Interest Rate Derivative Agreements - Summary of Interest Rate Derivatives, Excluding Interest Rate Swaps (Details) - USD ($)		6 Months Ended	12 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative, Fair Value - Asset (Liability)		$ 1,026,976	$ 597,221
Barclays Bank PLC 1 [Member]
Derivative [Line Items]
Derivative, Purchase Date		2014-07	2014-07
Derivative, Notional Amount		$ 30,462,845	$ 30,652,294
Derivative, Maturity Date		2019-08	2019-08
Derivative, Effective Capped Rate	[1]	3.00%	3.00%
Derivative, Index		SIFMA	SIFMA
Derivative, Variable Debt Financing Facility Hedged	[1]	M31 TEBS	M31 TEBS
Derivative, Fair Value - Asset (Liability)		$ 30	$ 169
Royal Bank of Canada-1 [Member]
Derivative [Line Items]
Derivative, Purchase Date		2014-07	2014-07
Derivative, Notional Amount		$ 30,462,845	$ 30,652,294
Derivative, Maturity Date		2019-08	2019-08
Derivative, Effective Capped Rate	[1]	3.00%	3.00%
Derivative, Index		SIFMA	SIFMA
Derivative, Variable Debt Financing Facility Hedged	[1]	M31 TEBS	M31 TEBS
Derivative, Fair Value - Asset (Liability)		$ 30	$ 169
SMBC Capital Markets, Inc-1 [Member]
Derivative [Line Items]
Derivative, Purchase Date		2014-07	2014-07
Derivative, Notional Amount		$ 30,462,845	$ 30,652,294
Derivative, Maturity Date		2019-08	2019-08
Derivative, Effective Capped Rate	[1]	3.00%	3.00%
Derivative, Index		SIFMA	SIFMA
Derivative, Variable Debt Financing Facility Hedged	[1]	M31 TEBS	M31 TEBS
Derivative, Fair Value - Asset (Liability)		$ 30	$ 169
Wells Fargo Bank [Member]
Derivative [Line Items]
Derivative, Purchase Date		2015-07	2015-07
Derivative, Notional Amount		$ 27,515,500	$ 27,666,739
Derivative, Maturity Date		2020-08	2020-08
Derivative, Effective Capped Rate	[1]	3.00%	3.00%
Derivative, Index		SIFMA	SIFMA
Derivative, Variable Debt Financing Facility Hedged	[1]	M33 TEBS	M33 TEBS
Derivative, Fair Value - Asset (Liability)		$ 6,004	$ 3,213
Royal Bank of Canada-2 [Member]
Derivative [Line Items]
Derivative, Purchase Date		2015-07	2015-07
Derivative, Notional Amount		$ 27,515,500	$ 27,666,739
Derivative, Maturity Date		2020-08	2020-08
Derivative, Effective Capped Rate	[1]	3.00%	3.00%
Derivative, Index		SIFMA	SIFMA
Derivative, Variable Debt Financing Facility Hedged	[1]	M33 TEBS	M33 TEBS
Derivative, Fair Value - Asset (Liability)		$ 6,004	$ 3,213
SMBC Capital Markets, Inc-2 [Member]
Derivative [Line Items]
Derivative, Purchase Date		2015-07	2015-07
Derivative, Notional Amount		$ 27,515,500	$ 27,666,739
Derivative, Maturity Date		2020-08	2020-08
Derivative, Effective Capped Rate	[1]	3.00%	3.00%
Derivative, Index		SIFMA	SIFMA
Derivative, Variable Debt Financing Facility Hedged	[1]	M33 TEBS	M33 TEBS
Derivative, Fair Value - Asset (Liability)		$ 6,004	$ 3,213
Barclays Bank PLC 2 [Member]
Derivative [Line Items]
Derivative, Purchase Date		2017-06	2017-06
Derivative, Notional Amount		$ 91,388,535	$ 91,956,883
Derivative, Maturity Date		2019-08	2019-08
Derivative, Effective Capped Rate	[1]	1.50%	1.50%
Derivative, Index		SIFMA	SIFMA
Derivative, Variable Debt Financing Facility Hedged	[1]	M31 TEBS	M31 TEBS
Derivative, Fair Value - Asset (Liability)		$ 252,431	$ 160,174
Barclays Bank PLC 3 [Member]
Derivative [Line Items]
Derivative, Purchase Date		2017-06	2017-06
Derivative, Notional Amount		$ 82,546,501	$ 83,000,217
Derivative, Maturity Date		2020-08	2020-08
Derivative, Effective Capped Rate	[1]	1.50%	1.50%
Derivative, Index		SIFMA	SIFMA
Derivative, Variable Debt Financing Facility Hedged	[1]	M33 TEBS	M33 TEBS
Derivative, Fair Value - Asset (Liability)		$ 755,358	$ 425,978
Barclays Bank PLC 4 [Member]
Derivative [Line Items]
Derivative, Purchase Date		2017-09	2017-09
Derivative, Notional Amount		$ 59,530,000	$ 59,935,000
Derivative, Maturity Date		2020-09	2020-09
Derivative, Effective Capped Rate	[1]	4.00%	4.00%
Derivative, Index		SIFMA	SIFMA
Derivative, Variable Debt Financing Facility Hedged	[1]	M24 TEBS	M24 TEBS
Derivative, Fair Value - Asset (Liability)		$ 1,085	$ 923

[1] For additional details, see Note 21 to the Partnership's condensed consolidated financial statements.