Note 12 - Fair Value Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Securities available-for-sale
Securities available-for-sale	$ 1,380,879	$ 1,318,935
Assets	1,384,279	1,320,838
Liabilities
Liabilities	15,895	9,633
US Treasury Securities [Member]
Securities available-for-sale
Securities available-for-sale	284,991	664,004
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale
Securities available-for-sale	1,004,398	544,303
Collateralized Mortgage Obligations [Member]
Securities available-for-sale
Securities available-for-sale	38	45
Corporate Debt Securities [Member]
Securities available-for-sale
Securities available-for-sale	73,830	94,472
Mutual Funds [Member]
Securities available-for-sale
Securities available-for-sale	5,899	5,866
Preferred Stock of Government Sponsored Entities [Member]
Securities available-for-sale
Securities available-for-sale	4,517	3,224
Other Equity Securities [Member]
Securities available-for-sale
Securities available-for-sale	7,206	7,021
Warrant [Member]
Securities available-for-sale
Assets	37	27
Foreign Exchange Contract [Member]
Securities available-for-sale
Assets	3,363	1,876
Liabilities
Liabilities	4,895	5,007
Interest Rate Swap [Member]
Liabilities
Liabilities	11,000	4,626
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities available-for-sale	290,890	669,870
Assets	290,890	669,870
Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Securities available-for-sale
Securities available-for-sale	284,991	664,004
Fair Value, Inputs, Level 1 [Member] | Mutual Funds [Member]
Securities available-for-sale
Securities available-for-sale	5,899	5,866
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities available-for-sale	1,089,989	649,065
Assets	1,093,352	650,941
Liabilities
Liabilities	15,895	9,633
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale
Securities available-for-sale	1,004,398	544,303
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Obligations [Member]
Securities available-for-sale
Securities available-for-sale	38	45
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Securities available-for-sale
Securities available-for-sale	73,830	94,472
Fair Value, Inputs, Level 2 [Member] | Preferred Stock of Government Sponsored Entities [Member]
Securities available-for-sale
Securities available-for-sale	4,517	3,224
Fair Value, Inputs, Level 2 [Member] | Other Equity Securities [Member]
Securities available-for-sale
Securities available-for-sale	7,206	7,021
Fair Value, Inputs, Level 2 [Member] | Foreign Exchange Contract [Member]
Securities available-for-sale
Assets	3,363	1,876
Liabilities
Liabilities	4,895	5,007
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Liabilities
Liabilities	11,000	4,626
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Assets	37	27
Fair Value, Inputs, Level 3 [Member] | Warrant [Member]
Securities available-for-sale
Assets	$ 37	$ 27