Debt - Summary of Notes Payable Secured by Real Property (Details)	12 Months Ended
Dec. 31, 2018 USD ($) instrument	Dec. 31, 2017 USD ($) instrument
Debt Instrument [Line Items]
Principal Outstanding	$ 641,138,114	$ 555,581,831
Deferred financing costs	(4,227,995)
Total notes payable, net	$ 693,501,574	$ 875,785,938
Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Number of Instruments \| instrument	30	46
Weighted Average Interest Rate	4.27%	3.87%
Principal Outstanding	$ 644,770,289	$ 789,154,854
Unamortized Portion of Net Debt Premium	302,530	673,653
Deferred financing costs	(3,934,705)	(4,264,667)
Total notes payable, net	641,138,114	785,563,840
Debt premiums	(960,519)	(2,468,041)
Debt issuance costs	$ (2,929,134)	$ (3,951,049)
Notes Payable to Banks [Member] \| Mortgage Notes Payable, Fixed Interest [Member]
Debt Instrument [Line Items]
Number of Instruments \| instrument	20	32
Weighted Average Interest Rate	3.95%	3.89%
Principal Outstanding	$ 361,723,899	$ 416,673,854
Notes Payable to Banks [Member] \| Mortgage Notes Payable, Fixed Interest [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.19%	3.19%
Notes Payable to Banks [Member] \| Mortgage Notes Payable, Fixed Interest [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.48%	5.75%
Notes Payable to Banks [Member] \| Mortgage Notes Payable, Variable Interest [Member]
Debt Instrument [Line Items]
Number of Instruments \| instrument	10	14
Weighted Average Interest Rate	4.69%	3.86%
Principal Outstanding	$ 283,046,390	$ 372,481,000
Notes Payable to Banks [Member] \| Mortgage Notes Payable, Variable Interest [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Variable Rate	2.02%	1.65%
Notes Payable to Banks [Member] \| Mortgage Notes Payable, Variable Interest [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Variable Rate	2.50%	2.65%

Accumulated Amortization, Debt Premiums

No definition available.

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- Definition

Debt Instrument, Number

+ References

No definition available.

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- Definition

Amount of accumulated amortization of debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount, after accumulated amortization, of debt discount (premium).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
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- Definition

Including the current and noncurrent portions, aggregate carrying amount of all types of notes payable, as of the balance sheet date, with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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