Statements Of Stockholders' Equity - USD ($)	Total	Class A voting Common Stock [Member]	Capital in Excess of Par Value [Member]	Deferred Directors' Compensation [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Balances at Sep. 30, 2017	$ 116,707,539	$ 280,938	$ 2,726,444	$ 3,459,909	$ 113,330,216	$ (3,089,968)
Balances, shares at Sep. 30, 2017		16,863,004
Balances, Treasury shares at Sep. 30, 2017						(184,988)
Net income (loss)	13,784,939				13,784,939
Purchase of treasury stock	(272,100)					$ (272,100)
Purchase of treasury stock, shares						(13,404)
Issuance of treasury shares to ESOP	6,735		2,009			$ 4,726
Issuance of treasury shares to ESOP, shares						283
Restricted stock awards	194,050		194,050
Dividends	(1,347,608)				(1,347,608)
Distribution of restricted stock to officers and directors	734		(735,965)			$ 736,699
Distribution of restricted stock to officers and directors, shares						44,065
Increase in deferred directors' compensation charged to expense	108,384			108,384
Balances at Dec. 31, 2017	129,182,673	$ 280,938	2,186,538	3,568,293	125,767,547	$ (2,620,643)
Balances, shares at Dec. 31, 2017		16,863,004
Balances, Treasury shares at Dec. 31, 2017						(154,044)
Balances at Sep. 30, 2017	116,707,539	$ 280,938	2,726,444	3,459,909	113,330,216	$ (3,089,968)
Balances, shares at Sep. 30, 2017		16,863,004
Balances, Treasury shares at Sep. 30, 2017						(184,988)
Net income (loss)	14,080,022
Balances at Jun. 30, 2018	129,234,714	$ 281,495	2,690,834	2,882,263	125,386,738	$ (2,006,616)
Balances, shares at Jun. 30, 2018		16,896,455
Balances, Treasury shares at Jun. 30, 2018						(117,946)
Balances at Dec. 31, 2017	129,182,673	$ 280,938	2,186,538	3,568,293	125,767,547	$ (2,620,643)
Balances, shares at Dec. 31, 2017		16,863,004
Balances, Treasury shares at Dec. 31, 2017						(154,044)
Net income (loss)	1,070,176				1,070,176
Restricted stock awards	153,788		153,788
Distribution of restricted stock to officers and directors	43		(43,435)			$ 43,478
Distribution of restricted stock to officers and directors, shares						2,556
Distribution of deferred directors' compensation		$ 543	269,112	(811,219)		$ 541,564
Distribution of deferred directors' compensation, shares		32,599				31,838
Increase in deferred directors' compensation charged to expense	62,442			62,442
Balances at Mar. 31, 2018	130,469,122	$ 281,481	2,566,003	2,819,516	126,837,723	$ (2,035,601)
Balances, shares at Mar. 31, 2018		16,895,603
Balances, Treasury shares at Mar. 31, 2018						(119,650)
Net income (loss)	(775,093)				(775,093)
Restricted stock awards	153,788		153,788
Dividends	(675,892)				(675,892)
Distribution of restricted stock to officers and directors	42	$ 14	(28,957)			$ 28,985
Distribution of restricted stock to officers and directors, shares		852				1,704
Increase in deferred directors' compensation charged to expense	62,747			62,747
Balances at Jun. 30, 2018	129,234,714	$ 281,495	2,690,834	2,882,263	125,386,738	$ (2,006,616)
Balances, shares at Jun. 30, 2018		16,896,455
Balances, Treasury shares at Jun. 30, 2018						(117,946)
Balances at Sep. 30, 2018	$ 128,765,205	$ 281,502	2,824,691	2,950,405	125,266,945	$ (2,558,338)
Balances, shares at Sep. 30, 2018		16,896,881
Balances, Treasury shares at Sep. 30, 2018	(145,467)					(145,467)
Net income (loss)	$ 12,735,940				12,735,940
Purchase of treasury stock	(1,140,559)					$ (1,140,559)
Purchase of treasury stock, shares						(74,457)
Restricted stock awards	159,469		159,469
Dividends	(1,347,789)				(1,347,789)
Distribution of restricted stock to officers and directors	160	$ 7	(159,869)			$ 160,022
Distribution of restricted stock to officers and directors, shares		425				9,194
Distribution of deferred directors' compensation			(8)	8
Increase in deferred directors' compensation charged to expense	80,287			80,287
Balances at Dec. 31, 2018	139,252,713	$ 281,509	2,824,283	3,030,700	136,655,096	$ (3,538,875)
Balances, shares at Dec. 31, 2018		16,897,306
Balances, Treasury shares at Dec. 31, 2018						(210,730)
Balances at Sep. 30, 2018	$ 128,765,205	$ 281,502	2,824,691	2,950,405	125,266,945	$ (2,558,338)
Balances, shares at Sep. 30, 2018		16,896,881
Balances, Treasury shares at Sep. 30, 2018	(145,467)					(145,467)
Net income (loss)	$ 15,408,842
Balances at Jun. 30, 2019	$ 136,500,196	$ 281,509	2,937,874	2,481,109	138,662,782	$ (7,863,078)
Balances, shares at Jun. 30, 2019		16,897,306
Balances, Treasury shares at Jun. 30, 2019	(508,582)					(508,582)
Balances at Dec. 31, 2018	$ 139,252,713	$ 281,509	2,824,283	3,030,700	136,655,096	$ (3,538,875)
Balances, shares at Dec. 31, 2018		16,897,306
Balances, Treasury shares at Dec. 31, 2018						(210,730)
Net income (loss)	(1,931,334)				(1,931,334)
Purchase of treasury stock	(2,827,126)					$ (2,827,126)
Purchase of treasury stock, shares						(175,175)
Restricted stock awards	286,852		286,852
Dividends	(381)				(381)
Distribution of restricted stock to officers and directors	75		(73,069)			$ 73,144
Distribution of restricted stock to officers and directors, shares						4,441
Distribution of deferred directors' compensation	(3)		(207,842)	(667,124)		$ 874,963
Distribution of deferred directors' compensation, shares						52,399
Increase in deferred directors' compensation charged to expense	51,993			51,993
Balances at Mar. 31, 2019	134,832,789	$ 281,509	2,830,224	2,415,569	134,723,381	$ (5,417,894)
Balances, shares at Mar. 31, 2019		16,897,306
Balances, Treasury shares at Mar. 31, 2019						(329,065)
Net income (loss)	4,604,236				4,604,236
Purchase of treasury stock	(2,497,501)					$ (2,497,501)
Purchase of treasury stock, shares						(182,901)
Restricted stock awards	159,911		159,911
Dividends	(664,835)				(664,835)
Distribution of restricted stock to officers and directors	56		(52,261)			$ 52,317
Distribution of restricted stock to officers and directors, shares						3,384
Increase in deferred directors' compensation charged to expense	65,540			65,540
Balances at Jun. 30, 2019	$ 136,500,196	$ 281,509	$ 2,937,874	$ 2,481,109	$ 138,662,782	$ (7,863,078)
Balances, shares at Jun. 30, 2019		16,897,306
Balances, Treasury shares at Jun. 30, 2019	(508,582)					(508,582)