Area of a real estate property.

No definition available.

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- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

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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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-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

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- Definition

The number of businesses acquired by the entity during the period.

+ References

No definition available.

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- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

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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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Investments in and Advances to Unconsolidated Affiliates - Core Portfolio (Details) $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2017 USD ($) ft²	Apr. 29, 2016 USD ($)	Mar. 31, 2017 USD ($) ft² property	Dec. 31, 2016 USD ($)	Jan. 31, 2016 ft²
Schedule of Equity Method Investments [Line Items]
Purchase Price \| $			$ 35,350	$ 558,755
Core Portfolio [Member] \| Crossroads [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			49.00%
Square footage of real estate property (in square feet)			311,000
Core Portfolio [Member] \| Georgetown Portfolio [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			50.00%
Square footage of real estate property (in square feet)			28,000
Core Portfolio [Member] \| Gotham Plaza [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			49.00%
Square footage of real estate property (in square feet)					123,000
Percentage of voting interests acquired					49.00%
Core Portfolio [Member] \| Renaissance Portfolio [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			20.00%
Square footage of real estate property (in square feet)			213,000
Percentage of voting interests acquired	20.00%
Number of businesses acquired \| property			18
Core Portfolio [Member] \| Brandywine Portfolio [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			22.22%
Square footage of real estate property (in square feet)			1,000,000
Repayments of debt \| $		$ 140,000
Core Portfolio [Member] \| Chicago, Illinois [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			88.43%
Square footage of real estate property (in square feet)			87,000
Core Portfolio [Member] \| Alexandria, Virginia [Member] \| Renaissance Portfolio [Member]
Schedule of Equity Method Investments [Line Items]
Square footage of real estate property (in square feet)	6,200
Purchase Price \| $	$ 3,000
Number of businesses acquired \| property			2
Core Portfolio [Member] \| Washington D.C. [Member] \| Renaissance Portfolio [Member]
Schedule of Equity Method Investments [Line Items]
Number of businesses acquired \| property			16