Note 16 - Fair Value Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Securities available-for-sale
Securities available-for-sale	$ 1,586,352	$ 1,318,935
Assets	1,589,753	1,320,838
Liabilities
Liabilities	10,648	9,633
US Treasury Securities [Member]
Securities available-for-sale
Securities available-for-sale	284,288	664,004
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale
Securities available-for-sale	148,160
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale
Securities available-for-sale	1,062,269	544,303
Collateralized Mortgage Obligations [Member]
Securities available-for-sale
Securities available-for-sale	36	45
Corporate Debt Securities [Member]
Securities available-for-sale
Securities available-for-sale	73,855	94,472
Mutual Funds [Member]
Securities available-for-sale
Securities available-for-sale	5,833	5,866
Preferred Stock of Government Sponsored Entities [Member]
Securities available-for-sale
Securities available-for-sale	3,216	3,224
Other Equity Securities [Member]
Securities available-for-sale
Securities available-for-sale	8,695	7,021
Warrant [Member]
Securities available-for-sale
Assets	62	27
Foreign Exchange Contract [Member]
Securities available-for-sale
Assets	3,339	1,876
Liabilities
Liabilities	4,124	5,007
Option Contracts [Member]
Liabilities
Liabilities	28
Interest Rate Swap [Member]
Liabilities
Liabilities	6,496	4,626
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities available-for-sale	290,121	669,870
Assets	290,121	669,870
Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Securities available-for-sale
Securities available-for-sale	284,288	664,004
Fair Value, Inputs, Level 1 [Member] | Mutual Funds [Member]
Securities available-for-sale
Securities available-for-sale	5,833	5,866
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities available-for-sale	1,296,231	649,065
Assets	1,299,570	650,941
Liabilities
Liabilities	10,648	9,633
Fair Value, Inputs, Level 2 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale
Securities available-for-sale	148,160
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale
Securities available-for-sale	1,062,269	544,303
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Obligations [Member]
Securities available-for-sale
Securities available-for-sale	36	45
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Securities available-for-sale
Securities available-for-sale	73,855	94,472
Fair Value, Inputs, Level 2 [Member] | Preferred Stock of Government Sponsored Entities [Member]
Securities available-for-sale
Securities available-for-sale	3,216	3,224
Fair Value, Inputs, Level 2 [Member] | Other Equity Securities [Member]
Securities available-for-sale
Securities available-for-sale	8,695	7,021
Fair Value, Inputs, Level 2 [Member] | Foreign Exchange Contract [Member]
Securities available-for-sale
Assets	3,339	1,876
Liabilities
Liabilities	4,124	5,007
Fair Value, Inputs, Level 2 [Member] | Option Contracts [Member]
Liabilities
Liabilities	28
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Liabilities
Liabilities	6,496	4,626
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Assets	62	27
Fair Value, Inputs, Level 3 [Member] | Warrant [Member]
Securities available-for-sale
Assets	$ 62	$ 27