Note 2 - Investment Securities (Detail) - Amortized Cost and Fair Value of Investment Securities (USD $)	Jun. 30, 2012	Dec. 31, 2011
Securities held to maturity:
Securities held to maturity, other bonds, amortized cost	$ 700,000	$ 200,000
Securities held to maturity, other bonds, gross unrealized gains	0	0
Securities held to maturity, other bonds, gross unrealized losses	0	0
Securities held to maturity, other bonds, fair value	700,000	200,000
Securities available for sale:
Available for Sale Securities, amortized cost	630,893,475	557,333,785
Available for Sale Securities, gross unrealized gains	8,008,924	7,809,612
Available for Sale Securities, gross unrealized losses	(764,563)	(114,106)
Available for Sale Securities, fair value	638,137,836	565,029,291
US Government Agencies Debt Securities [Member]
Securities available for sale:
Available for Sale Securities, amortized cost	387,413,822	426,581,913
Available for Sale Securities, gross unrealized gains	2,377,067	2,428,994
Available for Sale Securities, gross unrealized losses	(191,137)	(55,687)
Available for Sale Securities, fair value	389,599,752	428,955,220
Residential Mortgage Backed Securities [Member]
Securities available for sale:
Available for Sale Securities, amortized cost	162,415,855	105,373,614
Available for Sale Securities, gross unrealized gains	3,523,570	3,488,350
Available for Sale Securities, gross unrealized losses	(112,224)	(8,215)
Available for Sale Securities, fair value	165,827,201	108,853,749
US States and Political Subdivisions Debt Securities [Member]
Securities available for sale:
Available for Sale Securities, amortized cost	79,658,038	23,937,118
Available for Sale Securities, gross unrealized gains	1,834,640	1,752,246
Available for Sale Securities, gross unrealized losses	(420,770)	0
Available for Sale Securities, fair value	81,071,908	25,689,364
Trust preferred securities [Member]
Securities available for sale:
Available for Sale Securities, amortized cost	86,200	86,200
Available for Sale Securities, gross unrealized gains	15,800	0
Available for Sale Securities, gross unrealized losses	0	(5,400)
Available for Sale Securities, fair value	102,000	80,800
Securities (Assets) [Member]
Securities available for sale:
Available for Sale Securities, amortized cost	1,319,560	1,354,940
Available for Sale Securities, gross unrealized gains	257,847	140,022
Available for Sale Securities, gross unrealized losses	(40,432)	(44,804)
Available for Sale Securities, fair value	$ 1,536,975	$ 1,450,158

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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