Note 2 - Securities - Securities With Unrealized Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
US Government-sponsored Enterprises Debt Securities [Member]
Less than 12 months, fair value	$ 109,829	$ 102,098
Less than 12 months, Unrealized losses	34	500
12 months or more, Fair value	3,842	8,469
12 months or more, Unrealized losses	28	265
Fair value	113,671	110,567
Unrealized losses	62	765
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Less than 12 months, fair value	1,343	49,774
Less than 12 months, Unrealized losses	2	662
12 months or more, Fair value	18,589	29,936
12 months or more, Unrealized losses	138	992
Fair value	19,932	79,710
Unrealized losses	140	1,654
US States and Political Subdivisions Debt Securities [Member]
Less than 12 months, fair value	2,556	13,225
Less than 12 months, Unrealized losses	8	31
12 months or more, Fair value	1,338	1,955
12 months or more, Unrealized losses	7	19
Fair value	3,894	15,180
Unrealized losses	15	50
Less than 12 months, fair value	113,728	165,097
Less than 12 months, Unrealized losses	44	1,193
12 months or more, Fair value	23,769	40,360
12 months or more, Unrealized losses	173	1,276
Fair value	137,497	205,457
Unrealized losses	$ 217	$ 2,469