Organization and Summary of Significant Accounting Policies (Details)		3 Months Ended				9 Months Ended
	Aug. 31, 2016 Subsidiary	Sep. 30, 2018 USD ($) Aircraft	Jun. 30, 2018 USD ($) Aircraft	Sep. 30, 2017 USD ($) Aircraft	Jun. 30, 2017 USD ($) Aircraft	Sep. 30, 2018 USD ($) Aircraft Lease	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Organization and Summary of Significant Accounting Policies [Abstract]
Number of wholly owned subsidiaries | Subsidiary	2
Finance Leases [Abstract]
Impairment charge		$ 2,673,300		$ 68,800		$ 2,971,500	$ 523,100
Notes payable and accrued interest		$ 140,247,200				$ 140,247,200		$ 145,598,200
Number of aircraft with sales type finance leases | Aircraft		6				3
Number of aircraft with direct financing leases | Aircraft						3
Number of finance leases | Lease						6
Interest earned on finance lease		$ 261,700		415,700		$ 1,002,100	$ 1,173,400
Recent Accounting Pronouncements [Abstract]
Federal corporate tax rate		21.00%
SPE Financing [Member]
Finance Leases [Abstract]
Notes payable and accrued interest		$ 10,321,300				10,321,300		13,535,300
Level 3 [Member] | SPE Financing [Member]
Finance Leases [Abstract]
Notes payable and accrued interest		10,321,300				10,321,300		13,535,300
Level 3 [Member] | Credit Facility [Member]
Finance Leases [Abstract]
Notes payable and accrued interest		131,004,800				131,004,800		134,278,900
Recurring [Member]
Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis [Abstract]
Liabilities recorded at fair value		0				0		0
Recurring [Member] | Money Market Funds [Member]
Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis [Abstract]
Cash and cash equivalents		2,155,600				$ 2,155,600		$ 6,151,900
Nonrecurring [Member] | Aircraft [Member] | Held for Lease [Member]
Finance Leases [Abstract]
Impairment charge		$ 2,673,300	$ 298,200	$ 68,800	$ 454,300
Number of assets held for lease | Aircraft		4	1	1	1