Note 2 - Investment Securities (Tables)

3 Months Ended

Mar. 31, 2016

Note 2 - Investment Securities (Tables) [Line Items]

Unrealized Gain (Loss) on Investments [Table Text Block]

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Fair Value
March 31, 2016
Securities held to maturity:
Municipal securities	$	260,079,586	$	4,143,965	$	(858,829	)	$	263,364,722
Other securities		1,050,000		-		-			1,050,000
	$	261,129,586	$	4,143,965	$	(858,829	)	$	264,414,722
Securities available for sale:
U.S. govt. sponsored agency securities	$	132,080,737	$	786,623	$	(125,538	)	$	132,741,822
Residential mortgage-backed and related securities		116,012,771		761,091		(321,488	)		116,452,374
Municipal securities		24,113,773		839,125		(23,243	)		24,929,655
Other securities		1,637,366		428,027		(1,377	)		2,064,016
	$	273,844,647	$	2,814,866	$	(471,646	)	$	276,187,867
December 31, 2015:
Securities held to maturity:
Municipal securities	$	252,624,159	$	3,190,558	$	(1,173,432	)	$	254,641,285
Other securities		1,050,000		-		-			1,050,000
	$	253,674,159	$	3,190,558	$	(1,173,432	)	$	255,691,285
Securities available for sale:
U.S. govt. sponsored agency securities	$	216,281,416	$	104,524	$	(2,848,561	)	$	213,537,379
Residential mortgage-backed and related securities		81,442,479		511,095		(1,283,439	)		80,670,135
Municipal securities		26,764,981		872,985		(59,378	)		27,578,588
Other securities		1,108,124		540,919		(163	)		1,648,880
	$	325,597,000	$	2,029,523	$	(4,191,541	)	$	323,434,982

Schedule of Unrealized Loss on Investments [Table Text Block]

	Less than 12 Months					12 Months or More					Total
			Gross					Gross					Gross
	Fair		Unrealized			Fair		Unrealized			Fair		Unrealized
	Value		Losses			Value		Losses			Value		Losses
March 31, 2016:
Securities held to maturity:
Municipal securities	$	16,874,982	$	(669,283	)	$	7,610,345	$	(189,546	)	$	24,485,327	$	(858,829	)
Securities available for sale:
U.S. govt. sponsored agency securities	$	24,512,886	$	(76,931	)	$	4,946,100	$	(48,607	)	$	29,458,986	$	(125,538	)
Residential mortgage-backed and related securities		18,687,105		(81,719	)		29,708,984		(239,769	)		48,396,089		(321,488	)
Municipal securities		1,157,233		(2,185	)		849,972		(21,058	)		2,007,205		(23,243	)
Other securities		498,623		(1,377	)		-		-			498,623		(1,377	)
	$	44,855,847	$	(162,212	)	$	35,505,056	$	(309,434	)	$	80,360,903	$	(471,646	)
December 31, 2015:
Securities held to maturity:
Municipal securities	$	14,803,408	$	(294,438	)	$	19,927,581	$	(878,994	)	$	34,730,989	$	(1,173,432	)
Securities available for sale:
U.S. govt. sponsored agency securities	$	112,900,327	$	(1,397,591	)	$	64,476,661	$	(1,450,970	)	$	177,376,988	$	(2,848,561	)
Residential mortgage-backed and related securities		40,356,921		(730,466	)		19,836,637		(552,973	)		60,193,558		(1,283,439	)
Municipal securities		2,220,800		(31,807	)		848,329		(27,571	)		3,069,129		(59,378	)
Other securities		411		(163	)		-		-			411		(163	)
	$	155,478,459	$	(2,160,027	)	$	85,161,627	$	(2,031,514	)	$	240,640,086	$	(4,191,541	)

Realized Gain (Loss) on Investments [Table Text Block]

	Three Months Ended
	March 31, 2016			March 31, 2015
Proceeds from sales of securities	$	55,526,851		$	54,971,056
Pre-tax gross gains from sales of securities		515,515			573,684
Pre-tax gross losses from sales of securities		(157,035	)		(152,618	)

Investments Classified by Contractual Maturity Date [Table Text Block]

	Amortized Cost		Fair Value
Securities held to maturity:
Due in one year or less	$	4,206,670	$	4,213,609
Due after one year through five years		20,737,843		20,889,363
Due after five years		236,185,073		239,311,750
	$	261,129,586	$	264,414,722
Securities available for sale:
Due in one year or less	$	1,884,460	$	1,895,137
Due after one year through five years		68,198,829		69,027,450
Due after five years		86,111,221		86,748,890
	$	156,194,510	$	157,671,477
Residential mortgage-backed and related securities		116,012,771		116,452,374
Other securities		1,637,366		2,064,016
	$	273,844,647	$	276,187,867

	Amortized Cost		Fair Value
Securities held to maturity:
Municipal securities	$	135,926,431	$	137,921,557
Securities available for sale:
U.S. govt. sponsored agency securities		65,969,684		65,976,489
Municipal securities		15,335,099		15,728,025
	$	81,304,783	$	81,704,514

Bonds [Member]

Note 2 - Investment Securities (Tables) [Line Items]

Schedule of Debt [Table Text Block]

March 31, 2016:
U.S. State:	Number of Issuers		Amortized Cost		Fair Value		Average Exposure Per Issuer (Fair Value)
Iowa		15	$	19,974,438	$	20,309,435	$	1,353,962
Illinois		10		12,665,888		13,014,865		1,301,487
Missouri		12		7,393,378		7,488,699		624,058
North Dakota		6		16,403,026		16,616,824		2,769,471
Other		39		14,954,651		15,233,176		390,594
Total general obligation bonds		82	$	71,391,381	$	72,662,999	$	886,134

December 31, 2015:
U.S. State:	Number of Issuers		Amortized Cost		Fair Value		Average Exposure Per Issuer (Fair Value)
Iowa		15	$	19,974,939	$	20,247,108	$	1,349,807
Illinois		9		10,928,700		11,264,348		1,251,594
North Dakota		5		10,890,000		11,050,235		2,210,047
Missouri		12		7,924,800		7,986,856		665,571
Other		41		16,965,393		17,229,485		420,231
Total general obligation bonds		82	$	66,683,832	$	67,778,032	$	826,561

March 31, 2016:
U.S. State:	Number of Issuers		Amortized Cost		Fair Value		Average Exposure Per Issuer (Fair Value)
Missouri		42	$	76,260,706	$	77,142,220	$	1,836,720
Iowa		27		74,013,142		75,274,793		2,787,955
Indiana		17		39,342,789		39,675,326		2,333,843
Kansas		4		12,022,852		12,116,209		3,029,052
Other		5		11,162,489		11,422,830		2,284,566
Total revenue bonds		95	$	212,801,978	$	215,631,378	$	2,269,804

December 31, 2015:
U.S. State:	Number of Issuers		Amortized Cost		Fair Value		Average Exposure Per Issuer (Fair Value)
Missouri		41	$	78,593,590	$	79,015,378	$	1,927,204
Iowa		26		70,773,660		71,659,410		2,756,131
Indiana		17		40,018,381		40,210,320		2,365,313
Kansas		3		11,748,679		11,821,055		3,940,352
Other		5		11,570,998		11,735,678		2,347,136
Total revenue bonds		92	$	212,705,308	$	214,441,841	$	2,330,890