Note 3 - Investment Securities (Details) - Amortized Cost and Fair Value of Investment Securities (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Securities held to maturity:
Securities held to maturity, amortized cost	$ 131,361,845	$ 72,079,385
Securities held to maturity, gross unrealized gains	456,156	997,969
Securities held to maturity, gross unrealized losses	(6,525,639)	(71,648)
Securities held to maturity, fair value	125,292,362	73,005,706
Securities available for sale:
Securities available for sale, amortized cost	588,553,625	522,547,519
Securities available for sale, gross unrealized gains	2,822,773	7,985,963
Securities available for sale, gross unrealized losses	(19,039,069)	(373,496)
Securities available for sale, fair value	572,337,329	530,159,986
US States and Political Subdivisions Debt Securities [Member]
Securities held to maturity:
Securities held to maturity, amortized cost	130,311,845	71,429,385
Securities held to maturity, gross unrealized gains	456,156	997,969
Securities held to maturity, gross unrealized losses	(6,520,899)	(71,648)
Securities held to maturity, fair value	124,247,102	72,355,706
Securities available for sale:
Securities available for sale, amortized cost	36,242,570	24,508,015
Securities available for sale, gross unrealized gains	978,391	1,696,555
Securities available for sale, gross unrealized losses	(761,791)	(18,834)
Securities available for sale, fair value	36,459,170	26,185,736
Equity Securities, Other [Member]
Securities held to maturity:
Securities held to maturity, amortized cost	1,050,000	650,000
Securities held to maturity, gross unrealized gains	0	0
Securities held to maturity, gross unrealized losses	(4,740)	0
Securities held to maturity, fair value	1,045,260	650,000
Securities available for sale:
Securities available for sale, amortized cost	1,358,524	1,347,113
Securities available for sale, gross unrealized gains	450,278	300,732
Securities available for sale, gross unrealized losses	0	(23,469)
Securities available for sale, fair value	1,808,802	1,624,376
US Government-sponsored Enterprises Debt Securities [Member]
Securities available for sale:
Securities available for sale, amortized cost	383,193,241	336,570,995
Securities available for sale, gross unrealized gains	75,797	2,198,655
Securities available for sale, gross unrealized losses	(15,744,151)	(160,279)
Securities available for sale, fair value	367,524,887	338,609,371
Residential Mortgage Backed Securities [Member]
Securities available for sale:
Securities available for sale, amortized cost	167,759,290	160,035,196
Securities available for sale, gross unrealized gains	1,318,307	3,736,821
Securities available for sale, gross unrealized losses	(2,533,127)	(170,914)
Securities available for sale, fair value	166,544,470	163,601,103
Trust preferred securities [Member]
Securities available for sale:
Securities available for sale, amortized cost		86,200
Securities available for sale, gross unrealized gains		53,200
Securities available for sale, gross unrealized losses		0
Securities available for sale, fair value		$ 139,400