Note 2 - Investment Securities (Details) - Municipal Securities Portfolio - USD ($)	Dec. 31, 2015	Dec. 31, 2014
General obligation bonds:
Investment securities available for sale, amortized cost	$ 243,948,000	$ 286,779,000
Investment securities available for sale, at fair value	248,294,725	292,298,910
Municipal General Obligation Bonds [Member]
General obligation bonds:
Investment securities available for sale, amortized cost	34,435,000
Investment securities available for sale, at fair value	35,135,000
Municipal General Obligation Bonds [Member] | PENNSYLVANIA
General obligation bonds:
Investment securities available for sale, amortized cost	6,461,000
Investment securities available for sale, at fair value	6,589,000
Municipal General Obligation Bonds [Member] | CALIFORNIA
General obligation bonds:
Investment securities available for sale, amortized cost	3,612,000
Investment securities available for sale, at fair value	3,709,000
Municipal General Obligation Bonds [Member] | WASHINGTON
General obligation bonds:
Investment securities available for sale, amortized cost	3,430,000
Investment securities available for sale, at fair value	3,436,000
Municipal General Obligation Bonds [Member] | INDIANA
General obligation bonds:
Investment securities available for sale, amortized cost	2,468,000
Investment securities available for sale, at fair value	2,483,000
Municipal General Obligation Bonds [Member] | NORTH CAROLINA
General obligation bonds:
Investment securities available for sale, amortized cost	2,375,000
Investment securities available for sale, at fair value	2,408,000
Municipal General Obligation Bonds [Member] | SOUTH CAROLINA
General obligation bonds:
Investment securities available for sale, amortized cost	2,261,000
Investment securities available for sale, at fair value	2,321,000
Municipal General Obligation Bonds [Member] | ALABAMA
General obligation bonds:
Investment securities available for sale, amortized cost	1,839,000
Investment securities available for sale, at fair value	1,860,000
Municipal General Obligation Bonds [Member] | TEXAS
General obligation bonds:
Investment securities available for sale, amortized cost	1,814,000
Investment securities available for sale, at fair value	1,848,000
Municipal General Obligation Bonds [Member] | Other States [Member]
General obligation bonds:
Investment securities available for sale, amortized cost	10,175,000
Investment securities available for sale, at fair value	10,481,000
Municipal Revenue Bonds [Member]
General obligation bonds:
Investment securities available for sale, amortized cost	21,099,000
Investment securities available for sale, at fair value	21,696,000
Municipal Revenue Bonds [Member] | PENNSYLVANIA
General obligation bonds:
Investment securities available for sale, amortized cost	1,827,000
Investment securities available for sale, at fair value	1,886,000
Municipal Revenue Bonds [Member] | NORTH CAROLINA
General obligation bonds:
Investment securities available for sale, amortized cost	3,781,000
Investment securities available for sale, at fair value	3,893,000
Municipal Revenue Bonds [Member] | Other States [Member]
General obligation bonds:
Investment securities available for sale, amortized cost	3,559,000
Investment securities available for sale, at fair value	3,639,000
Municipal Revenue Bonds [Member] | NEW YORK
General obligation bonds:
Investment securities available for sale, amortized cost	7,307,000
Investment securities available for sale, at fair value	7,531,000
Municipal Revenue Bonds [Member] | MISSISSIPPI
General obligation bonds:
Investment securities available for sale, amortized cost	2,348,000
Investment securities available for sale, at fair value	2,378,000
Municipal Revenue Bonds [Member] | OKLAHOMA
General obligation bonds:
Investment securities available for sale, amortized cost	2,277,000
Investment securities available for sale, at fair value	2,369,000
US States and Political Subdivisions Debt Securities [Member]
General obligation bonds:
Investment securities available for sale, amortized cost	55,534,000	54,014,000
Investment securities available for sale, at fair value	56,831,000	$ 55,702,000
Municipal Revenue Bonds - University and College [Member]
General obligation bonds:
Investment securities available for sale, amortized cost	8,694,000
Investment securities available for sale, at fair value	8,945,000
Municipal Revenue Bonds - Public Improvements [Member]
General obligation bonds:
Investment securities available for sale, amortized cost	5,046,000
Investment securities available for sale, at fair value	5,204,000
Municipal Revenue Bonds - Pension Funding [Member]
General obligation bonds:
Investment securities available for sale, amortized cost	1,827,000
Investment securities available for sale, at fair value	1,886,000
Municipal Revenue Bonds - Refunding Bonds [Member]
General obligation bonds:
Investment securities available for sale, amortized cost	1,111,000
Investment securities available for sale, at fair value	1,128,000
Municipal Revenue Bonds - Other [Member]
General obligation bonds:
Investment securities available for sale, amortized cost	4,421,000
Investment securities available for sale, at fair value	$ 4,533,000