Note 9 - Securities Sold Under Agreements to Repurchase - Maturity of Short and Long-term Repurchase Agreements (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Short and long-term purchase agreements	$ 34,073	$ 36,370
Maturity Overnight [Member]
Short and long-term purchase agreements	31,386	33,682
Maturity Less than 30 Days [Member]
Short and long-term purchase agreements	258	1,203
Maturity 30 to 90 Days [Member]
Short and long-term purchase agreements	0	0
Maturity 90 Days to One Year [Member]
Short and long-term purchase agreements	1,400	458
Maturity Over One Year to Four Years [Member]
Short and long-term purchase agreements	1,029	1,027
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Short and long-term purchase agreements	34,073	36,370
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Maturity Overnight [Member]
Short and long-term purchase agreements	31,386	33,682
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Maturity Less than 30 Days [Member]
Short and long-term purchase agreements	258	1,203
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Maturity 30 to 90 Days [Member]
Short and long-term purchase agreements	0	0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Maturity 90 Days to One Year [Member]
Short and long-term purchase agreements	1,400	458
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Maturity Over One Year to Four Years [Member]
Short and long-term purchase agreements	$ 1,029	$ 1,027