Note 11 - Fair Value Measurements (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Securities available-for-sale
Securities available-for-sale	$ 1,485,124	$ 1,586,352
Assets	1,488,531	1,589,753
Liabilities
Liabilities	15,791	10,648
Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities available-for-sale	230,719	290,121
Assets	230,719	290,121
Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities available-for-sale	1,254,405	1,296,231
Assets	1,257,718	1,299,570
Liabilities
Liabilities	15,791	10,648
Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Assets	94	62
US Treasury Securities [Member]
Securities available-for-sale
Securities available-for-sale	224,804	284,288
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities available-for-sale	224,804	284,288
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale
Securities available-for-sale	100,010	148,160
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities available-for-sale	100,010	148,160
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale
Securities available-for-sale	1,070,493	1,062,269
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities available-for-sale	1,070,493	1,062,269
Collateralized Mortgage Obligations [Member]
Securities available-for-sale
Securities available-for-sale	34	36
Collateralized Mortgage Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities available-for-sale	34	36
Corporate Debt Securities [Member]
Securities available-for-sale
Securities available-for-sale	73,103	73,855
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities available-for-sale	73,103	73,855
Mutual Funds [Member]
Securities available-for-sale
Securities available-for-sale	5,915	5,833
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale
Securities available-for-sale	5,915	5,833
Preferred Stock of Government Sponsored Entities [Member]
Securities available-for-sale
Securities available-for-sale	2,803	3,216
Preferred Stock of Government Sponsored Entities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities available-for-sale	2,803	3,216
Other Equity Securities [Member]
Securities available-for-sale
Securities available-for-sale	7,962	8,695
Other Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Securities available-for-sale	7,962	8,695
Warrant [Member]
Securities available-for-sale
Assets	94	62
Warrant [Member] | Fair Value, Inputs, Level 3 [Member]
Securities available-for-sale
Assets	94	62
Foreign Exchange Contract [Member]
Securities available-for-sale
Assets	3,313	3,339
Liabilities
Liabilities	913	4,124
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Securities available-for-sale
Assets	3,313	3,339
Liabilities
Liabilities	913	4,124
Interest Rate Swap [Member]
Liabilities
Liabilities	14,878	6,496
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities
Liabilities	$ 14,878	6,496
Option Contracts [Member]
Liabilities
Liabilities		28
Option Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities
Liabilities		$ 28