Note 3 - Investment Securities (Detail) - Investment Securities in a Temporary Unrealized Loss Position (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Less than 12 Months - Fair Value	$ 61,112	$ 27,931	$ 7,437
Less than 12 Months - Unrealized Losses	473	193	35
12 Months or Longer - Fair Value	0	0
12 Months or Longer - Unrealized Losses	0	0
Total - Fair Value	61,112	27,931	7,437
Total - Unrealized Losses	473	193	35
US Government Agencies Debt Securities [Member]
Less than 12 Months - Fair Value	6,062	3,005	2,988
Less than 12 Months - Unrealized Losses	61	7	12
12 Months or Longer - Fair Value			0
12 Months or Longer - Unrealized Losses			0
Total - Fair Value	6,062	3,005	2,988
Total - Unrealized Losses	61	7	12
Residential Mortgage Backed Securities [Member]
Less than 12 Months - Fair Value	39,444	7,605
Less than 12 Months - Unrealized Losses	309	49
12 Months or Longer - Fair Value	0	0
12 Months or Longer - Unrealized Losses	0	0
Total - Fair Value	39,444	7,605
Total - Unrealized Losses	309	49
US States and Political Subdivisions Debt Securities [Member]
Less than 12 Months - Fair Value	12,584	12,168	240
Less than 12 Months - Unrealized Losses	66	106	2
12 Months or Longer - Fair Value	0		0
12 Months or Longer - Unrealized Losses	0		0
Total - Fair Value	12,584	12,168	240
Total - Unrealized Losses	66	106	2
Asset-backed Securities [Member]
Less than 12 Months - Fair Value	3,022	3,174	3,221
Less than 12 Months - Unrealized Losses	37	10	9
12 Months or Longer - Fair Value		0
12 Months or Longer - Unrealized Losses		0
Total - Fair Value	3,022	3,174	3,221
Total - Unrealized Losses	37	10	9
Corporate Debt Securities [Member]
Less than 12 Months - Fair Value		1,979	988
Less than 12 Months - Unrealized Losses		21	12
12 Months or Longer - Fair Value		0	0
12 Months or Longer - Unrealized Losses		0	0
Total - Fair Value		1,979	988
Total - Unrealized Losses		$ 21	$ 12