Significant Accounting Policies - Concentration of Credit Risks (Details)	12 Months Ended
Dec. 31, 2017 USD ($) item
Concentration of Credit Risks
Number of banks in which the entity maintains cash balances	2
Number of interest rate swap agreements	2
Cash balances with financial institutions \| Credit concentration risk \| Minimum
Concentration of Credit Risks
Insurance limit provided by Federal Deposit Insurance Corporation \| $	$ 250,000
Annualized rental revenues \| Single tenant rental revenues
Concentration of Credit Risks
Percentage of annualized rental revenues required for qualification as major tenant	10.00%

Represents the number of banks in which the entity maintains cash balances.

No definition available.

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- Definition

The amount of cash deposited in financial institutions as of the balance sheet date that is insured by the Federal Deposit Insurance Corporation.

+ References

No definition available.

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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.

+ Details

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 20
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- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

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- Details

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- Details

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