Other Comprehensive Income (Schedule of Other Comprehensive Income and Loss) (Details) - USD ($)	3 Months Ended				6 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	Mar. 31, 2019
Before-Tax Amount
Other comprehensive income (loss)	$ (1,615,654)		$ (61,990)		$ (1,238,811)	$ (174,184)
Tax (Expense) or Benefit
Other comprehensive loss	415,871		15,956		318,872	44,834
Net-of-Tax Amount
Other comprehensive income (loss), net of tax	(1,199,783)	$ 279,844	(46,034)	$ (83,316)	(919,939)	(129,350)
Interest rate swap [Member]
Before-Tax Amount
Other comprehensive income (loss) before reclassifications	(1,654,962)				(1,304,269)
Reclassifications from accumulated other comprehensive income	16,698				20,238
Other comprehensive income (loss)	(1,638,264)				(1,284,031)
Tax (Expense) or Benefit
Other comprehensive income before reclassifications	425,987				335,718
Reclassifications from accumulated other comprehensive income	(4,297)				(5,208)
Other comprehensive loss	421,690				330,510
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	(1,228,975)				(968,551)
Reclassifications from accumulated other comprehensive income	12,401				15,030
Other comprehensive income (loss), net of tax	(1,216,574)				(953,521)
Interest rate swap [Member]
Before-Tax Amount
Other comprehensive income (loss) before reclassifications			(40,059)			(134,015)
Reclassifications from accumulated other comprehensive income			(19,355)			(35,017)
Other comprehensive income (loss)			(59,414)			(169,032)
Tax (Expense) or Benefit
Other comprehensive income before reclassifications			10,311			34,495
Reclassifications from accumulated other comprehensive income			4,982			9,013
Other comprehensive loss			15,293			43,508
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications			(29,748)			(99,520)
Reclassifications from accumulated other comprehensive income			(14,373)			(26,004)
Other comprehensive income (loss), net of tax			(44,121)			(125,524)
Defined benefit plans [Member]
Before-Tax Amount
Other comprehensive income (loss)	22,610		(2,576)		45,220	(5,152)
Tax (Expense) or Benefit
Other comprehensive loss	(5,819)		663		(11,638)	1,326
Net-of-Tax Amount
Other comprehensive income (loss), net of tax	$ 16,791		$ (1,913)		$ 33,582	$ (3,826)