Note 3 - Investment Securities Available for Sale (Details) - The Amortized Cost and Estimated Fair Value of Investments Available for Sale (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
U. S. Government agency securities maturing:
Amortized Cost	$ 388,628	$ 383,665
Estimated Fair Value	387,790	378,133
US Government Agencies Debt Securities [Member]
U. S. Government agency securities maturing:
One year or less	19,012	19,025
One year or less	19,063	19,133
Amortized Cost	27,321	27,615
Estimated Fair Value	27,781	28,202
Amortized Cost	2,464
Estimated Fair Value	2,513
Residential Mortgage Backed Securities [Member]
U. S. Government agency securities maturing:
Amortized Cost	232,001	234,206
Estimated Fair Value	228,611	228,674
Municipal Bond [Member]
U. S. Government agency securities maturing:
Amortized Cost	31,725	25,718
Estimated Fair Value	32,598	26,008
Amortized Cost	75,709	76,705
Estimated Fair Value	76,807	75,732
Equity Investment Other [Member]
U. S. Government agency securities maturing:
Amortized Cost	396	396
Estimated Fair Value	$ 417	$ 384