Summary of Significant Accounting Policies (Details)					3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 10, 2020 $ / shares	Sep. 04, 2020 $ / shares	Jan. 01, 2018	Dec. 22, 2017	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2019 USD ($)
Number of business segments
Number of business segments in which the entity operates | segment					1
Long-Lived Assets
Impairment charges					$ 0	$ 0
Contract Balances
Balance at beginning of the period (contract liabilities)					313,365	313,365	$ 313,365	$ 313,365
Performance obligations satisfied during the period that were included in the contract liability balance at the beginning of the period							(278,472)
Increases due to invoicing prior to satisfaction of performance obligations							86,580
Balance at end of the period (contract liabilities)					121,473		$ 121,473	313,365
Customer Service Revenue
Customer Service Cost of Sales					2,303,829	1,909,781
Gross profit					$ 2,565,823	2,601,647
Income Taxes
U.S. Federal statutory tax rate (as a percent)			21.00%	34.00%	21.00%
Net operating losses (as a percent)					80.00%
Deferred income tax expense									$ 321,038
Engineering Development
Percentage of employees who were engineers engaged in various engineering development projects					21.00%
Warranty
Length of warranty period					24 months
Self-Insurance Reserves
Estimated liability for medical claims incurred but not reported					$ 44,787			48,200
Excess of funded premiums over estimated claims incurred but not reported					250,146			225,200
Restricted Cash
Cash dividends declared per share | $ / shares	$ 0.50	$ 0.65
Total cash dividend payment					8,600,000			11,200,000
Cash and cash equivalents					5,608,255			12,603,967
Restricted cash								11,180,900
Total cash and cash equivalents and restricted cash					5,608,255	22,158,756		$ 23,784,867		$ 22,416,830
Customer Service
Customer Service Revenue
Customer Service Sales					815,503	1,189,040
Customer Service Cost of Sales					316,637	349,615
Gross profit					$ 498,866	$ 839,425
Property and equipment except manufacturing facility and the corporate airplane | Minimum
Number of business segments
Estimated useful lives					3 years
Property and equipment except manufacturing facility and the corporate airplane | Maximum
Number of business segments
Estimated useful lives					7 years
Manufacturing facility
Number of business segments
Estimated useful lives					39 years
Corporate airplanes
Number of business segments
Estimated useful lives					10 years