Equity Commonwealth (EQC) 10-K 16 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2016	Feb. 13, 2017	Jun. 30, 2016
Document and Entity Information
Entity Registrant Name	Equity Commonwealth
Entity Central Index Key	803,649
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		124,064,195
Entity Public Float			$ 3.6

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Real estate properties:
Land	$ 286,186	$ 389,410
Buildings and improvements	2,570,704	3,497,942
Total real estate properties, at cost, gross	2,856,890	3,887,352
Accumulated depreciation	(755,255)	(898,939)
Total real estate properties, at cost, net	2,101,635	2,988,413
Acquired real estate leases, net	48,281	88,760
Cash and cash equivalents	2,094,674	1,802,729
Restricted cash	6,532	32,245
Rents receivable, net of allowance for doubtful accounts of $5,105 and $7,715, respectively	152,031	174,676
Other assets, net	122,922	144,341
Total assets	4,526,075	5,231,164
LIABILITIES AND SHAREHOLDERS’ EQUITY
Senior unsecured debt, net	1,063,950	1,450,606
Mortgage notes payable, net	77,717	246,510
Accounts payable and accrued expenses	95,395	123,587
Assumed real estate lease obligations, net	1,946	4,296
Rent collected in advance	18,460	27,340
Security deposits	8,160	10,338
Total liabilities	1,265,628	1,862,677
Commitments and Contingencies
Preferred shares of beneficial interest, $0.01 par value: 50,000,000 shares authorized;
Common shares of beneficial interest, $0.01 par value: 350,000,000 shares authorized; 123,994,465 and 126,349,914 shares issued and outstanding, respectively	1,240	1,263
Additional paid in capital	4,363,177	4,414,611
Cumulative net income	2,566,603	2,333,709
Cumulative other comprehensive loss	(208)	(3,687)
Cumulative common distributions	(3,111,868)	(3,111,868)
Cumulative preferred distributions	(677,760)	(650,195)
Total shareholders’ equity	3,260,447	3,368,487
Total liabilities and shareholders’ equity	4,526,075	5,231,164
Series D
Preferred shares of beneficial interest, $0.01 par value: 50,000,000 shares authorized;
Series D preferred shares; 6 1/2% cumulative convertible; 4,915,196 shares issued and outstanding, respectively, aggregate liquidation preference of $122,880	119,263	119,263
Total shareholders’ equity	119,263	119,263
Series E
Preferred shares of beneficial interest, $0.01 par value: 50,000,000 shares authorized;
Series E preferred shares; 7 1/4% cumulative redeemable on or after May 15, 2016; 0 and 11,000,000 shares issued and outstanding, respectively, aggregate liquidation preference $0 and $275,000, respectively	0	265,391
Total shareholders’ equity	$ 0	$ 265,391

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Rents receivable, allowance for doubtful accounts	$ 5,105	$ 7,715
Common shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares of beneficial interest, shares authorized (in shares)	350,000,000	350,000,000
Common shares of beneficial interest, shares issued (in shares)	123,994,465	126,349,914
Common shares of beneficial interest, shares outstanding (in shares)	123,994,465	126,349,914
Series D
Preferred shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred shares of beneficial interest, shares authorized (in shares)	50,000,000	50,000,000
Preferred shares, dividend yield	6.50%	6.50%
Preferred shares of beneficial interest, shares issued (in shares)	4,915,196	4,915,196
Preferred shares, of beneficial interest, shares outstanding (in shares)	4,915,196	4,915,196
Preferred shares, aggregate liquidation preference	$ 122,880	$ 122,880
Common shares of beneficial interest, shares issued (in shares)	4,915,196	4,915,196
Series E
Preferred shares of beneficial interest, par value (in dollars per share)	$ 0	$ 0.01
Preferred shares of beneficial interest, shares authorized (in shares)	0	50,000,000
Preferred shares, dividend yield	0.00%	7.25%
Preferred shares of beneficial interest, shares issued (in shares)	0	11,000,000
Preferred shares, of beneficial interest, shares outstanding (in shares)	0	11,000,000
Preferred shares, aggregate liquidation preference	$ 0	$ 275,000
Common shares of beneficial interest, shares issued (in shares)	0	11,000,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues:
Rental income	$ 409,071	$ 570,382	$ 691,699
Tenant reimbursements and other income	91,609	144,509	170,158
Total revenues	500,680	714,891	861,857
Expenses:
Operating expenses	200,706	324,948	387,982
Depreciation and amortization	131,806	194,001	227,532
General and administrative	50,256	57,457	113,155
Loss on asset impairment	58,476	17,162	185,067
Acquisition related costs	0	0	5
Total expenses	441,244	593,568	913,741
Operating income (loss)	59,436	121,323	(51,884)
Interest and other income	10,331	5,989	1,561
Interest expense (including net amortization of debt discounts, premiums and deferred financing fees of $3,725, $1,028, and $(549), respectively)	(84,329)	(107,316)	(143,230)
(Loss) gain on early extinguishment of debt	(2,680)	6,661	4,909
Gain on sale of equity investment	0	0	171,561
Gain on issuance of shares by an equity investee	0	0	17,020
Foreign currency exchange loss	(5)	(8,857)	0
Gain on sale of properties, net	250,886	84,421	0
Income (loss) from continuing operations before income taxes and equity in earnings of investees	233,639	102,221	(63)
Income tax expense	(745)	(2,364)	(3,191)
Equity in earnings of investees	0	0	24,460
Income from continuing operations	232,894	99,857	21,206
Discontinued operations:
Income from discontinued operations	0	0	8,389
Loss on asset impairment from discontinued operations	0	0	(2,238)
Loss on early extinguishment of debt from discontinued operations	0	0	(3,345)
Net income	232,894	99,857	24,012
Preferred distributions	(17,956)	(27,924)	(32,095)
Excess fair value of consideration paid over carrying value of preferred shares	(9,609)	0	0
Excess fair value of consideration over carrying value of preferred shares	0	0	(16,205)
Net income (loss) attributable to Equity Commonwealth common shareholders	205,329	71,933	(24,288)
Amounts attributable to Equity Commonwealth common shareholders:
Income (loss) from continuing operations	205,329	71,933	(27,094)
Income from discontinued operations	0	0	8,389
Loss on asset impairment from discontinued operations	0	0	(2,238)
Loss on early extinguishment of debt from discontinued operations	0	0	(3,345)
Net income (loss)	$ 205,329	$ 71,933	$ (24,288)
Weighted average common shares outstanding — basic (in shares)	125,474	128,621	125,163
Weighted average common shares outstanding — diluted (in shares)	126,768	129,437	125,163
Basic earnings per common share attributable to Equity Commonwealth common shareholders:
Income (loss) from continuing operations (in dollars per share)	$ 1.64	$ 0.56	$ (0.21)
Income from discontinued operations (in dollars per share)	0	0	0.02
Net income (loss) (in dollars per share)	1.64	0.56	(0.19)
Diluted earnings per common share attributable to Equity Commonwealth common shareholders:
Income (loss) from continuing operations (in dollars per share)	1.62	0.56	(0.21)
Income from discontinued operations (in dollars per share)	0	0	0.02
Net income (loss) (in dollars per share)	$ 1.62	$ 0.56	$ (0.19)

CONSOLIDATED STATEMENTS OF OPE5

CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Debt discounts, premiums and deferred financing fees	$ 3,725	$ 1,028	$ (549)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 232,894	$ 99,857	$ 24,012
Other comprehensive income (loss), net of tax:
Unrealized gain on derivative instruments and other assets	3,479	612	7,407
Foreign currency translation adjustments	0	48,917	(22,270)
Equity in unrealized loss of an investee	0	0	(22)
Total comprehensive income	$ 236,373	$ 149,386	$ 9,127

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Series D	Series E	Cumulative Preferred Distributions	Common Shares	Cumulative Common Distributions	Additional Paid in Capital	Cumulative Net Income	Cumulative Other Comprehensive Loss
Balance at Dec. 31, 2013	$ 3,363,586	$ 368,270	$ 265,391	$ (573,971)	$ 1,184	$ (3,082,271)	$ 4,213,474	$ 2,209,840	$ (38,331)
Balance (in shares) at Dec. 31, 2013		15,180,000	11,000,000		118,386,918
Comprehensive income (loss):
Net income	24,012							24,012
Unrealized gain on derivative instrument	7,407								7,407
Foreign currency translation adjustments	(22,270)								(22,270)
Equity in unrealized loss of an investee	(22)								(22)
Total comprehensive income	9,127
Issuance of shares, net	2,402				$ 0		2,402
Issuance of shares, net (in shares)					90,135
Redemption of shares	0	$ (249,004)		(16,205)	$ 104		265,105
Redemption of shares (in shares)		(10,264,503)			10,412,499
Excess fair value of consideration paid over carrying value of preferred shares	0
Share grants	6,160				$ 8		6,152
Share grants (in shares)					717,727
Distributions	(61,692)			(32,095)		(29,597)
Balance at Dec. 31, 2014	3,319,583	$ 119,266	$ 265,391	(622,271)	$ 1,296	(3,111,868)	4,487,133	2,233,852	(53,216)
Balance (in shares) at Dec. 31, 2014		4,915,497	11,000,000		129,607,279
Comprehensive income (loss):
Net income	99,857							99,857
Unrealized gain on derivative instrument	612								612
Foreign currency translation adjustments	48,917								48,917
Equity in unrealized loss of an investee	0
Total comprehensive income	149,386
Redemption of shares	0	$ (3)		0	$ 0		3
Redemption of shares (in shares)		(301)			144
Excess fair value of consideration paid over carrying value of preferred shares	0
Share grants	15,425				$ 2		15,423
Share grants (in shares)					152,791
Purchase of shares	(87,983)				$ (35)		(87,948)
Purchase of shares (in shares)					(3,410,300)
Distributions	(27,924)			(27,924)		0
Balance at Dec. 31, 2015	$ 3,368,487	$ 119,263	$ 265,391	(650,195)	$ 1,263	(3,111,868)	4,414,611	2,333,709	(3,687)
Balance (in shares) at Dec. 31, 2015	126,349,914	4,915,196	11,000,000		126,349,914
Comprehensive income (loss):
Net income	$ 232,894							232,894
Unrealized gain on derivative instrument	3,479								3,479
Foreign currency translation adjustments	0
Equity in unrealized loss of an investee	0
Total comprehensive income	236,373
Redemption of shares	(275,000)	$ 0	$ (275,000)	0	$ 0		0
Redemption of shares (in shares)		0	(11,000,000)		0
Excess fair value of consideration paid over carrying value of preferred shares	(9,609)		$ 9,609	(9,609)
Share grants	18,530				$ 2		18,528
Share grants (in shares)					136,226
Purchase of shares	(69,987)				$ (25)		(69,962)
Purchase of shares (in shares)					(2,491,675)
Distributions	(17,956)			(17,956)		0
Balance at Dec. 31, 2016	$ 3,260,447	$ 119,263	$ 0	$ (677,760)	$ 1,240	$ (3,111,868)	$ 4,363,177	$ 2,566,603	$ (208)
Balance (in shares) at Dec. 31, 2016	123,994,465	4,915,196	0		123,994,465

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 232,894	$ 99,857	$ 24,012
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	102,695	145,888	166,076
Net amortization of debt discounts, premiums and deferred financing fees	3,725	1,028	(552)
Straight line rental income	(14,083)	(5,255)	(12,759)
Amortization of acquired real estate leases	21,129	34,277	51,140
Other amortization	14,513	21,309	20,931
Share-based compensation	18,530	15,425	5,733
Loss on asset impairment	58,476	17,162	187,305
Loss (gain) on early extinguishment of debt	2,680	(6,661)	(1,564)
Equity in earnings of investees	0	0	(24,460)
Gain on sale of equity investments	0	0	(171,561)
Gain on issuance of shares by an equity investee	0	0	(17,020)
Distributions of earnings from investees	0	0	20,680
Foreign currency exchange loss	5	8,857	0
Net gain on sale of properties	(250,886)	(84,421)	0
Other non-cash expenses	0	0	2,402
Change in assets and liabilities:
Restricted cash	(687)	(6,570)	3,486
Rents receivable and other assets	(23,921)	(47,472)	(30,785)
Accounts payable and accrued expenses	4,663	(4,643)	10,389
Rent collected in advance	(6,981)	(8,462)	(229)
Security deposits	264	1,225	433
Due to related persons	0	0	(9,277)
Cash provided by operating activities	163,016	181,544	224,380
CASH FLOWS FROM INVESTING ACTIVITIES:
Real estate acquisitions	(2,802)	0	0
Real estate improvements	(121,450)	(70,633)	(99,651)
Insurance proceeds received	500	0	0
Principal payments received from direct financing lease	0	7,352	7,311
Proceeds from sale of properties, net	1,149,471	1,691,831	185,299
Purchase of securities	0	0	(23,988)
Proceeds from sale of securities	0	27,068	0
Proceeds from sale of equity investments, net	0	0	710,492
Decrease (increase) in restricted cash	26,400	(6,725)	(8,225)
Cash provided by investing activities	1,052,119	1,648,893	771,238
CASH FLOWS FROM FINANCING ACTIVITIES:
Purchase and retirement of common shares	(69,987)	(87,983)	0
Redemption of preferred shares	(275,000)	0	0
Payments on borrowings	(560,187)	(259,672)	(785,316)
Deferred financing fees	(52)	(7,143)	0
Distributions to common shareholders	0	0	(29,597)
Distributions to preferred shareholders	(17,956)	(27,924)	(32,095)
Cash used in financing activities	(923,182)	(382,722)	(847,008)
Effect of exchange rate changes on cash	(8)	(9,502)	(1,126)
Increase in cash and cash equivalents	291,945	1,438,213	147,484
Cash and cash equivalents at beginning of period	1,802,729	364,516	217,032
Cash and cash equivalents at end of period	2,094,674	1,802,729	364,516
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid	85,310	111,324	146,265
Taxes paid	327	6,028	2,732
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Increase (decrease) in capital expenditures recorded as liabilities	10,331	(13,528)	7,690
Mortgage note payable and interest payable transferred in consensual foreclosure	$ 0	$ 43,255	$ 0

Organization

Organization	12 Months Ended
	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Equity Commonwealth is a real estate investment trust, or REIT, formed in 1986 under the laws of the State of Maryland. Our primary business is the ownership and operation of real estate, primarily office buildings, throughout the United States. On November 10, 2016, Equity Commonwealth (the Company) converted to what is commonly referred to as an umbrella partnership real estate investment trust, or UPREIT, structure. In connection with this conversion, the Company contributed substantially all of its assets to EQC Operating Trust, a Maryland real estate investment trust through which the Company will conduct its business (the Operating Trust), and the Operating Trust assumed substantially all of the Company’s liabilities pursuant to a contribution and assignment agreement between the Company and the Operating Trust. The Company now conducts and intends to continue to conduct substantially all of its activities through the Operating Trust. The Company beneficially owned, directly and indirectly, 100.0% of the outstanding shares of beneficial interest, designated as units, in the Operating Trust (OP Units) as of December 31, 2016 and the Company is the sole trustee of the Operating Trust. As the sole trustee, the Company generally has the exclusive power under the declaration of trust of the Operating Trust to manage and conduct the business of the Operating Trust, subject to certain limited approval and voting rights of other holders of OP Units that may be admitted in the future. At December 31, 2016 , our portfolio included 33 properties ( 64 buildings), one land parcel and one property taken out of service which is now classified as a land parcel, with a combined 16.1 million square feet. All numbers of properties, numbers of buildings and square feet are unaudited.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation. The consolidated financial statements include our investments in 100% owned subsidiaries and majority owned subsidiaries that are controlled by us. References to we, us, our and the Company, refer to Equity Commonwealth and its consolidated subsidiaries as of December 31, 2016 , unless the context indicates otherwise. All intercompany transactions and balances have been eliminated. We account for our investments in 50% or less owned companies over which we can exercise influence, but do not control, using the equity method of accounting, which included our prior investments in Select Income REIT and its consolidated subsidiaries (SIR) (beginning on July 2, 2013 when SIR ceased to be our consolidated subsidiary through the sale date on July 9, 2014) and Affiliates Insurance Company, or AIC (until May 9, 2014, when we sold all of our AIC shares). We used the income statement method to account for issuance of common shares of beneficial interest by SIR, and shares of common stock by AIC. Under this method, gains and losses reflecting changes in the value of our investments at the date of issuance of additional common shares by SIR, or common stock by AIC, are recognized in our income statement. Real Estate Properties. We record real estate properties at cost. We depreciate real estate investments on a straight line basis over estimated useful lives of up to 40 years for buildings and improvements, and up to 12 years for personal property. Each time we enter into a new lease, or materially modify an existing lease, we evaluate its classification as either a capital or operating lease. The classification of a lease as capital or operating affects the carrying value of a property, as well as our recognition of rental payments as revenue. These evaluations require us to make estimates of, among other things, the remaining useful life and fair market value of a leased property, appropriate discount rates and future cash flows. We allocate the consideration paid for our properties among land, buildings and improvements and, for properties that qualify as acquired businesses under the Business Combinations Topic of the FASB Accounting Standards Codification ™ , or the Codification, to identified intangible assets and liabilities, consisting of the value of above market and below market leases, the value of acquired in place leases and the value of tenant relationships. Purchase price allocations and the determination of useful lives are based on our estimates and, under some circumstances, studies from independent real estate appraisal firms to provide market information and evaluations that are relevant to our purchase price allocations and determinations of useful lives; however, we are ultimately responsible for the purchase price allocations and determination of useful lives. We allocate the consideration to land, buildings and improvements based on a determination of the fair values of these assets assuming the property is vacant. We determine the fair value of a property using methods that we believe are similar to those used by independent appraisers. Purchase price allocations to above market and below market leases are based on the estimated present value (using an interest rate which reflects our assessment of the risks associated with the leases acquired) of the difference between (1) the contractual amounts to be paid pursuant to the acquired in place leases and (2) our estimate of fair market lease rates for the corresponding leases, measured over a period equal to the remaining non-cancelable terms of the respective leases. Purchase price allocations to acquired in place leases and tenant relationships are determined as the excess of (1) the purchase price paid for a property after adjusting existing in place leases to estimated market rental rates over (2) the estimated fair value of the property as if vacant. We aggregate this value between acquired in place lease values and tenant relationships based on our evaluation of the specific characteristics of each tenant's lease; however, the value of tenant relationships has not been separated from acquired in place lease value for our properties because we believe such value and related amortization expense is immaterial for acquisitions reflected in our historical financial statements. We consider certain factors in performing these analyses including estimates of carrying costs during the expected lease up periods, including real estate taxes, insurance and other operating income and expenses and costs to execute similar leases in current market conditions, such as leasing commissions, legal and other related costs. If we believe the value of tenant relationships is material in the future, those amounts will be separately allocated and amortized over the estimated lives of the relationships. We recognize the excess, if any, of the consideration paid over amounts allocated to land, buildings and improvements and identified intangible assets and liabilities as goodwill and we recognize gains if amounts allocated exceed the consideration paid. We amortize capitalized above market lease values (presented in our consolidated balance sheets as acquired real estate leases) as a reduction to rental income over the remaining terms of the respective leases. We amortize capitalized below market lease values (presented in our consolidated balance sheets as assumed real estate lease obligations) as an increase to rental income over the remaining terms of the respective leases. We amortize the value of acquired in place leases exclusive of the value of above market and below market acquired in place leases to expense over the remaining terms of the respective leases. If a lease is terminated prior to its stated expiration, the unamortized lease intangibles relating to that lease is written off. We review our properties for impairment quarterly, or whenever events or changes in circumstances indicate that their carrying amounts may not be recoverable. Impairment indicators may include declining tenant occupancy, lack of progress releasing vacant space, tenant bankruptcies, low long term prospects for improvement in property performance, weak or declining tenant profitability, cash flow or liquidity, our decision to dispose of an asset before the end of its estimated useful life. When indicators of potential impairment are present that suggest that the carrying amounts of real estate assets may not be recoverable, we assess the recoverability of these assets by determining whether the respective carrying values will be recovered through the estimated undiscounted future operating cash flows expected from the use of the assets and their eventual disposition. The determination of undiscounted cash flow includes consideration of many factors including income to be earned from the investment, holding costs (exclusive of interest), estimated selling prices, and prevailing economic and market conditions. In the event that such expected undiscounted future cash flows do not exceed the carrying values, we estimate the fair value of the assets and record an impairment charge equal to the amount by which the carrying value exceeds the estimated fair value. Estimated fair values are calculated based on the following information, (i) recently quoted market prices, (ii) market prices for comparable properties, or (iii) the present value of future cash flows. During the years ended December 31, 2016 , 2015 , and 2014 we recorded a loss on asset impairment in continuing operations totaling $58.5 million , $17.2 million and $185.1 million respectively, to reduce the carrying value of properties to their estimated fair values (see Note 15). When we classify properties as held for sale, we discontinue the recording of depreciation expense and estimate their fair value less costs to sell. If we determine that the carrying value for these properties exceed their estimated fair value less costs to sell, we record a loss on asset impairment. Certain of our real estate assets contain hazardous substances, including asbestos. We believe any asbestos in our buildings is contained in accordance with current regulations, and we have no current plans to remove any such asbestos. If we remove the asbestos or renovate or demolish these properties, certain environmental regulations govern the manner in which the asbestos must be handled and removed. We do not believe that there are other environmental conditions at any of our properties that have a material adverse effect on us. However, no assurances can be given that such conditions are not present in our properties or that other costs we incur to remediate contamination will not have a material adverse effect on our business or financial condition. As of December 31, 2016 and 2015 , we did not have any accrued environmental remediation costs. Cash and Cash Equivalents. Our cash and cash equivalents consist of cash maintained in time deposits, depository accounts and money market accounts. From time-to-time we may also invest in various U.S. government securities. We continually monitor the credit ratings of the financial institutions holding our deposits to minimize our exposure to credit risk. Throughout the year, we have cash balances in excess of federally insured limits deposited with various financial institutions. We do not believe we are exposed to any significant credit risk on cash and cash equivalents. Restricted Cash. Restricted cash consists of amounts escrowed for future real estate taxes, insurance, leasing costs, capital expenditures and debt service, as required by some of our mortgage debts, as well as security deposits paid to us by some of our tenants. Other Assets, Net. Other assets consist principally of deferred financing fees, deferred leasing costs, capitalized lease incentives and prepaid property operating expenses. Deferred financing fees include issuance costs related to borrowings and are capitalized and amortized over the terms of the respective loans. Deferred leasing costs include brokerage, legal and other fees associated with the successful negotiation of leases and are amortized on a straight line basis over the terms of the respective leases. Capitalized lease incentives are amortized on a straight line basis against rental income over the terms of the respective leases. Accounting Policy for Derivative Instruments. The Derivatives and Hedging Topic of the Codification requires companies to recognize all their derivative instruments as either assets or liabilities in the statement of financial position at fair value. The accounting for changes in the fair value of a derivative instrument depends on whether such instrument has been designated and qualifies as part of a hedging relationship and, further, on the type of hedging relationship. For those derivative instruments that are designated and qualify as hedging instruments, we must designate the hedging instrument, based upon the exposure being hedged, as a fair value hedge, cash flow hedge or a hedge of a net investment in a foreign operation. As of December 31, 2016 , we have an interest rate cap agreement that qualifies as a cash flow hedge. We are exposed to certain risks relating to our ongoing business operations. The primary risk managed by using derivative instruments is interest rate risk. Interest rate swaps and caps are entered into to manage interest rate risk associated with our floating rate borrowings. We designate interest rate swaps and caps as cash flow hedges of floating rate borrowings. Revenue Recognition. Rental income from operating leases, which includes rent concessions (including free rent and other lease incentives) and scheduled increases in rental rates during the lease term, is recognized on a straight line basis over the life of the lease agreements. We defer the recognition of contingent rental income, such as percentage rents, until the specific targets that trigger the contingent rental income are achieved. Tenant reimbursements and other income includes property level operating expenses reimbursed by our tenants, as well as other incidental revenues, which are recorded as expenses are incurred. Allowance for Doubtful Accounts. We maintain an allowance for doubtful accounts for estimated losses resulting from the inability or unwillingness of certain tenants to make payments required under their leases. The computation of the allowance is based on the tenants' payment histories and current credit profiles, as well as other considerations. Share-Based Compensation. All share-based compensation is measured at fair value on the grant date or date of modification, as applicable, and recognized in earnings over the requisite service period. Depending upon the settlement terms of the awards, all or a portion of the fair value of share-based awards may be presented as a liability or as equity in the consolidated balance sheets. Earnings Per Common Share. Earnings per common share, or EPS, is computed using the weighted average number of common shares outstanding during the period. Diluted EPS reflects the potential dilution that could occur if our series D convertible preferred shares or our restricted share units (RSUs) were converted into our common shares, which could result in a lower EPS amount. The effect of our series D convertible preferred shares on income from continuing operations and net income attributable to common shareholders is anti-dilutive for all periods presented. Reclassifications. Reclassifications have been made to the prior years' financial statements and notes to conform to the current year's presentation. Income Taxes. We are a REIT under the Internal Revenue Code of 1986, as amended, and are generally not subject to federal and state income taxes provided we distribute our taxable income to our shareholders and meet other requirements for qualifying as a real estate investment trust. However, we are subject to certain state and local taxes without regard to our REIT status. The Income Taxes Topic of the Codification prescribes how we should recognize, measure and present in our financial statements uncertain tax positions that have been taken or are expected to be taken in a tax return. Deferred tax assets are recognized to the extent that it is "more likely than not" that a particular tax position will be sustained upon examination or audit. To the extent the "more likely than not" standard has been satisfied, the benefit associated with a tax position is measured as the largest amount that has a greater than 50% likelihood of being realized upon settlement. We classify interest and penalties related to uncertain tax positions, if any, in our financial statements as a component of general and administrative expense. Use of Estimates. Preparation of these financial statements in conformity with U.S. generally accepted accounting principles, or GAAP, requires us to make estimates and assumptions that may affect the amounts reported in these financial statements and related notes. The actual results could differ from these estimates. Foreign Operations. During the year ended December 31, 2015, we sold our Australian properties (see Note 3) and as of each of December 31, 2016 and 2015, we did not have any foreign operations. The U.S. dollar was the functional currency for our consolidated subsidiaries operating in the United States prior to the sale of the Australian portfolio. The functional currency for our consolidated subsidiaries in countries other than the United States was the principal currency in which the entity's assets, liabilities, income and expenses were denominated. The functional currency of our consolidated subsidiary that operated in Australia was the Australian dollar. We translated our Australian subsidiary's financial statements into U.S. dollars when we consolidated that subsidiary's financial statements on a quarterly basis. Generally, we translated assets and liabilities at the exchange rate in effect as of the balance sheet date. The resulting translation adjustments were included in cumulative other comprehensive loss in our consolidated balance sheets. We translated income statement accounts using the average exchange rate for the period and income statement accounts that include significant non-recurring transactions at the rate in effect as of the date of the transaction. We were subject to foreign currency risk due to potential fluctuations in exchange rates between Australian and U.S. currencies. Subsequent to the disposition of the Australian properties, we recognized a foreign currency exchange loss of $8.9 million in our consolidated statement of operations for the year ended December 31, 2015. The foreign currency exchange loss for the year ended December 31, 2015 relates to the change in foreign currency rates resulting in losses on cash proceeds from the Australian portfolio disposition maintained in an Australian bank account prior to the transfer of cash from our Australian subsidiary to our U.S bank accounts. As of December 31, 2015, we did no t have any cumulative foreign currency translation adjustments as the cumulative foreign currency translation adjustment of $63.2 million was reclassified from other comprehensive loss to earnings upon disposition of the Australian properties. New Accounting Pronouncements. In February 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2017-01, Clarifying the Definition of a Business, that changes the definition of a business to assist entities with evaluating when a set of transferred assets and activities is a business. This update is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. Early adoption is permitted for transactions that occurred before the issuance date or effective date of the standard if the transactions were not reported in financial statements that have been issued or made available for issuance. We do not expect that the adoption of this ASU will have a material impact on our consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, which amends FASB Accounting Standards Codification (ASC) Topic 230, Statements of Cash Flows, to add or clarify guidance on the classification and presentation of restricted cash in the statement of cash flows. This update is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. We do not expect that the adoption of this ASU will have a material impact on our consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. This update is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. We do not expect that the adoption of this ASU will have a material impact on our consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires more timely recognition of credit losses associated with financial assets. This update is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years. Early adoption is permitted for fiscal years, and interim periods within those years, beginning after December 15, 2018. We are currently in the process of evaluating the impact, if any, the adoption of this ASU will have on our consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, which simplifies several aspects of the accounting for employee share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. This update is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods, but early adoption is permitted. We do not expect that the adoption of this ASU will have a material impact on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases, which amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets. The ASU also requires lessees or lessors to capitalize only initial direct costs of leases. This update is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, but early adoption is permitted. We are currently in the process of evaluating the impact the adoption of this ASU will have on our consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, which creates a single source of revenue guidance. The new standard provides accounting guidance for all revenue arising from contracts with customers and affects all entities that enter into contracts to provide goods or services to their customers (unless the contracts are in the scope of other GAAP requirements, such as the leasing literature). The guidance also provides a model for the measurement and recognition of gains and losses on the sale of certain nonfinancial assets, such as property and equipment, including real estate. The new standard is effective for fiscal years beginning after December 15, 2017 and for interim periods therein. Early adoption is permitted beginning after December 15, 2016. Upon adoption of ASU 2016-02, Leases, the majority of our revenue, will be subject to the allocation provisions outlined within the revenue standard. We are currently evaluating the specific implementation requirements for allocating the consideration within our contracts in accordance with ASU No. 2014-09. In April 2015, the FASB issued ASU No. 2015-03, Simplifying the Presentation of Debt Issuance Costs. This standard amends existing guidance to require the presentation of debt issuance costs in the balance sheet as a deduction from the carrying amount of the related debt liability instead of as a deferred charge. It is effective for annual reporting periods beginning after December 15, 2015, but early adoption is permitted. We adopted this standard on January 1, 2016 and made the following reclassifications to the prior years' consolidated balance sheet to conform to the current year's presentation (in thousands): Balance Sheet as of December 31, 2015 Originally Reported Effect of Change As Adjusted Other assets, net $ 157,549 $ (13,208 ) $ 144,341 Senior unsecured debt, net 1,460,592 (9,986 ) 1,450,606 Mortgage notes payable, net 249,732 (3,222 ) 246,510 In April 2014, the FASB issued ASU No. 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, or ASU 2014-08. ASU 2014-08 changes the criteria for reporting a discontinued operation. Under the new pronouncement, a disposal of a part of an organization that has a major effect on its operations and financial results is a discontinued operation. We adopted ASU 2014-08 on January 1, 2015, and determined that our 2016 dispositions and 2015 dispositions do not individually represent a strategic shift, as defined by the standard, that has or will have a major effect on our operations and financial results. As a result, the 2016 and 2015 dispositions have not been presented as discontinued operations in the statements of operations.

Real Estate Properties

Real Estate Properties	12 Months Ended
	Dec. 31, 2016
Real Estate [Abstract]
Real Estate Properties	Real Estate Properties Acquisitions and Expenditures In October 2016, we purchased a parcel of land adjacent to our Research Park property in Austin, Texas for $2.8 million . We did not make any acquisitions during the year ended December 31, 2015 . During the years ended December 31, 2016 , 2015 , and 2014 , we made improvements, excluding tenant-funded improvements, to our properties totaling $110.7 million , $ 75.7 million and $91.6 million , respectively. We committed $143.0 million for expenditures related to 4.3 million square feet of leases executed during 2016 . Committed but unspent tenant related obligations are leasing commissions and tenant improvements. Based on existing leases as of December 31, 2016 , committed but unspent tenant related obligations were $91.8 million . Properties Held For Sale: We classify all properties that meet the criteria outlined in the Property, Plant and Equipment Topic of the FASB Accounting Standards Codification (Codification) as held for sale on our consolidated balance sheets. During March 2014, the former management team ceased to actively market 31 properties ( 67 buildings) with a combined 5,641,450 square feet that we had previously classified as held for sale as of December 31, 2013. These properties were not under agreement for sale when our former Trustees were removed in March 2014. These properties were reclassified to properties held and used in operations because they no longer met the requirements under GAAP for classification as held for sale. Operating results for these properties were reclassified from discontinued operations to continuing operations for all periods presented herein. In connection with this reclassification, we reversed previously recorded impairment losses totaling $4.8 million , which included the elimination of estimated costs to sell. As of December 31, 2016 and 2015 , we had no properties classified as held for sale. Property Dispositions: During the year ended December 31, 2016, we disposed of the following properties (dollars in thousands): Asset Date Sold Number of Number of Square Footage Gross Sales Price Gain (Loss) on Sale Properties Executive Park February 2016 1 9 427,443 $ 50,865 $ 16,531 3330 N Washington Boulevard March 2016 1 1 55,719 11,250 5,455 111 East Kilbourn Avenue March 2016 1 1 373,669 60,500 14,687 1525 Locust Street April 2016 1 1 98,009 17,700 8,956 633 Ahua Street April 2016 1 1 93,141 29,000 15,963 Lakewood on the Park May 2016 1 2 180,558 37,100 13,616 Leased Land June 2016 1 7 — 48,450 15,914 9110 East Nichols Avenue June 2016 1 1 143,958 17,200 642 111 River Street (1) July 2016 1 1 566,215 235,000 78,207 Sky Park Centre July 2016 1 2 63,485 13,700 4,746 Raintree Industrial Park July 2016 1 12 563,182 11,500 (653 ) 8701 N Mopac August 2016 1 1 121,901 21,500 8,394 7800 Shoal Creek Boulevard October 2016 1 4 151,917 29,210 14,908 1200 Lakeside Drive November 2016 1 1 260,084 65,270 3,062 6200 Glenn Carlson Drive December 2016 1 1 338,000 23,050 7,706 Portfolios of properties 812 San Antonio Street May 2016 1 1 59,321 1601 Rio Grande Street May 2016 1 1 56,219 Downtown Austin portfolio 2 2 115,540 $ 32,600 $ 20,584 785 Schilinger Road South June 2016 1 1 72,000 401 Vine Street June 2016 1 1 53,980 633 Frazier Drive June 2016 1 1 150,000 9840 Gateway Boulevard North June 2016 1 1 72,000 3003 South Expressway 281 June 2016 1 1 150,000 1331 North Center Parkway June 2016 1 1 53,980 Movie theater portfolio 6 6 551,960 $ 109,100 $ 30,595 Asset Date Sold Number of Number of Square Footage Gross Sales Price Gain (Loss) on Sale 128 Crews Drive July 2016 1 1 185,600 111 Southchase Boulevard July 2016 1 1 168,087 1043 Global Avenue July 2016 1 1 450,000 South Carolina industrial portfolio 3 3 803,687 $ 30,000 $ 7,248 100 East Wisconsin Avenue August 2016 1 1 435,067 111 Monument Circle August 2016 1 2 1,121,764 101-115 W. Washington Street August 2016 1 1 634,058 North Point Office Complex August 2016 1 2 873,335 Midwest portfolio 4 6 3,064,224 $ 416,900 $ (15,800 ) Total 30 62 7,972,692 $ 1,259,895 $ 250,761 (1) Property sale represented a leasehold interest. During the year ended December 31, 2015, we disposed of the following properties (dollars in thousands): Asset Date Disposed Number of Number of Square Footage Gross Sales Price Gain (Loss) on Sale Properties 11350 North Meridian Street January 2015 1 1 72,264 $ 4,200 $ 766 333 Laurel Oak Drive (1) March 2015 — 1 27,164 2,450 251 1921 E. Alton Avenue March 2015 1 1 67,846 14,533 4,851 46 Inverness Center Parkway April 2015 — — — 2,000 1,857 225 Water Street (2) May 2015 1 1 318,997 — — Sorrento Valley Business Park June 2015 1 4 105,003 23,500 11,896 Illinois Center August 2015 1 2 2,090,162 376,000 26,956 16th and Race Street August 2015 1 1 608,625 43,000 7,922 185 Asylum Street September 2015 1 1 868,395 113,250 17,619 One South Church Avenue October 2015 1 1 240,811 32,000 4,282 775 Ridge Lake Boulevard October 2015 1 1 120,678 16,300 (360 ) One Park Square October 2015 1 6 259,737 34,300 9,512 Arizona Center December 2015 1 4 1,070,724 126,000 22,838 4 South 84th Avenue December 2015 1 1 236,007 18,000 8,393 Portfolio of properties 7450 Campus Drive May 2015 1 1 77,411 129 Worthington Ridge Road May 2015 1 1 227,500 599 Research Parkway May 2015 1 1 48,249 181 Marsh Hill Road May 2015 1 1 162,036 101 Barnes Road May 2015 1 1 45,755 15 Sterling Drive May 2015 1 1 173,015 35 Thorpe Avenue May 2015 1 1 79,862 50 Barnes Industrial Road North May 2015 1 1 154,255 5-9 Barnes Industrial Road May 2015 1 1 38,006 Asset Date Disposed Number of Number of Square Footage Gross Sales Price Gain (Loss) on Sale 860 North Main Street May 2015 1 1 31,165 One Barnes Industrial Road South May 2015 1 1 30,170 Village Lane May 2015 1 2 58,185 100 Northfield Drive May 2015 1 1 116,986 905 Meridian Lake Drive May 2015 1 1 74,652 1717 Deerfield Road May 2015 1 1 141,186 1955 West Field Court May 2015 1 1 59,130 5015 S. Water Circle May 2015 1 1 113,524 Adams Place May 2015 1 2 230,259 Cabot Business Park May 2015 1 2 252,755 2300 Crown Colony Drive May 2015 1 1 45,974 Myles Standish Industrial Park May 2015 1 2 74,800 340 Thompson Road May 2015 1 1 25,000 100 South Charles Street May 2015 1 1 159,616 6710 Oxon Hill May 2015 1 1 118,336 8800 Queen Avenue South May 2015 1 1 280,822 9800 Sherlard Parkway May 2015 1 1 46,765 Rosedale Corporate Plaza May 2015 1 3 149,116 1000 Shelard Parkway May 2015 1 1 62,499 525 Park Street May 2015 1 1 75,636 1900 Meyer Drury Drive May 2015 1 1 65,225 131-165 West Ninth Street May 2015 1 1 75,517 7-9 Vreeland Road May 2015 1 1 155,891 5 Paragon Drive May 2015 1 1 119,089 1000 Voorhees Drive and 400 Laurel Oak Drive (1) May 2015 1 2 125,415 1601 Veterans Highway May 2015 1 1 63,608 Two Corporate Center Drive May 2015 1 1 291,230 11311 Cornell Park Drive May 2015 1 1 93,413 5300 Kings Island Drive May 2015 1 1 159,421 3 Crown Point Court May 2015 1 1 73,987 515 Pennsylvania Avenue May 2015 1 1 82,000 443 Gulph Road May 2015 1 1 21,000 4350 Northern Pike May 2015 1 1 503,885 Thunderbolt Place May 2015 1 2 100,505 6160 Kempsville Circle May 2015 1 1 129,565 448 Viking Drive May 2015 1 1 75,374 Portfolio of small office and industrial assets 45 53 5,287,790 $ 376,000 $ (8,160 ) 2501 20th Place South June 2015 1 1 125,722 420 20th Street North June 2015 1 1 514,893 Inverness Center June 2015 1 4 475,882 Asset Date Disposed Number of Number of Square Footage Gross Sales Price Gain (Loss) on Sale 701 Poydras Street June 2015 1 1 1,256,971 300 North Greene Street June 2015 1 1 324,305 1320 Main Street June 2015 1 1 334,075 AL, LA, NC, SC office portfolio 6 9 3,031,848 $ 417,450 $ 41,596 12655 Olive Boulevard June 2015 1 1 98,588 1285 Fern Ridge Parkway June 2015 1 1 66,510 St. Louis portfolio (3) 2 2 165,098 $ 14,300 $ (2,349 ) 310-314 Invermay Road (4) April 2015 1 1 47,480 253-293 George Town Road (4) April 2015 1 1 143,914 7 Modal Crescent June 2015 1 1 164,160 71-93 Whiteside Road June 2015 1 1 303,488 9-13 Titanium Court June 2015 1 1 69,664 16 Rodborough Road June 2015 1 1 90,525 22 Rodborough Road June 2015 1 1 43,427 127-161 Cherry Lane June 2015 1 1 278,570 310-320 Pitt Street June 2015 1 1 313,865 44-46 Mandarin Street June 2015 1 1 226,718 19 Leadership Way June 2015 1 1 76,714 Australia portfolio (5) 11 11 1,758,525 $ 232,955 $ (47,872 ) Widewaters Parkway August 2015 1 8 514,241 5062 Brittonfield Parkway August 2015 1 1 40,162 Woodcliff Drive August 2015 1 6 516,760 Interstate Place August 2015 1 2 61,399 1000 Pittsford - Victor Road August 2015 1 1 73,358 1200 Pittsford - Victor Road August 2015 1 1 18,900 Corporate Crossing August 2015 1 5 216,126 Canal View Boulevard August 2015 1 3 118,375 14 Classic Street August 2015 1 1 37,084 110 W Fayette Street August 2015 1 1 304,906 251 Salina Meadows Parkway August 2015 1 1 65,617 Upstate New York portfolio (3) 11 30 1,966,928 $ 104,625 $ (12,518 ) 9040 Roswell Road October 2015 1 1 178,941 The Exchange October 2015 1 2 187,632 3920 Arkwright Road October 2015 1 1 196,156 1775 West Oak Commons Court October 2015 1 1 79,854 Georgia portfolio (3) 4 5 642,583 $ 48,550 $ (3,059 ) Total 91 135 18,939,185 $ 1,999,413 $ 84,421 (1) This property contains three buildings. We sold one building in March 2015 and two buildings in May 2015. (2) Title to this property was transferred to the lender pursuant to a consensual foreclosure in full satisfaction of the mortgage debt with a principal balance of $40.1 million , resulting in a gain on early extinguishment of debt of $17.3 million for the year ended December 31, 2015. See Note 9 for additional information. (3) Prior to the disposition of these properties, we recorded a total impairment charge of $17.2 million during the year ended December 31, 2015, based upon updated market information in accordance with our impairment analysis procedures. (4) These properties were sold in a separate transaction to a different buyer than the other Australian properties. (5) The loss on sale includes a $63.2 million cumulative foreign currency translation adjustment reclassified from cumulative other comprehensive loss due to the disposition of the Australian portfolio. During the year ended December 31, 2014, we sold 14 properties ( 43 buildings) with a combined 2,784,098 square feet for an aggregate gross sales price of $215.9 million , excluding closing costs and mortgage debt repayments. In connection with this transaction, we recognized a loss on asset impairment of $2.2 million and a loss on early extinguishment of debt of $3.3 million for the year ended December 31, 2014. Results of operations for properties sold prior to December 31, 2014, are included in discontinued operations in our consolidated statements of operations. Summarized income statement information for properties included in discontinued operations is as follows (in thousands): Year Ended December 31, 2014 Rental income $ 14,243 Tenant reimbursements and other income 1,900 Total revenues 16,143 Operating expenses 7,138 General and administrative 10 Total expenses 7,148 Operating income 8,995 Interest and other income 2 Interest expense (608 ) Income from discontinued operations $ 8,389 Lease Payments Our real estate properties are generally leased on gross lease, modified gross lease or triple net lease bases pursuant to non-cancelable, fixed term operating leases expiring between 2017 and 2034. Our triple net leases generally require the lessee to pay all property operating costs. Our gross leases and modified gross leases require us to pay all or some property operating expenses and to provide all or some property management services. A portion of these property operating expenses are reimbursed by the tenants. The future minimum lease payments, excluding tenant reimbursement revenue, scheduled to be received by us during the current terms of our leases as of December 31, 2016 are as follows (in thousands): 2017 $ 292,388 2018 299,449 2019 278,531 2020 244,953 2021 206,046 Thereafter 850,539 $ 2,171,906 One of our real estate properties that we sold in 2016, 111 River Street in Hoboken, New Jersey, was subject to a ground lease. The amount of ground lease expense included in operating expenses during the years ended December 31, 2016 , 2015 and 2014 , totaled $0.9 million , $1.8 million and $1.8 million , respectively. Ground lease expense includes percentage rent.

Lease Intangibles

Lease Intangibles	12 Months Ended
	Dec. 31, 2016
Leases [Abstract]
Leases Intangibles	Lease Intangibles The following table summarizes the carrying amounts for our acquired real estate leases and assumed real estate lease obligations as of December 31, 2016 , and 2015 , and (in thousands): December 31, 2016 2015 Acquired in-place leases $ 102,102 $ 147,056 Acquired above market leases 44,752 78,210 Acquired real estate leases 146,854 225,266 Accumulated amortization, acquired in-place leases (71,320 ) (91,301 ) Accumulated amortization, acquired above market leases (27,253 ) (45,205 ) Acquired real estate leases, net $ 48,281 $ 88,760 Acquired below market leases 10,434 19,742 Accumulated amortization (8,488 ) (15,446 ) Assumed real estate lease obligations, net $ 1,946 $ 4,296 Amortization of the lease intangibles for the years ended December 31, 2016 , 2015 , and 2014 , is as follows (in thousands): December 31, Income Statement Location 2016 2015 2014 Amortization of acquired in-place leases Depreciation and amortization $ 14,598 $ 26,787 $ 40,493 Amortization of above and below market leases Increase (decrease) to rental income (6,531 ) (7,515 ) (10,650 ) Future amortization of net intangible lease assets and liabilities to be recognized by us during the current terms of our leases as of December 31, 2016 , are approximately (in thousands): 2017 $ 9,670 2018 8,397 2019 6,178 2020 5,882 2021 5,252 Thereafter 10,956 $ 46,335

Investment in Direct Financing

Investment in Direct Financing Lease	12 Months Ended
	Dec. 31, 2016
Capital Leases, Net Investment in Direct Financing Leases [Abstract]
Investment in Direct Financing Lease	Investment in Direct Financing Lease We had an investment in a direct financing lease that related to a lease with a term that exceeded 75% of the useful life of an office tower located within a mixed use property in Phoenix, AZ. In December 2015, we sold this property. Prior to the sale of the property, we recognized income using the effective interest method to produce a level yield on funds not yet recovered.

Equity Investments

Equity Investments	12 Months Ended
	Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments	Equity Investments At December 31, 2016 , and 2015 , we did not have any ownership interests in equity investments. For the year ended December 31, 2014, equity in earnings is as follows (in thousands): Year Ended December 31, 2014 SIR $ 24,516 AIC (56 ) $ 24,460 Investment in SIR SIR was one of our consolidated subsidiaries until July 2, 2013 and was an unconsolidated equity investment from July 2, 2013 until July 9, 2014. Under the equity method, we recorded our percentage share of net earnings of SIR in our consolidated statements of operations. On July 9, 2014, we sold our entire stake of 22,000,000 common shares of SIR. We received $704.8 million in cash representing $32.04 per share and recognized a gain on sale of equity investment of $171.8 million in our consolidated statement of operations. Proceeds from this sale were used to repay our revolving credit facility and certain mortgage loans. As a result of this sale, we no longer hold any interest in SIR. See Note 18 for additional information about our investment in AIC. During the second quarter of 2014, SIR issued 10,000,000 common shares in a public offering for $29.00 per common share, raising net proceeds (after deducting underwriters’ discounts and commissions and expenses) of approximately $277.4 million . We recognized a gain on this sale by an equity investee of $16.9 million as a result of the per share sales price of this transaction being above our per share carrying value. Our ownership percentage in SIR was reduced to 36.7% as a result of the transaction. On July 2, 2013, SIR issued and sold to the public 10,500,000 of its common shares for $28.25 per common share. Prior to the completion of this offering, our 22,000,000 common shares of SIR represented approximately 56.0% of SIR's outstanding common shares, and SIR was one of our consolidated subsidiaries. Following the completion of this offering, our 22,000,000 common shares of SIR represented approximately 44.2% of SIR's outstanding common shares and SIR ceased to be our consolidated subsidiary. For the period from January 1, 2014, through July 9, 2014, we received cash distributions from SIR totaling $20.7 million . The following unaudited summarized income statement information of SIR for the period from January 1, 2014, through July 9, 2014, is as follows (in thousands, except per share data): For the Period from January 1, 2014 through July 9, 2014 Rental income $ 98,226 Tenant reimbursements and other income 16,980 Total revenues 115,206 Operating expenses 20,982 Depreciation and amortization 20,832 Acquisition related costs 374 General and administrative 7,731 Total expenses 49,919 Operating income 65,287 Interest expense (7,287 ) Gain on early extinguishment of debt 243 Income before income tax expense and equity in earnings of an investee 58,243 Income tax expense (90 ) Equity in earnings of an investee 32 Net income $ 58,185 Weighted average common shares outstanding 52,394 Net income per common share $ 1.11 Investment in AIC As of May 9, 2014, we had a net investment of $5.8 million in AIC, an insurance company that was owned in equal proportion by us, our former manager Reit Management & Research LLC (RMR), SIR and five other companies to which RMR provides management services. On May 9, 2014, as a result of the removal of the former Trustees and in accordance with the terms of the shareholder agreement between us and the other AIC shareholders, the other AIC shareholders exercised their right to purchase all of the 20,000 shares of AIC we then owned. We received $5.8 million in aggregate proceeds from this sale. We no longer own any interest in AIC. Our participation in the AIC property insurance program expired in June 2014. See Note 18 for additional information about our investment in AIC.

Other Assets

Other Assets	12 Months Ended
	Dec. 31, 2016
Other Assets [Abstract]
Other Assets	Other Assets Real Estate Mortgages Receivable As of December 31, 2016 , and 2015 , we had total real estate mortgages receivable with an aggregate carrying value of $8.1 million included in other assets in our consolidated balance sheets. We provided mortgage financing totaling $7.7 million at 6.0% per annum in connection with our sale of three properties ( 18 buildings) in January 2013 in Dearborn, MI; this real estate mortgage requires monthly interest payments and matures on January 24, 2023 . We also provided mortgage financing totaling $0.4 million at 6.0% per annum in connection with our sale of a property in Salina, NY in April 2012. This real estate mortgage requires monthly interest payments and matures on April 30, 2019 . We monitor the payment history of the borrowers and have determined that no allowance for losses related to these real estate mortgages receivable was necessary at December 31, 2016 , and 2015 . Deferred Financing Fees, Deferred Leasing Costs and Capitalized Lease Incentives The following table summarizes our deferred financing fees related to our unsecured revolving credit facility included in other assets, deferred leasing costs and capitalized lease incentives as of December 31, 2016 , and 2015 (in thousands): December 31, 2016 2015 Deferred financing fees $ 14,458 $ 14,458 Accumulated amortization (11,093 ) (9,478 ) Deferred financing fees, net $ 3,365 $ 4,980 Deferred leasing costs $ 133,771 $ 166,390 Accumulated amortization (41,148 ) (56,162 ) Deferred leasing costs, net $ 92,623 $ 110,228 Capitalized lease incentives $ 10,344 $ 11,623 Accumulated amortization (2,680 ) (2,498 ) Capitalized lease incentives, net $ 7,664 $ 9,125 Future amortization of deferred leasing costs and capitalized lease incentives to be recognized by us during the current terms of our leases as of December 31, 2016 are approximately (in thousands): Deferred Leasing Costs Capitalized Lease Incentives 2017 $ 12,796 $ 1,319 2018 12,318 1,287 2019 11,611 1,552 2020 10,291 1,273 2021 8,687 996 Thereafter 36,920 1,237 $ 92,623 $ 7,664

Indebtedness

Indebtedness	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Indebtedness	Indebtedness At December 31, 2016 and 2015 , our outstanding indebtedness included the following (in thousands): December 31, Interest Rate at December 31, 2016 Maturity Date 2016 2015 Unsecured revolving credit facility, at LIBOR plus a premium 2.02 % 1/28/2019 $ — $ — 5-year unsecured term loan, at LIBOR plus a premium 2.17 % 1/28/2020 200,000 200,000 7-year unsecured term loan, at LIBOR plus a premium 2.57 % 1/28/2022 200,000 200,000 Unsecured floating rate debt 2.37 % (1) $ 400,000 $ 400,000 6.25% Senior Unsecured Notes due 2016 — % — $ — $ 139,104 6.25% Senior Unsecured Notes due 2017 — % — — 250,000 6.65% Senior Unsecured Notes due 2018 6.65 % 1/15/2018 250,000 250,000 5.875% Senior Unsecured Notes due 2020 5.88 % 9/15/2020 250,000 250,000 5.75% Senior Unsecured Notes due 2042 5.75 % 8/1/2042 175,000 175,000 Unsecured fixed rate debt 6.13 % (1) $ 675,000 $ 1,064,104 Parkshore Plaza (2) 5.67 % 5/1/2017 $ 41,275 $ 41,275 1735 Market Street (3) — % — — 169,612 206 East 9th Street 5.69 % 1/5/2021 27,041 27,515 33 Stiles Lane 6.75 % 3/1/2022 2,415 2,785 97 Newberry Road 5.71 % 3/1/2026 5,903 6,375 Secured fixed rate debt 5.71 % (1) $ 76,634 $ 247,562 $ 1,151,634 $ 1,711,666 Unamortized net premiums, discounts and deferred financing fees (9,967 ) (14,550 ) $ 1,141,667 $ 1,697,116 (1) Represents weighted average interest rate at December 31, 2016 . (2) The Company guarantees $3.2 million of this non-recourse loan. (3) Interest on this loan was payable at LIBOR plus 2.625% but was fixed for the first seven years to December 1, 2016 by a cash flow hedge which set the rate at approximately 5.66% . Unsecured Revolving Credit Facility and Term Loan: Prior to January 29, 2015, we had a $750.0 million unsecured revolving credit facility. The unsecured revolving credit facility was set to mature on October 19, 2015, and had an interest rate of LIBOR plus a spread, which was 150 basis points as of December 31, 2014. We paid a facility fee of 35 basis points per annum on the total amount of lending commitments under our revolving credit facility. Prior to January 29, 2015, we also had a $500.0 million unsecured term loan that was set to mature on December 15, 2016. Our term loan had an interest rate of LIBOR plus a spread, which was 185 basis points as of December 31, 2014. On December 5, 2014, we paid $100.0 million of our unsecured term loan, reducing our term loan borrowings to $400.0 million . On January 29, 2015, we entered into a new credit agreement, pursuant to which the lenders agreed to provide (i) a $750.0 million unsecured revolving credit facility, (ii) a $200.0 million 5 -year term loan facility and (iii) a $200.0 million 7 -year term loan facility. The new agreement replaced our prior credit agreement, dated as of August 9, 2010, and our prior term loan agreement, dated as of December 16, 2010. In connection with the termination of the prior agreements, we recognized a loss on early extinguishment of debt of $0.4 million from the write-off of unamortized deferred financing fees for the year ended December 31, 2015. On November 10, 2016, in connection with our conversion to an UPREIT structure, the Operating Trust entered into an amended and restated credit agreement, replacing the Company’s prior credit agreement. Under the amended and restated credit agreement, the Operating Trust has assumed all obligations of the Company as borrower and the Company is released from such obligations. The economic terms of the amended and restated credit agreement are substantially the same as the terms of the Company’s prior credit agreement. The revolving credit facility has a scheduled maturity date of January 28, 2019, which maturity date may be extended for up to two additional periods of six months at our option subject to satisfaction of certain conditions and the payment of an extension fee of 0.075% of the aggregate amount available under the revolving credit facility. The 5 -year term loan and the 7 -year term loan have scheduled maturity dates of January 28, 2020 and January 28, 2022, respectively. We used the proceeds of borrowings under the credit agreement to repay all amounts outstanding and due under the previous term loan agreement. The credit agreement permits us to utilize up to $100.0 million of the revolving credit facility for the issuance of letters of credit. Amounts outstanding under the credit agreement generally may be prepaid at any time without premium or penalty, subject to certain exceptions. We have the right to request increases in the aggregate maximum amount of borrowings available under the revolving credit facility and term loans up to an additional $1.15 billion , subject to certain conditions. Borrowings under the 5 -year term loan and 7 -year term loan will, subject to certain exceptions, bear interest at a LIBOR rate plus a margin of 90 to 180 basis points for the 5 -year term loan and 140 to 235 basis points for the 7 -year term loan, in each case depending on our credit rating. Borrowings under the revolving credit facility will, subject to certain exceptions, bear interest at a rate equal to, at our option, either a LIBOR rate or a base rate plus a margin of 87.5 to 155 basis points for LIBOR rate advances and 0 to 55 basis points for base rate advances, in each case depending on our credit rating. In addition, we are required to pay a facility fee of 12.5 to 30 basis points, depending on our credit rating, on the borrowings available under the revolving credit facility, whether or not utilized. Borrowings under our revolving credit facility currently bear interest at LIBOR plus a spread, which was 125 basis points as of December 31, 2016 . As of December 31, 2016 , the interest rate payable on borrowings under our revolving credit facility was 2.02% . As of December 31, 2016 , we had no balance outstanding and $750.0 million available under our revolving credit facility and the facility fee as of December 31, 2016 was 0.25% . Our term loans currently bear interest at a rate of LIBOR plus a spread, which was 140 and 180 basis points for the 5 -year and 7 -year term loan, respectively, as of December 31, 2016 . As of December 31, 2016 , the interest rates for the amounts outstanding under our 5 -year term loan and 7 -year term loan were 2.17% and 2.57% , respectively. As of December 31, 2016 , we had $200.0 million outstanding under each of our 5 -year and 7 -year term loans. Debt Covenants: Our public debt indenture and related supplements and our credit agreement contain a number of financial and other covenants, including covenants that restrict our ability to incur indebtedness or to make distributions under certain circumstances and require us to maintain financial ratios and a minimum net worth. At December 31, 2016 , we believe we were in compliance with all of our respective covenants under our public debt indenture and related supplements, our credit agreement. Senior Unsecured Notes: On December 15, 2016, we redeemed at par $250.0 million of our 6.25% senior unsecured notes due 2017 and recognized a loss on early extinguishment of debt of $0.1 million from the write-off of an unamortized discount and unamortized deferred financing fees. On February 16, 2016, we redeemed at par $139.1 million of our 6.25% senior unsecured notes due 2016 and recognized a loss on early extinguishment of debt of $0.1 million from the write-off of an unamortized discount and unamortized deferred financing fees. On May 1, 2015, we redeemed at par $138.8 million of our 5.75% senior unsecured notes due 2015 and recognized a loss on early extinguishment of debt of $0.1 million from the write-off of an unamortized discount and unamortized deferred financing fees. On November 17, 2014, we redeemed at par $125.0 million of our 7.50% unsecured senior notes due 2019 and recognized a loss on early extinguishment of debt of $1.8 million from the write-off of an unamortized discount and deferred financing fees. On September 15, 2014, we redeemed at par $33.4 million of our 6.40% unsecured senior notes due 2015. Mortgage Notes Payable: At December 31, 2016 , four of our properties ( 7 buildings) with an aggregate net book value of $102.7 million had secured mortgage notes totaling $77.7 million (including net premiums and unamortized deferred financing fees) maturing from 2017 through 2026. On November 10, 2016, we repaid at par $167.8 million of mortgage debt at 1735 Market Street and recognized a loss on early extinguishment of debt of $2.4 million from the write-off of unamortized deferred financing fees and breakage costs for the year ended December 31, 2016. We also recognized $0.2 million of expense included in interest and other income related to an interest rate swap as a result of the early repayment of debt for the year ended December 31, 2016. On December 1, 2015, we repaid at par $116.0 million of mortgage debt at 111 Monument Circle and recognized a gain on early extinguishment of debt of $0.6 million for the year ended December 31, 2015 from the write-off of an unamortized premium, net of the write-off of unamortized deferred financing fees. In accordance with the agreement to sell Illinois Center, we were required to deliver the property unencumbered. On August 3, 2015, prior to the sale, we defeased the outstanding $141.4 million balance of the mortgage loan secured by 111 East Wacker Drive, one of the buildings included in Illinois Center. The defeasance costs and write off of the unamortized deferred financing costs, net of the write off of the unamortized premium, resulted in a net loss on early extinguishment of debt of $3.9 million for the year ended December 31, 2015. In accordance with the agreement to sell 2501 20th Place South, we were required to deliver the property unencumbered. On June 5, 2015, we prepaid $10.0 million of mortgage debt at 2501 20th Place South and recognized a loss on early extinguishment of debt totaling $0.6 million for the year ended December 31, 2015, which consisted of a prepayment premium and the write off of unamortized deferred financing fees, net of the write off of an unamortized premium. In accordance with the agreement to sell 1320 Main Street, we were required to deliver the property unencumbered. On June 3, 2015, prior to the sale, we defeased the $38.7 million outstanding balance of the mortgage loan secured by 1320 Main Street. The defeasance costs and write off of the unamortized deferred financing costs, net of the write off of the unamortized premium, resulted in a net loss on early extinguishment of debt of $6.2 million for the year ended December 31, 2015. During the quarter ended June 30, 2014, we made the decision to cease making loan servicing payments on 225 Water Street in Jacksonville, Florida. The first payment we determined not to make for this property was due on June 11, 2014. The property was secured by a non-recourse mortgage loan. On October 10, 2014, we were notified by the lender that our decision to cease making loan servicing payments created an event of default effective July 11, 2014, and the lender exercised its option to accelerate the maturity of the unpaid balance of the loan. Beginning July 11, 2014, we accrued interest on this loan at 10.03% , to include the 4.0% of default interest. The lender filed a suit of foreclosure for this property and we cooperated with the lender to allow for a consensual foreclosure process. On May 22, 2015, title to 225 Water Street was transferred to the lender pursuant to the consensual foreclosure in full satisfaction of the mortgage debt, with a principal balance of $40.1 million . The transaction resulted in a gain on early extinguishment of debt of $17.3 million for the excess of the debt principal balance over the net book value of the property for the year ended December 31, 2015. On October 31, 2014, we rep aid at par the $7.8 million mortgage loan encumbering 6200 Glenn Carlson Drive. On August 1, 2014, we prepaid at par the $265.0 million of mortgage debt at 600 West Chicago Avenue and recognized a net gain on early extinguishment of debt of $6.7 million from the write-off of an unamortized premium, net of the write-off of unamortized deferred financing fees. On June 27, 2014, we repaid $11.2 million of mortgage debt at Madrone Business Park and $8.5 million of mortgage debt at Stafford Commerce Center and Stafford Commerce Park in connection with the sale of the related properties and recognized a loss on early extinguishment of debt of $3.3 million , included in loss on early extinguishment of debt from discontinued operations, from prepayment penalties and the write-off of unamortized discounts and deferred financing fees. On March 11, 2014, we prepaid at par the $12.0 million of mortgage debt at 3920 Arkwright Road. Required Principal Payments: The required principal payments due during the next five years and thereafter under all of our outstanding debt at December 31, 2016 are as follows (in thousands): 2017 $ 42,675 2018 251,488 2019 1,580 2020 451,674 2021 25,982 Thereafter 378,235 $ 1,151,634

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders’ Equity Common Share Issuances: During the year ended December 31, 2015, we issued 144 common shares to holders of 301 of our series D cumulative convertible preferred shares (series D preferred shares) who elected to convert their series D preferred shares into our common shares. During the year ended December 31, 2014, we issued 10,412,499 common shares to holders of 10,264,503 of our series D preferred shares who converted their series D preferred shares into our common shares. During the year ended December 31, 2014, we issued 90,135 common shares to RMR pursuant to the amended and restated business management agreement. See Note 18 for further information regarding this agreement. See Note 13 for information regarding equity issuances related to share-based compensation. Common Share Repurchases: On August 24, 2015, our Board of Trustees approved a common share repurchase plan, which authorizes the repurchase of up to $100.0 million of our outstanding common shares over the twelve month period following the date of authorization. On September 14, 2015, our Board of Trustees authorized the repurchase of up to an additional $100.0 million of our outstanding common shares over the twelve month period following the date of authorization. On March 17, 2016, our Board of Trustees authorized the repurchase of up to an additional $150.0 million of our outstanding common shares over the twelve month period following the date of authorization. During the years ended December 31, 2016 and 2015 , we purchased and retired 2,491,675 and 3,410,300 of our common shares, respectively, at a weighted average price of $27.68 and $25.76 per share, respectively, for a total investment of $69.0 million and $87.8 million , respectively. Since the inception of the common share repurchase plan through December 31, 2016 , we have purchased and retired a total of 5,901,975 of our common shares at a weighted average price of $26.57 per share, for a total of $156.8 million . In August and September 2016, the first two share repurchase authorizations, of which $86.6 million was not utilized, expired. The $106.6 million of remaining authorization available under our share repurchase program as of December 31, 2016 is scheduled to expire in March 2017. During the year ended December 31, 2016, certain of our employees surrendered 31,025 common shares owned by them to satisfy their statutory tax withholding obligations in connection with the vesting of such common shares under the Equity Commonwealth 2015 Omnibus Incentive Plan (the 2015 Incentive Plan). Common Share Distributions: In January 2014, we declared a distribution of $0.25 per common share, or $29.6 million , which we paid on February 21, 2014 to shareholders of record on January 13, 2014. Our credit agreement contains a number of financial and other covenants, including a covenant which restricts our ability to make distributions under certain circumstances. See Note 8 for additional information regarding our credit agreement. The following characterizes distributions paid per common share for the years ended December 31, 2016 , 2015 , and 2014 : Year Ended December 31, 2016 2015 2014 Ordinary income — % — % — % Return of capital — % — % — % Capital gain — % — % 100.00 % Unrecaptured Section 1250 gain — % — % — % — % — % 100.00 % Series D Preferred Shares: Each of our 4,915,196 series D cumulative convertible preferred shares accrue dividends of $1.625 , or 6.50% per annum of the liquidation amount, payable in equal quarterly payments. Our series D preferred shares are convertible, at the holder's option, into our common shares at an initial conversion rate of 0.480775 common shares per series D preferred share, which is equivalent to an initial conversion price of $52.00 per common share, or 2,363,103 additional common shares at December 31, 2016 . On or after November 20, 2011, if our common shares trade at or above the then applicable conversion price, we may, at our option, convert some or all of the series D preferred shares into common shares at the then applicable conversion rate. If a fundamental change occurs, which generally will be deemed to occur upon a change in control or a termination of trading of our common shares (or other equity securities into which our series D preferred shares are then convertible), holders of our series D preferred shares will have a special right to convert their series D preferred shares into a number of our common shares per $25.00 liquidation preference, plus accrued and unpaid distributions, divided by 98% of the average closing market price of our common shares for a specified period before such event is effective, unless we exercise our right to repurchase these series D preferred shares for cash, at a purchase price equal to 100% of their liquidation preference, plus accrued and unpaid distributions. The issuance of a large number of common shares as a result of the exercise of this conversion right after a fundamental change may have a dilutive effect on income from continuing operations attributable to Equity Commonwealth common shareholders per share for future periods. The removal of our former Trustees on March 25, 2014, triggered a Fundamental Change Conversion Right of the series D preferred shares, as defined in our Articles Supplementary dated October 10, 2006, setting forth the terms of the series D preferred shares. Pursuant to such right, the holders of series D preferred shares had the option to elect to convert all or any portion of their series D preferred shares at any time from April 9, 2014 until the close of business on May 14, 2014 into a number of common shares per $25.00 liquidation preference of the series D preferred shares equal to the sum of such $25.00 liquidation preference plus accrued and unpaid dividends to, but not including, May 14, 2014, divided by 98% of the average of the closing sale prices of the common shares for the five consecutive trading days ending on May 9, 2014, or the Fundamental Change Conversion Rate. Holders of 10,263,003 series D preferred shares elected to exercise their Fundamental Change Conversion Right and converted their series D preferred shares into 10,411,779 of our common shares. As a result of this transaction, we recognized a non-cash preferred distribution of $16.2 million , for the excess of the market value of the common shares issued above the carrying value of the series D preferred shares redeemed. As of December 31, 2016 , we had 4,915,196 outstanding series D preferred shares that were convertible into 2,363,103 of our common shares. Series E Preferred Shares: On May 15, 2016, we redeemed all of our 11,000,000 outstanding series E preferred shares at a price of $25.00 per share, for a total of $275.0 million , plus any accrued and unpaid dividends. The redemption payment occurred on May 16, 2016 (the first business day following the redemption date). Each of our series E preferred shares had a liquidation preference of $25.00 and required dividends of $1.8125 , or 7.25% per annum of the liquidation amount, payable in equal quarterly payments. We recorded $9.6 million related to the excess fair value of consideration paid over the carrying value of the preferred shares as a reduction to net income attributable to common shareholders for the year ended December 31, 2016. Preferred Share Distributions: In 2016 , our Board of Trustees declared distributions on our series D preferred shares and series E cumulative redeemable preferred shares to date as follows: Declaration Date Record Date Payment Date Series D Dividend Per Share Series E Dividend Per Share January 26, 2016 February 5, 2016 February 16, 2016 $ 0.40625 $ 0.453125 April 15, 2016 April 25, 2016 May 16, 2016 $ 0.40625 $ 0.453125 July 11, 2016 July 29, 2016 August 15, 2016 $ 0.40625 $ — October 10, 2016 October 28, 2016 November 15, 2016 $ 0.40625 $ — Under our governing documents and Maryland law, distributions to our shareholders are to be authorized and declared by our Board of Trustees. Additionally, the removal of our former Trustees, which occurred on March 25, 2014, constituted an event of default under our credit agreement, under which we generally are prevented from making any distributions or paying any dividends during the pendency of an event of default. As a result of the foregoing, we were unable to declare and pay dividends between March 25, 2014, and June 6, 2014, the date on which we obtained waivers of the aforementioned events of default from our lenders. Alternative Minimum Tax: Alternative minimum tax adjustments are to be apportioned between a REIT and its shareholders under Internal Revenue Code Section 59(d). Although regulations have not yet been issued under that provision, based on regulations issued pursuant to a similar provision of prior law and the legislative history of the current provision, it appears that such alternative minimum tax adjustments are to be apportioned to a REIT’s shareholders to the extent that the REIT distributes its regular taxable income. It is our policy to distribute all of our regular taxable income and accordingly, all of our alternative minimum tax adjustments are being apportioned to our shareholders. We have determined that 96.31% , 0% and 15.41% of each distribution to our shareholders for the tax years ended December 31, 2016 , 2015 , and 2014 , respectively, consists of an alternative minimum tax adjustment.

Cumulative Other Comprehensive

Cumulative Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Cumulative Other Comprehensive Loss	Cumulative Other Comprehensive Loss The following tables present the amounts recognized in cumulative other comprehensive loss for the years ended December 31, 2016 and 2015 (in thousands): Unrealized Loss on Derivative Instruments Balance as of January 1, 2016 $ (3,687 ) Other comprehensive loss before reclassifications (554 ) Amounts reclassified from cumulative other comprehensive loss to net income 4,033 Net current period other comprehensive income 3,479 Balance as of December 31, 2016 $ (208 ) Unrealized Loss on Derivative Instruments and Other Assets Foreign Currency Translation Adjustments Total Balances as of January 1, 2015 $ (4,299 ) $ (48,917 ) $ (53,216 ) Other comprehensive loss before reclassifications (1,232 ) (14,290 ) (15,522 ) Amounts reclassified from cumulative other comprehensive loss to net income 1,844 63,207 65,051 Net current period other comprehensive income 612 48,917 49,529 Balances as of December 31, 2015 $ (3,687 ) $ — $ (3,687 ) The following tables present reclassifications out of cumulative other comprehensive loss for the years ended December 31, 2016 and 2015 (in thousands): Amounts Reclassified from Cumulative Other Comprehensive Loss to Net Income Year Ended December 31, Details about Cumulative Other Comprehensive Loss Components 2016 2015 Affected Line Items in the Statement of Operations Interest rate swap contracts $ 3,792 $ 4,924 Interest expense Interest rate swap contracts 241 — Interest and other income Foreign currency translation adjustment activity — 63,207 Gain on sale of properties Realized gain on available for sale securities — (3,080 ) Interest and other income $ 4,033 $ 65,051

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our provision for income taxes consists of the following (in thousands): Year Ended December 31, 2016 2015 2014 Current: State $ 745 $ 270 $ 350 Federal — 513 — Foreign — 2,336 2,772 745 3,119 3,122 Deferred: Foreign — (755 ) 69 — (755 ) 69 Income tax expense $ 745 $ 2,364 $ 3,191 Federal income tax expense for the year ended December 31, 2015 relates to taxes incurred as a result of a taxable built-in gain triggered by the sale of a property that was previously owned by a C corporation. As a result of the disposition of the Australian properties, we incurred net income tax expense of $1.6 million for the year ended December 31, 2015. A reconciliation of our effective tax rate and the U.S. Federal statutory income tax rate is as follows: Year Ended December 31, 2016 2015 2014 Taxes at statutory U.S. federal income tax rate 35.00 % 35.00 % 35.00 % Dividends paid deduction and net operating loss utilization (35.00 )% (35.00 )% (35.00 )% Federal taxes on built-in gain — % 0.50 % — % State, local, and foreign income taxes 0.32 % 1.81 % 11.73 % Effective tax rate 0.32 % 2.31 % 11.73 % We have a net operating loss carryforward from prior years and we have fully reserved the associated deferred tax assets due to the uncertainty of our ability to utilize the net operating losses in the future.

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Risk Management Objective of Using Derivatives We are exposed to certain risks relating to our ongoing business operations, including the effect of changes in interest rates. The only risk we currently manage by using derivative instruments is related to our interest rate risk. We may use derivative financial instruments, including interest rate swaps, caps, options, floors and other interest rate derivative contracts, to hedge all or a portion of the interest rate risk associated with our borrowings. The principal objective of such arrangements is to minimize the risks and/or costs associated with our operating and financial structure as well as to hedge specific anticipated transactions. We do not intend to utilize derivatives for speculative or other purposes other than interest rate risk management. The use of derivative financial instruments carries certain risks, including the risk that the counterparties to these contractual arrangements are not able to perform under the agreements. To mitigate this risk, we only enter into derivative financial instruments with counterparties with high credit ratings and with major financial institutions with which we and our affiliates may also have other financial relationships. We do not anticipate that any of the counterparties will fail to meet their obligations. Cash Flow Hedges of Interest Rate Risk Our objectives in using interest rate derivatives are to add stability to interest expense and to manage our exposure to interest rate movements. To accomplish this objective, we periodically use interest rate swaps, caps, or other similar instruments as part of our interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for us making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. The effective portion of changes in the fair value of derivatives designated and that qualify as cash flow hedges is recorded in cumulative other comprehensive loss and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. During 2016 , such derivatives were used to hedge the variable cash flows associated with variable-rate debt. The ineffective portion of the change in fair value of the derivatives is recognized directly in earnings. Amounts reported in cumulative other comprehensive loss related to derivatives will be reclassified to interest expense as interest payments are made on our variable-rate debt. During the next twelve months, we estimate that an additional $49,000 will be reclassified from cumulative other comprehensive loss as an increase to interest expense. We previously had interest rate swap agreements to manage our interest rate risk exposure on $167.8 million of mortgage debt at 1735 Market Street, which required interest at a spread over LIBOR. The interest rate swap agreements utilized by us qualified as cash flow hedges and effectively modified our exposure to interest rate risk by converting our floating interest rate debt to a fixed interest rate basis for this loan through December 1, 2016, thus reducing the impact of interest rate changes on future interest expense. On November 10, 2016 we repaid at par the mortgage debt at 1735 Market Street and terminated the related interest rate swap agreement. We recognized $0.2 million in interest and other income on the consolidated statement of operations for the year ended December 31, 2016 related to the early termination of the interest rate swap agreement. On March 4, 2016, we purchased an interest rate cap with a LIBOR strike price of 2.50% . The interest rate cap, effective April 1, 2016, has a notional amount of $400.0 million and a maturity date of March 1, 2019. As of December 31, 2016 , we had the following outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk: Interest Rate Derivative Number of Instruments Notional Amount (in thousands) Interest rate cap 1 $400,000 The table below presents the fair value of our derivative financial instruments as well as their classification on the consolidated balance sheets as of December 31, 2016 , and 2015 (amounts in thousands): Fair Value as of December 31, Interest Rate Derivative Designated as Hedging Instrument Balance Sheet Location 2016 2015 Interest rate cap Other assets $ 314 $ — Pay-fixed swaps Accounts payable and accrued expenses — 3,687 The table below details the location in the financial statements of the gain or loss recognized on interest rate derivatives designated as cash flow hedges for the years ended December 31, 2016 , 2015 , and 2014 (amounts in thousands) Year Ended December 31, 2016 2015 2014 Amount of loss recognized in cumulative other comprehensive loss (effective portion) $ (554 ) $ (1,149 ) $ (776 ) Amount of loss reclassified from cumulative other comprehensive loss into interest expense (effective portion) 3,792 4,924 5,020 Amount of loss recognized in income (ineffective portion and amount excluded from effectiveness testing) 241 — — Credit-risk-related Contingent Features Our agreements with each of our derivative counterparties contain a provision providing that if we default or are capable of being declared in default on any of our indebtedness, we could also be declared in default on our derivative obligations. As of December 31, 2016 , we did not have any derivatives in a net liability position including accrued interest but excluding any adjustment for nonperformance risk.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation Equity Commonwealth 2015 Omnibus Incentive Plan On June 16, 2015, at our 2015 annual meeting of shareholders, our shareholders approved the 2015 Incentive Plan. The 2015 Incentive Plan replaced the Equity Commonwealth 2012 Equity Compensation Plan (as amended, the 2012 Plan). The Board of Trustees approved the 2015 Incentive Plan, subject to shareholder approval, on March 18, 2015 (the Effective Date). On January 26, 2016, the Board of Trustees approved an amendment to the 2015 Incentive Plan to allow the Compensation Committee (Committee) to authorize in an award agreement a transfer of all or a part of certain equity awards not for value to a “family member” (as defined in the 2015 Incentive Plan). The following description of certain terms of the 2015 Incentive Plan is qualified in all respects by the terms of the 2015 Incentive Plan. Eligibility. Awards may be granted under the 2015 Incentive Plan to employees, officers and non-employee directors of the Company, its subsidiaries or its affiliates, or consultants and advisors (who are natural persons) providing services to the Company, its subsidiaries or its affiliates, or any other person whose participation in the 2015 Incentive Plan is determined by the Committee to be in the best interests of the Company. Term . The 2015 Incentive Plan terminates automatically ten years after the Effective Date, unless it is terminated earlier by the Board of Trustees. Shares Available for Issuance. Subject to adjustment as provided in the 2015 Incentive Plan, the maximum number of common shares of the Company that are available for issuance under the 2015 Incentive Plan is 3,250,000 shares. Awards. The following types of awards may be made under the 2015 Incentive Plan, subject to limitations set forth in the 2015 Incentive Plan: · Stock options; · Stock appreciation rights; · Restricted stock; · Restricted stock units; · Unrestricted stock; · Dividend equivalent rights; · Performance shares and other performance-based awards; · Limited partnership interests in any partnership entity through which the Company may conduct its business in the future; · Other equity-based awards; and · Cash bonus awards. Recipients of the Company’s restricted shares have the same voting rights as any other common shareholder. During the period of restriction, the Company’s unvested restricted shareholders are eligible to receive dividend payments on their shares at the same rate and on the same date as any other common shareholder. Recipients of the Company’s restricted stock units (RSUs) are entitled to receive dividends with respect to the common shares underlying the RSUs if and when the RSUs are earned, at which time the recipient will be entitled to receive an amount in cash equal to the aggregate amount of cash dividends that would have been paid in respect of the common shares underlying the recipient’s earned RSUs had such common shares been issued to the recipient on the first day of the performance period. To the extent that an award does not vest, the dividends will be forfeited. The RSUs are market based awards with a service condition and recipients may earn the RSU grants based on the Company’s total shareholder return (TSR) relative to the TSR's for the constituent REITs that comprise the NAREIT Office Index for a three year performance period. Following the end of the performance period, the number of earned awards will be determined. The earned awards vest in two tranches with 50% of the earned award vesting at the end of the performance period and the remaining 50% of the earned award vesting one year after the end of the performance period, subject to the grant recipient’s continued employment. Compensation expense for the RSU awards is determined using a Monte Carlo simulation model and is being recognized ratably from the grant date to the vesting date of each tranche. Administration. The 2015 Incentive Plan will be administered by the Committee, which will determine all terms and recipients of awards under the 2015 Incentive Plan. 2016 Equity Award Activity On June 15, 2016, in accordance with the Company’s compensation plan for independent Trustees, the Committee awarded each of the nine independent Trustees $0.1 million in restricted shares as part of their compensation for the 2016-2017 year of service on the Board of Trustees. These awards equated to 3,463 shares per Trustee, for a total of 31,167 shares, valued at $28.88 per share, the closing price of our common shares on the New York Stock Exchange (NYSE) on that day. These shares vest one year after the date of the award. On January 26, 2016, the Committee approved a grant of 136,623 restricted common shares and 277,386 RSUs at target ( 691,385 RSUs at maximum) to the Company’s officers, certain employees and to Mr. Zell, the Chairman of our Board of Trustees, as part of their compensation for fiscal year 2015. The restricted shares are service based awards and vest over a four -year period. The restricted shares were granted on January 26, 2016 and were valued at $26.93 per share, the closing price of our common shares on the NYSE on that day. 2015 Equity Award Activity On June 16, 2015, in accordance with the Company’s compensation plan for independent Trustees, the Committee awarded each of the nine independent Trustees $0.1 million in restricted shares as part of their compensation for the 2015-2016 year of service on the Board of Trustees. These awards equated to 3,843 shares per Trustee, for a total of 34,587 shares, valued at $26.02 per share, the closing price of our common shares on the NYSE on that day. These shares vest one year after the date of the award. On January 28, 2015, the Committee approved a grant of 126,319 restricted common shares and 256,467 RSUs at target ( 639,250 RSUs at maximum) to the Company’s officers, certain employees and to Mr. Zell, the Chairman of our Board of Trustees, as part of their compensation for fiscal year 2014. The restricted shares are service based awards and vest over a four -year period. The restricted shares were granted on January 28, 2015 and were valued at $26.58 per share, the closing price of our common shares on the NYSE on that day. 2014 Equity Award Activity On October 28, 2014, the Committee approved the one-time grant of restricted common shares and restricted share units under the 2012 Plan to certain of the Company’s officers and employees and to Mr. Zell, the Chairman of our Board of Trustees. The Committee also approved the one-time grant of restricted common shares under the 2012 Plan to our independent Trustees, a grant of restricted common shares to each independent Trustee as annual compensation for his or her service as a Trustee, and a pro-rata grant of fully vested common shares for five of our independent Trustees for their service from May 23, 2014 through July 31, 2014. Outstanding Equity Awards The table below presents a summary of restricted share and RSU activity under the 2015 Incentive Plan and the 2012 Plan for the years ended December 31, 2016 , 2015 and 2014 , excluding restricted shares granted to our former Trustees, former officers and certain employees of RMR, our former manager, under the terms of our 2012 Plan (which grants are further described below): Number Weighted Number Weighted Outstanding at December 31, 2013 — $ — — $ — Granted 713,727 26.66 1,266,237 15.99 Vested (3,545 ) 26.66 — — Outstanding at December 31, 2014 710,182 1,266,237 Granted 160,906 26.46 639,250 15.47 Vested (86,517 ) 26.02 — — Forfeited (8,115 ) 26.64 (21,377 ) 15.80 Outstanding at December 31, 2015 776,456 1,884,110 Granted 167,790 27.29 691,385 15.57 Vested (191,498 ) 26.54 — — Forfeited (539 ) 26.82 (2,727 ) 15.54 Outstanding at December 31, 2016 752,209 2,572,768 The 752,209 unvested restricted shares as of December 31, 2016 are scheduled to vest as follows: 216,486 shares in 2017 , 373,140 shares in 2018 , 95,554 shares in 2019 and 67,029 shares in 2020 . As of December 31, 2016 , the estimated future compensation expense for all unvested restricted share grants was $12.4 million . Compensation expense for the restricted share awards is being recognized on a straight-line basis over the requisite service period for each separately vesting portion of the award. The weighted average period over which the future compensation expense will be recorded for the restricted shares is approximately 2.1 years. As of December 31, 2016 , the estimated future compensation expense for all unvested RSUs was $19.2 million . The weighted average period over which the future compensation expense will be recorded for the RSUs is approximately 2.0 years. The assumptions and fair values for the RSUs granted for the years ended December 31, 2016 , 2015 and 2014 are included in the following table on a per share basis. 2016 2015 2014 Fair value of RSUs granted at the target amount $ 38.80 $ — $ — Fair value of RSUs granted at the maximum amount $ — $ 15.47 $ 15.99 Expected term (years) 4 4 4 Expected volatility — — — Expected dividend yield 1.86 % 1.88 % 1.88 % Risk-free rate 1.07 % 0.81 % 0.84 % During the years ended December 31, 2016 , 2015 and 2014 , we recorded $18.5 million , $15.4 million and $2.6 million , respectively, of compensation expense, net of forfeitures, in general and administrative expense for grants to our Board of Trustees and the Company's employees related to our Plan. At December 31, 2016 , 2,358,464 common shares remain available for issuance under the Plan. 2012 Equity Compensation Plan Prior to the adoption of the 2015 Incentive Plan, we had common shares available for issuance under the 2012 Plan. The 2012 Plan was adopted in May 2012 and replaced our 2003 Incentive Share Award Plan, or the 2003 Plan. We awarded common shares to our former officers and certain employees of RMR pursuant to both of these plans. On January 28, 2014, we granted 2,000 common shares of beneficial interest, par value $0.01 per share, valued at $23.46 per share, the closing price of our common shares on the New York Stock Exchange, or NYSE, on that day, to two of our former Trustees as part of their then annual compensation. The common shares awarded to our former Trustees vested immediately. We include the value of awarded shares in general and administrative expenses at the time the awards vest. See Note 18 for further information regarding grants of restricted shares we made to our former officers and certain employees of RMR. On October 28, 2014, the Board of Trustees approved an amendment to the 2012 Plan to permit the Company to issue RSUs. Additionally, on October 28, 2014, the Committee approved new forms of Restricted Share and Restricted Share Unit Agreements to be used for grants of restricted common shares to members of the Board of Trustees, as well as grants of restricted common shares and restricted share units to officers and employees of the Company. The 2015 Incentive Plan replaced the 2012 Plan. No future grants will be made under the 2012 Plan, although the terms and conditions of the 2012 Plan will continue to govern any outstanding awards granted under the 2012 Plan. A summary of shares granted and vested to our former Trustees, former officers and certain employees of RMR under the terms of our 2012 Plan and our 2003 Plan for the year ended December 31, 2014, is as follows: Number Weighted Unvested shares at December 31, 2013 130,914 $ 20.70 Granted 4,000 23.46 Vested (134,914 ) 25.79 Unvested shares at December 31, 2014 — $ — As a result of the removal of our former Trustees on March 25, 2014, the vesting of 130,914 common shares previously issued to our former officers and certain employees of RMR pursuant to our equity compensation plans accelerated in accordance with the terms of their governing share grants. During the year ended December 31, 2014, we recorded $3.4 million of general and administrative expense related to the vesting of these shares.

Defined Contribution Plan

Defined Contribution Plan	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Defined Contribution Plan	Defined Contribution Plan We have a defined contribution plan that covers employees meeting eligibility requirements. We match 100% of the first 3% of compensation that an employee elects to defer plus 50% of compensation that an employee elects to defer exceeding 3% but not exceeding 5% , subject to a maximum of $8,000 . The Company’s matching contribution vests immediately. The Company's contributions were $0.4 million and $0.3 million for the years ended December 31, 2016 and 2015 , respectively.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities	Fair Value of Assets and Liabilities The table below presents certain of our assets and liabilities measured at fair value during 2016 and 2015 , categorized by the level of inputs used in the valuation of each asset and liability (dollars in thousands): Fair Value at December 31, 2016 Using Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Description Total (Level 1) (Level 2) (Level 3) Recurring Fair Value Measurements: Effective portion of interest rate cap contract $ 314 $ — $ 314 $ — Fair Value at December 31, 2015 Using Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Description Total (Level 1) (Level 2) (Level 3) Recurring Fair Value Measurements: Effective portion of interest rate swap contracts $ (3,687 ) $ — $ (3,687 ) $ — Derivative liability (7,219 ) — — (7,219 ) Effective Portion of Interest Rate Swap and Cap Contracts The fair value of our interest rate swap and cap contracts is determined using the net discounted cash flows of each derivative based on the market based interest rate curve (level 2 inputs) and adjusted for our credit spread and the actual and estimated credit spreads of the counterparties (level 3 inputs). Although we have determined that the majority of the inputs used to value our derivatives fall within level 2 of the fair value hierarchy, the credit valuation adjustments associated with our derivatives utilize level 3 inputs, such as estimates of current credit spreads, to evaluate the likelihood of default by us and the counterparties. As of December 31, 2016 , we have assessed the significance of the impact of the credit valuation adjustments on the overall valuation of our derivative positions and have determined that the credit valuation adjustments are not significant to the overall valuation of our derivatives. As a result, we have determined that our derivative valuations in their entirety are classified as level 2 inputs in the fair value hierarchy. Derivative Liability On July 31, 2014, our shareholders voted to approve the reimbursement of verified expenses incurred by Related Fund Mangement, LLC and Corvex Management LP (Related/Corvex) (see Note 18 for additional information). Approximately $16.7 million was paid during the year ended December 31, 2014. Up to $8.4 million was to be reimbursed only if the average closing price of our common shares was at least $26.00 (as adjusted for any share splits or share dividends) during the one year period after the date on which the reimbursement was approved by shareholders, and up to $8.4 million was to be reimbursed only if the average closing price of our common shares was at least $26.00 (as adjusted for any share splits or share dividends) during the one year period between the first and second anniversaries of the date on which the reimbursement was approved by shareholders. The average closing price of our common shares was at least $26.00 during both the first and second one year periods after the date on which the reimbursement was approved by shareholders, and as a result, in August 2016 and 2015 we paid $8.2 million and $8.4 million , respectively, to Related/Corvex. Prior to the payment of the reimbursement in August 2016, the potential future reimbursement of $8.4 million for the second one year period represented a derivative instrument as codified in ASC 815 Derivatives and Hedging which required the potential future reimbursement to be recorded at fair value at each reporting date. We recognized expense of $1.0 million and $9.0 million , which was recorded in general and administrative expenses in our consolidated statements of operations for the years ended December 31, 2016 and 2015, respectively. The valuation techniques and significant unobservable inputs used for our level 3 fair value measurement at December 31, 2015 were as follows: Description Fair Value at December 31, 2015 Primary Valuation Technique Unobservable Inputs Rate Derivative liability $ 7,219 Monte Carlo simulation Risk-free rate 0.52% Volatility 20.0% Properties Held and Used As part of our disposition plan, and pursuant to our accounting policy, in 2016, we evaluated the recoverability of the carrying values of each of the real estate assets that comprised our portfolio and determined that due to the shortening of the expected periods of ownership as a result of the disposition plan and current estimates of market value, it was necessary to reduce the net book value of a portion of the real estate assets in our portfolio to their estimated fair values. We anticipate the potential disposition of certain properties prior to the end of their remaining useful lives. As a result, in the second quarter of 2016, we recorded an impairment charge related to 111 Monument Circle, 101-115 W. Washington Street and 100 East Wisconsin Avenue of $43.7 million for the year ended December 31, 2016 in accordance with our impairment analysis procedures. We reduced the aggregate carrying value of these properties from $308.6 million to their estimated fair value of $264.9 million . These properties were sold in August 2016 (see Note 3 for additional information). In the fourth quarter of 2016, we recorded an impairment charge related to Parkshore Plaza, Cabot Business Park Land, 625 Crane Street and 111 Market Place of $14.7 million for the year ended December 31, 2016 in accordance with our impairment analysis procedures. We reduced the aggregate carrying value of these properties from $98.2 million to their estimated fair value of $83.5 million . 111 Market Place was sold in January 2017 (see Note 20 for additional information). We determined these impairments based on third party offer prices and independent third party broker information, which are level 2 inputs according to the fair value hierarchy established in ASC 820. We evaluated each of our properties and determined there were no additional valuation adjustments necessary at December 31, 2016. As part of our disposition plan, and pursuant to our accounting policy, in 2015, we evaluated the recoverability of the carrying values of each of the real estate assets that comprised our portfolio and determined that due to the shortening of the expected periods of ownership as a result of the disposition plan, it was necessary to reduce the net book value of a portion of the real estate assets in our portfolio to reduce the assets to their estimated fair values. During the year ended December 31, 2015, we recorded an impairment charge of $17.2 million in accordance with our impairment analysis procedures. Financial Instruments In addition to the assets and liabilities described in the above table, our financial instruments include our cash and cash equivalents, real estate mortgages receivable, restricted cash, senior unsecured debt and mortgage notes payable. At December 31, 2016 and 2015 , the fair value of these additional financial instruments were not materially different from their carrying values, except as follows (in thousands): December 31, 2016 December 31, 2015 Principal Balance Fair Value Principal Balance Fair Value Senior unsecured debt and mortgage notes payable $ 1,151,634 $ 1,167,031 $ 1,711,666 $ 1,749,211 The fair values of our senior notes and mortgage notes payable are based on estimates using discounted cash flow analyses and currently prevailing interest rates adjusted by credit risk spreads (level 3 inputs). Other financial instruments that potentially subject us to concentrations of credit risk consist principally of rents receivable; however, as of December 31, 2016 , no single tenant of ours is responsible for more than 5.5% of our total annualized rents. Our derivative financial instruments, including interest rate swaps and caps, are entered with major financial institutions and we monitor the amount of credit exposure to any one counterparty.

Earnings Per Common Share

Earnings Per Common Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share The following table sets forth the computation of basic and diluted earnings per share (amounts in thousands except per share amounts): Year Ended December 31, 2016 2015 2014 Numerator for earnings per common share - basic and diluted: Income from continuing operations $ 232,894 $ 99,857 $ 21,206 Preferred distributions (17,956 ) (27,924 ) (32,095 ) Excess fair value of consideration paid over carrying value of preferred shares (9,609 ) — — Excess fair value of consideration over carrying vale of preferred shares — — (16,205 ) Income (loss) from continuing operations attributable to Equity Commonwealth common shareholders 205,329 71,933 (27,094 ) Discontinued operations — — 2,806 Numerator for net income (loss) per share - basic and diluted $ 205,329 $ 71,933 $ (24,288 ) Denominator for earnings per common share - basic and diluted: Weighted average number of common shares outstanding - basic 125,474 128,621 125,163 Weighted average number of common shares outstanding - diluted (1) 126,768 129,437 125,163 Earnings per share - basic: Income (loss) from continuing operations attributable to Equity Commonwealth common shareholders $ 1.64 $ 0.56 $ (0.21 ) Discontinued operations — — 0.02 Net income (loss) per share - basic $ 1.64 $ 0.56 $ (0.19 ) Earnings per share - diluted: Income (loss) from continuing operations attributable to Equity Commonwealth common shareholders $ 1.62 $ 0.56 $ (0.21 ) Discontinued operations — — 0.02 Net income (loss) per share - diluted $ 1.62 $ 0.56 $ (0.19 ) Anti-dilutive securities: Effect of Series D preferred shares; 6 1/2% cumulative convertible (2) 2,363 2,363 4,175 (1) As of December 31, 2016 , we had granted RSUs to certain employees, officers, and the chairman of the Board of Trustees. The RSUs contain both service and market-based vesting components. None of the RSUs have vested. If the market-based vesting component was measured as of December 31, 2016 and 2015 , 1,027 and 1,143 common shares would be issued to the RSU holders, respectively, and no shares would have been issued as of December 31, 2014. Using a weighted average basis, 1,294 and 816 common shares are reflected in diluted earnings per share for the years ended ended December 31, 2016 and 2015 , respectively. (2) The Series D preferred shares are excluded from the diluted earnings per share calculation because including the Series D preferred shares would also require that the preferred distributions be added back to net income, resulting in anti-dilution during the periods presented.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Segment Information	Segment Information Our primary business is the ownership and operation of office properties, and we currently have one reportable segment. Due to significant dispositions, during the fourth quarter of 2015, we changed the composition of our operating segments from two reportable segments (central business district properties and suburban properties) to one reportable segment. This change was made based on the financial information reviewed and used by the chief operating decision maker to make operating decisions, assess performance, develop strategy and allocate capital resources. More than 95% of our revenues for the year ended December 31, 2016 are from office properties.

Related Person Transactions

Related Person Transactions	12 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Related Person Transactions	Related Person Transactions The following discussion includes a description of our related person transactions for the years ended December 31, 2016 , 2015 and 2014 . Certain of these related person transactions, and their approvals, relate to RMR and RMR Australia Asset Management Pty Ltd (together, Former Manager) or occurred prior to the election of our new Board of Trustees at the special meeting of shareholders held on May 23, 2014 (Special Meeting) and the appointment of our current executive officers following the Special Meeting, as described under “—Transactions with Prior Related Persons.” Related Person Transactions Following the Special Meeting: Equity Group Investments and associated entities: Effective July 20, 2015, we entered into a lease with Two North Riverside Plaza Joint Venture Limited Partnership, an entity associated with Mr. Zell, our Chairman, to occupy office space on the twentieth and twenty-first floors of Two North Riverside Plaza in Chicago, Illinois (20th/21st Floor Office Lease). The initial term of the lease is approximately five years, with one 5 -year renewal option. We recently completed improvements to the office space utilizing the $0.7 million tenant improvement allowance provided for by the lease. In connection with the 20th/21st Floor Office Lease, we also have a lease with Two North Riverside Plaza Joint Venture Limited Partnership for storage space in the basement of Two North Riverside Plaza. The lease expires December 31, 2020, however, each party has the right to terminate on 30 days' prior written notice. During the year ended December 31, 2016, we recognized expense of $0.8 million pursuant to the 20th/21st Floor Office Lease and the related storage space. The future minimum lease payments scheduled to be paid by us during the current terms of this lease as of December 31, 2016 are as follows: $0.8 million in 2017, $0.9 million in 2018, $0.9 million in 2019 and $0.9 million in 2020. As of December 31, 2016, we had $0.1 million due to Two North Riverside Plaza Joint Venture Limited Partnership pursuant to the 20th/21st Floor Office Lease and the related storage space. We had a license agreement with Equity Group Investments, a private investment firm (Equity Group), to use office space on the sixth floor at Two North Riverside Plaza. The license fee included the non-exclusive use of additional areas on the sixth floor (such as conference rooms and common areas), certain administrative services (such as mail room services and reception desk staffing), office equipment, office furniture, supplies, licensee’s share of building operating expenses and real estate taxes and access to one parking space. Mr. Zell, our Chairman, is the Chairman and Chief Executive Officer of Equity Group, and Mr. Helfand, our President and Chief Executive Officer, is the Co-President of Equity Group. The license agreement was terminated as of December 30, 2015. During the years ended December 31, 2015 and 2014, we recognized expense of $0.2 million and $0.1 million , respectively, pursuant to the license agreement. We had a one -year lease with one 3 -month renewal option with Two North Riverside Plaza Joint Venture Limited Partnership to occupy office space on the fourteenth floor at Two North Riverside Plaza. This lease was terminated, effective January 31, 2015. During the years ended December 31, 2015 and 2014, we recognized expense of $13,000 and $0.1 million , respectively, pursuant to the office space on the fourteenth floor. We had a sublease with Equity Residential Management, L.L.C., an entity associated with Mr Zell, our Chairman, to occupy office space on the tenth floor of Two North Riverside Plaza. Equity Residential Management, L.L.C. leases the space from Two North Riverside Plaza Joint Venture Limited Partnership. The sublease agreement was terminated as of December 30, 2015. During the years ended December 31, 2015 and 2014, we recognized expense of $0.4 million and $38,000 , respectively, pursuant to the tenth floor office sublease. Related/Corvex: On July 31, 2014, at the reconvened session of our 2014 annual meeting of shareholders, our shareholders voted to approve the reimbursement of approximately $33.5 million of verified expenses incurred by Related/Corvex in connection with their consent solicitations to remove our former Trustees and elect the new Board of Trustees and to engage in related litigation. Approximately $16.7 million was paid during the year ended December 31, 2014. Up to $8.4 million was to be reimbursed only if the average closing price of our common shares was at least $26.00 (as adjusted for any share splits or share dividends) during the one year period after the date on which the reimbursement was approved by shareholders, and up to $8.4 million was to be reimbursed only if the average closing price of our common shares was at least $26.00 (as adjusted for any share splits or share dividends) during the one year period between the first and second anniversaries of the date on which the reimbursement was approved by shareholders. The average closing price of our common shares was at least $26.00 during both the first and second one year periods after the date on which the reimbursement was approved by shareholders, and as a result, in August 2016 and 2015, we paid $8.2 million and $8.4 million , respectively, to Related/Corvex. Transactions with Prior Related Persons: RMR : Prior to entering into the Termination and Cooperation Agreement with RMR, as further described below, we had three primary agreements with RMR and its affiliates to provide management and administrative services to us: (i) a business management agreement, which related to our business generally, (ii) a property management agreement, which related to our property level operations, and (iii) an Australia business and property management agreement, which related to our Australian properties. During the time we were externally managed by RMR, one of our former Managing Trustees, Mr. Barry Portnoy, was Chairman, majority owner and an employee of RMR. Another former Managing Trustee and our former President, Mr. Adam Portnoy, is the son of Mr. Barry Portnoy, and was an owner, President, Chief Executive Officer and a director of RMR. Mr. John Popeo, our former Treasurer and Chief Financial Officer, and Mr. David Lepore, our former Chief Operating Officer, were also officers of RMR. Two of our former independent Trustees served as independent directors or independent trustees of other public companies to which RMR provided management services. Mr. Barry Portnoy served as a managing director or managing trustee of a majority of the public companies to which RMR or its affiliate provided management services and Mr. Adam Portnoy served as a managing trustee of a majority of those companies. In addition, officers of RMR served as officers of those companies. As a result of the removal, effective March 25, 2014, of Mr. Barry Portnoy and Mr. Adam Portnoy as Trustees of the Company and the resignation on May 23, 2014, of Mr. Adam D. Portnoy, Mr. John C. Popeo, Mr. David M. Lepore and other officers of RMR from their respective positions as officers of the Company, they, RMR, RMR Australia Asset Management Pty Limited, or RMR Australia, Government Properties Income Trust (GOV), SIR and AIC have ceased to be related persons of the Company. Therefore, we only present related person transactions with these entities through June 30, 2014. On December 19, 2013, we and RMR entered into an amended and restated business management agreement, effective with respect to services performed on and after January 1, 2014. Under the terms of this amended and restated business management agreement: • The annual amount of the base management fee which was to be paid to RMR by us for each applicable period was to be equal to the lesser of: • the sum of (a) 0.7% of the average historical cost of our real estate investments during such period up to $250.0 million , plus (b) 1.0% of the average historical cost of our real estate investments located outside the United States, Puerto Rico and Canada during such period, plus (c) 0.5% of the average historical cost of our real estate investments during such period exceeding $250.0 million and the average historical cost of our real estate investments located outside the United States, Puerto Rico and Canada combined; and • the sum of (a) 0.7% of the average closing price per share of our common shares on the NYSE, during such period, multiplied by the average number of our common shares outstanding during such period, plus the daily weighted average of the aggregate liquidation preference of each class of our preferred shares outstanding during such period, plus the daily weighted average of the aggregate principal amount of our consolidated indebtedness during such period, or, together, our Average Market Capitalization, up to $250.0 million , plus (b) 1.0% of the average historical cost of our real estate investments located outside the United States, Puerto Rico and Canada during such period, plus (c) 0.5% of our Average Market Capitalization exceeding $250.0 million and the average historical cost of our real estate investments located outside the United States, Puerto Rico and Canada during such period combined. The average historical cost of our real estate investments included our consolidated assets invested, directly or indirectly, in equity interests in or loans secured by real estate and personal property owned in connection with such real estate (including acquisition related costs and costs which have been allocated to intangibles or are unallocated), all before reserves for depreciation, amortization, impairment charges or bad debts or other similar noncash reserves. Our investment in SIR (or in any other company which has a management agreement with RMR) was not counted for purposes of calculating the fees payable by us to RMR. • Although the fee calculation was stated in annual percentages, the base management fee was paid monthly to RMR, ninety percent ( 90% ) in cash and ten percent ( 10% ) in our common shares, which was to be fully-vested when issued. The number of our common shares to be issued in payment of the base management fee for each month was equal to the value of 10.0% of the total base management fee for that month divided by the average daily closing price of our common shares during that month. • The incentive management fee which may have been earned by RMR for an annual period was an amount, subject to a cap based on the value of our outstanding common shares, equal to 12.0% of the product of (a) our equity market capitalization on the last trading day on the year immediately prior to the relevant measurement period, and (b) the amount (expressed as a percentage) by which the total returns per share realized by the holders of our common shares (i.e., share price appreciation plus dividends) exceeded the total shareholder return of the SNL Office REIT Index (in each case subject to certain adjustments) for the relevant measurement period. The measurement periods were generally three -year periods ending with the year for which the incentive management fee was being calculated, with shorter periods applicable in the case of the calculation of the incentive management fee for 2014 ( one year ) and 2015 ( two years ). • The incentive management fee was payable in our common shares, with one-third of our common shares issued in payment of an incentive management fee vested on the date of issuance, and the remaining two-thirds vesting thereafter in two equal annual installments. If the issuance of common shares in payment of a portion of the base management fee or incentive management fee would be limited by applicable law and regulations, such portion of the applicable fee would instead be paid in cash. • RMR and certain eligible transferees of our common shares issued in payment of the base management fee or incentive management fee were entitled to demand registration rights, exercisable not more frequently than twice per year, and to "piggy-back" registration rights, with certain expenses to be paid by us. We and applicable selling shareholders also had agreed to indemnify each other (and their officers, trustees, directors and controlling persons) against certain liabilities, including liabilities under the Securities Act in connection with any such registration. Pursuant to our business management agreement with RMR as described above, we recognized business management fee expense of $31.7 million for the six months ended June 30, 2014. The fees for the six months ended June 30, 2014, include estimated 2014 incentive fees payable in common shares based on our common share total return. These amounts are included in general and administrative expenses, in our consolidated financial statements. In accordance with the terms of our business management agreement, as amended in December 2013, we issued 68,206 of our common shares to RMR for the six months ended June 30, 2014 as payment for 10% of the base business management fee we recognized for such period. Our property management agreement with RMR provided for management fees equal to 3.0% of gross collected rents and construction supervision fees for construction equal to 5.0% of construction costs. The aggregate property management and construction supervision fees we recognized on a consolidated basis were $13.8 million for the six months ended June 30, 2014. These amounts are included in operating expenses and income from discontinued operations or have been capitalized, as appropriate, in our consolidated financial statements. MacarthurCook Fund Management Limited (MacarthurCook) previously provided us with business and property management services related to our Australian properties. Our contract with MacarthurCook terminated on January 31, 2013, and on that date we entered into a business and property management agreement (Australia Management Agreement) with RMR Australia for the benefit of CWH Australia Trust, a subsidiary of ours (CWHAT). RMR Australia is owned by two of our former Trustees and our former President and it has been granted an Australian financial services license by the Australian Securities & Investments Commission. The Australia Management Agreement provides for compensation to RMR Australia for business management and real estate investment services at an annual rate equal to 0.5% of the average historical cost of CWHAT's real estate investments, as described in the Australia Management Agreement. The Australia Management Agreement also provides for additional compensation to RMR Australia (i) for property management services at an annual rate equal to 50% of the difference between 3.0% of collected gross rents and the aggregate of all amounts paid or payable by or on behalf of CWHAT to third party property managers, and (ii) for construction supervision services at an annual rate equal to 50% of the difference between 5.0% of constructions costs and any amounts paid to third parties for construction management and/or supervision. Similar to our prior arrangement with respect to fees we paid to MacarthurCook, RMR has agreed to waive half of the fees payable by us under our property management agreement with RMR and half of the business management fees otherwise payable by us under our business management agreement with RMR related to real estate investments that are subject to the Australia Management Agreement for so long as the Australia Management Agreement is in effect and we or any of our subsidiaries are paying the fees under that agreement. The aggregate business and property management fees we recognized pursuant to the Australia Management Agreement were $0.9 million for the six months ended June 30, 2014, which amounts are equal to the fees waived by RMR and excluded from the amount that was payable to RMR during the six months ended June 30, 2014. RMR also leased from us office space for eleven of its regional offices. We earned approximately $0.4 million for the six months ended June 30, 2014, with respect to approximately 36,500 square feet of office space, which we believe was commercially reasonable rent for this office space, not all of which was leased to RMR for the entire three -year period. These leases were terminated when our management agreements with RMR terminated. Under our share award plans, we granted restricted shares to certain employees of RMR, some of whom are our former officers. As a result of the removal of our former Trustees on March 25, 2014, the vesting of common shares previously issued to our former officers and certain employees of RMR pursuant to our equity compensation plans accelerated in accordance with the terms of their governing share grants (Note 13). Termination and Cooperation Agreement: On September 30, 2014, we entered into a termination and cooperation agreement (Cooperation Agreement) with Former Manager. Under the terms of the agreement, the existing business and property management agreements with RMR terminated effective September 30, 2014. Pursuant to the Cooperation Agreement, through February 28, 2015, Former Manager agreed to use best efforts to assist us in the transition of our management and operations. We paid Former Manager $1.2 million per month for transition services from October 1, 2014 to February 28, 2015, which included continued management and other services for the Australian assets pursuant to the Australian Management Agreement. Beginning March 1, 2015, we agreed to pay Former Manager $0.1 million per month until we no longer required such services or until the Australia Management Agreement was terminated, which was terminated in the third quarter of 2015, effective October 31, 2015. There is no future obligation to pay any fees to Former Manager. RMR is responsible for any severance payments to its employees. We paid accrued vacation benefits for any of Manager’s employees that were terminated as a result of the transition and we paid Manager the $15.3 million pro-rata portion of the current year’s incentive fee under the existing business management agreement for the period from January 1, 2014 to September 30, 2014. This incentive fee relates to the business management agreement entered into prior to the election of our new Board of Trustees on May 23, 2014. There is no future obligation to pay an incentive fee to RMR. GOV: GOV was formerly our 100% owned subsidiary. In 2009, GOV completed an initial public offering pursuant to which GOV ceased to be a majority owned subsidiary of ours. To facilitate this offering, we and GOV entered into a transaction agreement that governs our separation from and relationship with GOV. Pursuant to this transaction agreement and subject to certain conditions, among other things, we granted GOV the right of first purchase to acquire any property owned by us that we determine to divest (including sale, mortgage or other financing), if the property is then, or is reasonably expected within twelve ( 12 ) months to be, majority leased to a government tenant, which right of first purchase will also apply in the event of an indirect sale of any such properties as a result of a change of control of us. On July 23, 2014, we and GOV entered into a letter agreement whereby GOV irrevocably waived and released us from the right of first purchase described above. Additionally, pursuant to the letter agreement we and GOV each agreed to waive certain consent rights over the other party’s investments in certain categories of properties. During the time we were externally managed by RMR, RMR provided management services to both us and GOV, two of our former Trustees and our former President were managing trustees of GOV and GOV’s executive officers were officers of RMR. On March 15, 2013, we sold all of our 9,950,000 common shares of GOV in a public offering. SIR : SIR was formerly our 100% owned subsidiary. In March 2012, SIR completed an initial public offering, or the SIR IPO. As of June 30, 2014, we owned 22,000,000 common shares of SIR, which represented approximately 36.7% of SIR’s outstanding common shares. Two of our former Trustees and our former President were managing trustees of SIR and our former Treasurer and Chief Financial Officer served as the treasurer and chief financial officer of SIR and SIR’s executive officers were officers of RMR. In addition, one of our former independent Trustees was an independent trustee of SIR. In March 2012, SIR completed an initial public offering pursuant to which it issued 9,200,000 of its common shares for net proceeds (after deducting underwriters' discounts and commissions and expenses) of $180.8 million . In March 2013, we entered into a registration agreement with SIR, pursuant to which SIR agreed to, among other things, file a registration statement with respect to an offering of up to all of the 22,000,000 common shares of SIR that we owned, and SIR filed a registration statement on Form S-3 to permit the resale by us of some or all of the common shares of SIR we owned. By letter dated March 31, 2014, SIR notified us that, effective that same day, SIR had elected to terminate the registration agreement with us as a result of the removal of all the former Trustees effective March 25, 2014, which constituted a change of control of us as provided in that agreement. The letter also noted that SIR would welcome the opportunity to meet with our new Board of Trustees to discuss mutually beneficial arrangements regarding the registration of the shares of SIR owned by EQC. On July 9, 2014, we sold our entire stake of 22,000,000 common shares of SIR, for $32.04 per share, raising aggregate gross proceeds of $704.8 million . As a result of this sale, we no longer hold any interest in SIR. AIC : We previously owned 12.5% of AIC, an Indiana insurance company, and, as of May 9, 2014, had invested $5.2 million in AIC since we became an equity owner of AIC in 2009. RMR, GOV, SIR and four other companies to which RMR provides management services also own shares of AIC. During the time we were externally managed by RMR, RMR provided management and administrative services to AIC pursuant to a management and administrative services agreement with AIC and a majority of the former Trustees, our former President and most of the trustees and directors of the other AIC shareholders served on the board of directors of AIC. On March 25, 2014, as a result of the removal of the former Trustees, we underwent a change in control, as defined in the shareholders’ agreement among us, the other shareholders of AIC and AIC. As a result of that change in control and in accordance with the terms of the shareholders agreement, the other shareholders of AIC, on May 9, 2014, exercised their right to purchase the 20,000 shares of AIC we then owned. We received $5.8 million in aggregate proceeds from this sale and we no longer own any interest in AIC. We previously purchased property insurance providing $500.0 million of coverage pursuant to an insurance program arranged by AIC and with respect to which AIC was a reinsurer of certain coverage amounts. This program expired in June 2014. We paid AIC a premium, including taxes and fees, of approximately $6.0 million in connection with that policy. Indemnification : Pursuant to our declaration of trust and separate indemnification agreements, we have advanced amounts incurred for legal fees and costs on behalf of certain of the former Trustees and officers with respect to legal proceedings for shareholder litigation. No shareholder litigation related expenses were incurred during the year ended December 31, 2016. Pursuant to indemnification provisions in our business and property management agreements with RMR, we have also incurred legal fees and costs on behalf of RMR for claims brought against RMR in its capacity as our business and property manager with respect to certain legal proceedings. For the six months ended June 30, 2014, we incurred approximately $5.4 million in such legal fees and costs. Settlement of Certain Tenant Litigation : On March 1, 2014, pursuant to mediation, we and an affiliate of RMR agreed to terms of a settlement of a long running litigation with an unrelated third party that was a tenant, or the Tenant, of two separate properties: one property owned by us and one property owned by the RMR affiliate. This litigation arose as a result of flooding in 1999 and 2001 at both of these properties. After the flooding, the Tenant filed a complaint seeking declaratory and injunctive relief providing that Tenant was no longer obligated to pay rent at the two properties in question and brought claims against EQC and the RMR affiliate, as landlords, for, among other things, breach of the covenants of quiet enjoyment and habitability. We and RMR counterclaimed, seeking damages based in part upon Tenant’s failure to pay rent and make repairs. The settlement agreement regarding this litigation provides for a payment by Tenant of $12.0 million to EQC and the RMR affiliate, payable in three installments ( $6.0 million on June 30, 2014 and $3.0 million on each of September 30, 2014 and December 31, 2014), split pro-rata between EQC and the RMR affiliate based upon the balance of the rent due under each lease. The total rent due under the EQC lease was approximately $9.2 million ; the total rent due under the lease with the RMR affiliate was approximately $1.1 million . This settlement was approved by the court on May 6, 2014.

Selected Quarterly Financial Da

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	Selected Quarterly Financial Data (Unaudited) The following is a summary of our unaudited quarterly results of operations for 2016 and 2015 (dollars in thousands): 2016 First Quarter Second Quarter Third Quarter Fourth Quarter Total revenues $ 137,135 $ 145,367 $ 114,632 $ 103,546 Net income attributable to Equity Commonwealth common shareholders 39,421 71,254 84,391 10,263 Net income attributable to Equity Commonwealth common shareholders per share—basic 0.31 0.57 0.67 0.08 Net income attributable to Equity Commonwealth common shareholders per share—diluted 0.31 0.56 0.67 0.08 The increase in the second quarter 2016 total revenues was primarily attributable to a $16.6 million lease termination fee received at 111 Monument Circle. The decrease in the third and fourth quarter 2016 total revenues is primarily attributable to properties sold in 2016. The increase in the second and third quarter 2016 net income attributable to Equity Commonwealth common shareholders was primarily attributable to the gain on sale of properties of $106.4 million and $82.2 million , respectively. 2015 First Quarter Second Quarter Third Quarter Fourth Quarter Total revenues $ 213,055 $ 203,694 $ 159,208 $ 138,934 Net income attributable to Equity Commonwealth common shareholders 6,649 5,635 23,485 36,164 Net income attributable to Equity Commonwealth common shareholders per share—basic 0.05 0.04 0.18 0.29 Net income attributable to Equity Commonwealth common shareholders per share—diluted 0.05 0.04 0.18 0.28 The decrease in the third and fourth quarter 2015 total revenues and net income attributable to Equity Commonwealth common shareholders was primarily attributable to properties sold in the second, third and fourth quarters of 2015.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 12, 2017, we announced that our Board of Trustees declared a dividend of $0.40625 per series D preferred share, which was paid on February 15, 2017 to shareholders of record on January 30, 2017. On January 31, 2017, we sold 111 Market Place ( one building), with 589,380 square feet for $60.1 million . In February 2017, we purchased $100.0 million of 2 -year United States Treasury Notes with a coupon rate of 1.125% and a weighted average yield of 1.227% .

SCHEDULE II VALUATION AND QUALI

SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2016
Valuation and Qualifying Accounts [Abstract]
Schedule II Valuation and Qualifying Accounts	Description Balance at Charged to Deductions Balance at Year Ended December 31, 2014: Allowance for doubtful accounts $ 7,885 $ 2,196 $ (3,516 ) $ 6,565 Year Ended December 31, 2015: Allowance for doubtful accounts $ 6,565 $ 4,533 $ (3,383 ) $ 7,715 Year Ended December 31, 2016: Allowance for doubtful accounts $ 7,715 $ 1,056 $ (3,666 ) $ 5,105

SCHEDULE III REAL ESTATE AND AC

SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION	12 Months Ended
	Dec. 31, 2016
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
Schedule III Real Estate and Accumulated Depreciation	Initial Cost to Company Cost Amount Carried at Close of Period Property City State Encumbrances(1) Land Buildings and Improvements Costs Impairment/Write Downs Land Buildings and Improvements Total(2) Accumulated Depreciation(3) Date Acquired Original Construction Date Parkshore Plaza Folsom CA $ 41,275 $ 4,370 $ 41,749 $ 5,630 $ (6,310 ) $ 3,841 $ 41,598 $ 45,439 $ 6,695 6/16/2011 1999 1225 Seventeenth Street Denver CO — 22,400 110,090 24,798 (485 ) 22,400 134,403 156,803 25,990 6/24/2009 1982 5073, 5075, & 5085 S. Syracuse Street Denver CO — 4,720 58,890 — — 4,720 58,890 63,610 9,815 4/16/2010 2007 1601 Dry Creek Drive Longmont CO — 3,714 24,397 6,439 — 3,715 30,835 34,550 10,012 10/26/2004 1982 97 Newberry Road East Windsor CT 5,903 2,960 12,360 30 — 2,943 12,407 15,350 3,175 10/24/2006 1989 33 Stiles Lane North Haven CT 2,415 2,090 9,141 216 (1,654 ) 1,799 7,994 9,793 2,353 10/24/2006 1970 1250 H Street, NW Washington DC — 5,975 53,778 13,103 (248 ) 5,975 66,633 72,608 28,384 6/23/1998 1992 Georgetown-Green and Harris Buildings Washington DC — 24,000 35,979 44 — 24,000 36,023 60,023 6,600 9/3/2009 1960;1975 802 Delaware Avenue Wilmington DE — 4,409 39,681 10,562 (11,156 ) 3,390 40,106 43,496 24,217 7/23/1998 1986 6600 North Military Trail Boca Raton FL — 15,900 129,790 118 — 15,900 129,908 145,808 19,471 1/11/2011 2008 625 Crane Street Aurora IL — 1,180 3,411 (2 ) (4,589 ) — — — — 4/2/2007 1977 600 West Chicago Avenue Chicago IL — 34,980 315,643 44,821 — 34,980 360,464 395,444 45,839 8/10/2011 1908 8750 Bryn Mawr Avenue Chicago IL — 6,600 77,764 9,498 (257 ) 6,600 87,005 93,605 14,411 10/28/2010 1985 109 Brookline Avenue Boston MA — 3,168 30,397 14,090 (119 ) 3,168 44,368 47,536 20,196 9/28/1995 1915 Cabot Business Park Land Mansfield MA — 1,033 — — (458 ) 575 — 575 — 8/1/2003 - 111 Market Place Baltimore MD — 6,328 54,645 17,781 (7,199 ) 5,814 65,741 71,555 27,356 1/28/2003 1990 25 S. Charles Street Baltimore MD — 2,830 22,996 12,678 — 2,830 35,674 38,504 13,640 7/16/2004 1972 820 W. Diamond Gaithersburg MD — 4,381 18,798 10,516 (35 ) 4,461 29,199 33,660 12,777 3/31/1997 1995 Danac Stiles Business Park Rockville MD — 7,638 62,572 6,483 (10,975 ) 6,595 59,123 65,718 20,919 7/20/2004 2002 East Eisenhower Parkway Ann Arbor MI — 6,760 46,988 2,628 — 6,760 49,616 56,376 8,189 6/15/2010 1975;2006 2250 Pilot Knob Road Mendota Heights MN — 533 4,795 1,202 — 533 5,997 6,530 2,896 3/19/1998 1995 411 Farwell Avenue South St. Paul MN — 1,303 10,451 4,603 — 1,304 15,053 16,357 4,056 6/2/2004 1970 4700 Belleview Avenue Kansas City MO — 1,165 3,097 2,989 (26 ) 1,165 6,060 7,225 1,286 7/17/2008 1986 Cherrington Corporate Center Moon Township PA — 11,369 39,892 28,319 (7,616 ) 10,664 61,300 71,964 22,494 9/14/1998; 8/23/1999 1987;1988; 1989;1990; 1500 Market Street Philadelphia PA — 18,758 167,487 119,060 (759 ) 18,758 285,788 304,546 88,717 10/10/2002 1974 Initial Cost to Company Cost Amount Carried at Close of Period Property City State Encumbrances(1) Land Buildings and Improvements Costs Impairment/Write Downs Land Buildings and Improvements Total(2) Accumulated Depreciation(3) Date Acquired Original Construction Date 1600 Market Street Philadelphia PA — 3,462 111,946 20,637 (194 ) 3,462 132,389 135,851 59,435 3/30/1998 1983 1735 Market Street Philadelphia PA — 24,753 222,775 67,076 (12,071 ) 24,747 277,786 302,533 118,405 6/30/1998 1990 Foster Plaza Pittsburgh PA — 6,168 51,588 20,229 (1,729 ) 6,170 70,086 76,256 21,553 9/16/2005 1987;1990; 1994; 206 East 9th Street Austin TX 27,041 7,900 38,533 2,776 (12 ) 7,900 41,297 49,197 4,879 5/31/2012 1984 4515 Seton Center Parkway Austin TX — 2,038 18,338 2,814 (60 ) 2,037 21,093 23,130 9,749 10/8/1999 1996 4516 Seton Center Parkway Austin TX — 2,028 18,251 4,003 (25 ) 2,027 22,230 24,257 10,497 10/8/1999 1998 Bridgepoint Square Austin TX — 7,784 70,526 13,727 (705 ) 7,785 83,547 91,332 39,708 12/5/1997 1986;1996;1997 Research Park Austin TX — 15,859 60,175 17,410 — 21,213 72,231 93,444 32,295 10/7/1998 1968;1998; 2001 333 108th Avenue NE Bellevue WA — 14,400 136,412 2,438 (31 ) 14,400 138,819 153,219 25,788 11/12/2009 2008 600 108th Avenue NE Bellevue WA — 3,555 30,244 17,305 (508 ) 3,555 47,041 50,596 13,458 7/16/2004 1980 $ 76,634 $ 286,511 $ 2,133,579 $ 504,021 $ (67,221 ) $ 286,186 $ 2,570,704 $ 2,856,890 $ 755,255 Analysis of the carrying amount of real estate properties and accumulated depreciation: Real Estate Accumulated Balance at January 1, 2014 $ 5,537,165 $ 895,059 Additions(4) 70,963 164,815 Loss on asset impairment (191,490 ) (6,423 ) Properties reclassified to discontinued operations 341,024 5,724 Disposals (29,219 ) (28,730 ) Balance at December 31, 2014 5,728,443 1,030,445 Additions(4) 68,118 144,844 Loss on asset impairment (17,162 ) — Disposals (1,892,047 ) (276,350 ) Balance at December 31, 2015 3,887,352 898,939 Additions(4) 113,258 101,647 Loss on asset impairment (58,595 ) (119 ) Disposals (1,085,125 ) (245,212 ) Balance at December 31, 2016 $ 2,856,890 $ 755,255 (1) Excludes net unamortized premiums and net unamortized deferred financing costs. (2) Excludes value of real estate intangibles. Aggregate cost for federal income tax purposes is approximately $2,988,563 . (3) Depreciation is calculated using the straight line method over estimated useful lives of up to 40 years for buildings and improvements and up to 12 years for personal property. (4) Includes adjustments related to changes in foreign currency exchange rates for real estate properties additions of $0 , $(13,217) and $(20,445) , and adjustments to accumulated depreciation additions of $0 , $(887) and $(1,279) , during 2016 , 2015 and 2014 , respectively.

SCHEDULE IV MORTGAGE LOANS ON R

SCHEDULE IV MORTGAGE LOANS ON REAL ESTATE (Schedule)	12 Months Ended
	Dec. 31, 2016
Mortgage Loans on Real Estate [Abstract]
Schedule IV Mortgage Loans on Real Estate	Location Interest Rate Final Periodic Payment Terms Face Carrying Principal Amount of Salina, NY 6.00% 4/30/2019 Interest payable monthly in arrears. $419 due at maturity. $ 419 392 $ — Dearborn, MI 6.00% 1/24/2023 Interest payable monthly in arrears. $7,688 due at maturity. 7,688 7,688 — $ 8,107 $ 8,080 $ — Reconciliation of the carrying amount of mortgage loans at the beginning of the period: Balance at December 31, 2014 $ 8,107 Balance at December 31, 2015 $ 8,107 Balance at December 31, 2016 $ 8,107 (1) Also represents cost for federal income tax purposes.

Summary of Significant Accoun32

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation. The consolidated financial statements include our investments in 100% owned subsidiaries and majority owned subsidiaries that are controlled by us. References to we, us, our and the Company, refer to Equity Commonwealth and its consolidated subsidiaries as of December 31, 2016 , unless the context indicates otherwise. All intercompany transactions and balances have been eliminated. We account for our investments in 50% or less owned companies over which we can exercise influence, but do not control, using the equity method of accounting, which included our prior investments in Select Income REIT and its consolidated subsidiaries (SIR) (beginning on July 2, 2013 when SIR ceased to be our consolidated subsidiary through the sale date on July 9, 2014) and Affiliates Insurance Company, or AIC (until May 9, 2014, when we sold all of our AIC shares). We used the income statement method to account for issuance of common shares of beneficial interest by SIR, and shares of common stock by AIC. Under this method, gains and losses reflecting changes in the value of our investments at the date of issuance of additional common shares by SIR, or common stock by AIC, are recognized in our income statement.
Real Estate Properties	Real Estate Properties. We record real estate properties at cost. We depreciate real estate investments on a straight line basis over estimated useful lives of up to 40 years for buildings and improvements, and up to 12 years for personal property. Each time we enter into a new lease, or materially modify an existing lease, we evaluate its classification as either a capital or operating lease. The classification of a lease as capital or operating affects the carrying value of a property, as well as our recognition of rental payments as revenue. These evaluations require us to make estimates of, among other things, the remaining useful life and fair market value of a leased property, appropriate discount rates and future cash flows. We allocate the consideration paid for our properties among land, buildings and improvements and, for properties that qualify as acquired businesses under the Business Combinations Topic of the FASB Accounting Standards Codification ™ , or the Codification, to identified intangible assets and liabilities, consisting of the value of above market and below market leases, the value of acquired in place leases and the value of tenant relationships. Purchase price allocations and the determination of useful lives are based on our estimates and, under some circumstances, studies from independent real estate appraisal firms to provide market information and evaluations that are relevant to our purchase price allocations and determinations of useful lives; however, we are ultimately responsible for the purchase price allocations and determination of useful lives. We allocate the consideration to land, buildings and improvements based on a determination of the fair values of these assets assuming the property is vacant. We determine the fair value of a property using methods that we believe are similar to those used by independent appraisers. Purchase price allocations to above market and below market leases are based on the estimated present value (using an interest rate which reflects our assessment of the risks associated with the leases acquired) of the difference between (1) the contractual amounts to be paid pursuant to the acquired in place leases and (2) our estimate of fair market lease rates for the corresponding leases, measured over a period equal to the remaining non-cancelable terms of the respective leases. Purchase price allocations to acquired in place leases and tenant relationships are determined as the excess of (1) the purchase price paid for a property after adjusting existing in place leases to estimated market rental rates over (2) the estimated fair value of the property as if vacant. We aggregate this value between acquired in place lease values and tenant relationships based on our evaluation of the specific characteristics of each tenant's lease; however, the value of tenant relationships has not been separated from acquired in place lease value for our properties because we believe such value and related amortization expense is immaterial for acquisitions reflected in our historical financial statements. We consider certain factors in performing these analyses including estimates of carrying costs during the expected lease up periods, including real estate taxes, insurance and other operating income and expenses and costs to execute similar leases in current market conditions, such as leasing commissions, legal and other related costs. If we believe the value of tenant relationships is material in the future, those amounts will be separately allocated and amortized over the estimated lives of the relationships. We recognize the excess, if any, of the consideration paid over amounts allocated to land, buildings and improvements and identified intangible assets and liabilities as goodwill and we recognize gains if amounts allocated exceed the consideration paid. We amortize capitalized above market lease values (presented in our consolidated balance sheets as acquired real estate leases) as a reduction to rental income over the remaining terms of the respective leases. We amortize capitalized below market lease values (presented in our consolidated balance sheets as assumed real estate lease obligations) as an increase to rental income over the remaining terms of the respective leases. We amortize the value of acquired in place leases exclusive of the value of above market and below market acquired in place leases to expense over the remaining terms of the respective leases. If a lease is terminated prior to its stated expiration, the unamortized lease intangibles relating to that lease is written off. We review our properties for impairment quarterly, or whenever events or changes in circumstances indicate that their carrying amounts may not be recoverable. Impairment indicators may include declining tenant occupancy, lack of progress releasing vacant space, tenant bankruptcies, low long term prospects for improvement in property performance, weak or declining tenant profitability, cash flow or liquidity, our decision to dispose of an asset before the end of its estimated useful life. When indicators of potential impairment are present that suggest that the carrying amounts of real estate assets may not be recoverable, we assess the recoverability of these assets by determining whether the respective carrying values will be recovered through the estimated undiscounted future operating cash flows expected from the use of the assets and their eventual disposition. The determination of undiscounted cash flow includes consideration of many factors including income to be earned from the investment, holding costs (exclusive of interest), estimated selling prices, and prevailing economic and market conditions. In the event that such expected undiscounted future cash flows do not exceed the carrying values, we estimate the fair value of the assets and record an impairment charge equal to the amount by which the carrying value exceeds the estimated fair value. Estimated fair values are calculated based on the following information, (i) recently quoted market prices, (ii) market prices for comparable properties, or (iii) the present value of future cash flows. During the years ended December 31, 2016 , 2015 , and 2014 we recorded a loss on asset impairment in continuing operations totaling $58.5 million , $17.2 million and $185.1 million respectively, to reduce the carrying value of properties to their estimated fair values (see Note 15). When we classify properties as held for sale, we discontinue the recording of depreciation expense and estimate their fair value less costs to sell. If we determine that the carrying value for these properties exceed their estimated fair value less costs to sell, we record a loss on asset impairment. Certain of our real estate assets contain hazardous substances, including asbestos. We believe any asbestos in our buildings is contained in accordance with current regulations, and we have no current plans to remove any such asbestos. If we remove the asbestos or renovate or demolish these properties, certain environmental regulations govern the manner in which the asbestos must be handled and removed. We do not believe that there are other environmental conditions at any of our properties that have a material adverse effect on us. However, no assurances can be given that such conditions are not present in our properties or that other costs we incur to remediate contamination will not have a material adverse effect on our business or financial condition.
Cash and Cash Equivalents	Cash and Cash Equivalents. Our cash and cash equivalents consist of cash maintained in time deposits, depository accounts and money market accounts. From time-to-time we may also invest in various U.S. government securities. We continually monitor the credit ratings of the financial institutions holding our deposits to minimize our exposure to credit risk. Throughout the year, we have cash balances in excess of federally insured limits deposited with various financial institutions. We do not believe we are exposed to any significant credit risk on cash and cash equivalents.
Restricted Cash	Restricted Cash. Restricted cash consists of amounts escrowed for future real estate taxes, insurance, leasing costs, capital expenditures and debt service, as required by some of our mortgage debts, as well as security deposits paid to us by some of our tenants.
Other Assets, Net	Other Assets, Net. Other assets consist principally of deferred financing fees, deferred leasing costs, capitalized lease incentives and prepaid property operating expenses. Deferred financing fees include issuance costs related to borrowings and are capitalized and amortized over the terms of the respective loans. Deferred leasing costs include brokerage, legal and other fees associated with the successful negotiation of leases and are amortized on a straight line basis over the terms of the respective leases. Capitalized lease incentives are amortized on a straight line basis against rental income over the terms of the respective leases.
Accounting Policy for Derivative Instruments	Accounting Policy for Derivative Instruments. The Derivatives and Hedging Topic of the Codification requires companies to recognize all their derivative instruments as either assets or liabilities in the statement of financial position at fair value. The accounting for changes in the fair value of a derivative instrument depends on whether such instrument has been designated and qualifies as part of a hedging relationship and, further, on the type of hedging relationship. For those derivative instruments that are designated and qualify as hedging instruments, we must designate the hedging instrument, based upon the exposure being hedged, as a fair value hedge, cash flow hedge or a hedge of a net investment in a foreign operation. As of December 31, 2016 , we have an interest rate cap agreement that qualifies as a cash flow hedge. We are exposed to certain risks relating to our ongoing business operations. The primary risk managed by using derivative instruments is interest rate risk. Interest rate swaps and caps are entered into to manage interest rate risk associated with our floating rate borrowings. We designate interest rate swaps and caps as cash flow hedges of floating rate borrowings.
Revenue Recognition	Revenue Recognition. Rental income from operating leases, which includes rent concessions (including free rent and other lease incentives) and scheduled increases in rental rates during the lease term, is recognized on a straight line basis over the life of the lease agreements. We defer the recognition of contingent rental income, such as percentage rents, until the specific targets that trigger the contingent rental income are achieved. Tenant reimbursements and other income includes property level operating expenses reimbursed by our tenants, as well as other incidental revenues, which are recorded as expenses are incurred.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts. We maintain an allowance for doubtful accounts for estimated losses resulting from the inability or unwillingness of certain tenants to make payments required under their leases. The computation of the allowance is based on the tenants' payment histories and current credit profiles, as well as other considerations.
Share-Based Compensation	Share-Based Compensation. All share-based compensation is measured at fair value on the grant date or date of modification, as applicable, and recognized in earnings over the requisite service period. Depending upon the settlement terms of the awards, all or a portion of the fair value of share-based awards may be presented as a liability or as equity in the consolidated balance sheets.
Earnings Per Common Share	Earnings Per Common Share. Earnings per common share, or EPS, is computed using the weighted average number of common shares outstanding during the period. Diluted EPS reflects the potential dilution that could occur if our series D convertible preferred shares or our restricted share units (RSUs) were converted into our common shares, which could result in a lower EPS amount. The effect of our series D convertible preferred shares on income from continuing operations and net income attributable to common shareholders is anti-dilutive for all periods presented.
Reclassifications	Reclassifications. Reclassifications have been made to the prior years' financial statements and notes to conform to the current year's presentation.
Income Taxes	Income Taxes. We are a REIT under the Internal Revenue Code of 1986, as amended, and are generally not subject to federal and state income taxes provided we distribute our taxable income to our shareholders and meet other requirements for qualifying as a real estate investment trust. However, we are subject to certain state and local taxes without regard to our REIT status. The Income Taxes Topic of the Codification prescribes how we should recognize, measure and present in our financial statements uncertain tax positions that have been taken or are expected to be taken in a tax return. Deferred tax assets are recognized to the extent that it is "more likely than not" that a particular tax position will be sustained upon examination or audit. To the extent the "more likely than not" standard has been satisfied, the benefit associated with a tax position is measured as the largest amount that has a greater than 50% likelihood of being realized upon settlement. We classify interest and penalties related to uncertain tax positions, if any, in our financial statements as a component of general and administrative expense.
Use of Estimates	Use of Estimates. Preparation of these financial statements in conformity with U.S. generally accepted accounting principles, or GAAP, requires us to make estimates and assumptions that may affect the amounts reported in these financial statements and related notes. The actual results could differ from these estimates.
Foreign Operations	Foreign Operations. During the year ended December 31, 2015, we sold our Australian properties (see Note 3) and as of each of December 31, 2016 and 2015, we did not have any foreign operations. The U.S. dollar was the functional currency for our consolidated subsidiaries operating in the United States prior to the sale of the Australian portfolio. The functional currency for our consolidated subsidiaries in countries other than the United States was the principal currency in which the entity's assets, liabilities, income and expenses were denominated. The functional currency of our consolidated subsidiary that operated in Australia was the Australian dollar. We translated our Australian subsidiary's financial statements into U.S. dollars when we consolidated that subsidiary's financial statements on a quarterly basis. Generally, we translated assets and liabilities at the exchange rate in effect as of the balance sheet date. The resulting translation adjustments were included in cumulative other comprehensive loss in our consolidated balance sheets. We translated income statement accounts using the average exchange rate for the period and income statement accounts that include significant non-recurring transactions at the rate in effect as of the date of the transaction. We were subject to foreign currency risk due to potential fluctuations in exchange rates between Australian and U.S. currencies.
New Accounting Pronouncements	New Accounting Pronouncements. In February 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2017-01, Clarifying the Definition of a Business, that changes the definition of a business to assist entities with evaluating when a set of transferred assets and activities is a business. This update is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. Early adoption is permitted for transactions that occurred before the issuance date or effective date of the standard if the transactions were not reported in financial statements that have been issued or made available for issuance. We do not expect that the adoption of this ASU will have a material impact on our consolidated financial statements. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, which amends FASB Accounting Standards Codification (ASC) Topic 230, Statements of Cash Flows, to add or clarify guidance on the classification and presentation of restricted cash in the statement of cash flows. This update is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. We do not expect that the adoption of this ASU will have a material impact on our consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. This update is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. We do not expect that the adoption of this ASU will have a material impact on our consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires more timely recognition of credit losses associated with financial assets. This update is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years. Early adoption is permitted for fiscal years, and interim periods within those years, beginning after December 15, 2018. We are currently in the process of evaluating the impact, if any, the adoption of this ASU will have on our consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, which simplifies several aspects of the accounting for employee share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. This update is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods, but early adoption is permitted. We do not expect that the adoption of this ASU will have a material impact on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases, which amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets. The ASU also requires lessees or lessors to capitalize only initial direct costs of leases. This update is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, but early adoption is permitted. We are currently in the process of evaluating the impact the adoption of this ASU will have on our consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, which creates a single source of revenue guidance. The new standard provides accounting guidance for all revenue arising from contracts with customers and affects all entities that enter into contracts to provide goods or services to their customers (unless the contracts are in the scope of other GAAP requirements, such as the leasing literature). The guidance also provides a model for the measurement and recognition of gains and losses on the sale of certain nonfinancial assets, such as property and equipment, including real estate. The new standard is effective for fiscal years beginning after December 15, 2017 and for interim periods therein. Early adoption is permitted beginning after December 15, 2016. Upon adoption of ASU 2016-02, Leases, the majority of our revenue, will be subject to the allocation provisions outlined within the revenue standard. We are currently evaluating the specific implementation requirements for allocating the consideration within our contracts in accordance with ASU No. 2014-09. In April 2015, the FASB issued ASU No. 2015-03, Simplifying the Presentation of Debt Issuance Costs. This standard amends existing guidance to require the presentation of debt issuance costs in the balance sheet as a deduction from the carrying amount of the related debt liability instead of as a deferred charge. It is effective for annual reporting periods beginning after December 15, 2015, but early adoption is permitted. We adopted this standard on January 1, 2016 and made the following reclassifications to the prior years' consolidated balance sheet to conform to the current year's presentation (in thousands): Balance Sheet as of December 31, 2015 Originally Reported Effect of Change As Adjusted Other assets, net $ 157,549 $ (13,208 ) $ 144,341 Senior unsecured debt, net 1,460,592 (9,986 ) 1,450,606 Mortgage notes payable, net 249,732 (3,222 ) 246,510 In April 2014, the FASB issued ASU No. 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, or ASU 2014-08. ASU 2014-08 changes the criteria for reporting a discontinued operation. Under the new pronouncement, a disposal of a part of an organization that has a major effect on its operations and financial results is a discontinued operation. We adopted ASU 2014-08 on January 1, 2015, and determined that our 2016 dispositions and 2015 dispositions do not individually represent a strategic shift, as defined by the standard, that has or will have a major effect on our operations and financial results. As a result, the 2016 and 2015 dispositions have not been presented as discontinued operations in the statements of operations.

Summary of Significant Accoun33

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	We adopted this standard on January 1, 2016 and made the following reclassifications to the prior years' consolidated balance sheet to conform to the current year's presentation (in thousands): Balance Sheet as of December 31, 2015 Originally Reported Effect of Change As Adjusted Other assets, net $ 157,549 $ (13,208 ) $ 144,341 Senior unsecured debt, net 1,460,592 (9,986 ) 1,450,606 Mortgage notes payable, net 249,732 (3,222 ) 246,510

Real Estate Properties (Tables)

Real Estate Properties (Tables)	12 Months Ended
	Dec. 31, 2016
Real Estate [Abstract]
Summary of Properties Disposed and Income Statement Information for Properties Included in Discontinued Operations	Summarized income statement information for properties included in discontinued operations is as follows (in thousands): Year Ended December 31, 2014 Rental income $ 14,243 Tenant reimbursements and other income 1,900 Total revenues 16,143 Operating expenses 7,138 General and administrative 10 Total expenses 7,148 Operating income 8,995 Interest and other income 2 Interest expense (608 ) Income from discontinued operations $ 8,389 During the year ended December 31, 2016, we disposed of the following properties (dollars in thousands): Asset Date Sold Number of Number of Square Footage Gross Sales Price Gain (Loss) on Sale Properties Executive Park February 2016 1 9 427,443 $ 50,865 $ 16,531 3330 N Washington Boulevard March 2016 1 1 55,719 11,250 5,455 111 East Kilbourn Avenue March 2016 1 1 373,669 60,500 14,687 1525 Locust Street April 2016 1 1 98,009 17,700 8,956 633 Ahua Street April 2016 1 1 93,141 29,000 15,963 Lakewood on the Park May 2016 1 2 180,558 37,100 13,616 Leased Land June 2016 1 7 — 48,450 15,914 9110 East Nichols Avenue June 2016 1 1 143,958 17,200 642 111 River Street (1) July 2016 1 1 566,215 235,000 78,207 Sky Park Centre July 2016 1 2 63,485 13,700 4,746 Raintree Industrial Park July 2016 1 12 563,182 11,500 (653 ) 8701 N Mopac August 2016 1 1 121,901 21,500 8,394 7800 Shoal Creek Boulevard October 2016 1 4 151,917 29,210 14,908 1200 Lakeside Drive November 2016 1 1 260,084 65,270 3,062 6200 Glenn Carlson Drive December 2016 1 1 338,000 23,050 7,706 Portfolios of properties 812 San Antonio Street May 2016 1 1 59,321 1601 Rio Grande Street May 2016 1 1 56,219 Downtown Austin portfolio 2 2 115,540 $ 32,600 $ 20,584 785 Schilinger Road South June 2016 1 1 72,000 401 Vine Street June 2016 1 1 53,980 633 Frazier Drive June 2016 1 1 150,000 9840 Gateway Boulevard North June 2016 1 1 72,000 3003 South Expressway 281 June 2016 1 1 150,000 1331 North Center Parkway June 2016 1 1 53,980 Movie theater portfolio 6 6 551,960 $ 109,100 $ 30,595 Asset Date Sold Number of Number of Square Footage Gross Sales Price Gain (Loss) on Sale 128 Crews Drive July 2016 1 1 185,600 111 Southchase Boulevard July 2016 1 1 168,087 1043 Global Avenue July 2016 1 1 450,000 South Carolina industrial portfolio 3 3 803,687 $ 30,000 $ 7,248 100 East Wisconsin Avenue August 2016 1 1 435,067 111 Monument Circle August 2016 1 2 1,121,764 101-115 W. Washington Street August 2016 1 1 634,058 North Point Office Complex August 2016 1 2 873,335 Midwest portfolio 4 6 3,064,224 $ 416,900 $ (15,800 ) Total 30 62 7,972,692 $ 1,259,895 $ 250,761 (1) Property sale represented a leasehold interest. During the year ended December 31, 2015, we disposed of the following properties (dollars in thousands): Asset Date Disposed Number of Number of Square Footage Gross Sales Price Gain (Loss) on Sale Properties 11350 North Meridian Street January 2015 1 1 72,264 $ 4,200 $ 766 333 Laurel Oak Drive (1) March 2015 — 1 27,164 2,450 251 1921 E. Alton Avenue March 2015 1 1 67,846 14,533 4,851 46 Inverness Center Parkway April 2015 — — — 2,000 1,857 225 Water Street (2) May 2015 1 1 318,997 — — Sorrento Valley Business Park June 2015 1 4 105,003 23,500 11,896 Illinois Center August 2015 1 2 2,090,162 376,000 26,956 16th and Race Street August 2015 1 1 608,625 43,000 7,922 185 Asylum Street September 2015 1 1 868,395 113,250 17,619 One South Church Avenue October 2015 1 1 240,811 32,000 4,282 775 Ridge Lake Boulevard October 2015 1 1 120,678 16,300 (360 ) One Park Square October 2015 1 6 259,737 34,300 9,512 Arizona Center December 2015 1 4 1,070,724 126,000 22,838 4 South 84th Avenue December 2015 1 1 236,007 18,000 8,393 Portfolio of properties 7450 Campus Drive May 2015 1 1 77,411 129 Worthington Ridge Road May 2015 1 1 227,500 599 Research Parkway May 2015 1 1 48,249 181 Marsh Hill Road May 2015 1 1 162,036 101 Barnes Road May 2015 1 1 45,755 15 Sterling Drive May 2015 1 1 173,015 35 Thorpe Avenue May 2015 1 1 79,862 50 Barnes Industrial Road North May 2015 1 1 154,255 5-9 Barnes Industrial Road May 2015 1 1 38,006 Asset Date Disposed Number of Number of Square Footage Gross Sales Price Gain (Loss) on Sale 860 North Main Street May 2015 1 1 31,165 One Barnes Industrial Road South May 2015 1 1 30,170 Village Lane May 2015 1 2 58,185 100 Northfield Drive May 2015 1 1 116,986 905 Meridian Lake Drive May 2015 1 1 74,652 1717 Deerfield Road May 2015 1 1 141,186 1955 West Field Court May 2015 1 1 59,130 5015 S. Water Circle May 2015 1 1 113,524 Adams Place May 2015 1 2 230,259 Cabot Business Park May 2015 1 2 252,755 2300 Crown Colony Drive May 2015 1 1 45,974 Myles Standish Industrial Park May 2015 1 2 74,800 340 Thompson Road May 2015 1 1 25,000 100 South Charles Street May 2015 1 1 159,616 6710 Oxon Hill May 2015 1 1 118,336 8800 Queen Avenue South May 2015 1 1 280,822 9800 Sherlard Parkway May 2015 1 1 46,765 Rosedale Corporate Plaza May 2015 1 3 149,116 1000 Shelard Parkway May 2015 1 1 62,499 525 Park Street May 2015 1 1 75,636 1900 Meyer Drury Drive May 2015 1 1 65,225 131-165 West Ninth Street May 2015 1 1 75,517 7-9 Vreeland Road May 2015 1 1 155,891 5 Paragon Drive May 2015 1 1 119,089 1000 Voorhees Drive and 400 Laurel Oak Drive (1) May 2015 1 2 125,415 1601 Veterans Highway May 2015 1 1 63,608 Two Corporate Center Drive May 2015 1 1 291,230 11311 Cornell Park Drive May 2015 1 1 93,413 5300 Kings Island Drive May 2015 1 1 159,421 3 Crown Point Court May 2015 1 1 73,987 515 Pennsylvania Avenue May 2015 1 1 82,000 443 Gulph Road May 2015 1 1 21,000 4350 Northern Pike May 2015 1 1 503,885 Thunderbolt Place May 2015 1 2 100,505 6160 Kempsville Circle May 2015 1 1 129,565 448 Viking Drive May 2015 1 1 75,374 Portfolio of small office and industrial assets 45 53 5,287,790 $ 376,000 $ (8,160 ) 2501 20th Place South June 2015 1 1 125,722 420 20th Street North June 2015 1 1 514,893 Inverness Center June 2015 1 4 475,882 Asset Date Disposed Number of Number of Square Footage Gross Sales Price Gain (Loss) on Sale 701 Poydras Street June 2015 1 1 1,256,971 300 North Greene Street June 2015 1 1 324,305 1320 Main Street June 2015 1 1 334,075 AL, LA, NC, SC office portfolio 6 9 3,031,848 $ 417,450 $ 41,596 12655 Olive Boulevard June 2015 1 1 98,588 1285 Fern Ridge Parkway June 2015 1 1 66,510 St. Louis portfolio (3) 2 2 165,098 $ 14,300 $ (2,349 ) 310-314 Invermay Road (4) April 2015 1 1 47,480 253-293 George Town Road (4) April 2015 1 1 143,914 7 Modal Crescent June 2015 1 1 164,160 71-93 Whiteside Road June 2015 1 1 303,488 9-13 Titanium Court June 2015 1 1 69,664 16 Rodborough Road June 2015 1 1 90,525 22 Rodborough Road June 2015 1 1 43,427 127-161 Cherry Lane June 2015 1 1 278,570 310-320 Pitt Street June 2015 1 1 313,865 44-46 Mandarin Street June 2015 1 1 226,718 19 Leadership Way June 2015 1 1 76,714 Australia portfolio (5) 11 11 1,758,525 $ 232,955 $ (47,872 ) Widewaters Parkway August 2015 1 8 514,241 5062 Brittonfield Parkway August 2015 1 1 40,162 Woodcliff Drive August 2015 1 6 516,760 Interstate Place August 2015 1 2 61,399 1000 Pittsford - Victor Road August 2015 1 1 73,358 1200 Pittsford - Victor Road August 2015 1 1 18,900 Corporate Crossing August 2015 1 5 216,126 Canal View Boulevard August 2015 1 3 118,375 14 Classic Street August 2015 1 1 37,084 110 W Fayette Street August 2015 1 1 304,906 251 Salina Meadows Parkway August 2015 1 1 65,617 Upstate New York portfolio (3) 11 30 1,966,928 $ 104,625 $ (12,518 ) 9040 Roswell Road October 2015 1 1 178,941 The Exchange October 2015 1 2 187,632 3920 Arkwright Road October 2015 1 1 196,156 1775 West Oak Commons Court October 2015 1 1 79,854 Georgia portfolio (3) 4 5 642,583 $ 48,550 $ (3,059 ) Total 91 135 18,939,185 $ 1,999,413 $ 84,421 (1) This property contains three buildings. We sold one building in March 2015 and two buildings in May 2015. (2) Title to this property was transferred to the lender pursuant to a consensual foreclosure in full satisfaction of the mortgage debt with a principal balance of $40.1 million , resulting in a gain on early extinguishment of debt of $17.3 million for the year ended December 31, 2015. See Note 9 for additional information. (3) Prior to the disposition of these properties, we recorded a total impairment charge of $17.2 million during the year ended December 31, 2015, based upon updated market information in accordance with our impairment analysis procedures. (4) These properties were sold in a separate transaction to a different buyer than the other Australian properties. (5) The loss on sale includes a $63.2 million cumulative foreign currency translation adjustment reclassified from cumulative other comprehensive loss due to the disposition of the Australian portfolio.
Schedule of Future Minimum Lease Payments	The future minimum lease payments, excluding tenant reimbursement revenue, scheduled to be received by us during the current terms of our leases as of December 31, 2016 are as follows (in thousands): 2017 $ 292,388 2018 299,449 2019 278,531 2020 244,953 2021 206,046 Thereafter 850,539 $ 2,171,906

Lease Intangibles (Tables)

Lease Intangibles (Tables)	12 Months Ended
	Dec. 31, 2016
Leases [Abstract]
Summary of the Carrying Amounts for Acquired Real Estate Leases and Assumed Real Estate Lease Obligations	The following table summarizes the carrying amounts for our acquired real estate leases and assumed real estate lease obligations as of December 31, 2016 , and 2015 , and (in thousands): December 31, 2016 2015 Acquired in-place leases $ 102,102 $ 147,056 Acquired above market leases 44,752 78,210 Acquired real estate leases 146,854 225,266 Accumulated amortization, acquired in-place leases (71,320 ) (91,301 ) Accumulated amortization, acquired above market leases (27,253 ) (45,205 ) Acquired real estate leases, net $ 48,281 $ 88,760 Acquired below market leases 10,434 19,742 Accumulated amortization (8,488 ) (15,446 ) Assumed real estate lease obligations, net $ 1,946 $ 4,296
Schedule of Amortization of Lease Intangibles	Amortization of the lease intangibles for the years ended December 31, 2016 , 2015 , and 2014 , is as follows (in thousands): December 31, Income Statement Location 2016 2015 2014 Amortization of acquired in-place leases Depreciation and amortization $ 14,598 $ 26,787 $ 40,493 Amortization of above and below market leases Increase (decrease) to rental income (6,531 ) (7,515 ) (10,650 )
Schedule of Future Amortization of Net Intangible Lease Assets and Liabilities	Future amortization of net intangible lease assets and liabilities to be recognized by us during the current terms of our leases as of December 31, 2016 , are approximately (in thousands): 2017 $ 9,670 2018 8,397 2019 6,178 2020 5,882 2021 5,252 Thereafter 10,956 $ 46,335

Equity Investments (Tables)

Equity Investments (Tables)	12 Months Ended
	Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Equity Investments	At December 31, 2016 , and 2015 , we did not have any ownership interests in equity investments. For the year ended December 31, 2014, equity in earnings is as follows (in thousands): Year Ended December 31, 2014 SIR $ 24,516 AIC (56 ) $ 24,460
Summary of Unaudited Income Statement Information of Equity Method Investee	The following unaudited summarized income statement information of SIR for the period from January 1, 2014, through July 9, 2014, is as follows (in thousands, except per share data): For the Period from January 1, 2014 through July 9, 2014 Rental income $ 98,226 Tenant reimbursements and other income 16,980 Total revenues 115,206 Operating expenses 20,982 Depreciation and amortization 20,832 Acquisition related costs 374 General and administrative 7,731 Total expenses 49,919 Operating income 65,287 Interest expense (7,287 ) Gain on early extinguishment of debt 243 Income before income tax expense and equity in earnings of an investee 58,243 Income tax expense (90 ) Equity in earnings of an investee 32 Net income $ 58,185 Weighted average common shares outstanding 52,394 Net income per common share $ 1.11

Other Assets (Tables)

Other Assets (Tables)	12 Months Ended
	Dec. 31, 2016
Other Assets [Abstract]
Summary of Deferred Financing Fees, Deferred Leasing Costs and Capitalized Lease Incentives	The following table summarizes our deferred financing fees related to our unsecured revolving credit facility included in other assets, deferred leasing costs and capitalized lease incentives as of December 31, 2016 , and 2015 (in thousands): December 31, 2016 2015 Deferred financing fees $ 14,458 $ 14,458 Accumulated amortization (11,093 ) (9,478 ) Deferred financing fees, net $ 3,365 $ 4,980 Deferred leasing costs $ 133,771 $ 166,390 Accumulated amortization (41,148 ) (56,162 ) Deferred leasing costs, net $ 92,623 $ 110,228 Capitalized lease incentives $ 10,344 $ 11,623 Accumulated amortization (2,680 ) (2,498 ) Capitalized lease incentives, net $ 7,664 $ 9,125
Summary of Future Amortization of Deferred Leasing Costs and Capitalized Lease Incentives	Future amortization of deferred leasing costs and capitalized lease incentives to be recognized by us during the current terms of our leases as of December 31, 2016 are approximately (in thousands): Deferred Leasing Costs Capitalized Lease Incentives 2017 $ 12,796 $ 1,319 2018 12,318 1,287 2019 11,611 1,552 2020 10,291 1,273 2021 8,687 996 Thereafter 36,920 1,237 $ 92,623 $ 7,664

Indebtedness (Tables)

Indebtedness (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Schedule of Outstanding Indebtedness	At December 31, 2016 and 2015 , our outstanding indebtedness included the following (in thousands): December 31, Interest Rate at December 31, 2016 Maturity Date 2016 2015 Unsecured revolving credit facility, at LIBOR plus a premium 2.02 % 1/28/2019 $ — $ — 5-year unsecured term loan, at LIBOR plus a premium 2.17 % 1/28/2020 200,000 200,000 7-year unsecured term loan, at LIBOR plus a premium 2.57 % 1/28/2022 200,000 200,000 Unsecured floating rate debt 2.37 % (1) $ 400,000 $ 400,000 6.25% Senior Unsecured Notes due 2016 — % — $ — $ 139,104 6.25% Senior Unsecured Notes due 2017 — % — — 250,000 6.65% Senior Unsecured Notes due 2018 6.65 % 1/15/2018 250,000 250,000 5.875% Senior Unsecured Notes due 2020 5.88 % 9/15/2020 250,000 250,000 5.75% Senior Unsecured Notes due 2042 5.75 % 8/1/2042 175,000 175,000 Unsecured fixed rate debt 6.13 % (1) $ 675,000 $ 1,064,104 Parkshore Plaza (2) 5.67 % 5/1/2017 $ 41,275 $ 41,275 1735 Market Street (3) — % — — 169,612 206 East 9th Street 5.69 % 1/5/2021 27,041 27,515 33 Stiles Lane 6.75 % 3/1/2022 2,415 2,785 97 Newberry Road 5.71 % 3/1/2026 5,903 6,375 Secured fixed rate debt 5.71 % (1) $ 76,634 $ 247,562 $ 1,151,634 $ 1,711,666 Unamortized net premiums, discounts and deferred financing fees (9,967 ) (14,550 ) $ 1,141,667 $ 1,697,116 (1) Represents weighted average interest rate at December 31, 2016 . (2) The Company guarantees $3.2 million of this non-recourse loan. (3) Interest on this loan was payable at LIBOR plus 2.625% but was fixed for the first seven years to December 1, 2016 by a cash flow hedge which set the rate at approximately 5.66% .
Schedule of Required Principal Payments on Outstanding Debt	The required principal payments due during the next five years and thereafter under all of our outstanding debt at December 31, 2016 are as follows (in thousands): 2017 $ 42,675 2018 251,488 2019 1,580 2020 451,674 2021 25,982 Thereafter 378,235 $ 1,151,634

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Schedule of Declared Distributions	In 2016 , our Board of Trustees declared distributions on our series D preferred shares and series E cumulative redeemable preferred shares to date as follows: Declaration Date Record Date Payment Date Series D Dividend Per Share Series E Dividend Per Share January 26, 2016 February 5, 2016 February 16, 2016 $ 0.40625 $ 0.453125 April 15, 2016 April 25, 2016 May 16, 2016 $ 0.40625 $ 0.453125 July 11, 2016 July 29, 2016 August 15, 2016 $ 0.40625 $ — October 10, 2016 October 28, 2016 November 15, 2016 $ 0.40625 $ — The following characterizes distributions paid per common share for the years ended December 31, 2016 , 2015 , and 2014 : Year Ended December 31, 2016 2015 2014 Ordinary income — % — % — % Return of capital — % — % — % Capital gain — % — % 100.00 % Unrecaptured Section 1250 gain — % — % — % — % — % 100.00 %

Cumulative Other Comprehensiv40

Cumulative Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Amounts Recognized in Cumulative Other Comprehensive Loss	The following tables present the amounts recognized in cumulative other comprehensive loss for the years ended December 31, 2016 and 2015 (in thousands): Unrealized Loss on Derivative Instruments Balance as of January 1, 2016 $ (3,687 ) Other comprehensive loss before reclassifications (554 ) Amounts reclassified from cumulative other comprehensive loss to net income 4,033 Net current period other comprehensive income 3,479 Balance as of December 31, 2016 $ (208 ) Unrealized Loss on Derivative Instruments and Other Assets Foreign Currency Translation Adjustments Total Balances as of January 1, 2015 $ (4,299 ) $ (48,917 ) $ (53,216 ) Other comprehensive loss before reclassifications (1,232 ) (14,290 ) (15,522 ) Amounts reclassified from cumulative other comprehensive loss to net income 1,844 63,207 65,051 Net current period other comprehensive income 612 48,917 49,529 Balances as of December 31, 2015 $ (3,687 ) $ — $ (3,687 )
Schedule of Reclassifications Out of Cumulative Other Comprehensive Loss	The following tables present reclassifications out of cumulative other comprehensive loss for the years ended December 31, 2016 and 2015 (in thousands): Amounts Reclassified from Cumulative Other Comprehensive Loss to Net Income Year Ended December 31, Details about Cumulative Other Comprehensive Loss Components 2016 2015 Affected Line Items in the Statement of Operations Interest rate swap contracts $ 3,792 $ 4,924 Interest expense Interest rate swap contracts 241 — Interest and other income Foreign currency translation adjustment activity — 63,207 Gain on sale of properties Realized gain on available for sale securities — (3,080 ) Interest and other income $ 4,033 $ 65,051

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Schedule of Provision for Income Taxes	Our provision for income taxes consists of the following (in thousands): Year Ended December 31, 2016 2015 2014 Current: State $ 745 $ 270 $ 350 Federal — 513 — Foreign — 2,336 2,772 745 3,119 3,122 Deferred: Foreign — (755 ) 69 — (755 ) 69 Income tax expense $ 745 $ 2,364 $ 3,191
Schedule of Reconciliation of Effective Tax Rate and the U.S. Federal Statutory Income Tax Rate	A reconciliation of our effective tax rate and the U.S. Federal statutory income tax rate is as follows: Year Ended December 31, 2016 2015 2014 Taxes at statutory U.S. federal income tax rate 35.00 % 35.00 % 35.00 % Dividends paid deduction and net operating loss utilization (35.00 )% (35.00 )% (35.00 )% Federal taxes on built-in gain — % 0.50 % — % State, local, and foreign income taxes 0.32 % 1.81 % 11.73 % Effective tax rate 0.32 % 2.31 % 11.73 %

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Outstanding Interest Rate Derivatives Designated as Cash Flow Hedges of Interest Rate Risk	As of December 31, 2016 , we had the following outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk: Interest Rate Derivative Number of Instruments Notional Amount (in thousands) Interest rate cap 1 $400,000
Schedule of Fair Value of Derivative Financial Instruments	The table below presents the fair value of our derivative financial instruments as well as their classification on the consolidated balance sheets as of December 31, 2016 , and 2015 (amounts in thousands): Fair Value as of December 31, Interest Rate Derivative Designated as Hedging Instrument Balance Sheet Location 2016 2015 Interest rate cap Other assets $ 314 $ — Pay-fixed swaps Accounts payable and accrued expenses — 3,687
Schedule of Gain or Loss Recognized on Interest Rate Derivatives Designated as Cash Flow Hedges	The table below details the location in the financial statements of the gain or loss recognized on interest rate derivatives designated as cash flow hedges for the years ended December 31, 2016 , 2015 , and 2014 (amounts in thousands) Year Ended December 31, 2016 2015 2014 Amount of loss recognized in cumulative other comprehensive loss (effective portion) $ (554 ) $ (1,149 ) $ (776 ) Amount of loss reclassified from cumulative other comprehensive loss into interest expense (effective portion) 3,792 4,924 5,020 Amount of loss recognized in income (ineffective portion and amount excluded from effectiveness testing) 241 — —

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Restricted Share and Restricted Stock Unit Activity	The table below presents a summary of restricted share and RSU activity under the 2015 Incentive Plan and the 2012 Plan for the years ended December 31, 2016 , 2015 and 2014 , excluding restricted shares granted to our former Trustees, former officers and certain employees of RMR, our former manager, under the terms of our 2012 Plan (which grants are further described below): Number Weighted Number Weighted Outstanding at December 31, 2013 — $ — — $ — Granted 713,727 26.66 1,266,237 15.99 Vested (3,545 ) 26.66 — — Outstanding at December 31, 2014 710,182 1,266,237 Granted 160,906 26.46 639,250 15.47 Vested (86,517 ) 26.02 — — Forfeited (8,115 ) 26.64 (21,377 ) 15.80 Outstanding at December 31, 2015 776,456 1,884,110 Granted 167,790 27.29 691,385 15.57 Vested (191,498 ) 26.54 — — Forfeited (539 ) 26.82 (2,727 ) 15.54 Outstanding at December 31, 2016 752,209 2,572,768
Summary of Assumptions and Fair Values for Restricted Stock Units Granted in the Period	The assumptions and fair values for the RSUs granted for the years ended December 31, 2016 , 2015 and 2014 are included in the following table on a per share basis. 2016 2015 2014 Fair value of RSUs granted at the target amount $ 38.80 $ — $ — Fair value of RSUs granted at the maximum amount $ — $ 15.47 $ 15.99 Expected term (years) 4 4 4 Expected volatility — — — Expected dividend yield 1.86 % 1.88 % 1.88 % Risk-free rate 1.07 % 0.81 % 0.84 %
Schedule of Shares Granted and Vested	A summary of shares granted and vested to our former Trustees, former officers and certain employees of RMR under the terms of our 2012 Plan and our 2003 Plan for the year ended December 31, 2014, is as follows: Number Weighted Unvested shares at December 31, 2013 130,914 $ 20.70 Granted 4,000 23.46 Vested (134,914 ) 25.79 Unvested shares at December 31, 2014 — $ —

Fair Value of Assets and Liab44

Fair Value of Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value	The table below presents certain of our assets and liabilities measured at fair value during 2016 and 2015 , categorized by the level of inputs used in the valuation of each asset and liability (dollars in thousands): Fair Value at December 31, 2016 Using Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Description Total (Level 1) (Level 2) (Level 3) Recurring Fair Value Measurements: Effective portion of interest rate cap contract $ 314 $ — $ 314 $ — Fair Value at December 31, 2015 Using Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Description Total (Level 1) (Level 2) (Level 3) Recurring Fair Value Measurements: Effective portion of interest rate swap contracts $ (3,687 ) $ — $ (3,687 ) $ — Derivative liability (7,219 ) — — (7,219 )
Schedule of Valuation Techniques and Significant Unobservable Inputs used for Level 3 Fair Value Measurements	The valuation techniques and significant unobservable inputs used for our level 3 fair value measurement at December 31, 2015 were as follows: Description Fair Value at December 31, 2015 Primary Valuation Technique Unobservable Inputs Rate Derivative liability $ 7,219 Monte Carlo simulation Risk-free rate 0.52% Volatility 20.0%
Schedule of Fair Value and Carrying Value of Financial Instruments	At December 31, 2016 and 2015 , the fair value of these additional financial instruments were not materially different from their carrying values, except as follows (in thousands): December 31, 2016 December 31, 2015 Principal Balance Fair Value Principal Balance Fair Value Senior unsecured debt and mortgage notes payable $ 1,151,634 $ 1,167,031 $ 1,711,666 $ 1,749,211

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per share (amounts in thousands except per share amounts): Year Ended December 31, 2016 2015 2014 Numerator for earnings per common share - basic and diluted: Income from continuing operations $ 232,894 $ 99,857 $ 21,206 Preferred distributions (17,956 ) (27,924 ) (32,095 ) Excess fair value of consideration paid over carrying value of preferred shares (9,609 ) — — Excess fair value of consideration over carrying vale of preferred shares — — (16,205 ) Income (loss) from continuing operations attributable to Equity Commonwealth common shareholders 205,329 71,933 (27,094 ) Discontinued operations — — 2,806 Numerator for net income (loss) per share - basic and diluted $ 205,329 $ 71,933 $ (24,288 ) Denominator for earnings per common share - basic and diluted: Weighted average number of common shares outstanding - basic 125,474 128,621 125,163 Weighted average number of common shares outstanding - diluted (1) 126,768 129,437 125,163 Earnings per share - basic: Income (loss) from continuing operations attributable to Equity Commonwealth common shareholders $ 1.64 $ 0.56 $ (0.21 ) Discontinued operations — — 0.02 Net income (loss) per share - basic $ 1.64 $ 0.56 $ (0.19 ) Earnings per share - diluted: Income (loss) from continuing operations attributable to Equity Commonwealth common shareholders $ 1.62 $ 0.56 $ (0.21 ) Discontinued operations — — 0.02 Net income (loss) per share - diluted $ 1.62 $ 0.56 $ (0.19 ) Anti-dilutive securities: Effect of Series D preferred shares; 6 1/2% cumulative convertible (2) 2,363 2,363 4,175 (1) As of December 31, 2016 , we had granted RSUs to certain employees, officers, and the chairman of the Board of Trustees. The RSUs contain both service and market-based vesting components. None of the RSUs have vested. If the market-based vesting component was measured as of December 31, 2016 and 2015 , 1,027 and 1,143 common shares would be issued to the RSU holders, respectively, and no shares would have been issued as of December 31, 2014. Using a weighted average basis, 1,294 and 816 common shares are reflected in diluted earnings per share for the years ended ended December 31, 2016 and 2015 , respectively. (2) The Series D preferred shares are excluded from the diluted earnings per share calculation because including the Series D preferred shares would also require that the preferred distributions be added back to net income, resulting in anti-dilution during the periods presented.

Selected Quarterly Financial 46

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Summary of Unaudited Quarterly Results of Operations	The following is a summary of our unaudited quarterly results of operations for 2016 and 2015 (dollars in thousands): 2016 First Quarter Second Quarter Third Quarter Fourth Quarter Total revenues $ 137,135 $ 145,367 $ 114,632 $ 103,546 Net income attributable to Equity Commonwealth common shareholders 39,421 71,254 84,391 10,263 Net income attributable to Equity Commonwealth common shareholders per share—basic 0.31 0.57 0.67 0.08 Net income attributable to Equity Commonwealth common shareholders per share—diluted 0.31 0.56 0.67 0.08 2015 First Quarter Second Quarter Third Quarter Fourth Quarter Total revenues $ 213,055 $ 203,694 $ 159,208 $ 138,934 Net income attributable to Equity Commonwealth common shareholders 6,649 5,635 23,485 36,164 Net income attributable to Equity Commonwealth common shareholders per share—basic 0.05 0.04 0.18 0.29 Net income attributable to Equity Commonwealth common shareholders per share—diluted 0.05 0.04 0.18 0.28

Organization (Details)

Organization (Details)	Dec. 31, 2016ft²buildingproperty	Mar. 31, 2014ft²
Segment Reporting Information [Line Items]
Property square feet		5,641,450
Consolidated portfolio
Segment Reporting Information [Line Items]
Number of properties | property	33
Number of buildings | building	64
Property square feet	16,100,000

Summary of Significant Accoun48

Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Percentage of investments in subsidiaries	100.00%
Asset impairment charges	$ 58,476,000	$ 17,162,000	$ 185,067,000
Minimum percentage of likelihood of realization of tax benefits (greater than)	50.00%
Foreign currency exchange gain (loss)	$ (5,000)	(8,857,000)	$ 0
Other assets, net	122,922,000	144,341,000
Senior unsecured debt, net	1,063,950,000	1,450,606,000
Mortgage notes payable, net	$ 77,717,000	246,510,000
Accounting Standards Update 2015-03
Property, Plant and Equipment [Line Items]
Other assets, net		144,341,000
Senior unsecured debt, net		1,450,606,000
Mortgage notes payable, net		246,510,000
Originally Reported | Accounting Standards Update 2015-03
Property, Plant and Equipment [Line Items]
Other assets, net		157,549,000
Senior unsecured debt, net		1,460,592,000
Mortgage notes payable, net		249,732,000
Effect of Change | Accounting Standards Update 2015-03
Property, Plant and Equipment [Line Items]
Other assets, net		(13,208,000)
Senior unsecured debt, net		(9,986,000)
Mortgage notes payable, net		(3,222,000)
Australia Portfolio
Property, Plant and Equipment [Line Items]
Foreign currency exchange gain (loss)		8,900,000
Foreign currency translation adjustments		0
Foreign Currency Translation Adjustments
Property, Plant and Equipment [Line Items]
Total amounts reclassified		(63,207,000)
Foreign Currency Translation Adjustments | Australia Portfolio
Property, Plant and Equipment [Line Items]
Total amounts reclassified		$ (63,200,000)
Maximum
Property, Plant and Equipment [Line Items]
Maximum percentage of investment accounted for under equity method of accounting	50.00%
Maximum | Buildings and improvements
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years
Maximum | Personal property
Property, Plant and Equipment [Line Items]
Estimated useful life	12 years

Real Estate Properties - Narrat

Real Estate Properties - Narrative (Details) $ in Thousands	1 Months Ended			12 Months Ended
	Oct. 31, 2016USD ($)	Mar. 31, 2014USD ($)ft²buildingproperty	Jan. 31, 2013buildingproperty	Dec. 31, 2016USD ($)ft²buildingproperty	Dec. 31, 2015USD ($)buildingproperty	Dec. 31, 2014USD ($)ft²buildingproperty
Real Estate Properties [Line Items]
Real estate property improvements				$ 110,700	$ 75,700	$ 91,600
Committed expenditures on leases executed during period				$ 143,000
Square feet of leases committed for expenditures during the period | ft²				4,300,000
Committed but unspent tenant related obligations based on existing leases				$ 91,800
Number of real estate properties held for use | property		31
Number of buildings held for use | building		67
Property square feet | ft²		5,641,450
Reversal of previously recorded impairment losses		$ 4,800
Number of real estate properties held for sale | property				0	0
Number of properties sold or agreed to be sold | property			3
Number of buildings sold | building			18
Loss (gain) on asset impairment from discontinued operations				$ 0	$ 0	2,238
Gain (loss) on early extinguishment of debt from discontinued operations				0	0	3,345
Ground lease expenses				$ 900	$ 1,800	$ 1,800
Disposed of by Sale
Real Estate Properties [Line Items]
Property square feet | ft²						2,784,098
Number of properties sold or agreed to be sold | property						14
Number of buildings sold | building				62	135	43
Gross Sales Price				$ 1,259,895	$ 1,999,413	$ 215,900
Loss (gain) on asset impairment from discontinued operations						2,200
Gain (loss) on early extinguishment of debt from discontinued operations						$ (3,300)
Austin, Texas
Real Estate Properties [Line Items]
Payments to acquire land	$ 2,800

Real Estate Properties - Summar

Real Estate Properties - Summary of Properties Disposed (Details) $ in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

Dec. 31, 2016USD ($)ft²buildingproperty

Nov. 30, 2016USD ($)ft²buildingproperty

Oct. 31, 2016USD ($)ft²buildingproperty

Aug. 31, 2016USD ($)ft²buildingproperty

Jul. 31, 2016USD ($)ft²buildingproperty

Jun. 30, 2016USD ($)ft²buildingproperty

May 31, 2016USD ($)ft²buildingproperty

Apr. 30, 2016USD ($)ft²buildingproperty

Mar. 31, 2016USD ($)ft²buildingproperty

Feb. 29, 2016USD ($)ft²buildingproperty

Dec. 31, 2015USD ($)ft²buildingproperty

Oct. 31, 2015USD ($)ft²buildingproperty

Sep. 30, 2015USD ($)ft²buildingproperty

Aug. 31, 2015USD ($)ft²buildingproperty

Jun. 30, 2015USD ($)ft²buildingproperty

May 31, 2015USD ($)ft²buildingproperty

Apr. 30, 2015USD ($)ft²buildingproperty

Mar. 31, 2015USD ($)ft²buildingproperty

Jan. 31, 2015USD ($)ft²buildingproperty

Jan. 31, 2013building

Jun. 30, 2015USD ($)ft²buildingproperty

May 31, 2015building

Dec. 31, 2016USD ($)ft²buildingproperty

Dec. 31, 2015USD ($)ft²buildingproperty

Dec. 31, 2014USD ($)building

Real Estate Properties [Line Items]

Number of Buildings

18

Gain (Loss) on Sale | $

$ 250,886

$ 84,421

$ 0

Disposed of by Sale

Real Estate Properties [Line Items]

Number of Properties | property

30

91

Number of Buildings

62

135

43

Square Footage | ft²

7,972,692

18,939,185

Gross Sales Price | $

$ 1,259,895

$ 1,999,413

$ 215,900

Gain (Loss) on Sale | $

$ 250,761

$ 84,421

Disposed of by Sale | Executive Park

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

9

Square Footage | ft²

427,443

Gross Sales Price | $

$ 50,865

Gain (Loss) on Sale | $

$ 16,531

Disposed of by Sale | 3330 N Washington Boulevard

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

55,719

Gross Sales Price | $

$ 11,250

Gain (Loss) on Sale | $

$ 5,455

Disposed of by Sale | 111 East Kilbourn Avenue

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

373,669

Gross Sales Price | $

$ 60,500

Gain (Loss) on Sale | $

$ 14,687

Disposed of by Sale | 1525 Locust Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

98,009

Gross Sales Price | $

$ 17,700

Gain (Loss) on Sale | $

$ 8,956

Disposed of by Sale | 633 Ahua Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

93,141

Gross Sales Price | $

$ 29,000

Gain (Loss) on Sale | $

$ 15,963

Disposed of by Sale | Lakewood on the Park

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

180,558

Gross Sales Price | $

$ 37,100

Gain (Loss) on Sale | $

$ 13,616

Disposed of by Sale | Leased Land

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

7

Square Footage | ft²

0

Gross Sales Price | $

$ 48,450

Gain (Loss) on Sale | $

$ 15,914

Disposed of by Sale | 9110 East Nichols Avenue

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

143,958

Gross Sales Price | $

$ 17,200

Gain (Loss) on Sale | $

$ 642

Disposed of by Sale | 111 River Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

566,215

Gross Sales Price | $

$ 235,000

Gain (Loss) on Sale | $

$ 78,207

Disposed of by Sale | Sky Park Centre

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

63,485

Gross Sales Price | $

$ 13,700

Gain (Loss) on Sale | $

$ 4,746

Disposed of by Sale | Raintree Industrial Park

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

12

Square Footage | ft²

563,182

Gross Sales Price | $

$ 11,500

Gain (Loss) on Sale | $

$ (653)

Disposed of by Sale | 8701 N Mopac

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

121,901

Gross Sales Price | $

$ 21,500

Gain (Loss) on Sale | $

$ 8,394

Disposed of by Sale | 7800 Shoal Creek Boulevard

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

4

Square Footage | ft²

151,917

Gross Sales Price | $

$ 29,210

Gain (Loss) on Sale | $

$ 14,908

Disposed of by Sale | 1200 Lakeside Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

260,084

Gross Sales Price | $

$ 65,270

Gain (Loss) on Sale | $

$ 3,062

Disposed of by Sale | 6200 Glenn Carlson Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

338,000

Gross Sales Price | $

$ 23,050

Gain (Loss) on Sale | $

$ 7,706

Disposed of by Sale | 812 San Antonio Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

59,321

Disposed of by Sale | 1601 Rio Grande Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

56,219

Disposed of by Sale | Downtown Austin portfolio

Real Estate Properties [Line Items]

Number of Properties | property

2

Number of Buildings

2

Square Footage | ft²

115,540

Gross Sales Price | $

$ 32,600

Gain (Loss) on Sale | $

$ 20,584

Disposed of by Sale | 785 Schilinger Road South

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

72,000

Disposed of by Sale | 401 Vine Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

53,980

Disposed of by Sale | 633 Frazier Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

150,000

Disposed of by Sale | 9840 Gateway Boulevard North

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

72,000

Disposed of by Sale | 3003 South Expressway 281

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

150,000

Disposed of by Sale | 1331 North Center Parkway

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

53,980

Disposed of by Sale | Movie theater portfolio

Real Estate Properties [Line Items]

Number of Properties | property

6

Number of Buildings

6

Square Footage | ft²

551,960

Gross Sales Price | $

$ 109,100

Gain (Loss) on Sale | $

$ 30,595

Disposed of by Sale | 128 Crews Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

185,600

Disposed of by Sale | 111 Southchase Boulevard

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

168,087

Disposed of by Sale | 1043 Global Avenue

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

450,000

Disposed of by Sale | South Carolina industrial portfolio

Real Estate Properties [Line Items]

Number of Properties | property

3

Number of Buildings

3

Square Footage | ft²

803,687

Gross Sales Price | $

$ 30,000

Gain (Loss) on Sale | $

$ 7,248

Disposed of by Sale | 100 East Wisconsin Avenue

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

435,067

Disposed of by Sale | 111 Monument Circle

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

1,121,764

Disposed of by Sale | 101-115 W. Washington Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

634,058

Disposed of by Sale | North Point Office Complex

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

873,335

Disposed of by Sale | Midwest portfolio

Real Estate Properties [Line Items]

Number of Properties | property

4

Number of Buildings

6

Square Footage | ft²

3,064,224

Gross Sales Price | $

$ 416,900

Gain (Loss) on Sale | $

$ (15,800)

Disposed of by Sale | 11350 North Meridian Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

72,264

Gross Sales Price | $

$ 4,200

Gain (Loss) on Sale | $

$ 766

Disposed of by Sale | 333 Laurel Oak Drive

Real Estate Properties [Line Items]

Number of Properties | property

0

Number of Buildings

2

1

3

Square Footage | ft²

27,164

Gross Sales Price | $

$ 2,450

Gain (Loss) on Sale | $

$ 251

Disposed of by Sale | 1921 E. Alton Avenue

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

67,846

Gross Sales Price | $

$ 14,533

Gain (Loss) on Sale | $

$ 4,851

Disposed of by Sale | 46 Inverness Center Parkway

Real Estate Properties [Line Items]

Number of Properties | property

0

Number of Buildings

0

Square Footage | ft²

0

Gross Sales Price | $

$ 2,000

Gain (Loss) on Sale | $

$ 1,857

Disposed of by Sale | Sorrento Valley Business Park

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

4

Square Footage | ft²

105,003

Gross Sales Price | $

$ 23,500

Gain (Loss) on Sale | $

$ 11,896

Disposed of by Sale | Illinois Center

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

2,090,162

Gross Sales Price | $

$ 376,000

Gain (Loss) on Sale | $

$ 26,956

Disposed of by Sale | 16th and Race Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

608,625

Gross Sales Price | $

$ 43,000

Gain (Loss) on Sale | $

$ 7,922

Disposed of by Sale | 185 Asylum Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

868,395

Gross Sales Price | $

$ 113,250

Gain (Loss) on Sale | $

$ 17,619

Disposed of by Sale | One South Church Avenue

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

240,811

Gross Sales Price | $

$ 32,000

Gain (Loss) on Sale | $

$ 4,282

Disposed of by Sale | 775 Ridge Lake Boulevard

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

120,678

Gross Sales Price | $

$ 16,300

Gain (Loss) on Sale | $

$ (360)

Disposed of by Sale | One Park Square

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

6

Square Footage | ft²

259,737

Gross Sales Price | $

$ 34,300

Gain (Loss) on Sale | $

$ 9,512

Disposed of by Sale | Arizona Center

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

4

Square Footage | ft²

1,070,724

Gross Sales Price | $

$ 126,000

Gain (Loss) on Sale | $

$ 22,838

Disposed of by Sale | 4 South 84th Avenue

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

236,007

Gross Sales Price | $

$ 18,000

Gain (Loss) on Sale | $

$ 8,393

Disposed of by Sale | 7450 Campus Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

77,411

Disposed of by Sale | 129 Worthington Ridge Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

227,500

Disposed of by Sale | 599 Research Parkway

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

48,249

Disposed of by Sale | 181 Marsh Hill Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

162,036

Disposed of by Sale | 101 Barnes Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

45,755

Disposed of by Sale | 15 Sterling Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

173,015

Disposed of by Sale | 35 Thorpe Avenue

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

79,862

Disposed of by Sale | 50 Barnes Industrial Road North

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

154,255

Disposed of by Sale | 5-9 Barnes Industrial Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

38,006

Disposed of by Sale | 860 North Main Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

31,165

Disposed of by Sale | One Barnes Industrial Road South

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

30,170

Disposed of by Sale | Village Lane

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

58,185

Disposed of by Sale | 100 Northfield Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

116,986

Disposed of by Sale | 905 Meridian Lake Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

74,652

Disposed of by Sale | 1717 Deerfield Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

141,186

Disposed of by Sale | 1955 West Field Court

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

59,130

Disposed of by Sale | 5015 S. Water Circle

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

113,524

Disposed of by Sale | Adams Place

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

230,259

Disposed of by Sale | Cabot Business Park

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

252,755

Disposed of by Sale | 2300 Crown Colony Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

45,974

Disposed of by Sale | Myles Standish Industrial Park

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

74,800

Disposed of by Sale | 340 Thompson Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

25,000

Disposed of by Sale | 100 South Charles Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

159,616

Disposed of by Sale | 6710 Oxon Hill

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

118,336

Disposed of by Sale | 8800 Queen Avenue South

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

280,822

Disposed of by Sale | 9800 Sherlard Parkway

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

46,765

Disposed of by Sale | Rosedale Corporate Plaza

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

3

Square Footage | ft²

149,116

Disposed of by Sale | 1000 Shelard Parkway

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

62,499

Disposed of by Sale | 525 Park Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

75,636

Disposed of by Sale | 1900 Meyer Drury Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

65,225

Disposed of by Sale | 131-165 West Ninth Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

75,517

Disposed of by Sale | 7-9 Vreeland Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

155,891

Disposed of by Sale | 5 Paragon Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

119,089

Disposed of by Sale | 1000 Voorhees Drive and 400 Laurel Oak Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

125,415

Disposed of by Sale | 1601 Veterans Highway

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

63,608

Disposed of by Sale | Two Corporate Center Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

291,230

Disposed of by Sale | 11311 Cornell Center Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

93,413

Disposed of by Sale | 5300 Kings Island Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

159,421

Disposed of by Sale | 3 Crown Point Court

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

73,987

Disposed of by Sale | 515 Pennsylvania Avenue

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

82,000

Disposed of by Sale | 443 Gulph Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

21,000

Disposed of by Sale | 4350 Northern Pike

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

503,885

Disposed of by Sale | Thunderbolt Place

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

100,505

Disposed of by Sale | 6160 Kempsville Circle

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

129,565

Disposed of by Sale | 448 Viking Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

75,374

Disposed of by Sale | Portfolio of Small Office and Industrial Assets

Real Estate Properties [Line Items]

Number of Properties | property

45

Number of Buildings

53

Square Footage | ft²

5,287,790

Gross Sales Price | $

$ 376,000

Gain (Loss) on Sale | $

$ (8,160)

Disposed of by Sale | 2501 20th Place South

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

125,722

Disposed of by Sale | 420 20th Street North

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

514,893

Disposed of by Sale | Inverness Center

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

4

Square Footage | ft²

475,882

Disposed of by Sale | 701 Poydras Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

1,256,971

Disposed of by Sale | 300 North Greene Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

324,305

Disposed of by Sale | 1320 Main Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

334,075

Disposed of by Sale | AL, LA, NC, SC Office Portfolio

Real Estate Properties [Line Items]

Number of Properties | property

6

Number of Buildings

9

Square Footage | ft²

3,031,848

Gross Sales Price | $

$ 417,450

Gain (Loss) on Sale | $

$ 41,596

Disposed of by Sale | 12655 Olive Boulevard

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

98,588

Disposed of by Sale | 1285 Fern Ridge Parkway

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

66,510

Disposed of by Sale | St. Louis Portfolio

Real Estate Properties [Line Items]

Number of Properties | property

2

Number of Buildings

2

Square Footage | ft²

165,098

Gross Sales Price | $

$ 14,300

Gain (Loss) on Sale | $

$ (2,349)

Disposed of by Sale | 310-314 Invermay Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

47,480

Disposed of by Sale | 253-293 George Town Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

143,914

Disposed of by Sale | 7 Modal Crescent

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

164,160

Disposed of by Sale | 71-93 Whiteside Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

303,488

Disposed of by Sale | 9-13 Titanium Court

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

69,664

Disposed of by Sale | 16 Rodborough Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

90,525

Disposed of by Sale | 22 Rodborough Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

43,427

Disposed of by Sale | 127-161 Cherry Lane

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

278,570

Disposed of by Sale | 310-320 Pitt Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

313,865

Disposed of by Sale | 44-46 Mandarin Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

226,718

Disposed of by Sale | 19 Leadership Way

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

76,714

Disposed of by Sale | Australia Portfolio

Real Estate Properties [Line Items]

Number of Properties | property

11

Number of Buildings

11

Square Footage | ft²

1,758,525

Gross Sales Price | $

$ 232,955

Gain (Loss) on Sale | $

$ (47,872)

Disposed of by Sale | Widewaters Parkway

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

8

Square Footage | ft²

514,241

Disposed of by Sale | 5062 Brittonfield Parkway

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

40,162

Disposed of by Sale | Woodcliff Drive

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

6

Square Footage | ft²

516,760

Disposed of by Sale | Interstate Place

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

61,399

Disposed of by Sale | 1000 Pittsford - Victor Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

73,358

Disposed of by Sale | 1200 Pittsford - Victor Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

18,900

Disposed of by Sale | Corporate Crossing

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

5

Square Footage | ft²

216,126

Disposed of by Sale | Canal View Boulevard

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

3

Square Footage | ft²

118,375

Disposed of by Sale | 14 Classic Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

37,084

Disposed of by Sale | 110 W Fayette Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

304,906

Disposed of by Sale | 251 Salina Meadows Parkway

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

65,617

Disposed of by Sale | Upstate New York Portfolio

Real Estate Properties [Line Items]

Number of Properties | property

11

Number of Buildings

30

Square Footage | ft²

1,966,928

Gross Sales Price | $

$ 104,625

Gain (Loss) on Sale | $

$ (12,518)

Disposed of by Sale | 9040 Roswell Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

178,941

Disposed of by Sale | The Exchange

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

2

Square Footage | ft²

187,632

Disposed of by Sale | 3920 Arkwright Road

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

196,156

Disposed of by Sale | 1775 West Oak Commons Court

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

79,854

Disposed of by Sale | Georgia Portfolio

Real Estate Properties [Line Items]

Number of Properties | property

4

Number of Buildings

5

Square Footage | ft²

642,583

Gross Sales Price | $

$ 48,550

Gain (Loss) on Sale | $

$ (3,059)

Foreclosure | 225 Water Street

Real Estate Properties [Line Items]

Number of Properties | property

1

Number of Buildings

1

Square Footage | ft²

318,997

Gross Sales Price | $

$ 0

Gain (Loss) on Sale | $

$ 0

Real Estate Properties - Summ51

Real Estate Properties - Summary of Properties Disposed (Footnote) (Details) $ in Thousands	1 Months Ended			3 Months Ended		12 Months Ended
	May 31, 2015USD ($)building	Mar. 31, 2015building	Jan. 31, 2013building	Jun. 30, 2015building	May 31, 2015USD ($)building	Dec. 31, 2016USD ($)building	Dec. 31, 2015USD ($)building	Dec. 31, 2014USD ($)building
Real Estate Properties [Line Items]
Number of buildings sold | building			18
Principal balance						$ 1,151,634	$ 1,711,666
(Loss) gain on early extinguishment of debt						$ (2,680)	6,661	$ 4,909
Impairment of real estate							17,200
Foreign Currency Translation Adjustments
Real Estate Properties [Line Items]
Amounts reclassified from cumulative other comprehensive loss to net income							$ (63,207)
Disposed of by Sale
Real Estate Properties [Line Items]
Number of buildings sold | building						62	135	43
333 Laurel Oak Drive | Disposed of by Sale
Real Estate Properties [Line Items]
Number of buildings sold | building	2	1			3
225 Water Street | Mortgage notes
Real Estate Properties [Line Items]
Principal balance	$ 40,100				$ 40,100
(Loss) gain on early extinguishment of debt							$ 17,300
Australia Portfolio | Foreign Currency Translation Adjustments
Real Estate Properties [Line Items]
Amounts reclassified from cumulative other comprehensive loss to net income							$ (63,200)
Australia Portfolio | Disposed of by Sale
Real Estate Properties [Line Items]
Number of buildings sold | building				11

Real Estate Properties - Summ52

Real Estate Properties - Summary of Properties Sold (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2013buildingproperty	Dec. 31, 2016USD ($)building	Dec. 31, 2015USD ($)building	Dec. 31, 2014USD ($)ft²buildingproperty	Mar. 31, 2014ft²
Real Estate Properties [Line Items]
Number of Properties | property	3
Number of Buildings | building	18
Square Footage | ft²					5,641,450
Loss (gain) on asset impairment from discontinued operations		$ 0	$ 0	$ 2,238
Gain (loss) on early extinguishment of debt from discontinued operations		$ 0	$ 0	$ 3,345
Disposed of by Sale
Real Estate Properties [Line Items]
Number of Properties | property				14
Number of Buildings | building		62	135	43
Square Footage | ft²				2,784,098
Sales Price		$ 1,259,895	$ 1,999,413	$ 215,900
Loss (gain) on asset impairment from discontinued operations				2,200
Gain (loss) on early extinguishment of debt from discontinued operations				$ (3,300)

Real Estate Properties - Summ53

Real Estate Properties - Summary of Income Statement Information for Properties Included in Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statements of Operations:
Rental income									$ 409,071	$ 570,382	$ 691,699
Tenant reimbursements and other income									91,609	144,509	170,158
Total revenues	$ 103,546	$ 114,632	$ 145,367	$ 137,135	$ 138,934	$ 159,208	$ 203,694	$ 213,055	500,680	714,891	861,857
Operating expenses									200,706	324,948	387,982
General and administrative									50,256	57,457	113,155
Total expenses									441,244	593,568	913,741
Operating income (loss)									59,436	121,323	(51,884)
Interest and other income									10,331	5,989	1,561
Interest expense									(84,329)	(107,316)	(143,230)
Income from discontinued operations									$ 0	$ 0	8,389
Discontinued operations, properties sold
Statements of Operations:
Rental income											14,243
Tenant reimbursements and other income											1,900
Total revenues											16,143
Operating expenses											7,138
General and administrative											10
Total expenses											7,148
Operating income (loss)											8,995
Interest and other income											2
Interest expense											(608)
Income from discontinued operations											$ 8,389

Real Estate Properties - Schedu

Real Estate Properties - Schedule of Future Minimum Lease Payment Receivables and Payments (Details) $ in Thousands	Dec. 31, 2016USD ($)
Future minimum lease payments receivable:
2,017	$ 292,388
2,018	299,449
2,019	278,531
2,020	244,953
2,021	206,046
Thereafter	850,539
Total	$ 2,171,906

Lease Intangibles - Summary of

Lease Intangibles - Summary of the Carrying Amounts for Acquired Real Estate Leases and Assumed Real Estate Lease Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Acquired real estate leases	$ 146,854	$ 225,266
Acquired real estate leases, net	48,281	88,760
Leases, Acquired-in-Place
Finite-Lived Intangible Assets [Line Items]
Acquired real estate leases	102,102	147,056
Accumulated amortization	(71,320)	(91,301)
Leases Acquired-in-Place, Above Market Lease
Finite-Lived Intangible Assets [Line Items]
Acquired real estate leases	44,752	78,210
Accumulated amortization	(27,253)	(45,205)
Leases Acquired-in-Place, Below Market Lease
Finite-Lived Intangible Assets [Line Items]
Acquired real estate leases	10,434	19,742
Accumulated amortization	(8,488)	(15,446)
Assumed real estate lease obligations, net	$ 1,946	$ 4,296

Lease Intangibles - Schedule of

Lease Intangibles - Schedule of Amortization of Lease Intangibles (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Leases [Abstract]
Amortization of acquired in-place leases, Depreciation and amortization	$ 14,598	$ 26,787	$ 40,493
Amortization of above and below market leases, Increase (decrease) to rental income	$ (6,531)	$ (7,515)	$ (10,650)

Lease Intangibles - Schedule 57

Lease Intangibles - Schedule of Future Amortization of Net Intangible Lease Assets and Liabilities (Details) $ in Thousands	Dec. 31, 2016USD ($)
Leases [Abstract]
2,017	$ 9,670
2,018	8,397
2,019	6,178
2,020	5,882
2,021	5,252
Thereafter	10,956
Total	$ 46,335

Investment in Direct Financin58

Investment in Direct Financing Lease - Narrative (Details)	Dec. 31, 2016
Capital Leases, Net Investment in Direct Financing Leases [Abstract]
Percentage of term exceeding useful life of one office tower	75.00%

Equity Investments - Schedule o

Equity Investments - Schedule of Equity Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Equity in earnings of investees	$ 0	$ 0	$ 24,460
SIR
Schedule of Equity Method Investments [Line Items]
Equity in earnings of investees			24,516
AIC
Schedule of Equity Method Investments [Line Items]
Equity in earnings of investees			$ (56)

Equity Investments - Narrative

Equity Investments - Narrative (Details) $ / shares in Units, $ in Thousands	Jul. 09, 2014USD ($)$ / sharesshares	May 09, 2014USD ($)companyshares	Jul. 02, 2013$ / sharesshares	Jun. 30, 2014USD ($)$ / sharesshares	Jul. 09, 2014USD ($)$ / shares	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Jul. 03, 2013shares
Schedule of Equity Method Investments [Line Items]
Gain on sale of equity investment						$ 0	$ 0	$ 171,561
Gain on issuance of shares by an equity investee						$ 0	$ 0	$ 17,020
AIC
Schedule of Equity Method Investments [Line Items]
Equity investments, number of shares sold (in shares) | shares		20,000
Equity investments, proceeds from sale		$ 5,800
Ownership percentage		0.00%
Amount invested in equity investee		$ 5,800
Number of other companies which are shareholders of related party | company		5
SIR
Schedule of Equity Method Investments [Line Items]
Equity investments, number of shares sold (in shares) | shares	22,000,000
Equity investments, proceeds from sale	$ 704,800
Price per common share (in dollars per share) | $ / shares	$ 32.04				$ 32.04
Gain on sale of equity investment	$ 171,800
Ownership percentage	0.00%		56.00%	36.70%	0.00%
Issuance of shares, net (in shares) | shares			10,500,000	10,000,000
Common stock price per share (in dollars per share) | $ / shares			$ 28.25	$ 29
Proceeds from issuance of common shares, net				$ 277,400
Gain on issuance of shares by an equity investee				$ 16,900
Equity investments, common shares owned (in shares) | shares			22,000,000						22,000,000
Less than wholly owned subsidiary, parent ownership interest percentage									44.20%
Cash distributions					$ 20,700

Equity Investments - Summary of

Equity Investments - Summary of Unaudited Income Statement Information of Equity Method Investee (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								6 Months Ended	12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Jul. 09, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statements:
Rental income										$ 409,071	$ 570,382	$ 691,699
Tenant reimbursements and other income										91,609	144,509	170,158
Total revenues	$ 103,546	$ 114,632	$ 145,367	$ 137,135	$ 138,934	$ 159,208	$ 203,694	$ 213,055		500,680	714,891	861,857
Operating expenses										200,706	324,948	387,982
General and administrative										50,256	57,457	113,155
Total expenses										441,244	593,568	913,741
Operating income (loss)										59,436	121,323	(51,884)
Interest expense										(84,329)	(107,316)	(143,230)
(Loss) gain on early extinguishment of debt										(2,680)	6,661	4,909
Income (loss) from continuing operations before income taxes and equity in earnings of investees										233,639	102,221	(63)
Income tax expense										(745)	(2,364)	(3,191)
Equity in earnings of investees										0	0	24,460
Net income										$ 232,894	$ 99,857	$ 24,012
Weighted average common shares outstanding (in shares)										125,474	128,621	125,163
Net income per common share (in dollars per share)	$ 0.08	$ 0.67	$ 0.57	$ 0.31	$ 0.29	$ 0.18	$ 0.04	$ 0.05		$ 1.64	$ 0.56	$ (0.19)
SIR
Income Statements:
Rental income									$ 98,226
Tenant reimbursements and other income									16,980
Total revenues									115,206
Operating expenses									20,982
Depreciation and amortization									20,832
Acquisition related costs									374
General and administrative									7,731
Total expenses									49,919
Operating income (loss)									65,287
Interest expense									(7,287)
(Loss) gain on early extinguishment of debt									243
Income (loss) from continuing operations before income taxes and equity in earnings of investees									58,243
Income tax expense									(90)
Equity in earnings of investees									32
Net income									$ 58,185
Weighted average common shares outstanding (in shares)									52,394
Net income per common share (in dollars per share)									$ 1.11

Other Assets - Narrative (Detai

Other Assets - Narrative (Details)	1 Months Ended		12 Months Ended
	Jan. 31, 2013USD ($)buildingproperty	Apr. 30, 2012USD ($)	Dec. 31, 2016USD ($)building	Dec. 31, 2015USD ($)building	Dec. 31, 2014buildingproperty
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total real estate mortgage receivable included in other assets, carrying value			$ 8,080,000	$ 8,100,000
Number of properties sold or agreed to be sold | property	3
Number of buildings sold | building	18
Real estate mortgages receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for losses related to real estate mortgages receivable			$ 0	$ 0
Sales of properties resulting in gains and losses | Properties Sold in December
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage financing related to property sold		$ 400,000
Interest rate on real estate mortgage receivable		6.00%
Disposed of by Sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of properties sold or agreed to be sold | property					14
Number of buildings sold | building			62	135	43
Disposed of by Sale | Sales of properties resulting in gains and losses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage financing related to property sold	$ 7,700,000
Interest rate on real estate mortgage receivable	6.00%

Other Assets - Summary of Defer

Other Assets - Summary of Deferred Financing Fees, Deferred Leasing Costs and Capitalized Lease Incentives (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Other Assets [Abstract]
Deferred financing fees	$ 14,458	$ 14,458
Accumulated amortization	(11,093)	(9,478)
Deferred financing fees, net	3,365	4,980
Deferred leasing costs	133,771	166,390
Accumulated amortization	(41,148)	(56,162)
Deferred leasing costs, net	92,623	110,228
Capitalized lease incentives	10,344	11,623
Accumulated amortization	(2,680)	(2,498)
Capitalized lease incentives, net	$ 7,664	$ 9,125

Other Assets - Summary of Futur

Other Assets - Summary of Future Amortization of Deferred Leasing Costs and Capitalized Lease Incentives (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred Leasing Costs
2,017	$ 12,796
2,018	12,318
2,019	11,611
2,020	10,291
2,021	8,687
Thereafter	36,920
Deferred leasing costs, net	92,623	$ 110,228
Capitalized Lease Incentives
2,017	1,319
2,018	1,287
2,019	1,552
2,020	1,273
2,021	996
Thereafter	1,237
Capitalized lease incentives, net	$ 7,664	$ 9,125

Indebtedness - Schedule of Outs

Indebtedness - Schedule of Outstanding Indebtedness (Details) - USD ($)	Dec. 31, 2016	Dec. 15, 2016	Feb. 16, 2016	Dec. 31, 2015	Jan. 29, 2015
Debt Instrument [Line Items]
Outstanding indebtedness	$ 1,151,634,000			$ 1,711,666,000
Unamortized net premiums, discounts and deferred financing fees	(9,967,000)			(14,550,000)
Total	$ 1,141,667,000			1,697,116,000
Unsecured revolving credit facility, at LIBOR plus a premium
Debt Instrument [Line Items]
Interest rate stated percentage	2.02%
Outstanding indebtedness	$ 0			0
5-year unsecured term loan, at LIBOR plus a premium
Debt Instrument [Line Items]
Interest rate stated percentage	2.17%
Outstanding indebtedness	$ 200,000,000			200,000,000
Total	$ 200,000,000				$ 200,000,000
7-year unsecured term loan, at LIBOR plus a premium
Debt Instrument [Line Items]
Interest rate stated percentage	2.57%
Outstanding indebtedness	$ 200,000,000			200,000,000
Total	$ 200,000,000				$ 200,000,000
Unsecured floating rate debt
Debt Instrument [Line Items]
Interest rate stated percentage	2.37%
Outstanding indebtedness	$ 400,000,000			400,000,000
6.25% Senior Unsecured Notes due 2016
Debt Instrument [Line Items]
Interest rate stated percentage	0.00%		6.25%
Outstanding indebtedness	$ 0			139,104,000
6.25% Senior Unsecured Notes due 2017
Debt Instrument [Line Items]
Interest rate stated percentage	0.00%	6.25%
Outstanding indebtedness	$ 0			250,000,000
6.65% Senior Unsecured Notes due 2018
Debt Instrument [Line Items]
Interest rate stated percentage	6.65%
Outstanding indebtedness	$ 250,000,000			250,000,000
5.875% Senior Unsecured Notes due 2020
Debt Instrument [Line Items]
Interest rate stated percentage	5.88%
Outstanding indebtedness	$ 250,000,000			250,000,000
5.75% Senior Unsecured Notes due 2042
Debt Instrument [Line Items]
Interest rate stated percentage	5.75%
Outstanding indebtedness	$ 175,000,000			175,000,000
Unsecured fixed rate debt
Debt Instrument [Line Items]
Interest rate stated percentage	6.13%
Outstanding indebtedness	$ 675,000,000			1,064,104,000
Mortgage Notes Payable Encumbering Parkshore Plaza
Debt Instrument [Line Items]
Interest rate stated percentage	5.67%
Outstanding indebtedness	$ 41,275,000			41,275,000
Mortgage Notes Payable Encumbering 1735 Market Street
Debt Instrument [Line Items]
Interest rate stated percentage	0.00%
Outstanding indebtedness	$ 0			169,612,000
Mortgage Notes Payable Encumbering 206 East 9th Street
Debt Instrument [Line Items]
Interest rate stated percentage	5.69%
Outstanding indebtedness	$ 27,041,000			27,515,000
Mortgage Notes Payable Encumbering 33 Stiles Lane
Debt Instrument [Line Items]
Interest rate stated percentage	6.75%
Outstanding indebtedness	$ 2,415,000			2,785,000
Mortgage Notes Payable Encumbering 97 Newberry Road
Debt Instrument [Line Items]
Interest rate stated percentage	5.71%
Outstanding indebtedness	$ 5,903,000			6,375,000
Secured Fixed Rate Debt
Debt Instrument [Line Items]
Interest rate stated percentage	5.71%
Outstanding indebtedness	$ 76,634,000			$ 247,562,000

Indebtedness - Schedule of Ou66

Indebtedness - Schedule of Outstanding Indebtedness (Footnote) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Outstanding indebtedness	$ 1,151,634	$ 1,711,666
Mortgage Notes Payable Encumbering Parkshore Plaza, Non-Recourse
Debt Instrument [Line Items]
Outstanding indebtedness	3,200
Mortgage Notes Payable Encumbering 1735 Market Street
Debt Instrument [Line Items]
Outstanding indebtedness	$ 0	$ 169,612
Period for which interest on loan payable is fixed by a cash flow hedge	7 years
Interest accrual rate	5.66%
LIBOR | Mortgage Notes Payable Encumbering 1735 Market Street
Debt Instrument [Line Items]
Basis points on variable rate	2.625%

Indebtedness - Narrative (Detai

Indebtedness - Narrative (Details)

Dec. 15, 2016USD ($)

Nov. 10, 2016USD ($)

Feb. 16, 2016USD ($)

Dec. 01, 2015USD ($)

Aug. 03, 2015USD ($)

Jun. 05, 2015USD ($)

Jun. 03, 2015USD ($)

May 01, 2015USD ($)

Jan. 29, 2015USD ($)option

Dec. 05, 2014USD ($)

Nov. 17, 2014USD ($)

Oct. 31, 2014USD ($)

Sep. 15, 2014USD ($)

Aug. 01, 2014USD ($)

Jun. 27, 2014USD ($)

Mar. 11, 2014USD ($)

Dec. 31, 2015USD ($)

May 22, 2015

Dec. 31, 2015USD ($)

Dec. 31, 2016USD ($)buildingproperty

Dec. 31, 2015USD ($)

Dec. 31, 2014USD ($)

May 31, 2015USD ($)

Jan. 28, 2015USD ($)

Debt Instrument [Line Items]

Commitment fee percentage

0.25%

Outstanding indebtedness

$ 1,711,666,000

$ 1,711,666,000

$ 1,151,634,000

$ 1,711,666,000

Term loan amount outstanding

1,697,116,000

1,697,116,000

1,141,667,000

1,697,116,000

(Loss) gain on early extinguishment of debt

(2,680,000)

6,661,000

$ 4,909,000

Expense related to an interest rate swap

(10,331,000)

(5,989,000)

$ (1,561,000)

Real estate properties, net

2,988,413,000

2,988,413,000

2,101,635,000

2,988,413,000

Mortgage notes payable, net

246,510,000

$ 246,510,000

77,717,000

246,510,000

Designated as hedging instrument | Interest Rate Swap [Member] | Cash flow hedging

Debt Instrument [Line Items]

Expense related to an interest rate swap

$ 200,000

Revolving credit facility

Debt Instrument [Line Items]

Interest rate payable percentage

2.02%

Revolving credit facility

$ 0

Revolving credit facility | Minimum

Debt Instrument [Line Items]

Commitment fee percentage

0.125%

Revolving credit facility | Maximum

Debt Instrument [Line Items]

Commitment fee percentage

0.30%

Revolving credit facility | LIBOR

Debt Instrument [Line Items]

Basis points on variable rate

1.25%

Revolving credit facility | LIBOR | Minimum

Debt Instrument [Line Items]

Basis points on variable rate

0.875%

Revolving credit facility | LIBOR | Maximum

Debt Instrument [Line Items]

Basis points on variable rate

1.55%

Revolving credit facility | Base rate | Minimum

Debt Instrument [Line Items]

Basis points on variable rate

0.00%

Revolving credit facility | Base rate | Maximum

Debt Instrument [Line Items]

Basis points on variable rate

0.55%

Unsecured revolving credit facility | Revolving credit facility

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 750,000,000

$ 750,000,000

Basis points on variable rate

1.50%

Commitment fee percentage

0.35%

(Loss) gain on early extinguishment of debt

(400,000)

Number of extension options | option

2

Extension option term

6 months

Extension option fee, percent

0.075%

Amount available for borrowing

750,000,000

Unsecured revolving credit facility | Letter of credit

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 100,000,000

Unsecured term loan, due December 2016

Debt Instrument [Line Items]

Basis points on variable rate

1.85%

Outstanding indebtedness

$ 400,000,000

$ 500,000,000

Repayments of debt

$ 100,000,000

Loan facility, 5-year term

Debt Instrument [Line Items]

Outstanding indebtedness

200,000,000

$ 200,000,000

200,000,000

200,000,000

Term loan amount outstanding

$ 200,000,000

$ 200,000,000

Interest accrual rate

2.17%

Interest rate stated percentage

2.17%

Loan facility, 5-year term | LIBOR

Debt Instrument [Line Items]

Basis points on variable rate

1.40%

Loan facility, 5-year term | LIBOR | Minimum

Debt Instrument [Line Items]

Basis points on variable rate

0.90%

Loan facility, 5-year term | LIBOR | Maximum

Debt Instrument [Line Items]

Basis points on variable rate

1.80%

Loan facility, 5-year term | Revolving credit facility

Debt Instrument [Line Items]

Debt instrument, term

5 years

Loan facility, 7-year term

Debt Instrument [Line Items]

Outstanding indebtedness

200,000,000

$ 200,000,000

$ 200,000,000

200,000,000

Term loan amount outstanding

$ 200,000,000

$ 200,000,000

Interest accrual rate

2.57%

Interest rate stated percentage

2.57%

Loan facility, 7-year term | LIBOR

Debt Instrument [Line Items]

Basis points on variable rate

1.80%

Loan facility, 7-year term | LIBOR | Minimum

Debt Instrument [Line Items]

Basis points on variable rate

1.40%

Loan facility, 7-year term | LIBOR | Maximum

Debt Instrument [Line Items]

Basis points on variable rate

2.35%

Loan facility, 7-year term | Revolving credit facility

Debt Instrument [Line Items]

Debt instrument, term

7 years

Revolving credit facility and term loans

Debt Instrument [Line Items]

Additional increases in maximum amount of borrowings available

$ 1,150,000,000

6.25% Senior Unsecured Notes due 2017

Debt Instrument [Line Items]

Outstanding indebtedness

250,000,000

$ 250,000,000

$ 0

250,000,000

(Loss) gain on early extinguishment of debt

$ (100,000)

Amount of debt, redeemed, defeased, or prepaid

$ 250,000,000

Interest rate stated percentage

6.25%

0.00%

6.25% Senior Unsecured Notes due 2016

Debt Instrument [Line Items]

Outstanding indebtedness

139,104,000

139,104,000

$ 0

139,104,000

(Loss) gain on early extinguishment of debt

$ (100,000)

Amount of debt, redeemed, defeased, or prepaid

$ 139,100,000

Interest rate stated percentage

6.25%

0.00%

5.75% Senior Unsecured Notes due 2015

Debt Instrument [Line Items]

(Loss) gain on early extinguishment of debt

$ (100,000)

Amount of debt, redeemed, defeased, or prepaid

$ 138,800,000

Interest rate stated percentage

5.75%

Senior Notes 7.50% Due 2019 | Mortgage notes

Debt Instrument [Line Items]

(Loss) gain on early extinguishment of debt

$ (1,800,000)

Amount of debt, redeemed, defeased, or prepaid

$ 125,000,000

Interest rate stated percentage

7.50%

Senior Notes 6.40% Due 2015 | Mortgage notes

Debt Instrument [Line Items]

Amount of debt, redeemed, defeased, or prepaid

$ 33,400,000

Interest rate stated percentage

6.40%

Mortgage notes

Debt Instrument [Line Items]

Number of real estate properties secured by mortgage | property

4

Number of buildings secured by mortgage | building

7

Real estate properties, net

$ 102,700,000

Mortgage notes payable, net

77,700,000

Mortgage notes | 111 East Wacker Drive

Debt Instrument [Line Items]

(Loss) gain on early extinguishment of debt

(3,900,000)

Amount of debt, redeemed, defeased, or prepaid

$ 141,400,000

Mortgage notes | 1320 Main Street

Debt Instrument [Line Items]

(Loss) gain on early extinguishment of debt

(6,200,000)

Amount of debt, redeemed, defeased, or prepaid

$ 38,700,000

Mortgage notes | 225 Water Street in Jacksonville, Florida

Debt Instrument [Line Items]

Outstanding indebtedness

$ 40,100,000

(Loss) gain on early extinguishment of debt

17,300,000

Interest accrual rate

10.03%

Default interest

4.00%

Mortgage notes | Mortgage notes

Debt Instrument [Line Items]

(Loss) gain on early extinguishment of debt

$ (3,300,000)

Mortgage Notes Payable Encumbering 1735 Market Street

Debt Instrument [Line Items]

Outstanding indebtedness

$ 169,612,000

$ 169,612,000

$ 0

169,612,000

(Loss) gain on early extinguishment of debt

$ (2,400,000)

Interest accrual rate

5.66%

Interest rate stated percentage

0.00%

Mortgage Notes Payable Encumbering 1735 Market Street | LIBOR

Debt Instrument [Line Items]

Basis points on variable rate

2.625%

Mortgage Notes Payable Encumbering 1735 Market Street | Mortgage notes

Debt Instrument [Line Items]

Amount of debt, redeemed, defeased, or prepaid

$ 167,800,000

Mortgage Notes Payable Encumbering 111 Monument Circle | Mortgage notes

Debt Instrument [Line Items]

(Loss) gain on early extinguishment of debt

$ 600,000

Amount of debt, redeemed, defeased, or prepaid

$ 116,000,000

7.36% Mortgage Debt | Mortgage notes | 2501 20th Place South

Debt Instrument [Line Items]

(Loss) gain on early extinguishment of debt

$ (600,000)

Amount of debt, redeemed, defeased, or prepaid

$ 10,000,000

Mortgage Notes Payable Encumbering 6200 Glenn Carlson Drive | Mortgage notes

Debt Instrument [Line Items]

Repayments of debt

$ 7,800,000

Mortgage Notes Payable Encumbering 600 West Chicago Avenue | Mortgage notes

Debt Instrument [Line Items]

(Loss) gain on early extinguishment of debt

$ 6,700,000

Amount of debt, redeemed, defeased, or prepaid

$ 265,000,000

Mortgage Notes Payable Six Point One Four Percent Due in 2023 | Mortgage notes | Madrone Business Park

Debt Instrument [Line Items]

Amount of debt, redeemed, defeased, or prepaid

11,200,000

Mortgage Notes Payable 5.78% Due in 2015 | Mortgage notes | Stafford Commerce Center and Stafford Commerce Park

Debt Instrument [Line Items]

Amount of debt, redeemed, defeased, or prepaid

$ 8,500,000

Mortgage Notes Payable Encumbering 3920 Arkwright Road | Mortgage notes

Debt Instrument [Line Items]

Amount of debt, redeemed, defeased, or prepaid

$ 12,000,000

Indebtedness - Schedule of Requ

Indebtedness - Schedule of Required Principal Payments on Outstanding Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
2,017	$ 42,675
2,018	251,488
2,019	1,580
2,020	451,674
2,021	25,982
Thereafter	378,235
Total	$ 1,151,634	$ 1,711,666

Shareholders' Equity - Narrativ

Shareholders' Equity - Narrative (Details)	May 15, 2016USD ($)$ / sharesshares	Mar. 17, 2016USD ($)	Aug. 24, 2015USD ($)	Mar. 25, 2014USD ($)$ / sharesshares	Jan. 31, 2014USD ($)$ / shares	Sep. 30, 2016USD ($)authorization	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)shares	Dec. 31, 2016USD ($)$ / sharesshares	Sep. 14, 2015USD ($)
Class of Stock [Line Items]
Stock repurchase program, period in force		12 months	12 months
Redemption of shares | $							$ 275,000,000	$ 0	$ 0
Stock repurchase program, number of authorizations expired | authorization						2
Stock repurchase program, amount not utilized | $						$ 86,600,000
Distributions on common stock declared (in dollars per share) | $ / shares					$ 0.25
Distributions paid or declared on common shares | $					$ 29,600,000
Distribution for the excess of the market value of common shares issued above carrying value of series D preferred shares redeemed | $							0	0	16,205,000
Preferred stock redemption premium | $							$ 9,609,000	$ 0	$ 0
Distribution percentage to shareholders consisting of an alternative minimum tax adjustment							96.31%	0.00%	15.41%
RMR
Class of Stock [Line Items]
Common shares issued (in shares) | shares									90,135
Common Shares
Class of Stock [Line Items]
Common shares issued to holders of preferred shares (in shares) | shares								144	10,412,499
Number of shares repurchased (in shares) | shares							2,491,675	3,410,300		5,901,975
Stock Repurchased and Retired During Period, Price Per Share | $ / shares							$ 27.68	$ 25.76		$ 26.57
Stock repurchase program, authorized amount | $			$ 100,000,000
Stock repurchase program, additional authorized amount | $		$ 150,000,000									$ 100,000,000
Redemption of shares | $							$ 69,000,000	$ 87,800,000		$ 156,800,000
Stock repurchase program, remaining authorized repurchase amount | $							$ 106,600,000			$ 106,600,000
Stock repurchase program, number of shares surrendered (in shares) | shares							31,025
Common shares from conversion of preferred shares (in shares) | shares							2,363,103			2,363,103
Common Shares | Fundamental change conversion right
Class of Stock [Line Items]
Preferred shares converted into common shares (in shares) | shares				10,411,779
Series D
Class of Stock [Line Items]
Number of shares repurchased (in shares) | shares							0	301	10,264,503
Redemption of shares | $							$ 0	$ 3,000	$ 249,004,000
Preferred shares, of beneficial interest, shares outstanding (in shares) | shares							4,915,196	4,915,196		4,915,196
Preferred shares dividend (in dollars per share) | $ / shares							$ 1.625
Preferred shares, dividend yield							6.50%	6.50%
Initial conversion rate							0.480775			0.480775
Initial conversion price per share (in dollars per share) | $ / shares							$ 52			$ 52
Additional common shares (in shares) | shares							2,363,103
Liquidation preference (in dollars per share) | $ / shares				$ 25			$ 25			$ 25
Percentage of average closing market price of the entity's common stock based on which ratio for conversion of preferred shares into common shares is determined				98.00%			98.00%
Purchase price as a percentage of liquidation preference							100.00%
Number of consecutive trading days for calculating the average closing sale price of common shares				5 days
Common shares from conversion of preferred shares (in shares) | shares							4,915,196			4,915,196
Series D | Fundamental change conversion right
Class of Stock [Line Items]
Preferred shares converted into common shares (in shares) | shares				10,263,003
Distribution for the excess of the market value of common shares issued above carrying value of series D preferred shares redeemed | $				$ 16,200,000
Series E
Class of Stock [Line Items]
Number of shares repurchased (in shares) | shares							11,000,000
Redemption of shares | $							$ 275,000,000
Preferred shares, of beneficial interest, shares outstanding (in shares) | shares							0	11,000,000		0
Preferred shares dividend (in dollars per share) | $ / shares							$ 1.8125
Preferred shares, dividend yield							0.00%	7.25%
Liquidation preference (in dollars per share) | $ / shares							$ 25			$ 25
Stock redeemed during period (in shares) | shares	11,000,000
Redemption price (in dollars per share) | $ / shares	$ 25
Preferred stock, redemption amount | $	$ 275,000,000
Preferred stock redemption premium | $							$ (9,609,000)

Shareholders' Equity - Schedule

Shareholders' Equity - Schedule of Distributions Paid Per Common Share (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
Ordinary income	0.00%	0.00%	0.00%
Return of capital	0.00%	0.00%	0.00%
Capital gain	0.00%	0.00%	100.00%
Unrecaptured Section 1250 gain	0.00%	0.00%	0.00%
Common share, distributions paid	0.00%	0.00%	100.00%

Shareholders' Equity - Schedu71

Shareholders' Equity - Schedule of Declared Distributions (Details) - $ / shares	Oct. 10, 2016	Jul. 11, 2016	Apr. 15, 2016	Jan. 26, 2016
Series D
Class of Stock [Line Items]
Dividend declared (in dollars per share)	$ 0.40625	$ 0.40625	$ 0.40625	$ 0.40625
Series E
Class of Stock [Line Items]
Dividend declared (in dollars per share)	$ 0	$ 0	$ 0.453125	$ 0.453125

Cumulative Other Comprehensiv72

Cumulative Other Comprehensive Loss - Schedule of Amounts Recognized in Cumulative Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Unrealized Loss on Derivative Instruments and Other Assets
Amounts recognized in cumulative other comprehensive income (Loss) by component
Beginning balance	$ (3,687)	$ (4,299)
Other comprehensive loss before reclassifications	(554)	(1,232)
Amounts reclassified from cumulative other comprehensive loss to net income	4,033	1,844
Net current period other comprehensive income	3,479	612
Ending balance	(208)	(3,687)
Foreign Currency Translation Adjustments
Amounts recognized in cumulative other comprehensive income (Loss) by component
Beginning balance	0	(48,917)
Other comprehensive loss before reclassifications		(14,290)
Amounts reclassified from cumulative other comprehensive loss to net income		63,207
Net current period other comprehensive income		48,917
Ending balance		0
Cumulative Other Comprehensive Loss
Amounts recognized in cumulative other comprehensive income (Loss) by component
Beginning balance	$ (3,687)	(53,216)
Other comprehensive loss before reclassifications		(15,522)
Amounts reclassified from cumulative other comprehensive loss to net income		65,051
Net current period other comprehensive income		49,529
Ending balance		$ (3,687)

Cumulative Other Comprehensiv73

Cumulative Other Comprehensive Loss - Schedule of Reclassifications Out of Cumulative Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassifications out of cumulative other comprehensive income (Loss)
Interest expense	$ 84,329	$ 107,316	$ 143,230
Interest and other income	10,331	5,989	1,561
Gain on sale of properties, net	250,886	84,421	$ 0
Unrealized Loss on Derivative Instruments and Other Assets
Reclassifications out of cumulative other comprehensive income (Loss)
Amounts reclassified from cumulative other comprehensive loss to net income	(4,033)	(1,844)
Unrealized Loss on Derivative Instruments and Other Assets | Amounts Reclassified from Cumulative Other Comprehensive Loss to Net Income | Interest rate swap contracts
Reclassifications out of cumulative other comprehensive income (Loss)
Interest expense	3,792	4,924
Interest and other income	241	0
Foreign Currency Translation Adjustments
Reclassifications out of cumulative other comprehensive income (Loss)
Amounts reclassified from cumulative other comprehensive loss to net income		(63,207)
Foreign Currency Translation Adjustments | Amounts Reclassified from Cumulative Other Comprehensive Loss to Net Income
Reclassifications out of cumulative other comprehensive income (Loss)
Gain on sale of properties, net	0	63,207
Accumulated Net Investment Gain (Loss) Attributable to Parent | Amounts Reclassified from Cumulative Other Comprehensive Loss to Net Income
Reclassifications out of cumulative other comprehensive income (Loss)
Interest and other income	0	3,080
Cumulative Other Comprehensive Loss
Reclassifications out of cumulative other comprehensive income (Loss)
Amounts reclassified from cumulative other comprehensive loss to net income		(65,051)
Cumulative Other Comprehensive Loss | Amounts Reclassified from Cumulative Other Comprehensive Loss to Net Income
Reclassifications out of cumulative other comprehensive income (Loss)
Amounts reclassified from cumulative other comprehensive loss to net income	$ 4,033	$ 65,051

Income Taxes - Schedule of Prov

Income Taxes - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
State	$ 745	$ 270	$ 350
Federal	0	513	0
Foreign	0	2,336	2,772
Current income tax expense (benefit)	745	3,119	3,122
Deferred:
Foreign	0	(755)	69
Deferred income tax expense (benefit)	0	(755)	69
Income tax expense	$ 745	$ 2,364	$ 3,191

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Effective Tax Rate and the U.S. Federal Statutory Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Taxes at statutory U.S. federal income tax rate	35.00%	35.00%	35.00%
Dividends paid deduction and net operating loss utilization	(35.00%)	(35.00%)	(35.00%)
Federal taxes on built-in gain	0.00%	0.50%	0.00%
State, local, and foreign income taxes	0.32%	1.81%	11.73%
Effective tax rate	0.32%	2.31%	11.73%

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Australian Properties
Real Estate Properties [Line Items]
Income tax expense (benefit)	$ 1.6

Derivative Instruments - Narrat

Derivative Instruments - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Mar. 04, 2016
Derivative [Line Items]
Expense related to an interest rate swap	$ (10,331)	$ (5,989)	$ (1,561)
Cash flow hedging | Designated as hedging instrument
Derivative [Line Items]
Estimated gain (loss) reclassification from OCI to income	(49)
Cash flow hedging | Designated as hedging instrument | Interest rate swap contracts
Derivative [Line Items]
Amount of hedged item	167,800
Expense related to an interest rate swap	200
Cash flow hedging | Designated as hedging instrument | Interest rate cap
Derivative [Line Items]
Derivative, notional amount	$ 400,000			$ 400,000
LIBOR | Interest rate cap
Derivative [Line Items]
Derivative, cap interest rate				2.50%

Derivative Instruments - Schedu

Derivative Instruments - Schedule of Outstanding Interest Rate Derivatives Designated as Cash Flow Hedges of Interest Rate Risk (Details) - Interest rate cap - Cash flow hedging - Designated as hedging instrument $ in Thousands	Dec. 31, 2016USD ($)financial_instrument	Mar. 04, 2016USD ($)
Derivative [Line Items]
Number of Instruments | financial_instrument	1
Notional Amount (in thousands) | $	$ 400,000	$ 400,000

Derivative Instruments - Sche79

Derivative Instruments - Schedule of Fair Value of Derivative Financial Instruments (Details) - Cash flow hedging - Designated as hedging instrument - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Interest rate cap | Other assets
Derivatives, Fair Value [Line Items]
Interest Rate Derivative Designated as Hedging Instrument	$ 314	$ 0
Interest rate swap contracts | Accounts payable and accrued expenses
Derivatives, Fair Value [Line Items]
Interest Rate Derivative Designated as Hedging Instrument	$ 0	$ 3,687

Derivative Instruments - Sche80

Derivative Instruments - Schedule of Gain or Loss Recognized on Interest Rate Derivatives Designated as Cash Flow Hedges (Details) - Cash flow hedging - Designated as hedging instrument - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss recognized in cumulative other comprehensive loss (effective portion)	$ (554)	$ (1,149)	$ (776)
Amount of loss reclassified from cumulative other comprehensive loss into interest expense (effective portion)	3,792	4,924	5,020
Amount of loss recognized in income (ineffective portion and amount excluded from effectiveness testing)	$ 241	$ 0	$ 0

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) $ / shares in Units, $ in Millions	Jun. 15, 2016USD ($)trustee$ / sharesshares	Jan. 26, 2016tranche$ / sharesshares	Jun. 16, 2015USD ($)trustee$ / sharesshares	Jan. 28, 2015$ / sharesshares	Mar. 25, 2014shares	Jan. 28, 2014trustee$ / sharesshares	Dec. 31, 2020shares	Dec. 31, 2019shares	Dec. 31, 2018shares	Dec. 31, 2017shares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Jul. 31, 2014trustee	Dec. 31, 2013shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity awards granted (in shares)													4,000
Granted (in dollars per share) | $ / shares											$ 0		$ 23.46
Number of independent trustees | trustee														5
Unvested (in shares)													0		130,914
Vested (in shares)													134,914
Common shares of beneficial interest, par value (in dollars per share) | $ / shares											$ 0.01	$ 0.01
Trustees | Common Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares granted in period (in shares)						2,000
Common shares of beneficial interest, par value (in dollars per share) | $ / shares						$ 0.01
Price per common share (in dollars per share) | $ / shares						$ 23.46
Number of trustees | trustee						2
Officers and Employees | Employee Stock | RMR
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense | $													$ 3.4
Officers and Employees | Employee Stock | Common Shares | RMR
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares issued (in shares)					130,914
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term of incentive plan after effective date											4 years	4 years	4 years
Number of tranches | tranche		2
Number of equity awards granted (in shares)		277,386		256,467
Unvested (in shares)											2,572,768	1,884,110	1,266,237		0
Vested (in shares)											0	0	0
Estimated future compensation expense for unvested shares | $											$ 19.2
Weighted average period over which compensation expense will be recorded											2 years
Restricted stock units | Vesting on January 26, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percent		50.00%
Restricted stock units | Vesting on January 26, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percent		50.00%
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of independent trustees | trustee	9		9
Share based compensation amount | $	$ 0.1		$ 0.1
Number of equity awards granted (in shares)	31,167	136,623	34,587	126,319							167,790	160,906	713,727
Price per share (in dollars per share) | $ / shares	$ 28.88		$ 26.02
Vesting period	1 year	4 years	1 year	4 years
Granted (in dollars per share) | $ / shares		$ 26.93		$ 26.58							$ 27.29	$ 26.46	$ 26.66
Unvested (in shares)											752,209	776,456	710,182		0
Vested (in shares)											191,498	86,517	3,545
Estimated future compensation expense for unvested shares | $											$ 12.4
Weighted average period over which compensation expense will be recorded											2 years 1 month 6 days
Restricted shares | Scenario, Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested (in shares)							67,029	95,554	373,140	216,486
Restricted shares | Independent Trustee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity awards granted (in shares)	3,463		3,843
Restricted stock units, maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity awards granted (in shares)		691,385		639,250									1,266,237
Granted (in dollars per share) | $ / shares											$ 15.57	$ 15.47	$ 15.99
2015 Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term of incentive plan after effective date			10 years
2015 Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares available for issuance (in shares)			3,250,000
Share award plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares available for issuance (in shares)											2,358,464
Share award plan | General and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense | $											$ 18.5	$ 15.4	$ 2.6

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Restricted Share and Restricted Stock Unit Activity (Details) - $ / shares	Jun. 15, 2016	Jan. 26, 2016	Jun. 16, 2015	Jan. 28, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Number of Shares
Unvested, Beginning (in shares)						0	130,914
Granted (in shares)							4,000
Vested (in shares)							(134,914)
Unvested, Ending (in shares)							0
Weighted Average Grant Date Fair Value
Unvested Shares, Weighted Average Grant Date Fair Value (in dollars per share)							$ 0	$ 20.70
Granted (in dollars per share)					$ 0		23.46
Vested (in dollars per share)							$ 25.79
Restricted shares
Number of Shares
Unvested, Beginning (in shares)					776,456	710,182	0
Granted (in shares)	31,167	136,623	34,587	126,319	167,790	160,906	713,727
Vested (in shares)					(191,498)	(86,517)	(3,545)
Forfeited (in shares)					(539)	(8,115)
Unvested, Ending (in shares)					752,209	776,456	710,182
Weighted Average Grant Date Fair Value
Unvested Shares, Weighted Average Grant Date Fair Value (in dollars per share)								0
Granted (in dollars per share)		$ 26.93		$ 26.58	$ 27.29	$ 26.46	$ 26.66
Vested (in dollars per share)					26.54	26.02	$ 26.66
Forfeited (in dollars per share)					$ 26.82	$ 26.64
Restricted stock units
Number of Shares
Unvested, Beginning (in shares)					1,884,110	1,266,237	0
Granted (in shares)		277,386		256,467
Vested (in shares)					0	0	0
Forfeited (in shares)					(2,727)	(21,377)
Unvested, Ending (in shares)					2,572,768	1,884,110	1,266,237
Weighted Average Grant Date Fair Value
Unvested Shares, Weighted Average Grant Date Fair Value (in dollars per share)								$ 0
Vested (in dollars per share)					$ 0	$ 0	$ 0
Forfeited (in dollars per share)					15.54	15.80
Restricted stock units, maximum
Number of Shares
Granted (in shares)		691,385		639,250			1,266,237
Weighted Average Grant Date Fair Value
Granted (in dollars per share)					$ 15.57	$ 15.47	$ 15.99

Share-Based Compensation - Su83

Share-Based Compensation - Summary of Assumptions and Fair Values for Restricted Stock Units Granted in the Period (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology
Fair value of RSUs granted (in dollars per share)	$ 0		$ 23.46
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology
Expected term	4 years	4 years	4 years
Expected volatility	0.00%	0.00%	0.00%
Expected dividend yield	1.86%	1.88%	1.88%
Risk-free rate	1.07%	0.81%	0.84%
Restricted stock units, target
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology
Fair value of RSUs granted (in dollars per share)	$ 38.80	$ 0	$ 0
Restricted stock units, maximum
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology
Fair value of RSUs granted (in dollars per share)	$ 15.57	$ 15.47	$ 15.99

Share-Based Compensation - Sche

Share-Based Compensation - Schedule of Shares Granted and Vested (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2014
Number of Shares
Unvested, Beginning (in shares)		130,914
Granted (in shares)		4,000
Vested (in shares)		(134,914)
Unvested, Ending (in shares)		0
Weighted Average Grant Date Fair Value
Unvested Shares, Beginning (in dollars per share)		$ 20.70
Granted (in dollars per share)	$ 0	23.46
Vested (in dollars per share)		25.79
Unvested Shares, Ending (in dollars per share)		$ 0

Defined Contribution Plan (Deta

Defined Contribution Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent of match	100.00%
Employer matching contribution, percent of employees' gross pay	3.00%
Employer matching contribution in excess of three percent of employee contribution, percent of match	50.00%
Employer maximum contribution	$ 8,000
Employer contribution amount	$ 400,000	$ 300,000
Minimum
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent of employees' gross pay	3.00%
Maximum
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution, percent of employees' gross pay	5.00%

Fair Value of Assets and Liab86

Fair Value of Assets and Liabilities - Schedule of Assets and Liabilities Measure at Fair Value (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Recurring Fair Value Measurements:
Effective portion of interest rate cap contract	$ 314	$ (3,687)
Derivative liability		(7,219)
Level 1
Recurring Fair Value Measurements:
Effective portion of interest rate cap contract	0	0
Derivative liability		0
Level 2
Recurring Fair Value Measurements:
Effective portion of interest rate cap contract	314	(3,687)
Derivative liability		0
Level 3
Recurring Fair Value Measurements:
Effective portion of interest rate cap contract	$ 0	0
Derivative liability		$ (7,219)

Fair Value of Assets and Liab87

Fair Value of Assets and Liabilities - Narrative (Details) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2016USD ($)	Aug. 31, 2015USD ($)	Dec. 31, 2016USD ($)Tenant	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Jul. 31, 2014USD ($)$ / 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
Average closing price per common share during first and second year after date (in dollars per share) | $ / shares						$ 26

Fair Value of Assets and Liab88

Fair Value of Assets and Liabilities - Schedule of Valuation Techniques and Significant Unobservable Inputs Used for Level 3 Fair Value Measurements (Details) - Derivative Financial Instruments, Liabilities - Level 3 $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair value of liabilities	$ 7,219
Risk-free rate	0.52%
Volatility	20.00%

Fair Value of Assets and Liab89

Fair Value of Assets and Liabilities - Schedule of Fair Value and Carrying Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Principal Balance
Fair value of financial instruments
Senior unsecured debt and mortgage notes payable	$ 1,151,634	$ 1,711,666
Fair Value
Fair value of financial instruments
Senior unsecured debt and mortgage notes payable	$ 1,167,031	$ 1,749,211

Earnings Per Common Share - Sch

Earnings Per Common Share - Schedule of Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator for earnings per common share - basic and diluted:
Income from continuing operations									$ 232,894	$ 99,857	$ 21,206
Preferred distributions									(17,956)	(27,924)	(32,095)
Excess fair value of consideration paid over carrying value of preferred shares									(9,609)	0	0
Excess fair value of consideration over carrying value of preferred shares									0	0	(16,205)
Income (loss) from continuing operations attributable to Equity Commonwealth common shareholders									205,329	71,933	(27,094)
Discontinued operations									0	0	2,806
Net income (loss) attributable to Equity Commonwealth common shareholders	$ 10,263	$ 84,391	$ 71,254	$ 39,421	$ 36,164	$ 23,485	$ 5,635	$ 6,649	$ 205,329	$ 71,933	$ (24,288)
Denominator for earnings per common share - basic and diluted:
Weighted average common shares outstanding — basic (in shares)									125,474	128,621	125,163
Weighted average common shares outstanding — diluted (in shares)									126,768	129,437	125,163
Earnings per share - basic:
Income from continuing operations attributable to Equity Commonwealth common shareholders (in dollars per share)									$ 1.64	$ 0.56	$ (0.21)
Discontinued operations (in dollars per share)									0	0	0.02
Net income (loss) (in dollars per share)	$ 0.08	$ 0.67	$ 0.57	$ 0.31	$ 0.29	$ 0.18	$ 0.04	$ 0.05	1.64	0.56	(0.19)
Earnings per share - diluted:
Income from continuing operations attributable to Equity Commonwealth common shareholders (in dollars per share)									1.62	0.56	(0.21)
Discontinued operations (in dollars per share)									0	0	0.02
Net income (loss) (in dollars per share)	$ 0.08	$ 0.67	$ 0.56	$ 0.31	$ 0.28	$ 0.18	$ 0.04	$ 0.05	$ 1.62	$ 0.56	$ (0.19)
Effect of Series D preferred shares; 6 1/2% cumulative convertible
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred shares, dividend yield									6.50%	6.50%	6.50%
Anti-dilutive securities:
Anti-dilutive securities (in shares)									2,363	2,363	4,175
Effect of Series D preferred shares; 6 1/2% cumulative convertible
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred shares, dividend yield									6.50%	6.50%

Earnings Per Common Share - S91

Earnings Per Common Share - Schedule of Computation of Basic and Diluted Earnings Per Share (Footnote) (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
RSUs vested (in shares)			134,914
Restricted stock units
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
RSUs vested (in shares)	0	0	0
Common shares issued (in shares)	1,027,000	1,143,000	0
Weighted average common shares outstanding — diluted (in shares)	1,294,000	816,000

Segment Information - Narrative

Segment Information - Narrative (Details) - segment	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016
Segment Reporting [Abstract]
Number of reportable segments	2	1
Percentage of CBD and suburban properties that are office properties (more than)		95.00%

Related Person Transactions - N

Related Person Transactions - Narrative (Details)

Jul. 20, 2015option

Mar. 01, 2015USD ($)

Dec. 31, 2014USD ($)

Sep. 30, 2014USD ($)trustee

Sep. 29, 2014trusteeagreement

Jul. 09, 2014USD ($)$ / sharesshares

Jun. 30, 2014USD ($)ft²shares

Jun. 01, 2014optionparking_space

May 09, 2014USD ($)companyshares

Mar. 01, 2014USD ($)property

Dec. 19, 2013USD ($)

Mar. 15, 2013shares

Feb. 29, 2012

Aug. 31, 2016USD ($)

Aug. 31, 2015USD ($)

Mar. 31, 2012USD ($)shares

Jun. 30, 2014ft²officeshares

Feb. 28, 2015USD ($)

Jun. 30, 2014USD ($)ft²shares

Sep. 30, 2014USD ($)

Dec. 31, 2016USD ($)trustee

Dec. 31, 2015USD ($)installment

Dec. 31, 2014USD ($)

Dec. 31, 2009trustee

Jul. 31, 2014USD ($)$ / shares

May 31, 2014USD ($)

May 08, 2014

Mar. 31, 2014ft²

Jan. 31, 2013trustee

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Property square feet | ft²

5,641,450

SIR

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Number of former managing trustees | trustee

2

Number of former independent trustees | trustee

1

Prior ownership percentage

100.00%

Shares sold (in shares) | shares

9,200,000

Less than wholly owned subsidiary, common shares owned (in shares) | shares

22,000,000

22,000,000

22,000,000

Proceeds from IPO

$ 180,800,000

Equity investments, number of shares sold (in shares) | shares

22,000,000

Price per common share (in dollars per share) | $ / shares

$ 32.04

Equity investments, proceeds from sale

$ 704,800,000

Ownership percentage

0.00%

36.70%

36.70%

36.70%

Parent Company

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Number of properties | property

1

Maximum

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Ownership percentage

50.00%

Two North Riverside Plaza Joint Venture Limited Partnership

Related Party Transaction [Line Items]

Lease term

5 years

Number of renewal options | option

1

Renewal option term

5 years

Tenant Improvements

$ 700,000

Expenses from transactions with related party

800,000

$ 13,000

$ 100,000

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

2,017

800,000

2,018

900,000

2,019

900,000

2,020

900,000

Due to related party

$ 100,000

Equity Group

Related Party Transaction [Line Items]

Lease term

1 year

Number of renewal options | option

1

Renewal option term

3 months

Equity Group | Terminated Agreement [Member]

Related Party Transaction [Line Items]

Expenses from transactions with related party

200,000

100,000

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Number of parking spaces | parking_space

1

Equity Residential Management, L.L.C.

Related Party Transaction [Line Items]

Expenses from transactions with related party

$ 400,000

38,000

Related/Corvex

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Amount of reimbursements payable to related party

$ 33,500,000

Reimbursement amount paid

$ 8,200,000

$ 8,400,000

$ 16,700,000

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

8,400,000

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

$ 8,400,000

Related/Corvex | Minimum

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Price per common share during one year period after date (in dollars per share) | $ / shares

$ 26

Price per common share during first and second year after date (in dollars per share) | $ / shares

$ 26

RMR

Related Party Transaction [Line Items]

Lease term

3 years

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Number of agreements | agreement

3

Number of former managing trustees | trustee

1

Number of former independent trustees | trustee

2

Business management fees

$ 31,700,000

Shares issued (in shares) | shares

68,206

Property management fees as a percentage of gross collected rents

3.00%

3.00%

3.00%

Construction supervision fees as a percentage of construction costs

5.00%

5.00%

5.00%

Property management and construction supervision fees

$ 13,800,000

Number of regional offices leased | office

11

Rental income earned

$ 400,000

Property square feet | ft²

36,500

36,500

36,500

Legal fees and costs

$ 5,400,000

Number of properties | property

2

Total rent due

$ 1,100,000

RMR | Parent Company

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Number of properties acquired or agreed to be acquired | property

1

RMR | Amended Agreement

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Base management fee payable as a percentage of average historical cost of real estate investments, up to specified amount

0.70%

Base management fee payable as a percentage of average historical cost of real estate investments, located outside the United States, Puerto Rico and Canada

1.00%

Base management fee payable as a percentage of average historical cost of real estate investments, exceeding specified amount

0.50%

Base management fee payable as a percentage of average closing price per share of common shares on NYSE

0.70%

Base management fee payable as a percentage of average market capitalization exceeding specified amount

0.50%

Base business management fee payable in cash

90.00%

Base business management fee payable in common shares

10.00%

10.00%

10.00%

10.00%

Minimum ownership of outstanding common shares of related party required to engage the same manager or common managing trustees

10.00%

Percentage for limitation and adjustments of incentive management fee payable

12.00%

Measurement period of incentive management fee

3 years

Incentive management fee vesting on the date of issuance, percent

33.33%

Incentive management fee vesting one year from the date of issuance, percent

33.34%

Incentive management fee vesting in two years from the date of issuance, percent

33.33%

RMR | Amended Agreement | 2014

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Measurement period of incentive management fee

1 year

RMR | Amended Agreement | 2015

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Measurement period of incentive management fee

2 years

RMR | Maximum | Amended Agreement

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Threshold amount of real estate investments for payment of base management fee

$ 250,000,000

Base management fee payable, average market capitalization

$ 250,000,000

RMR Australia

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Property management fees as a percentage of gross collected rents

3.00%

Construction supervision fees as a percentage of construction costs

5.00%

Number of former trustees owning subsidiary | trustee

2

Compensation for business management and real estate investment services as a percentage of average historical cost of CWHAT's real estate investments

0.50%

Compensation for property management services as a percentage of difference between 3.5% of collected gross rents and the aggregate of all amounts paid or payable by or on behalf of CWHAT to third party property managers

50.00%

Compensation for construction supervision services as a percentage of difference between 5.0% of construction costs and any amounts paid to third parties for construction management and/or supervision

50.00%

Business and property management fees

$ 900,000

RMR and RMR Australia

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Monthly management fees

$ 100,000

$ 1,200,000

Pro rata portion of the current year's incentive fee under the existing business management agreement

$ 15,300,000

GOV

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Prior ownership percentage

100.00%

Number of former trustees currently managing trustees | trustee

2

Shares sold (in shares) | shares

9,950,000

AIC

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Equity investments, number of shares sold (in shares) | shares

20,000

Equity investments, proceeds from sale

$ 5,800,000

Ownership percentage

0.00%

12.50%

Amount invested in equity investee

$ 5,200,000

Number of other companies which are shareholders of related party | company

4

Coverage amount for property insurance

$ 500,000,000

Premium for property insurance

$ 6,000,000

Equity Commonwealth and REIT Management and Research LLC

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Settlement receivable

$ 12,000,000

Number of settlement receivable installments | installment

3

Settlement receivable installment amount

$ 3,000,000

$ 3,000,000

$ 6,000,000

Equity Commonwealth

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

Total rent due

$ 9,200,000

Selected Quarterly Financial 94

Selected Quarterly Financial Data - Summary of Unaudited Quarterly Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 103,546	$ 114,632	$ 145,367	$ 137,135	$ 138,934	$ 159,208	$ 203,694	$ 213,055	$ 500,680	$ 714,891	$ 861,857
Net income attributable to Equity Commonwealth common shareholders	$ 10,263	$ 84,391	$ 71,254	$ 39,421	$ 36,164	$ 23,485	$ 5,635	$ 6,649	$ 205,329	$ 71,933	$ (24,288)
Net income attributable to Equity Commonwealth common shareholders per share—basic (in dollars per share)	$ 0.08	$ 0.67	$ 0.57	$ 0.31	$ 0.29	$ 0.18	$ 0.04	$ 0.05	$ 1.64	$ 0.56	$ (0.19)
Net income attributable to Equity Commonwealth common shareholders per share—diluted (in dollars per share)	$ 0.08	$ 0.67	$ 0.56	$ 0.31	$ 0.28	$ 0.18	$ 0.04	$ 0.05	$ 1.62	$ 0.56	$ (0.19)

Selected Quarterly Financial 95

Selected Quarterly Financial Data - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2016	Jun. 30, 2016
Schedule of Equity Method Investments [Line Items]
Gain on sale of properties	$ 82.2	$ 106.4
111 Monument Circle
Schedule of Equity Method Investments [Line Items]
Lease termination fee		$ 16.6

Subsequent Events - Narrative (

Subsequent Events - Narrative (Details) $ / shares in Units, $ in Millions

Feb. 15, 2017$ / shares

Jan. 31, 2017USD ($)ft²building

Jan. 12, 2017$ / shares

Oct. 10, 2016$ / shares

Jul. 11, 2016$ / shares

Apr. 15, 2016$ / shares

Jan. 26, 2016$ / shares

Feb. 28, 2017USD ($)

Jan. 31, 2013building

Dec. 31, 2016building

Dec. 31, 2015building

Dec. 31, 2014ft²building

Mar. 31, 2014ft²

Subsequent Event [Line Items]

Number of buildings sold | building

18

Property square feet | ft²

5,641,450

Series D

Subsequent Event [Line Items]

Dividend declared (in dollars per share) | $ / shares

$ 0.40625

$ 0.40625

$ 0.40625

$ 0.40625

Disposed of by Sale

Subsequent Event [Line Items]

Number of buildings sold | building

62

135

43

Property square feet | ft²

2,784,098

Subsequent event | Series D

Subsequent Event [Line Items]

Dividend declared (in dollars per share) | $ / shares

$ 0.40625

Dividends paid (in dollars per share) | $ / shares

$ 0.40625

Subsequent event | Disposed of by Sale

Subsequent Event [Line Items]

Number of buildings sold | building

1

Property square feet | ft²

589,380

Gross proceeds from sale of real estate anticipated | $

$ 60.1

US Treasury Notes | Subsequent event

Subsequent Event [Line Items]

Purchase of US Treasury Notes | $

$ 100

Treasury notes, term

2 years

Treasury notes, coupon rate

1.125%

Treasury notes, weighted average yield

1.227%

SCHEDULE II VALUATION AND QUA97

SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS (Details) - Allowance for doubtful accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in valuation and qualifying accounts
Balance at Beginning of Period	$ 7,715	$ 6,565	$ 7,885
Charged to Costs and Expenses	1,056	4,533	2,196
Deductions	(3,666)	(3,383)	(3,516)
Balance at End of Period	$ 5,105	$ 7,715	$ 6,565

SCHEDULE III REAL ESTATE AND 98

SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 76,634
Initial Cost to Company
Land	286,511
Buildings and Improvements	2,133,579
Costs Capitalized Subsequent to Acquisition, Net	504,021
Impairment/Write Downs	(67,221)
Cost Amount Carried at Close of Period
Land	286,186
Buildings and Improvements	2,570,704
Total	2,856,890
Accumulated Depreciation	755,255	$ 898,939	$ 1,030,445	$ 895,059
Parkshore Plaza, Folsom, CA
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	41,275
Initial Cost to Company
Land	4,370
Buildings and Improvements	41,749
Costs Capitalized Subsequent to Acquisition, Net	5,630
Impairment/Write Downs	(6,310)
Cost Amount Carried at Close of Period
Land	3,841
Buildings and Improvements	41,598
Total	45,439
Accumulated Depreciation	6,695
1225 Seventeenth Street, Denver, CO
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	22,400
Buildings and Improvements	110,090
Costs Capitalized Subsequent to Acquisition, Net	24,798
Impairment/Write Downs	(485)
Cost Amount Carried at Close of Period
Land	22,400
Buildings and Improvements	134,403
Total	156,803
Accumulated Depreciation	25,990
5073, 5075, & 5085 S. Syracuse Street, Denver, CO
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	4,720
Buildings and Improvements	58,890
Costs Capitalized Subsequent to Acquisition, Net	0
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	4,720
Buildings and Improvements	58,890
Total	63,610
Accumulated Depreciation	9,815
1601 Dry Creek Drive, Longmont, CO
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	3,714
Buildings and Improvements	24,397
Costs Capitalized Subsequent to Acquisition, Net	6,439
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	3,715
Buildings and Improvements	30,835
Total	34,550
Accumulated Depreciation	10,012
97 Newberry Road, East Windsor, CT
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	5,903
Initial Cost to Company
Land	2,960
Buildings and Improvements	12,360
Costs Capitalized Subsequent to Acquisition, Net	30
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	2,943
Buildings and Improvements	12,407
Total	15,350
Accumulated Depreciation	3,175
33 Stiles Lane, North Haven, CT
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	2,415
Initial Cost to Company
Land	2,090
Buildings and Improvements	9,141
Costs Capitalized Subsequent to Acquisition, Net	216
Impairment/Write Downs	(1,654)
Cost Amount Carried at Close of Period
Land	1,799
Buildings and Improvements	7,994
Total	9,793
Accumulated Depreciation	2,353
1250 H Street, NW, Washington, DC
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	5,975
Buildings and Improvements	53,778
Costs Capitalized Subsequent to Acquisition, Net	13,103
Impairment/Write Downs	(248)
Cost Amount Carried at Close of Period
Land	5,975
Buildings and Improvements	66,633
Total	72,608
Accumulated Depreciation	28,384
Georgetown-Green and Harris Buildings, Washington, DC
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	24,000
Buildings and Improvements	35,979
Costs Capitalized Subsequent to Acquisition, Net	44
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	24,000
Buildings and Improvements	36,023
Total	60,023
Accumulated Depreciation	6,600
802 Delaware Avenue, Wilmington, DE
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	4,409
Buildings and Improvements	39,681
Costs Capitalized Subsequent to Acquisition, Net	10,562
Impairment/Write Downs	(11,156)
Cost Amount Carried at Close of Period
Land	3,390
Buildings and Improvements	40,106
Total	43,496
Accumulated Depreciation	24,217
6600 North Military Trail, Boca Raton, FL
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	15,900
Buildings and Improvements	129,790
Costs Capitalized Subsequent to Acquisition, Net	118
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	15,900
Buildings and Improvements	129,908
Total	145,808
Accumulated Depreciation	19,471
625 Crane Street, Aurora, IL
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	1,180
Buildings and Improvements	3,411
Costs Capitalized Subsequent to Acquisition, Net	(2)
Impairment/Write Downs	(4,589)
Cost Amount Carried at Close of Period
Land	0
Buildings and Improvements	0
Total	0
Accumulated Depreciation	0
600 West Chicago Avenue, Chicago, IL
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	34,980
Buildings and Improvements	315,643
Costs Capitalized Subsequent to Acquisition, Net	44,821
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	34,980
Buildings and Improvements	360,464
Total	395,444
Accumulated Depreciation	45,839
8750 Bryn Mawr Avenue, Chicago, IL
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	6,600
Buildings and Improvements	77,764
Costs Capitalized Subsequent to Acquisition, Net	9,498
Impairment/Write Downs	(257)
Cost Amount Carried at Close of Period
Land	6,600
Buildings and Improvements	87,005
Total	93,605
Accumulated Depreciation	14,411
109 Brookline Avenue, Boston, MA
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	3,168
Buildings and Improvements	30,397
Costs Capitalized Subsequent to Acquisition, Net	14,090
Impairment/Write Downs	(119)
Cost Amount Carried at Close of Period
Land	3,168
Buildings and Improvements	44,368
Total	47,536
Accumulated Depreciation	20,196
Cabot Business Park Land, Mansfield, MA
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	1,033
Buildings and Improvements	0
Costs Capitalized Subsequent to Acquisition, Net	0
Impairment/Write Downs	(458)
Cost Amount Carried at Close of Period
Land	575
Buildings and Improvements	0
Total	575
Accumulated Depreciation	0
111 Market Place, Baltimore, MD
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	6,328
Buildings and Improvements	54,645
Costs Capitalized Subsequent to Acquisition, Net	17,781
Impairment/Write Downs	(7,199)
Cost Amount Carried at Close of Period
Land	5,814
Buildings and Improvements	65,741
Total	71,555
Accumulated Depreciation	27,356
25 S. Charles Street, Baltimore, MD
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	2,830
Buildings and Improvements	22,996
Costs Capitalized Subsequent to Acquisition, Net	12,678
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	2,830
Buildings and Improvements	35,674
Total	38,504
Accumulated Depreciation	13,640
820 W. Diamond, Gaithersburg, MD
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	4,381
Buildings and Improvements	18,798
Costs Capitalized Subsequent to Acquisition, Net	10,516
Impairment/Write Downs	(35)
Cost Amount Carried at Close of Period
Land	4,461
Buildings and Improvements	29,199
Total	33,660
Accumulated Depreciation	12,777
Danac Stiles Business Park, Rockville, MD
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	7,638
Buildings and Improvements	62,572
Costs Capitalized Subsequent to Acquisition, Net	6,483
Impairment/Write Downs	(10,975)
Cost Amount Carried at Close of Period
Land	6,595
Buildings and Improvements	59,123
Total	65,718
Accumulated Depreciation	20,919
East Eisenhower Parkway, Ann Arbor, MI
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	6,760
Buildings and Improvements	46,988
Costs Capitalized Subsequent to Acquisition, Net	2,628
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	6,760
Buildings and Improvements	49,616
Total	56,376
Accumulated Depreciation	8,189
2250 Pilot Knob Road, Mendota Heights, MN
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	533
Buildings and Improvements	4,795
Costs Capitalized Subsequent to Acquisition, Net	1,202
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	533
Buildings and Improvements	5,997
Total	6,530
Accumulated Depreciation	2,896
411 Farwell Avenue, South St. Paul, MN
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	1,303
Buildings and Improvements	10,451
Costs Capitalized Subsequent to Acquisition, Net	4,603
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	1,304
Buildings and Improvements	15,053
Total	16,357
Accumulated Depreciation	4,056
4700 Belleview Avenue, Kansas City, MO
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	1,165
Buildings and Improvements	3,097
Costs Capitalized Subsequent to Acquisition, Net	2,989
Impairment/Write Downs	(26)
Cost Amount Carried at Close of Period
Land	1,165
Buildings and Improvements	6,060
Total	7,225
Accumulated Depreciation	1,286
Cherrington Corporate Center Moon, Township, PA
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	11,369
Buildings and Improvements	39,892
Costs Capitalized Subsequent to Acquisition, Net	28,319
Impairment/Write Downs	(7,616)
Cost Amount Carried at Close of Period
Land	10,664
Buildings and Improvements	61,300
Total	71,964
Accumulated Depreciation	22,494
1500 Market Street, Philadelphia, PA
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	18,758
Buildings and Improvements	167,487
Costs Capitalized Subsequent to Acquisition, Net	119,060
Impairment/Write Downs	(759)
Cost Amount Carried at Close of Period
Land	18,758
Buildings and Improvements	285,788
Total	304,546
Accumulated Depreciation	88,717
1600 Market Street, Philadelphia, PA
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	3,462
Buildings and Improvements	111,946
Costs Capitalized Subsequent to Acquisition, Net	20,637
Impairment/Write Downs	(194)
Cost Amount Carried at Close of Period
Land	3,462
Buildings and Improvements	132,389
Total	135,851
Accumulated Depreciation	59,435
1735 Market Street, Philadelphia, PA
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	24,753
Buildings and Improvements	222,775
Costs Capitalized Subsequent to Acquisition, Net	67,076
Impairment/Write Downs	(12,071)
Cost Amount Carried at Close of Period
Land	24,747
Buildings and Improvements	277,786
Total	302,533
Accumulated Depreciation	118,405
Foster Plaza, Pittsburgh, PA
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	6,168
Buildings and Improvements	51,588
Costs Capitalized Subsequent to Acquisition, Net	20,229
Impairment/Write Downs	(1,729)
Cost Amount Carried at Close of Period
Land	6,170
Buildings and Improvements	70,086
Total	76,256
Accumulated Depreciation	21,553
206 East 9th Street, Austin, TX
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	27,041
Initial Cost to Company
Land	7,900
Buildings and Improvements	38,533
Costs Capitalized Subsequent to Acquisition, Net	2,776
Impairment/Write Downs	(12)
Cost Amount Carried at Close of Period
Land	7,900
Buildings and Improvements	41,297
Total	49,197
Accumulated Depreciation	4,879
4515 Seton Center Parkway, Austin, TX
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	2,038
Buildings and Improvements	18,338
Costs Capitalized Subsequent to Acquisition, Net	2,814
Impairment/Write Downs	(60)
Cost Amount Carried at Close of Period
Land	2,037
Buildings and Improvements	21,093
Total	23,130
Accumulated Depreciation	9,749
4516 Seton Center Parkway, Austin, TX
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	2,028
Buildings and Improvements	18,251
Costs Capitalized Subsequent to Acquisition, Net	4,003
Impairment/Write Downs	(25)
Cost Amount Carried at Close of Period
Land	2,027
Buildings and Improvements	22,230
Total	24,257
Accumulated Depreciation	10,497
Bridgepoint Square, Austin, TX
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	7,784
Buildings and Improvements	70,526
Costs Capitalized Subsequent to Acquisition, Net	13,727
Impairment/Write Downs	(705)
Cost Amount Carried at Close of Period
Land	7,785
Buildings and Improvements	83,547
Total	91,332
Accumulated Depreciation	39,708
Research Park, Austin, TX
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	15,859
Buildings and Improvements	60,175
Costs Capitalized Subsequent to Acquisition, Net	17,410
Impairment/Write Downs	0
Cost Amount Carried at Close of Period
Land	21,213
Buildings and Improvements	72,231
Total	93,444
Accumulated Depreciation	32,295
333 108th Avenue NE, Bellevue, WA
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	14,400
Buildings and Improvements	136,412
Costs Capitalized Subsequent to Acquisition, Net	2,438
Impairment/Write Downs	(31)
Cost Amount Carried at Close of Period
Land	14,400
Buildings and Improvements	138,819
Total	153,219
Accumulated Depreciation	25,788
600 108th Avenue NE, Bellevue, WA
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company
Land	3,555
Buildings and Improvements	30,244
Costs Capitalized Subsequent to Acquisition, Net	17,305
Impairment/Write Downs	(508)
Cost Amount Carried at Close of Period
Land	3,555
Buildings and Improvements	47,041
Total	50,596
Accumulated Depreciation	$ 13,458

SCHEDULE III REAL ESTATE AND 99

SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION - Analysis of Carrying Amount of Real Estate Properties and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Real Estate Properties
Loss on asset impairment	$ (58,476)	$ (17,162)	$ (185,067)
Balance at the end of the year	2,856,890
Accumulated Depreciation
Balance at the beginning of the year	898,939	1,030,445	895,059
Additions	101,647	144,844	164,815
Loss on asset impairment	(119)	0	(6,423)
Properties reclassified to discontinued operations			5,724
Disposals	(245,212)	(276,350)	(28,730)
Balance at the end of the year	755,255	898,939	1,030,445
Real Estate
Real Estate Properties
Balance at the beginning of the year	3,887,352	5,728,443	5,537,165
Additions	113,258	68,118	70,963
Loss on asset impairment	(58,595)	(17,162)	(191,490)
Properties reclassified to discontinued operations			341,024
Disposals	(1,085,125)	(1,892,047)	(29,219)
Balance at the end of the year	$ 2,856,890	$ 3,887,352	$ 5,728,443

SCHEDULE III REAL ESTATE AND100

SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION - Analysis of Carrying Amount of Real Estate Properties and Accumulated Depreciation (Footnote) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Aggregate cost of properties for federal income tax purposes	$ 2,988,563
Real estate properties additions due to changes in foreign currency exchange	0	$ (13,217)	$ (20,445)
Accumulated depreciation additions due to changes in foreign currency exchange	$ 0	$ (887)	$ (1,279)
Maximum | Buildings and improvements
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Estimated useful lives	40 years
Maximum | Personal property
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Estimated useful lives	12 years

SCHEDULE IV MORTGAGE LOANS O101

SCHEDULE IV MORTGAGE LOANS ON REAL ESTATE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
SCHEDULE IV MORTGAGE LOANS ON REAL ESTATE
Face Amount of Mortgage	$ 8,107
Carrying Amount of Mortgage	8,080	$ 8,100
Principal Amount of Loans Subject to Delinquent Principal or Interest	0
Balance at the end of period	$ 8,107	$ 8,107	$ 8,107
Salina, NY
SCHEDULE IV MORTGAGE LOANS ON REAL ESTATE
Interest Rate	6.00%
Periodic Payment Terms	$ 419
Face Amount of Mortgage	419
Carrying Amount of Mortgage	392
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
Dearborn, MI
SCHEDULE IV MORTGAGE LOANS ON REAL ESTATE
Interest Rate	6.00%
Periodic Payment Terms	$ 7,688
Face Amount of Mortgage	7,688
Carrying Amount of Mortgage	7,688
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0