Note 15 - Fair Value Measurements and Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Securities available-for-sale	$ 1,036,550	$ 1,451,842
Equity securities	23,744	28,005
Assets, fair value disclosure	1,068,382	1,484,478
Liabilities, fair value disclosure	12,486	15,651
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	80,948	74,936
Equity securities	23,744	28,005
Assets, fair value disclosure	104,692	102,941
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	955,602	1,376,906
Equity securities	0	0
Assets, fair value disclosure	963,669	1,381,498
Liabilities, fair value disclosure	12,486	15,651
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Equity securities	0	0
Assets, fair value disclosure	21	39
Liabilities, fair value disclosure	0	0
US Treasury Securities [Member]
Securities available-for-sale	80,948	74,936
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	80,948	74,936
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	99,838	90,796
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0	0
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	99,838	90,796
US Government Corporations and Agencies Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Commercial Mortgage Backed Securities [Member]
Securities available-for-sale	727,068	887,790
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	727,068	887,790
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale		224,443
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale		0
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale		224,443
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale		0
Collateralized Mortgage Obligations [Member]
Securities available-for-sale	10,324	552
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	10,324	552
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Corporate Debt Securities [Member]
Securities available-for-sale	118,372	173,325
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	118,372	173,325
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Mutual Funds [Member]
Equity securities	6,413	6,277
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Equity securities	6,413	6,277
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Equity securities	0	0
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Equity securities	0	0
Preferred Stock of Government Sponsored Entities [Member]
Equity securities	5,485	10,529
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 1 [Member]
Equity securities	5,485	10,529
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 2 [Member]
Equity securities	0	0
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 3 [Member]
Equity securities	0	0
Other Equity Securities [Member]
Equity securities	11,846	11,199
Other Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Equity securities	11,846	11,199
Other Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Equity securities	0	0
Other Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Equity securities	0	0
Warrant [Member]
Assets, fair value disclosure	21	39
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	21	39
Interest Rate Swap [Member]
Assets, fair value disclosure	3,409	2,181
Liabilities, fair value disclosure	10,286	14,229
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	3,409	2,181
Liabilities, fair value disclosure	10,286	14,229
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	4,658	2,411
Liabilities, fair value disclosure	2,200	1,415
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	4,658	2,411
Liabilities, fair value disclosure	2,200	1,415
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
Option Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities, fair value disclosure		0
Option Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities, fair value disclosure		7
Option Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities, fair value disclosure		$ 0