Investments in Real Estate and Real Estate Under Construction - Summary of acquisitions and build-to-suit transactions (Details) $ in Thousands	9 Months Ended
Sep. 30, 2016 USD ($)
Investments in Real Estate and Real Estate Under Construction [Line Items]
Investment in real estate under construction	$ 137,576
Office Building [Member] \| Lake Jackson, Texas [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Investment in real estate under construction	101,203
Office Building [Member] \| Charlotte, North Carolina [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Investment in real estate under construction	32,613
Industrial Property [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	134,144
Land and Land Estate	12,611
Building and Improvements	102,400
Lease in-place Value Intangible	21,148
Below Market Lease Intangible	(2,015)
Industrial Property [Member] \| Opelika, Alabama [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Investment in real estate under construction	3,760
Industrial Property [Member] \| Detroit, Michigan [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	29,697
Land and Land Estate	1,133
Building and Improvements	25,009
Lease in-place Value Intangible	3,555
Below Market Lease Intangible	0
Industrial Property [Member] \| Anderson, South Carolina [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	61,347
Land and Land Estate	4,663
Building and Improvements	45,011
Lease in-place Value Intangible	11,673
Below Market Lease Intangible	0
Industrial Property [Member] \| Wilsonville, Oregon [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	43,100
Land and Land Estate	6,815
Building and Improvements	32,380
Lease in-place Value Intangible	5,920
Below Market Lease Intangible	(2,015)
LCIF [Member] \| Office Building [Member] \| Charlotte, North Carolina [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Investment in real estate under construction	32,613
Capitalized interest	$ 654

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

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- Definition

Amount before amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life.

+ References

No definition available.

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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

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-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
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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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- Definition

This element represents the amount of value allocated by a lessor (acquirer) to lease agreements which exist at acquisition of a leased property. Such amount may include the value assigned to existing tenant relationships and excludes the market adjustment component of the value assigned for above or below-market leases acquired.

+ References

No definition available.

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- Definition

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

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

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- Definition

Aggregate of the carrying amounts as of the balance sheet date of investments in building and building improvements.

+ 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 210.7-03.1(d))
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- Definition

Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 4
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6812-107765

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-Name Accounting Standards Codification
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.13)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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