Note 15 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Securities available-for-sale	$ 1,451,842	$ 1,242,509
Equity securities	28,005	25,098
Assets, fair value disclosure	1,484,478	1,275,998
Liabilities, fair value disclosure	15,651	3,312
Equity securities	28,005	25,098
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	74,936	124,751
Equity securities	28,005	25,098
Assets, fair value disclosure	102,941	149,849
Liabilities, fair value disclosure	0	0
Equity securities	28,005	25,098
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	1,376,906	1,117,758
Equity securities	0	0
Assets, fair value disclosure	1,381,498	1,125,965
Liabilities, fair value disclosure	15,651	3,312
Equity securities	0	0
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Equity securities	0	0
Assets, fair value disclosure	39	184
Liabilities, fair value disclosure	0	0
Equity securities	0	0
US Treasury Securities [Member]
Securities available-for-sale	74,936	124,751
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	74,936	124,751
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	0	0
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
US Government Corporations and Agencies Securities [Member]
Securities available-for-sale	90,796
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	90,796
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0
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		0
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		0
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	224,443	388,363
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0	0
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	224,443	388,363
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Commercial Mortgage Backed Securities [Member]
Securities available-for-sale	887,790	656,744
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0	0
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	887,790	656,744
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Collateralized Mortgage Obligations [Member]
Securities available-for-sale	552	977
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0	0
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	552	977
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Corporate Debt Securities [Member]
Securities available-for-sale	173,325	65,803
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	173,325	65,803
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Mutual Funds [Member]
Equity securities	6,277	6,094
Equity securities	6,277	6,094
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Equity securities	6,277	6,094
Equity securities	6,277	6,094
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Equity securities	0	0
Equity securities	0	0
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Equity securities	0	0
Equity securities	0	0
Preferred Stock of Government Sponsored Entities [Member]
Equity securities	10,529	7,822
Equity securities	10,529	7,822
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 1 [Member]
Equity securities	10,529	7,822
Equity securities	10,529	7,822
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 2 [Member]
Equity securities	0	0
Equity securities	0	0
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 3 [Member]
Equity securities	0	0
Equity securities	0	0
Other Equity Securities [Member]
Equity securities	11,199	11,182
Equity securities	11,199	11,182
Other Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Equity securities	11,199	11,182
Equity securities	11,199	11,182
Other Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Equity securities	0	0
Equity securities	0	0
Other Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Equity securities	0	0
Equity securities	0	0
Warrant [Member]
Assets, fair value disclosure	39	184
Warrant [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure	0	0
Warrant [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure	0	0
Warrant [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure	39	184
Interest Rate Swap [Member]
Assets, fair value disclosure	2,181	7,810
Liabilities, fair value disclosure	14,229	1,543
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure	2,181	7,810
Liabilities, fair value disclosure	14,229	1,543
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Foreign Exchange Contract [Member]
Assets, fair value disclosure	2,411	397
Liabilities, fair value disclosure	1,415	1,763
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure	2,411	397
Liabilities, fair value disclosure	1,415	1,763
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Option Contracts [Member]
Liabilities, fair value disclosure	7	6
Option Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities, fair value disclosure	0	0
Option Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities, fair value disclosure	7	6
Option Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities, fair value disclosure	$ 0	$ 0