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Represents the amount of reimbursement payable to related party if specified minimum common share price maintain during the one year period after the date on which the reimbursement is approved by shareholders.

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Represents the amount of reimbursement payable to related party if specified minimum common share price maintain during the one year period between the first and second anniversaries of the date on which the reimbursement is approved by shareholders.

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Share Price, During First and Second Year After Date

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Share Price, During One Year Period After Date

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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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.

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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.

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Amount of unrealized gain (loss) recognized in the income statement for a financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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The charge against earnings in the period to reduce the carrying amount of real property to fair value.

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Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

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Fair Value of Assets and Liabilities - Narrative (Details) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2016 USD ($)	Aug. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) Tenant	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jul. 31, 2014 USD ($) $ / shares
Fair value of assets and liabilities
Asset impairment charges			$ 58,476	$ 17,162	$ 185,067
Real estate properties, net			$ 2,101,635	2,988,413
Impairment of real estate				17,200
Number of tenants responsible for more than 3% of total annualized rents \| Tenant			0
Total rents \| Credit concentration
Fair value of assets and liabilities
Concentration risk			5.50%
111 Monument Circle, 101-115 W. Washington Street and 100 East Wisconsin Avenue
Fair value of assets and liabilities
Asset impairment charges			$ 43,700
Parkshore Plaza, Cabot Business Park Land, 625 Crane Street and 111 Market Place
Fair value of assets and liabilities
Asset impairment charges			14,700
Level 2 \| Real estate properties held for sale \| Market Approach Valuation Technique \| 111 Monument Circle, 101-115 W. Washington Street and 100 East Wisconsin Avenue
Fair value of assets and liabilities
Fair value of assets			264,900
Level 2 \| Real estate properties held for sale \| Market Approach Valuation Technique \| Parkshore Plaza, Cabot Business Park Land, 625 Crane Street and 111 Market Place
Fair value of assets and liabilities
Fair value of assets			83,500
Disposition Plan \| Principal Balance \| Nonrecurring \| 111 Monument Circle, 101-115 W. Washington Street and 100 East Wisconsin Avenue
Fair value of assets and liabilities
Real estate properties, net			308,600
Disposition Plan \| Principal Balance \| Nonrecurring \| Parkshore Plaza, Cabot Business Park Land, 625 Crane Street and 111 Market Place
Fair value of assets and liabilities
Real estate properties, net			98,200
General and administrative expense
Fair value of assets and liabilities
Change in fair value of derivatives			$ 1,000	$ 9,000
Related/Corvex
Fair value of assets and liabilities
Amount of reimbursements payable to related party if specified minimum common share price maintain during the one year period after the date on which the reimbursement is approved by shareholders						$ 8,400
Amount of reimbursements payable to related party if specified minimum common share price maintain during the one year period between the first and second anniversaries of the date on which the reimbursement is approved by shareholders						$ 8,400
Amount of reimbursements payable to related party upon the approval of shareholders	$ 8,200	$ 8,400			$ 16,700
Related/Corvex \| Minimum
Fair value of assets and liabilities
Average closing price per common share during one year period after date (in dollars per share) \| $ / shares						$ 26.00
Average closing price per common share during first and second year after date (in dollars per share) \| $ / shares						$ 26.00