Note 3 - Investment Securities Available for Sale - Investment Securities with Unrealized Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
US Government Agencies Debt Securities [Member]
Less than 12 months fair value		$ 1,977
Less than 12 months unrealized losses		17
12 months or more fair value
12 months or more unrealized losses
Total fair value		1,977
Total unrealized losses		17
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Less than 12 months fair value	2,662	45,398
Less than 12 months unrealized losses	3	327
12 months or more fair value	2,212	11,880
12 months or more unrealized losses	25	324
Total fair value	4,874	57,278
Total unrealized losses	28	651
US States and Political Subdivisions Debt Securities [Member]
Less than 12 months fair value	264	1,037
Less than 12 months unrealized losses	1	7
12 months or more fair value		160
12 months or more unrealized losses		1
Total fair value	264	1,197
Total unrealized losses	1	8
Less than 12 months fair value	2,926	48,412
Less than 12 months unrealized losses	4	351
12 months or more fair value	2,212	12,040
12 months or more unrealized losses	25	325
Total fair value	5,138	60,452
Total unrealized losses	$ 29	$ 676