Note 15 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Securities available-for-sale	$ 1,242,509,000	$ 1,333,626,000
Equity securities	25,098,000	28,100,000
Assets, fair value disclosure	1,275,998,000	1,340,767,000
Liabilities, fair value disclosure	3,312,000	3,161,000
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	124,751,000	277,622,000
Equity securities	25,098,000
Assets, fair value disclosure	149,849,000	277,622,000
Liabilities, fair value disclosure
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	1,117,758,000	1,056,004,000
Equity securities
Assets, fair value disclosure	1,125,965,000	1,063,054,000
Liabilities, fair value disclosure	3,312,000	3,161,000
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Equity securities
Assets, fair value disclosure	184,000	91,000
Liabilities, fair value disclosure
US Treasury Securities [Member]
Securities available-for-sale	124,751,000	249,520,000
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	124,751,000	249,520,000
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	5,871,000
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	5,871,000
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		8,988
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		8,988
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	388,363,000	390,336,000
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	388,363,000	390,336,000
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	656,744,000	571,969,000
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	656,744,000	571,969,000
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale		1,914
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale		1,914
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Collateralized Mortgage Obligations [Member]
Securities available-for-sale	977,000	1,516,000
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	977,000	1,516,000
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Corporate Debt Securities [Member]
Securities available-for-sale	65,803,000	81,281,000
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	65,803,000	81,281,000
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Mutual Funds [Member]
Securities available-for-sale		6,230,000
Equity securities	6,094,000
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale		6,230,000
Equity securities	6,094,000
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Equity securities
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Equity securities
Preferred Stock of Government Sponsored Entities [Member]
Securities available-for-sale		10,102,000
Equity securities	7,822,000
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale		10,102,000
Equity securities	7,822,000
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Equity securities
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Equity securities
Other Equity Securities [Member]
Securities available-for-sale		11,770,000
Equity securities	11,182,000
Other Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale		11,770,000
Equity securities	11,182,000
Other Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Equity securities
Other Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Equity securities
Warrant [Member]
Assets, fair value disclosure	184,000	91,000
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	184,000	91,000
Interest Rate Swap [Member]
Assets, fair value disclosure	7,810,000	5,218,000
Liabilities, fair value disclosure	1,543,000	2,699,000
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	7,810,000	5,218,000
Liabilities, fair value disclosure	1,543,000	2,699,000
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	397,000	1,832,000
Liabilities, fair value disclosure	1,763,000	453,000
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	397,000	1,832,000
Liabilities, fair value disclosure	1,763,000	453,000
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	6,000	9,000
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	6,000	9,000
Option Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities, fair value disclosure