Note 11 - Fair Value Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Assets	$ 580,500	$ 668,740
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Assets
Collateralized Mortgage Backed Securities [Member]
Assets:
Assets	580,500	668,740
Other Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Assets	361,444	317,445
Other Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Assets	7,167	7,212
Other Securities [Member]
Assets:
Assets	368,611	324,657
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Assets		48
Liabilities:
Liabilities	16,201	4,314
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Assets
Liabilities:
Liabilities
Interest Rate Swap [Member]
Assets:
Assets		48
Liabilities:
Liabilities	16,201	4,314
Borrowed Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities:
Liabilities
Borrowed Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities:
Liabilities	27,485	29,018
Borrowed Funds [Member]
Liabilities:
Liabilities	27,485	29,018
Fair Value, Inputs, Level 2 [Member]
Assets:
Assets	941,944	986,233
Liabilities:
Liabilities	16,201	4,314
Fair Value, Inputs, Level 3 [Member]
Assets:
Assets	7,167	7,212
Liabilities:
Liabilities	27,485	29,018
Assets	949,111	993,445
Liabilities	$ 43,686	$ 33,332