Other Comprehensive Income (Schedule of Other Comprehensive Income and Loss) (Details) - USD ($)	3 Months Ended				6 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2019	Mar. 31, 2018
Before-Tax Amount
Other comprehensive loss	$ (61,990)		$ 80,838		$ (174,184)	$ 137,606
Tax (Expense) or Benefit
Other comprehensive loss	15,956		(23,314)		44,834	(39,686)
Net-of-Tax Amount
Other comprehensive loss	(46,034)	$ (83,316)	57,524	$ 40,396	(129,350)	97,920
Interest rate swap [Member]
Before-Tax Amount
Other comprehensive income before reclassifications	(40,059)		90,363		(134,015)	151,944
Reclassifications from accumulated other comprehensive income	(19,355)		(3,554)		(35,017)	(2,396)
Other comprehensive loss	(59,414)		86,809		(169,032)	149,548
Tax (Expense) or Benefit
Other comprehensive income before reclassifications	10,311		(26,061)		34,495	(43,821)
Reclassifications from accumulated other comprehensive income	4,982		1,025		9,013	691
Other comprehensive loss	15,293		(25,036)		43,508	(43,130)
Net-of-Tax Amount
Other comprehensive income before reclassifications	(29,748)		64,302		(99,520)	108,123
Reclassifications from accumulated other comprehensive income	(14,373)		(2,529)		(26,004)	(1,705)
Other comprehensive loss	(44,121)		61,773		(125,524)	106,418
Defined benefit plans [Member]
Before-Tax Amount
Other comprehensive loss	(2,576)		(5,971)		(5,152)	(11,942)
Tax (Expense) or Benefit
Other comprehensive loss	663		1,722		1,326	3,444
Net-of-Tax Amount
Other comprehensive loss	$ (1,913)		$ (4,249)		$ (3,826)	$ (8,498)