Amount of unfavorable leases, assumed at the acquisition date.

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Area of a real estate property.

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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.

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The amount of identifiable intangible assets recognized as of the acquisition date.

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Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

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The amount of property, plant, and equipment recognized as of the acquisition date.

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

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Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

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Significant Acquisitons (Details)	3 Months Ended								12 Months Ended
Significant Acquisitons (Details)	Dec. 31, 2016 USD ($) ft² shares	Sep. 30, 2016 shares	Jun. 30, 2016 shares	Mar. 31, 2016 shares	Dec. 31, 2015 shares	Sep. 30, 2015 shares	Jun. 30, 2015 shares	Mar. 31, 2015 shares	Dec. 31, 2016 USD ($) ft² property $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 shares
Significant Acquisitions
Number of properties acquired \| property									3
Rentable square feet \| ft²	1,099,000								1,099,000
Aggregate purchase price									$ 282,000,000
Closing costs and adjustments	$ 9,000,000								9,000,000
Acquisition costs									479,000
Estimated fair value of the assets acquired at the date of acquisition
Real estate assets	221,119,000								221,119,000
Value of acquired real estate leases	54,299,000								54,299,000
Acquired unfavorable leases	(2,790,000)								(2,790,000)
Total	$ 272,628,000								272,628,000
Pro forma operating results for the company and acquisitions
Revenue									274,873,000	$ 279,173,000
Income from continuing operations									5,093,000	31,143,000
Net income									$ 5,093,000	$ 31,143,000
Weighted average number of shares outstanding, basic and diluted (in shares) \| shares	107,231,000	103,709,000	100,187,000	100,187,000	100,187,000	100,187,000	100,187,000	100,187,000	102,843,000	100,187,000	100,187,000
Income from continuing operations per share (in dollars per share) \| $ / shares									$ 0.05	$ 0.31
Net income per share (in dollars per share) \| $ / shares									$ 0.05	$ 0.31
Revenue recognized due to the acquisitions									$ 10,500,000
Net income from operations recognized due to the acquisitions									$ (100,000)
Minneapolis, MN
Significant Acquisitions
Number of properties acquired \| property									1
Atlanta, GA
Significant Acquisitions
Number of properties acquired \| property									1
Denver, CO
Significant Acquisitions
Number of properties acquired \| property									1