Note 13 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Securities available-for-sale	$ 1,427,438	$ 1,242,509
Equity securities	32,862	25,098
Assets, fair value disclosure	1,462,993	1,275,998
Liabilities, fair value disclosure	20,175	3,312
Securities available-for-sale
Securities available-for-sale	1,427,438	1,242,509
Equity securities	32,862	25,098
Assets, fair value disclosure	1,462,993	1,275,998
Liabilities, fair value disclosure	20,175	3,312
US Government Corporations and Agencies Securities [Member]
Securities available-for-sale	92,954
Securities available-for-sale
Securities available-for-sale	92,954
US Treasury Securities [Member]
Securities available-for-sale		124,751
Securities available-for-sale
Securities available-for-sale		124,751
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	347,699	388,363
Securities available-for-sale
Securities available-for-sale	347,699	388,363
US Government Agencies Debt Securities [Member]
Securities available-for-sale		5,871
Securities available-for-sale
Securities available-for-sale		5,871
Commercial Mortgage Backed Securities [Member]
Securities available-for-sale	886,735	656,744
Securities available-for-sale
Securities available-for-sale	886,735	656,744
Collateralized Mortgage Obligations [Member]
Securities available-for-sale	665	977
Securities available-for-sale
Securities available-for-sale	665	977
Corporate Debt Securities [Member]
Securities available-for-sale	99,385	65,803
Securities available-for-sale
Securities available-for-sale	99,385	65,803
Mutual Funds [Member]
Equity securities	6,307	6,094
Securities available-for-sale
Equity securities	6,307	6,094
Preferred Stock of Government Sponsored Entities [Member]
Equity securities	15,145	7,822
Securities available-for-sale
Equity securities	15,145	7,822
Other Equity Securities [Member]
Equity securities	11,410	11,182
Securities available-for-sale
Equity securities	11,410	11,182
Warrant [Member]
Assets, fair value disclosure	31	184
Securities available-for-sale
Assets, fair value disclosure	31	184
Interest Rate Swap [Member]
Assets, fair value disclosure	1,697	7,810
Liabilities, fair value disclosure	17,734	1,543
Securities available-for-sale
Assets, fair value disclosure	1,697	7,810
Liabilities, fair value disclosure	17,734	1,543
Foreign Exchange Contract [Member]
Assets, fair value disclosure	965	397
Liabilities, fair value disclosure	2,435	1,763
Securities available-for-sale
Assets, fair value disclosure	965	397
Liabilities, fair value disclosure	2,435	1,763
Option Contracts [Member]
Liabilities, fair value disclosure	6	6
Securities available-for-sale
Liabilities, fair value disclosure	6	6
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	0	124,751
Equity securities	32,862	25,098
Assets, fair value disclosure	32,862	149,849
Liabilities, fair value disclosure	0	0
Securities available-for-sale
Securities available-for-sale	0	124,751
Equity securities	32,862	25,098
Assets, fair value disclosure	32,862	149,849
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | US Government Corporations and Agencies Securities [Member]
Securities available-for-sale	0
Securities available-for-sale
Securities available-for-sale	0
Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Securities available-for-sale		124,751
Securities available-for-sale
Securities available-for-sale		124,751
Fair Value, Inputs, Level 1 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	0	0
Securities available-for-sale
Securities available-for-sale	0	0
Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities [Member]
Securities available-for-sale		0
Securities available-for-sale
Securities available-for-sale		0
Fair Value, Inputs, Level 1 [Member] | Commercial Mortgage Backed Securities [Member]
Securities available-for-sale	0	0
Securities available-for-sale
Securities available-for-sale	0	0
Fair Value, Inputs, Level 1 [Member] | Collateralized Mortgage Obligations [Member]
Securities available-for-sale	0	0
Securities available-for-sale
Securities available-for-sale	0	0
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Securities available-for-sale	0	0
Securities available-for-sale
Securities available-for-sale	0	0
Fair Value, Inputs, Level 1 [Member] | Mutual Funds [Member]
Equity securities	6,307	6,094
Securities available-for-sale
Equity securities	6,307	6,094
Fair Value, Inputs, Level 1 [Member] | Preferred Stock of Government Sponsored Entities [Member]
Equity securities	15,145	7,822
Securities available-for-sale
Equity securities	15,145	7,822
Fair Value, Inputs, Level 1 [Member] | Other Equity Securities [Member]
Equity securities	11,410	11,182
Securities available-for-sale
Equity securities	11,410	11,182
Fair Value, Inputs, Level 1 [Member] | Warrant [Member]
Assets, fair value disclosure	0	0
Securities available-for-sale
Assets, fair value disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Interest Rate Swap [Member]
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Securities available-for-sale
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Exchange Contract [Member]
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Securities available-for-sale
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Option Contracts [Member]
Liabilities, fair value disclosure	0	0
Securities available-for-sale
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	1,427,438	1,117,758
Equity securities	0	0
Assets, fair value disclosure	1,430,100	1,125,965
Liabilities, fair value disclosure	20,175	3,312
Securities available-for-sale
Securities available-for-sale	1,427,438	1,117,758
Equity securities	0	0
Assets, fair value disclosure	1,430,100	1,125,965
Liabilities, fair value disclosure	20,175	3,312
Fair Value, Inputs, Level 2 [Member] | US Government Corporations and Agencies Securities [Member]
Securities available-for-sale	92,954
Securities available-for-sale
Securities available-for-sale	92,954
Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member]
Securities available-for-sale		0
Securities available-for-sale
Securities available-for-sale		0
Fair Value, Inputs, Level 2 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	347,699	388,363
Securities available-for-sale
Securities available-for-sale	347,699	388,363
Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member]
Securities available-for-sale		5,871
Securities available-for-sale
Securities available-for-sale		5,871
Fair Value, Inputs, Level 2 [Member] | Commercial Mortgage Backed Securities [Member]
Securities available-for-sale	886,735	656,744
Securities available-for-sale
Securities available-for-sale	886,735	656,744
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Obligations [Member]
Securities available-for-sale	665	977
Securities available-for-sale
Securities available-for-sale	665	977
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Securities available-for-sale	99,385	65,803
Securities available-for-sale
Securities available-for-sale	99,385	65,803
Fair Value, Inputs, Level 2 [Member] | Mutual Funds [Member]
Equity securities	0	0
Securities available-for-sale
Equity securities	0	0
Fair Value, Inputs, Level 2 [Member] | Preferred Stock of Government Sponsored Entities [Member]
Equity securities	0	0
Securities available-for-sale
Equity securities	0	0
Fair Value, Inputs, Level 2 [Member] | Other Equity Securities [Member]
Equity securities	0	0
Securities available-for-sale
Equity securities	0	0
Fair Value, Inputs, Level 2 [Member] | Warrant [Member]
Assets, fair value disclosure	0	0
Securities available-for-sale
Assets, fair value disclosure	0	0
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Assets, fair value disclosure	1,697	7,810
Liabilities, fair value disclosure	17,734	1,543
Securities available-for-sale
Assets, fair value disclosure	1,697	7,810
Liabilities, fair value disclosure	17,734	1,543
Fair Value, Inputs, Level 2 [Member] | Foreign Exchange Contract [Member]
Assets, fair value disclosure	965	397
Liabilities, fair value disclosure	2,435	1,763
Securities available-for-sale
Assets, fair value disclosure	965	397
Liabilities, fair value disclosure	2,435	1,763
Fair Value, Inputs, Level 2 [Member] | Option Contracts [Member]
Liabilities, fair value disclosure	6	6
Securities available-for-sale
Liabilities, fair value disclosure	6	6
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale	0	0
Equity securities	0	0
Assets, fair value disclosure	31	184
Liabilities, fair value disclosure	0	0
Securities available-for-sale
Securities available-for-sale	0	0
Equity securities	0	0
Assets, fair value disclosure	31	184
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | US Government Corporations and Agencies Securities [Member]
Securities available-for-sale	0
Securities available-for-sale
Securities available-for-sale	0
Fair Value, Inputs, Level 3 [Member] | US Treasury Securities [Member]
Securities available-for-sale		0
Securities available-for-sale
Securities available-for-sale		0
Fair Value, Inputs, Level 3 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	0	0
Securities available-for-sale
Securities available-for-sale	0	0
Fair Value, Inputs, Level 3 [Member] | US Government Agencies Debt Securities [Member]
Securities available-for-sale		0
Securities available-for-sale
Securities available-for-sale		0
Fair Value, Inputs, Level 3 [Member] | Commercial Mortgage Backed Securities [Member]
Securities available-for-sale	0	0
Securities available-for-sale
Securities available-for-sale	0	0
Fair Value, Inputs, Level 3 [Member] | Collateralized Mortgage Obligations [Member]
Securities available-for-sale	0	0
Securities available-for-sale
Securities available-for-sale	0	0
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Securities available-for-sale	0	0
Securities available-for-sale
Securities available-for-sale	0	0
Fair Value, Inputs, Level 3 [Member] | Mutual Funds [Member]
Equity securities	0	0
Securities available-for-sale
Equity securities	0	0
Fair Value, Inputs, Level 3 [Member] | Preferred Stock of Government Sponsored Entities [Member]
Equity securities	0	0
Securities available-for-sale
Equity securities	0	0
Fair Value, Inputs, Level 3 [Member] | Other Equity Securities [Member]
Equity securities	0	0
Securities available-for-sale
Equity securities	0	0
Fair Value, Inputs, Level 3 [Member] | Warrant [Member]
Assets, fair value disclosure	31	184
Securities available-for-sale
Assets, fair value disclosure	31	184
Fair Value, Inputs, Level 3 [Member] | Interest Rate Swap [Member]
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Securities available-for-sale
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Exchange Contract [Member]
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Securities available-for-sale
Assets, fair value disclosure	0	0
Liabilities, fair value disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Option Contracts [Member]
Liabilities, fair value disclosure	0	0
Securities available-for-sale
Liabilities, fair value disclosure	$ 0	$ 0