Note 11 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016		Mar. 31, 2016
Securities available-for-sale	$ 1,227,729,000	$ 1,314,345,000	[1]	$ 1,300,000,000
Assets, fair value disclosure	1,230,830,000	1,316,664,000
Liabilities, fair value disclosure	4,055,000	6,997,000
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	440,570,000	513,376,000	[1]
Assets, fair value disclosure	440,570,000	513,376,000
Liabilities, fair value disclosure
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale	787,159,000	800,969,000	[1]
Assets, fair value disclosure	790,158,000	803,209,000
Liabilities, fair value disclosure	4,055,000	6,997,000
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale			[1]
Assets, fair value disclosure	102,000	79,000
Liabilities, fair value disclosure
US Treasury Securities [Member]
Securities available-for-sale	419,470,000	489,017,000
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	419,470,000	489,017,000
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-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale	391,986,000	390,331,000
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	391,986,000	390,331,000
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	320,163,000	336,260,000
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	320,163,000	336,260,000
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Corporate Debt Securities [Member]
Securities available-for-sale	75,011,000	74,350,000
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	75,010,000	74,350,000
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Collateralized Mortgage Obligations [Member]
Securities available-for-sale		28,000
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		28,000
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Mutual Funds [Member]
Securities available-for-sale	6,230,000	6,230,000
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	6,230,000	6,230,000
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	5,978,000	7,308,000	[2]
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	5,978,000	7,308,000	[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	8,892,000	10,821,000	[2]
Other Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	8,892,000	10,821,000	[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	102,000	79,000
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	102,000	79,000
Interest Rate Swap [Member]
Assets, fair value disclosure	1,851,000	938,000
Liabilities, fair value disclosure	3,228,000	3,744,000
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	1,851,000	938,000
Liabilities, fair value disclosure	3,228,000	3,744,000
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	1,148,000	1,302,000
Liabilities, fair value disclosure	647,000	3,132,000
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	1,148,000	1,302,000
Liabilities, fair value disclosure	647,000	3,132,000
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	180,000	121,000
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	180,000	121,000
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.