,117,758
Equity securities
Assets, fair value disclosure	1,165,552	1,125,965
Liabilities, fair value disclosure	6,384	3,312
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Equity securities
Assets, fair value disclosure	181	184
Liabilities, fair value disclosure
US Treasury Securities [Member]
Securities available-for-sale	149,240	124,751
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	149,240	124,751
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
US Government Corporations and Agencies Securities [Member]
Securities available-for-sale	5,531
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	5,531
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
US Government Agencies Debt Securities [Member]
Securities available-for-sale		5,871
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale		5,871
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	393,274	388,363
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	393,274	388,363
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Commercial Mortgage Backed Securities [Member]
Securities available-for-sale	695,961	656,744
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	695,961	656,744
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Collateralized Mortgage Obligations [Member]
Securities available-for-sale	881	977
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	881	977
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Corporate Debt Securities [Member]
Securities available-for-sale	64,966	65,803
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	64,966	65,803
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Mutual Funds [Member]
Equity securities	6,171	6,094
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Equity securities	6,171	6,094
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Equity securities
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Equity securities
Preferred Stock of Government Sponsored Entities [Member]
Equity securities	11,443	7,822
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 1 [Member]
Equity securities	11,443	7,822
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 2 [Member]
Equity securities
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 3 [Member]
Equity securities
Other Equity Securities [Member]
Equity securities	11,647	11,182
Other Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Equity securities	11,647	11,182
Other Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Equity securities
Other Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Equity securities
Warrant [Member]
Assets, fair value disclosure	181	184
Warrant [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure
Warrant [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure
Warrant [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure	181	184
Interest Rate Swap [Member]
Assets, fair value disclosure	4,480	7,810
Liabilities, fair value disclosure	5,727	1,543
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure
Liabilities, fair value disclosure
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure	4,480	7,810
Liabilities, fair value disclosure	5,727	1,543
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure
Liabilities, fair value disclosure
Foreign Exchange Contract [Member]
Assets, fair value disclosure	459	397
Liabilities, fair value disclosure	645	1,763
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure
Liabilities, fair value disclosure
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure	459	397
Liabilities, fair value disclosure	645	1,763
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure
Liabilities, fair value disclosure
Option Contracts [Member]
Liabilities, fair value disclosure	12	6
Option Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities, fair value disclosure
Option Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities, fair value disclosure	12	6
Option Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities, fair value disclosure