Note 11 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Liabilities, fair value disclosure	$ 5,641	$ 6,997
Securities available-for-sale	1,368,351	1,314,345	[1]
Assets, fair value disclosure	1,372,445	1,316,664
Fair Value, Inputs, Level 1 [Member]
Liabilities, fair value disclosure
Securities available-for-sale	591,403	513,376	[1]
Assets, fair value disclosure	591,403	513,376
Fair Value, Inputs, Level 2 [Member]
Liabilities, fair value disclosure	5,641	6,997
Securities available-for-sale	776,948	800,969	[1]
Assets, fair value disclosure	780,934	803,209
Fair Value, Inputs, Level 3 [Member]
Liabilities, fair value disclosure
Securities available-for-sale			[1]
Assets, fair value disclosure	108	79
US Treasury Securities [Member]
Securities available-for-sale	569,045	489,017
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	569,045	489,017
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-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	394,631	390,331
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	394,631	390,331
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	306,907	336,260
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	306,907	336,260
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Corporate Debt Securities [Member]
Securities available-for-sale	75,410	74,350
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	75,410	74,350
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Collateralized Mortgage Obligations [Member]
Securities available-for-sale		28
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		28
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Mutual Funds [Member]
Securities available-for-sale	6,265	6,230
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	6,265	6,230
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Mutual Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Preferred Stock of Government Sponsored Entities [Member]
Securities available-for-sale	5,224	7,308	[2]
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	5,224	7,308	[2]
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale			[2]
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale			[2]
Other Equity Securities [Member]
Securities available-for-sale	10,869	10,821	[2]
Other Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	10,869	10,821	[2]
Other Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale			[2]
Other Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Warrant [Member]
Assets, fair value disclosure	108	79
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	108	79
Foreign Exchange Contract [Member]
Liabilities, fair value disclosure	640	3,132
Assets, fair value disclosure	2,378	1,302
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities, fair value disclosure
Assets, fair value disclosure
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities, fair value disclosure	640	3,132
Assets, fair value disclosure	2,378	1,302
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities, fair value disclosure
Assets, fair value disclosure
Interest Rate Swap [Member]
Liabilities, fair value disclosure	4,770	3,744
Assets, fair value disclosure	1,608	938
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities, fair value disclosure
Assets, fair value disclosure
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities, fair value disclosure	4,770	3,744
Assets, fair value disclosure	1,608	938
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities, fair value disclosure
Assets, fair value disclosure
Option Contracts [Member]
Liabilities, fair value disclosure	231	121
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	231	121
Option Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities, fair value disclosure

[1] Preferred stock of government sponsored entities and other equity securities as of December 31, 2015 were reclassified as level 1 rather than level 2 as originally classified due to the availability of quoted prices in active markets.

[2] Preferred stock of government sponsored entities and other equity securities as of December 31, 2015 were reclassified as level 1 rather than level 2 as originally classified due to the availability of quoted prices in active markets.