Investments in Real Estate and Real Estate Under Construction - Summary of development arrangements outstanding (Details) ft² in Thousands, $ in Thousands	3 Months Ended
Mar. 31, 2017 USD ($) ft²	Dec. 31, 2016 ft²
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square Feet (000's) \| ft²	366	475
Maximum Commitment/Estimated Completion Cost	$ 99,445
Investment in real estate under construction	$ 69,128
Charlotte, North Carolina [Member] \| Office Building [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square Feet (000's) \| ft²	201
Maximum Commitment/Estimated Completion Cost	$ 62,445
Lease Term (Years)	15 years
Investment in real estate under construction	$ 49,210
Charlotte, North Carolina [Member] \| Office Building [Member] \| LCIF [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square Feet (000's) \| ft²	201
Maximum Commitment/Estimated Completion Cost	$ 62,445
Lease Term (Years)	15 years
Investment in real estate under construction	$ 49,210
Capitalized interest	$ 1,455
Opelika, Alabama [Member] \| Industrial Property [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Square Feet (000's) \| ft²	165
Maximum Commitment/Estimated Completion Cost	$ 37,000
Lease Term (Years)	25 years
Investment in real estate under construction	$ 19,918

Construction Commitment, Maximum Amount

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Investments in Real Estate and Real Estate Under Construction [Line Items]

+ References

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- Definition

Area of a real estate property.

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- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

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Amount of interest capitalized during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Allowance for Funds Used during Construction
-URI http://asc.fasb.org/extlink&oid=6504829

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

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Term of the lessor's leasing arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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