Note 3 - Investment Securities (Details) - Interest income from investment securities (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Taxable:
Interest income from investment taxable securities	$ 5,591	$ 5,348	$ 11,125	$ 10,038
Tax-exempt	7,498	7,808	15,030	15,760
Total interest income from investment securities	13,089	13,156	26,155	25,798
Mortgage Related Securities [Member]
Taxable:
Interest income from investment taxable securities	3,371	3,713	6,933	7,076
Other Securities [Member]
Taxable:
Interest income from investment taxable securities	$ 2,220	$ 1,635	$ 4,192	$ 2,962