Debt - Mortgages Payable (Details) - USD ($)	3 Months Ended
Mar. 31, 2019	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term Debt, Total	$ 775,200,000
Mortgages [Member]
Debt Instrument [Line Items]
Total	60,847,000	$ 61,519,000
Unamortized debt issuance costs	(544,000)	(593,000)
Long-term Debt, Total	60,303,000	60,926,000
Notes Payable Due October 2019 3.32 percent [Member] \| Mortgages [Member]
Debt Instrument [Line Items]
Total	$ 21,500,000	21,500,000
Debt Instrument, Interest Rate, Stated Percentage	3.32%
Debt Instrument, Maturity Date	Oct. 01, 2019
Notes Payable Due January 2020 6.90 Percent [Member] \| Mortgages [Member]
Debt Instrument [Line Items]
Total	$ 1,491,000	1,922,000
Debt Instrument, Periodic Payment, Principal	$ 153,838
Debt Instrument, Interest Rate, Stated Percentage	6.90%
Debt Instrument, Maturity Date	Jan. 01, 2020
Notes Payable Due February 2020 6.24 Percent [Member] \| Mortgages [Member]
Debt Instrument [Line Items]
Total	$ 2,848,000	2,872,000
Debt Instrument, Periodic Payment, Principal	23,004
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid	$ 2,781,819
Debt Instrument, Interest Rate, Stated Percentage	6.24%
Debt Instrument, Maturity Date	Feb. 01, 2020
Notes Payable Due January 2023 3.60 Percent [Member] \| Mortgages [Member]
Debt Instrument [Line Items]
Total	$ 23,640,000	23,640,000
Debt Instrument, Interest Rate, Stated Percentage	3.60%
Debt Instrument, Maturity Date	Jan. 01, 2023
Notes Payable Due September 2023 5.01 Percent [Member] \| Mortgages [Member]
Debt Instrument [Line Items]
Total	$ 4,914,000	4,959,000
Debt Instrument, Periodic Payment, Principal	35,673
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid	$ 4,034,627
Debt Instrument, Interest Rate, Stated Percentage	5.01%
Debt Instrument, Maturity Date	Sep. 01, 2023
Notes Payable Due July 2026 6.27 Percent [Member] \| Mortgages [Member]
Debt Instrument [Line Items]
Total	$ 6,454,000	$ 6,626,000
Debt Instrument, Periodic Payment, Principal	$ 91,675
Debt Instrument, Interest Rate, Stated Percentage	6.27%
Debt Instrument, Maturity Date	Jul. 01, 2026

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
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- Definition

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

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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

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
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-Name Accounting Standards Codification
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- Definition

Amount of the required periodic payments applied to principal.

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- Definition

Amount of payment greater than the preceding installment payments to be paid at final maturity date of debt.

+ References

No definition available.

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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-SubTopic 10
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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.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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