Office Properties Income Trust (OPI) 10-K 1 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2018	Feb. 25, 2019	Jun. 29, 2018
Document and Entity Information
Entity Registrant Name	OFFICE PROPERTIES INCOME TRUST
Entity Central Index Key	1,456,772
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		48,082,903
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 1.6

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Real estate properties:
Land	$ 924,164	$ 627,108
Buildings and improvements	3,020,472	2,348,613
Total real estate properties, gross	3,944,636	2,975,721
Accumulated depreciation	(375,147)	(341,848)
Total real estate properties, net	3,569,489	2,633,873
Assets of discontinued operations - Equity investment in Select Income REIT	0	467,499
Assets of properties held for sale	253,501	0
Investment in unconsolidated joint ventures	43,665	50,202
Acquired real estate leases, net	1,056,558	351,872
Cash and cash equivalents	35,349	16,569
Restricted cash	3,594	3,111
Rents receivable, net	72,051	61,429
Deferred leasing costs, net	25,672	22,977
Other assets, net	178,704	96,033
Total assets	5,238,583	3,703,565
LIABILITIES AND SHAREHOLDERS’ EQUITY
Unsecured revolving credit facility	175,000	570,000
Unsecured term loans, net	387,152	547,852
Senior unsecured notes, net	2,357,497	944,140
Mortgage notes payable, net	335,241	183,100
Liabilities of properties held for sale	4,271	0
Accounts payable and other liabilities	145,536	89,440
Due to related persons	34,887	4,859
Assumed real estate lease obligations, net	20,031	13,635
Total liabilities	3,459,615	2,353,026
Commitments and contingencies
Preferred units of limited partnership	0	20,496
Shareholders’ equity:
Common shares of beneficial interest, $.01 par value: 200,000,000 shares authorized, respectively, 48,082,903 and 24,786,479 shares issued and outstanding, respectively	481	248
Additional paid in capital	2,609,801	1,968,960
Cumulative net income	146,882	108,144
Cumulative other comprehensive income	106	60,427
Cumulative common distributions	(978,302)	(807,736)
Total shareholders’ equity	1,778,968	1,330,043
Total liabilities and shareholders’ equity	$ 5,238,583	$ 3,703,565

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares of beneficial interest, shares authorized	200,000,000	200,000,000
Common shares of beneficial interest, shares issued	48,082,903	24,786,479
Common shares of beneficial interest, shares outstanding	48,082,903	24,786,479

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Rental income	$ 426,560	$ 316,532	$ 258,180
EXPENSES:
Real estate taxes	49,708	37,942	30,703
Cost of goods and services sold	26,425	20,998	17,269
Other operating expenses	89,610	65,349	54,290
Depreciation and amortization	162,488	109,588	73,153
Loss on impairment of real estate	8,630	9,490	0
Acquisition and transaction related costs	14,508	0	1,191
General and administrative	24,922	18,847	14,897
Total expenses	376,291	262,214	191,503
Gain on sale of real estate	20,661	0	79
Dividend income	1,337	1,216	971
Unrealized loss on equity securities	(7,552)	0	0
Interest income	639	1,962	158
Interest expense (including net amortization of debt premiums and discounts and deferred financing fees of $3,626, $3,420, and $2,832, respectively)	(89,865)	(65,406)	(45,060)
Gain (loss) on early extinguishment of debt	(709)	(1,715)	104
Income (loss) from continuing operations before income taxes, equity in earnings of investees and gain on sale of real estate	(25,220)	(9,625)	22,929
Income tax expense	(117)	(101)	(101)
Equity in net earnings (losses) of investees	(2,269)	(13)	137
Income (loss) from continuing operations	(27,606)	(9,739)	22,965
Income from discontinued operations	5,722	21,829	34,878
Net income (loss)	(21,884)	12,090	57,843
Other comprehensive income (loss):
Unrealized gain on equity securities	0	24,042	30,465
Equity in unrealized gain (loss) of investees	(40)	9,428	11,359
Other comprehensive income (loss)	(40)	33,470	41,824
Comprehensive income (loss)	(21,924)	45,560	99,667
Net income (loss)	(21,884)	12,090	57,843
Preferred units of limited partnership distributions	(371)	(275)	0
Net income (loss) available for common shareholders	$ (22,255)	$ 11,815	$ 57,843
Weighted average common shares outstanding (basic) (in shares)	24,830	21,158	17,763
Weighted average common shares outstanding (diluted) (in shares)	24,830	21,158	17,768
Per common share amounts (basic and diluted):
Income (loss) from continuing operations (in dollars per share)	$ (1.13)	$ (0.47)	$ 1.29
Income from discontinued operations (in dollars per share)	0.23	1.03	1.96
Net income (loss) available for common shareholders (in dollars per share)	$ (0.90)	$ 0.56	$ 3.26

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net amortization of debt premiums and discounts and debt issuance costs	$ 3,626	$ 3,420	$ 2,832

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Shares	Additional Paid In Capital	Cumulative Net Income	Cumulative Other Comprehensive Income (Loss)	Cumulative Common Distributions
Balance beginning at Dec. 31, 2015	$ 956,651	$ 178	$ 1,473,015	$ 38,486	$ (14,867)	$ (540,161)
Balance (in shares) at Dec. 31, 2015		17,781,577
Increase (Decrease) in Shareholders' Equity
Share grants	1,389		1,389
Share grants (in shares)		16,475
Share repurchases	(337)		(337)
Share repurchases (in shares)		(3,575)
Equity in unrealized gain of investees	11,359				11,359
Unrealized gain on equity securities	30,465				30,465
Net income (loss) available for common shareholders	57,843			57,843
Distributions to common shareholders	(122,366)					(122,366)
Balance ending at Dec. 31, 2016	935,004	$ 178	1,474,067	96,329	26,957	(662,527)
Balance (in shares) at Dec. 31, 2016		17,794,477
Increase (Decrease) in Shareholders' Equity
Issuance of shares, net	493,866	$ 70	493,796
Issuance of shares, net (in shares)		6,976,757
Share grants	1,361		1,361
Share grants (in shares)		18,836
Share repurchases	(264)		(264)
Share repurchases (in shares)		(3,591)
Equity in unrealized gain of investees	9,428				9,428
Unrealized gain on equity securities	24,042				24,042
Net income (loss) available for common shareholders	11,815			11,815
Distributions to common shareholders	(145,209)					(145,209)
Balance ending at Dec. 31, 2017	1,330,043	$ 248	1,968,960	108,144	60,427	(807,736)
Balance (in shares) at Dec. 31, 2017		24,786,479
Increase (Decrease) in Shareholders' Equity
Cumulative adjustment upon adoption | ASU 2016-01				60,281	(60,281)
Cumulative adjustment upon adoption | ASU 2014-09	712			712
Adjusted balance	1,330,755	$ 248	1,968,960	169,137	146	(807,736)
Issuance of shares, net	639,783	$ 233	639,550
Issuance of shares, net (in shares)		23,281,738
Share grants	1,523		1,523
Share grants (in shares)		19,925
Shares forfeitures or repurchases	(232)		(232)
Shares forfeitures or repurchases (in shares)		(5,239)
Equity in unrealized gain of investees	(40)				(40)
Net income (loss) available for common shareholders	(22,255)			(22,255)
Distributions to common shareholders	(170,566)					(170,566)
Balance ending at Dec. 31, 2018	$ 1,778,968	$ 481	$ 2,609,801	$ 146,882	$ 106	$ (978,302)
Balance (in shares) at Dec. 31, 2018		48,082,903

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ (21,884)	$ 12,090	$ 57,843
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation	66,685	52,427	42,489
Net amortization of debt premiums, discounts and issuance costs	3,626	3,420	2,832
Gain on sale of real estate	(20,661)	0	(79)
(Gain) loss on early extinguishment of debt	709	1,715	(104)
Straight line rental income	(10,164)	(5,582)	(2,691)
Amortization of acquired real estate leases	94,375	56,174	29,003
Amortization of deferred leasing costs	4,833	3,802	3,265
Other non-cash expenses, net	250	300	284
Loss on impairment of real estate	8,630	9,490	0
Unrealized loss on equity securities	7,552	0	0
Increase in carrying value of property included in discontinued operations	0	(619)	0
Equity in net (earnings) losses of investees	2,269	13	(137)
Equity in earnings of Select Income REIT included in discontinued operations	(20,873)	(21,584)	(35,381)
Net gain on issuance of shares by Select Income REIT included in discontinued operations	(29)	(72)	(86)
Loss on sale of Select Income REIT shares included in discontinued operations	15,180	0	0
Distributions of earnings from Select Income REIT	20,873	21,584	35,381
Change in assets and liabilities:
Deferred leasing costs	(9,203)	(5,017)	(10,196)
Rents receivable	5,021	(4,990)	1,670
Other assets	1,127	1,368	25
Accounts payable and other liabilities	(3,303)	11,696	1,970
Due to related persons	(97)	1,339	634
Net cash provided by operating activities	144,916	137,554	126,722
CASH FLOWS FROM INVESTING ACTIVITIES:
Real estate acquisitions and deposits	25,221	(1,187,012)	(200,331)
Real estate improvements	(47,500)	(45,940)	(32,999)
Distributions in excess of earnings from Select Income REIT	17,251	29,248	14,954
Distributions in excess of earnings from unconsolidated joint ventures	3,751	482	0
Proceeds from sale of properties, net	304,808	15,083	263
Proceeds from sale of Select Income REIT shares	435,125	0	0
Net cash provided by (used in) investing activities	738,656	(1,188,139)	(218,113)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of mortgage notes payable	(3,708)	(11,909)	(107,933)
Repayment of unsecured term loan	(162,000)	0	0
Proceeds from issuance of senior notes, after discounts	0	297,954	300,235
Proceeds from issuance of common shares, net	0	493,866	0
Borrowings on unsecured revolving credit facility	238,000	645,000	399,000
Repayments on unsecured revolving credit facility	(741,000)	(235,000)	(356,000)
Payment of debt issuance costs	(3,936)	(4,644)	(544)
Repurchase of common shares	(232)	(264)	(337)
Redemption of preferred units of limited partnership	(20,221)	0	0
Preferred units of limited partnership distributions	(646)	0	0
Distributions to common shareholders	(170,566)	(145,209)	(122,366)
Net cash (used in) provided by financing activities	(864,309)	1,039,794	112,055
Increase (decrease) in cash, cash equivalents and restricted cash	19,263	(10,791)	20,664
Cash, cash equivalents and restricted cash at beginning of period	19,680	30,471	9,807
Cash, cash equivalents and restricted cash at end of period	38,943	19,680	30,471
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid	65,188	55,048	41,139
Income taxes paid	68	117	111
NON-CASH INVESTING ACTIVITIES:
Sale of real estate	0	0	3,600
Mortgage note receivable related to sale of real estate	0	0	(3,600)
Working capital assumed	30,483	(1,596)	0
Real estate and investment acquired by issuance of common shares	(639,809)	0	0
Real estate and investment acquired by assumption of debt	(1,719,772)	0	0
NON-CASH FINANCING ACTIVITIES:
SIR unsecured revolving credit facility	108,000	0
Assumption of mortgage notes payable	161,772	167,548	0
Assumption of senior unsecured notes	1,450,000	0	0
Preferred units of limited partnership issued	0	20,221	0
Issuance of common shares	$ 639,809	$ 0	$ 0

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS - SUPPLEMENTAL DISCLOSURE OF CASH, CASH EQUIVALENTS AND RESTRICTED CASH - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Cash Flows [Abstract]
Cash and cash equivalents	$ 35,349	$ 16,569	$ 29,941
Restricted cash	3,594	3,111	530
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$ 38,943	$ 19,680	$ 30,471	$ 9,807

Organization

Organization	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Office Properties Income Trust (formerly Government Properties Income Trust, or GOV), or OPI, we, us or our, is a real estate investment trust, or REIT, formed in 2009 under Maryland law. As of December 31, 2018 , our wholly owned properties were comprised of 247 buildings, or our consolidated properties, located in 38 states and the District of Columbia containing approximately 31.9 million rentable square feet and we had a noncontrolling ownership interest in two unconsolidated joint ventures that own three buildings totaling an additional approximately 0.4 million rentable square feet. Merger with Select Income REIT On September 14, 2018, we and our wholly owned subsidiary, GOV MS REIT, a Maryland real estate investment trust, or Merger Sub, and Select Income REIT, or SIR, a REIT that owned properties that are primarily net leased to single tenants, entered into an Agreement and Plan of Merger, or the SIR Merger Agreement, pursuant to which SIR merged with and into Merger Sub, with Merger Sub continuing as the surviving entity in the merger, or the SIR Merger. The SIR Merger was consummated and became effective at 4:01 p.m., Eastern Time, on December 31, 2018. Pursuant to the terms set forth in the SIR Merger Agreement, at the effective time of the SIR Merger, we issued to SIR’s shareholders 1.04 of our common shares of beneficial interest, $.01 par value per share, or our common shares, for each common share of SIR issued and outstanding immediately prior to the effective time of the SIR Merger (other than SIR common shares held by us or any of our or SIR’s wholly owned subsidiaries), with cash paid in lieu of fractional shares and any outstanding unvested SIR common share awards under SIR’s equity compensation plan were converted into awards under our 2009 Incentive Share Award Plan, or the 2009 Plan, subject to substantially similar vesting requirements and other terms and conditions, of a number of our common shares determined by multiplying the number of unvested SIR common shares subject to such award by 1.04 (rounded down to the nearest whole number), or the Exchange Ratio. Later on December 31, 2018, Merger Sub merged with and into us, with us as the surviving entity and we changed our name to “Office Properties Income Trust.” Effective January 1, 2019, the ticker symbol for our common shares, which continue to be traded on The Nasdaq Stock Market LLC, or Nasdaq, was changed to “OPI.” As a condition of the SIR Merger, on October 9, 2018, we sold all of the 24,918,421 common shares of SIR we then owned, or the Secondary Sale, in an underwritten public offering at a price of $18.25 per share, raising net proceeds of $435,125 after deducting underwriting discounts and offering expenses. We used the net proceeds from the Secondary Sale to repay amounts outstanding under our revolving credit facility. In addition, as a condition of the SIR Merger, on December 27, 2018, SIR paid a pro rata distribution to SIR's shareholders as of the close of business on December 20, 2018 of all 45,000,000 common shares of beneficial interest of Industrial Logistics Properties Trust, or ILPT, that SIR owned, or the ILPT Distribution. Upon consummation of the SIR Merger, SIR’s separate business and property management agreements with RMR LLC were terminated for convenience and RMR LLC waived its right to receive payment of the termination fees due on account thereof, pursuant to the terms of the letter agreement entered into between SIR and RMR LLC on September 14, 2018. Also upon consummation of the SIR Merger, we assumed all of the principal and interest on all of SIR’s outstanding $400,000 aggregate principal amount of 3.60% Senior Notes due 2020, $300,000 aggregate principal amount of 4.15% Senior Notes due 2022, $350,000 aggregate principal amount of 4.250% Senior Notes due 2024 and $400,000 aggregate principal amount of 4.50% Senior Notes due 2025. The aggregate transaction value, based on the closing price of our common shares on December 31, 2018 of $6.87 per share (prior to the Reverse Share Split, as defined below), was approximately $2,415,053 , excluding closing costs of approximately $27,497 ( $14,508 of which was paid by us and $12,989 of which was paid by SIR) and including the repayment or assumption of $1,719,772 of SIR debt. Following the SIR Merger and the other transactions contemplated by the SIR Merger Agreement, including the Secondary Sale and the ILPT Distribution, or, collectively, the SIR Transactions, we acquired SIR's property portfolio of 99 buildings with approximately 16.5 million rentable square feet. Reverse Share Split After the SIR Merger and the other SIR Transactions, on December 31, 2018, we effected a reverse share split of our common shares, or the Reverse Share Split, pursuant to which every four of our common shares issued and outstanding as of the effective time of the Reverse Share Split were converted and reclassified into one of our common shares of beneficial interest, par value $.04 per share, subject to the receipt of cash in lieu of fractional shares. Following the effective time of the Reverse Share Split on December 31, 2018, we changed the par value of our common shares from $.04 per share back to $.01 per share. The Reverse Share Split affected all record holders of our common shares uniformly and did not affect any record shareholder’s percentage ownership interest in us. The Reverse Share Split reduced the number of our issued and outstanding common shares from 192,331,612 to 48,082,903 . All impacted amounts and share information included in the consolidated financial statements and notes hereto have been retroactively adjusted for the Reverse Share Split as if the Reverse Share Split occurred on the first day of the first period presented. Certain adjusted amounts in the notes to these consolidated financial statements may not agree with previously reported amounts due to rounding of fractional shares.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation. These consolidated financial statements include the accounts of us and our subsidiaries, all of which are wholly owned directly or indirectly by us. All intercompany transactions and balances with or among our consolidated subsidiaries have been eliminated. Real Estate Properties. We record our properties at cost and provide depreciation on real estate investments on a straight line basis over estimated useful lives generally ranging from 7 to 40 years. In some circumstances, we engage independent real estate appraisal firms to provide market information and evaluations which are relevant to our purchase price allocations and determinations of useful lives; however, we are ultimately responsible for the purchase price allocations and determinations of useful lives. We allocate the purchase prices of our properties to land, building and improvements based on determinations of the relative fair values of these assets assuming the properties are vacant. We determine the fair value of each property using methods similar to those used by independent appraisers. We allocate a portion of the purchase price of our properties to above market and below market leases based on the present value (using an interest rate which reflects the risks associated with acquired in place leases at the time each property was acquired by us) of the difference, if any, between (i) the contractual amounts to be paid pursuant to the acquired in place leases and (ii) our estimates of fair market lease rates for the corresponding leases, measured over a period equal to the terms of the respective leases. We allocate a portion of the purchase price to acquired in place leases and tenant relationships based upon market estimates to lease up the property based on the leases in place at the time of purchase. We allocate this aggregate value between acquired in place lease values and tenant relationships based on our evaluation of the specific characteristics of each tenant’s lease. However, we have not separated the value of tenant relationships from the value of acquired in place leases because such value and related amortization expense is immaterial to the accompanying consolidated financial statements. In making these allocations, we consider factors such as estimated carrying costs during the expected lease up periods, including real estate taxes, insurance and other operating income and expenses and costs, such as leasing commissions, legal and other related expenses, to execute similar leases in current market conditions at the time a property was acquired by us. If the value of tenant relationships becomes material in the future, we may separately allocate those amounts and amortize the allocated amounts over the estimated life of the relationships. For transactions that qualify as business combinations, we allocate the excess, if any, of the consideration over the fair value of the assets acquired to goodwill. We amortize capitalized above market lease values (included in acquired in place real estate leases, net in our consolidated balance sheets) and below market lease values (presented as assumed real estate lease obligations, net in our consolidated balance sheets) as a reduction or increase, respectively, to rental income over the terms of the associated leases. Such amortization resulted in net decreases to rental income of $2,903 , $2,764 and $1,457 during the years ended December 31, 2018 , 2017 and 2016 , respectively. We amortize the value of acquired in place leases (included in acquired real estate leases, net in our consolidated balance sheets), exclusive of the value of above market and below market acquired in place leases, over the terms of the associated leases. Such amortization, which is included in depreciation and amortization expense, amounted to $91,472 , $53,410 , and $27,546 during the years ended December 31, 2018 , 2017 and 2016 , respectively. If a lease is terminated prior to its stated expiration, we write off the unamortized amounts relating to that lease. As of December 31, 2018 and 2017 , our acquired real estate leases and assumed real estate obligations, excluding properties classified as held for sale, were as follows: December 31, 2018 2017 Acquired real estate leases: Capitalized above market lease values $ 62,260 $ 46,096 Less: accumulated amortization (20,956 ) (27,259 ) Capitalized above market lease values, net 41,304 18,837 Lease origination value 1,168,979 472,928 Less: accumulated amortization (153,725 ) (139,893 ) Lease origination value, net 1,015,254 333,035 Acquired real estate leases, net $ 1,056,558 $ 351,872 Assumed real estate lease obligations: Capitalized below market lease values $ 31,091 $ 25,973 Less: accumulated amortization (11,060 ) (12,338 ) Assumed real estate lease obligations, net $ 20,031 $ 13,635 As of December 31, 2018 , the weighted average amortization periods for capitalized above market leases, lease origination value and capitalized below market lease values were 5.4 years, 6.9 years and 5.8 years, respectively. Future amortization of net intangible lease assets and liabilities, to be recognized over the current terms of the associated leases as of December 31, 2018 are estimated to be $203,554 in 2019 , $180,025 in 2020 , $153,089 in 2021 , $136,515 in 2022 , $112,524 in 2023 and $250,820 thereafter. We regularly evaluate whether events or changes in circumstances have occurred that could indicate an impairment in the value of long lived assets. If there is an indication that the carrying value of an asset is not recoverable, we estimate the projected undiscounted cash flows to determine if an impairment loss should be recognized. We determine the amount of any impairment loss by comparing the historical carrying value to estimated fair value. We estimate fair value through an evaluation of recent financial performance and projected discounted cash flows using standard industry valuation techniques. In addition to consideration of impairment upon the events or changes in circumstances described above, we regularly evaluate the remaining lives of our long lived assets. If we change our estimate of the remaining lives, we allocate the carrying value of the affected assets over their revised remaining lives. Cash and Cash Equivalents. We consider highly liquid investments with original maturities of three months or less at the date of purchase to be 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 certain of our mortgage debts. Deferred Leasing Costs . Deferred leasing costs include brokerage, legal and other fees associated with our entering leases and we amortize those costs, which are included in depreciation and amortization expense, on a straight line basis over the terms of the respective leases. Deferred leasing costs, excluding properties classified as held for sale, totaled $38,840 and $32,990 at December 31, 2018 and 2017 , respectively, and accumulated amortization of deferred leasing costs totaled $13,168 and $10,013 at December 31, 2018 and 2017 , respectively. Future amortization of deferred leasing costs to be recognized during the current terms of our existing leases as of December 31, 2018 are estimated to be $4,925 in 2019 , $4,215 in 2020 , $3,599 in 2021 , $2,902 in 2022 , $2,363 in 2023 and $7,668 thereafter. Debt Issuance Costs . Debt issuance costs include capitalized issuance or assumption costs related to borrowings, which are amortized to interest expense over the terms of the respective loans. Debt issuance costs, net of accumulated amortization, for our revolving credit facility are included in other assets in our consolidated balance sheets. As of December 31, 2018 and 2017 , debt issuance costs for our revolving credit facility were $4,125 and $5,234 and accumulated amortization of debt issuance costs for our revolving credit facility were $49 and $3,849 , respectively. Debt issuance costs, net of accumulated amortization, for our unsecured term loans, senior unsecured notes and mortgage notes payable are presented as a direct deduction from the associated debt liability in our consolidated balance sheets. As of December 31, 2018 and 2017 , debt issuance costs, net of accumulated amortization, for our unsecured term loans, senior unsecured notes, and mortgage notes payable totaled $12,888 and $15,750 , respectively. Future amortization of debt issuance costs to be recognized with respect to our revolving credit facility, unsecured term loans, senior unsecured notes and mortgage notes as of December 31, 2018 are estimated to be $2,890 in 2019 , $2,189 in 2020 , $2,049 in 2021 , $1,725 in 2022 , $406 in 2023 and $7,705 thereafter. Equity Securities. As of December 31, 2018 , we owned 2,801,061 common shares of class A common stock of RMR Inc., including 1,586,836 common shares acquired from SIR on December 31, 2018 in connection with the SIR Merger. Our equity securities are recorded at fair value based on their quoted market price at the end of each reporting period. Effective January 1, 2018, changes in the fair value of our equity securities are recorded through earnings in accordance with the Financial Accounting Standards Board, or FASB, Accounting Standards Update, or ASU, No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities . Prior to January 1, 2018, unrealized gains and losses on equity securities were recorded as a component of cumulative comprehensive income (loss) in shareholders' equity. As further described in Note 7 , we initially acquired 1,541,201 shares of class A common stock of RMR Inc. on June 5, 2015 for cash and share consideration of $17,462 . We concluded, for accounting purposes, that the cash and share consideration we paid for our investment in these shares represented a discount to the fair value of these shares. We initially accounted for this investment under the cost method of accounting and recorded this investment at its estimated fair value of $39,833 as of June 5, 2015 using Level 3 inputs, as defined in the fair value hierarchy under U.S. generally accepted accounting principles, or GAAP. As a result, we recorded a liability for the amount by which the estimated fair value of these shares exceeded the price we paid for these shares. This liability is included in accounts payable and other liabilities in our consolidated balance sheets. This liability is being amortized on a straight line basis through December 31, 2035 as an allocated reduction to our business management and property management fee expense. We amortized $1,087 of this liability during each of the years ended December 31, 2018 , 2017 and 2016 . These amounts are included in the net business management and property management fee amounts for such periods. As of December 31, 2018 , the remaining unamortized amount of this liability was $18,493 . Future amortization of this liability as of December 31, 2018 is estimated to be $1,087 in 2019 through 2023 and $13,058 thereafter. Equity Method Investments. We account for our investments in Affiliates Insurance Company, or AIC, and SIR, until we sold the SIR common shares we owned as described in Note 1, using the equity method of accounting. Significant influence is present through common representation on the boards of trustees or directors of us, AIC and, until December 31, 2018, SIR. One of our Managing Trustees, Adam D. Portnoy, as the sole trustee of ABP Trust, is the controlling shareholder of The RMR Group Inc., or RMR Inc. He is also a director and officer of RMR Inc. Substantially all of the business of RMR Inc. is conducted by its majority owned subsidiary, RMR LLC, which is our manager, the manager of AIC and, until December 31, 2018, SIR. Most of our Trustees are directors of AIC. See Notes 7, 12 and 13 for further information of our investments in AIC and SIR. In connection with our acquisition of First Potomac Realty Trust, or FPO, in 2017, we acquired 50% and 51% interests in two unconsolidated joint ventures which own three buildings. The buildings owned by these joint ventures are encumbered by an aggregate $82,000 of mortgage indebtedness. We do not control the activities that are most significant to these joint ventures and, as a result, we account for our investment in these joint ventures under the equity method of accounting. See Note 5 for further information regarding our unconsolidated joint ventures. We periodically evaluate our equity method investments for possible indicators of other than temporary impairment whenever events or changes in circumstances indicate the carrying amount of the investment might not be recoverable. These indicators may include the length of time and the extent to which the market value of our investment is below our carrying value, the financial condition of our investees, our intent and ability to be a long term holder of the investment and other considerations. If the decline in fair value is judged to be other than temporary, we record an impairment charge to adjust the basis of the investment to its estimated fair value. Revenue Recognition. We recognize rental income from operating leases that contain fixed contractual rent changes on a straight line basis over the term of the lease agreements. We increased rental income by $10,164 , $5,582 and $2,691 to record revenue on a straight line basis during the years ended December 31, 2018 , 2017 and 2016 , respectively. Rents receivable, excluding properties classified as held for sale, include $34,006 and $27,267 of straight line rent receivables at December 31, 2018 and 2017 , respectively. Certain of our leases with government tenants provide the tenant the right to terminate its lease if its respective legislature or other funding authority does not appropriate the funding necessary for the government tenant to meet its lease obligations; we have determined the fixed non-cancelable lease term of these leases to be the fully executed term of the lease because we believe the occurrence of termination to be a remote contingency based on both our historical experience and our assessment of the likelihood of lease cancellation on a separate lease basis. Income Taxes. We have elected to be taxed as a REIT under the United States Internal Revenue Code of 1986, as amended, or the IRC, and, accordingly, we generally will not be subject to federal income taxes provided we distribute our taxable income and meet certain other requirements to qualify as a REIT. We are, however, subject to certain state and local taxes. Cumulative Other Comprehensive Income. Cumulative other comprehensive income represents our share of the cumulative comprehensive income of our equity method investees and, prior to the adoption of FASB ASU No. 2016-01 on January 1, 2018, unrealized gains and losses related to our investment in RMR Inc. See Notes 5 and 7 for further information regarding these investments. Per Common Share Amounts. We calculate basic earnings per common share by dividing net income (loss) available for common shareholders by the weighted average number of our common shares of beneficial ownership, $.01 par value, or our common shares, outstanding during the period. We calculate diluted earnings per share using the more dilutive of the two class method or the treasury stock method. Unvested share awards and other potentially dilutive common shares and the related impact on earnings, are considered when calculating diluted earnings per share. Use of Estimates. Preparation of these financial statements in conformity with GAAP requires us to make estimates and assumptions that may affect the amounts reported in these consolidated financial statements and related notes. The actual results could differ from these estimates. Reclassifications. Reclassifications have been made to the prior years’ consolidated financial statements to conform to the current year’s presentation. Segment Reporting. We operate in one business segment: direct ownership of real estate properties.

Weighted Average Common Shares

Weighted Average Common Shares	12 Months Ended
	Dec. 31, 2018
Earnings Per Share, Basic and Diluted [Abstract]
Weighted Average Common Shares	Weighted Average Common Shares The following table provides a reconciliation of the weighted average number of common shares used in the calculation of basic and diluted earnings per share (in thousands): For the Year Ended December 31, 2018 2017 2016 Weighted average common shares for basic earnings per share 24,830 21,158 17,763 Effect of dilutive securities: unvested share awards — — 5 Weighted average common shares for diluted earnings per share (1) 24,830 21,158 17,768 (1) For the years ended December 31, 2018 and 2017, four and five unvested common shares, respectively, were not included in the calculation of diluted earnings per share because to do so would have been antidilutive.

New Accounting Pronouncements

New Accounting Pronouncements	12 Months Ended
	Dec. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements On January 1, 2018, we adopted FASB ASU No. 2014-09 (and related clarifying guidance issued by the FASB), Revenue From Contracts With Customers , which outlines a comprehensive model for entities to use in accounting for revenue arising from contracts with customers. ASU No. 2014-09 states that “an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services.” While ASU No. 2014-09 specifically references contracts with customers, it may apply to certain other transactions such as the sale of real estate or equipment. A substantial portion of our revenue consists of rental income from leasing arrangements, which is specifically excluded from ASU No. 2014-09. We have adopted ASU No. 2014-09 using the modified retrospective approach, which resulted in an adjustment to reclassify a previous deferred gain on sale of real estate of $712 from accounts payable and other liabilities to cumulative net income. The adoption of ASU No. 2014-09 did not have a material impact on the amount or timing of our revenue recognition in our consolidated financial statements except for profit recognition on real estate sales. On January 1, 2018, we adopted FASB ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities , which changes how entities measure certain equity investments and present changes in the fair value of financial liabilities measured under the fair value option that are attributable to their own credit. The implementation of ASU No. 2016-01 resulted in the reclassification of historical changes in the fair value of our equity securities of $45,116 from cumulative other comprehensive income to cumulative net income. We also reclassified $15,165 from cumulative other comprehensive income to cumulative net income for our share of cumulative other comprehensive income of certain of our equity method investees. Effective January 1, 2018, changes in the fair value of our equity securities are recorded through earnings in accordance with ASU No. 2016-01. On January 1, 2018, we adopted FASB ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments , which clarifies how companies present and classify certain cash receipts and cash payments in the statements of cash flows. The implementation of this update resulted in the reclassification of $2,944 and $2,956 of accretion recorded in our equity in the earnings of SIR from cash flow from investing activities to cash flow from operating activities for the year ended December 31, 2017 and 2016 , respectively. See Note 12 for further information regarding our investment in SIR. On January 1, 2018, we adopted FASB ASU No. 2016-18, Restricted Cash , which requires companies to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. The implementation of ASU No. 2016-18 resulted in a decrease of $1,563 and an increase of $492 of net cash provided by operating activities for the years ended December 31, 2017 and 2016 , respectively. This update also requires a reconciliation of the totals in the statements of cash flows to the related captions in the balance sheets. As a result, amounts included in restricted cash on our consolidated balance sheets are included with cash and cash equivalents on the consolidated statements of cash flows. The adoption of this update did not change our balance sheet presentation. On October 1, 2018, we adopted FASB ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting , which aligns the measurement and classification guidance for share based payments to nonemployees with the guidance for share based payments to employees, with certain exceptions. The adoption of this standard did not have a material impact in our consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases . In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements . In December 2018, the FASB issued ASU No. 2018-20 Leases (Topic 842), Narrow-Scope Improvements for Lessors . Collectively, these standards set out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). ASU No. 2016-02 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase of the leased asset by the lessee. This classification will determine whether the lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales type leases, direct financing leases and operating leases. These standards are effective as of January 1, 2019. Upon adoption, we applied the package of practical expedients that allows an entity to not reassess (i) whether any expired or existing contracts are or contain leases, (ii) lease classification for any expired or existing leases and (iii) initial direct costs for any expired or existing leases. Furthermore, we applied the optional transition method in ASU No. 2018-11 which allows entities to initially apply the new leases standard at the adoption date and recognize a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption, if any. Additionally, our leases met the criteria in ASU No. 2018-11 to not separate non-lease components from the related lease component; therefore, the accounting for these leases remained largely unchanged from the previous standard. The adoption of ASU No. 2016-02 and the related improvements did not have a material impact in our consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which requires that entities use a new forward looking “expected loss” model that generally will result in the earlier recognition of allowance for credit losses. The measurement of expected credit losses is based upon historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. ASU No. 2016-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. We are currently assessing the potential impact the adoption of ASU No. 2016-13 will have in our consolidated financial statements. We currently expect to adopt the standard using the modified retrospective approach.

Real Estate Properties

Real Estate Properties	12 Months Ended
	Dec. 31, 2018
Real Estate [Abstract]
Real Estate Properties	Real Estate Properties As of December 31, 2018 , our wholly owned properties were comprised of 247 buildings, with an undepreciated carrying value of $4,161,591 and had a noncontrolling ownership interest in two unconsolidated joint ventures that own three buildings. We generally lease space at our properties on a gross lease, modified gross lease or net lease basis pursuant to fixed term contracts expiring between 2019 and 2039. Our leases generally require us to pay all or some property operating expenses and to provide all or most property management services. During the year ended December 31, 2018 , we entered into 128 leases for 1,382,821 rentable square feet for a weighted (by rentable square feet) average lease term of 6.8 years and we made commitments for approximately $37,135 of leasing related costs. As of December 31, 2018 , we have estimated unspent leasing related obligations of $58,380 . Merger with Select Income REIT As described in Note 1, on December 31, 2018, we completed the SIR Merger, pursuant to which we acquired SIR's property portfolio of 99 buildings with approximately 16.5 million rentable square feet. The total consideration transferred and assumed debt for the SIR Merger is $2,415,053 , including the assumption of $1,719,772 of debt and excluding acquisition related costs. The following table summarizes the estimated consideration transferred and liabilities assumed: Total Purchase Price (excluding acquisition costs): OPI common shares issued 23,282,704 Closing price of OPI common shares on December 31, 2018 $ 27.48 Value of consideration transferred $ 639,809 Cash consideration for fractional shares 8 Equity issuance costs (239 ) Value of consideration transferred $ 639,578 Assumed working capital 55,703 Assumed senior unsecured notes, principal balance 1,450,000 Assumed mortgage notes payable, principal balance 161,772 SIR unsecured revolving credit facility repaid at closing 108,000 Non-cash portion of purchase price 1,775,475 Total consideration transferred and liabilities assumed $ 2,415,053 The following table summarizes the preliminary purchase price allocation for SIR based on estimated fair values as of the December 31, 2018: Preliminary Purchase Price Allocation: Land $ 475,893 Buildings and improvements 960,286 Assets of properties held for sale 7,022 Acquired real estate leases 858,121 Cash 24,744 Restricted cash 476 Rents receivable, net 11,389 Other assets (1) 89,188 Total assets 2,427,119 Unsecured revolving credit facility (2) (108,000 ) Senior unsecured notes (3) (1,410,947 ) Mortgage notes payable (4) (159,490 ) Accounts payable and other liabilities (67,151 ) Assumed real estate lease obligations (11,833 ) Due to related persons (30,120 ) Net assets acquired 639,578 Assumed working capital 55,703 SIR unsecured revolving credit facility repaid at closing (2) 108,000 Assumed senior unsecured notes, principal balance 1,450,000 Assumed mortgage notes payable, principal balance 161,772 Consideration transferred and liabilities assumed (5) $ 2,415,053 (1) Other assets includes $84,229 for SIR's investment in shares of class A common stock of RMR Inc. which was recorded at fair value as of December 31, 2018 . (2) We repaid the outstanding balance under SIR's revolving credit facility at the closing of the SIR Merger with borrowings under our revolving credit facility. (3) The aggregate principal balance of the senior unsecured notes was $1,450,000 as of December 31, 2018 . (4) The aggregate principal balance of the mortgage notes payable was $161,772 as of December 31, 2018 . (5) The allocation of purchase price is based on preliminary estimates and may change significantly following the completion of (i) third party appraisals and (ii) our analysis of intangibles and building valuations. Purchase price excludes acquisition related costs. We were the accounting acquirer of SIR and accounted for the SIR Merger as a business combination because substantially all of the fair value of the gross assets acquired was not concentrated in a single identifiable asset or a group of similar identifiable assets and we acquired inputs and a substantive process that together significantly contributed to the ability to create outputs. Although we and SIR have no employees, the personnel and various services required to operate our businesses are provided pursuant to business and property management agreements with RMR LLC. These agreements were in effect before, and, in the case of us, remain in effect after, the SIR Merger. As a result, our acquisition of SIR included a substantive process for accounting purposes. The assets acquired and liabilities assumed were recorded at their respective fair values and added to our consolidated balance sheet as of December 31, 2018. We allocated the purchase price based on the estimated fair values of the acquired assets and liabilities assumed in a manner consistent with our purchase price allocation accounting policy described in Note 2. We engaged an independent real estate consulting firm to assist us with determining the purchase price allocations and to provide market information and evaluations which are relevant to purchase price allocations and determinations of useful lives. As of the date acquired, the weighted average amortization periods for capitalized above market lease values, lease origination value and capitalized below market lease values were 5.8 years, 7.2 years and 5.7 years, respectively. FPO Transaction On October 2, 2017, we completed our acquisition of FPO pursuant to merger transactions, as a result of which we acquired 72 buildings with 6.0 million rentable square feet, and FPO's 50% and 51% interests in two joint ventures that own three buildings with 0.4 million rentable square feet, or collectively, the FPO Transaction. The aggregate value we paid for FPO was $1,370,888 , including $651,696 in cash to FPO's shareholders, the repayment of $483,000 of FPO corporate debt, the assumption of $167,548 of mortgage debt; this amount excludes the $82,000 of mortgage debt that encumber the two properties owned by the two joint ventures and the payment of certain transaction fees and expenses, net of FPO cash on hand. We financed the cash payments for the FPO Transaction with borrowings under our revolving credit facility and with cash on hand, including net proceeds from our public offerings of common shares and senior unsecured notes, as described further in Notes 9 and 11. We accounted for the FPO Transaction as an asset acquisition. Our allocation of the purchase price was based on estimates of the relative fair value of the acquired assets and assumed liabilities. The following table summarizes the total consideration paid and the estimated fair values of the assets acquired and liabilities assumed in the FPO Transaction: Total Purchase Price: Cash consideration $ 1,175,140 Acquisition related costs 9,575 Total cash consideration 1,184,715 Preferred units of limited partnership issued (1) 20,221 Acquired net working capital (1,596 ) Assumed mortgage notes 167,548 Non-cash portion of purchase price 186,173 Gross purchase price $ 1,370,888 Purchase Price Allocation: Land $ 360,909 Buildings and improvements 681,340 Acquired real estate leases (2) 283,498 Investment in unconsolidated joint ventures 51,305 Cash 11,191 Restricted cash 1,018 Rents receivable 2,672 Other assets 3,640 Total assets 1,395,573 Mortgage notes payable (3) (167,936 ) Assumed real estate lease obligations (2) (5,776 ) Accounts payable and accrued expenses (10,640 ) Rents collected in advance (1,436 ) Security deposits (4,849 ) Net assets acquired 1,204,936 Assumed working capital (1,596 ) Assumed principal balance of debt 167,548 Gross purchase price $ 1,370,888 (1) Pursuant to the terms of the FPO Transaction, each unit of limited partnership interest in FPO's operating partnership that was not liquidated on the closing date was exchanged on a one-for-one basis for 5.5% Series A Cumulative Preferred Units of the surviving subsidiary. As of December 31, 2017, the carrying value of these Series A Cumulative Preferred Units was $20,496 and was recorded as temporary equity on our consolidated balance sheet. On May 1, 2018, we redeemed all 1,813,504 of the outstanding 5.5% Series A Cumulative Preferred Units for $11.15 per unit (plus accrued and unpaid distributions) for an aggregate of $20,310 . (2) As of the date acquired, the weighted average amortization periods for capitalized above market lease values, lease origination value and capitalized below market lease values were 3.2 years , 3.1 years and 3.8 years , respectively. (3) Includes fair value adjustments totaling $388 on $167,936 principal amount of mortgage notes we assumed in connection with the FPO Transaction. Pro Forma Information (Unaudited): The following table presents our pro forma results of operations for the years ended December 31, 2018 and 2017 as if the SIR Transactions and the FPO Transaction and related financing activities, had occurred on January 1, 2017. The SIR results of operations included in this pro forma financial information have been adjusted to remove ILPT's results of operations for the years ended December 31, 2018 and 2017 . The effect of these adjustments was to decrease pro forma rental income $152,735 and $156,506 for the years ended December 31, 2018 and 2017 , respectively, and to decrease net income $46,237 and $64,661 for the years ended December 31, 2018 and 2017 , respectively. The FPO results of operations included in this pro forma financial information have been adjusted to remove the results of operations of properties and joint venture interests FPO sold from January 1, 2017 to October 2, 2017, the closing date of the FPO Transaction. The effect of these adjustments was to decrease pro forma rental income $804 for the year ended December 31, 2017 and to decrease net loss $47,019 for the year ended December 31, 2017. This pro forma financial information is not necessarily indicative of what our actual financial position or results of operations would have been for the periods presented or for any future period. Differences could result from numerous factors, including future changes in our portfolio of investments, capital structure, property level operating expenses and revenues, including rents expected to be received on our existing leases or leases we may enter during and after 2019, changes in interest rates and other reasons. Actual future results are likely to be different from amounts presented in this pro forma financial information and such differences could be significant. Year Ended December 31, 2018 2017 Rental income $ 758,596 $ 746,801 Net loss $ (87,240 ) $ (74,556 ) Net loss per common share $ (1.82 ) $ (1.55 ) During the year ended December 31, 2018, we did not recognize any revenue or operating income from the assets acquired and liabilities assumed in the SIR Merger. During the year ended December 31, 2017, we recognized revenues of $36,722 and operating income of $3,230 from the consolidated properties acquired in the FPO Transaction and ($621) in equity in losses from our unconsolidated joint ventures acquired in the FPO Transaction. Unconsolidated Joint Ventures We own interests in two joint ventures that own three buildings. We account for these investments under the equity method of accounting. As of December 31, 2018 and 2017 , our investment in unconsolidated joint ventures consisted of the following: OPI Ownership OPI Carrying Value of Investment at December 31, Number of Office Buildings Location Square Feet Joint Venture 2018 2017 Prosperity Metro Plaza 51% $ 23,969 $ 27,888 2 Fairfax, VA 328,456 1750 H Street, NW 50% 19,696 22,314 1 Washington, D.C. 115,411 Total $ 43,665 $ 50,202 3 443,867 The following table provides a summary of the mortgage debt of our unconsolidated joint ventures: Joint Venture Interest Rate (1) Maturity Date Principal Balance at December 31, 2018 and 2017 Prosperity Metro Plaza 4.09% 12/1/2029 $ 50,000 1750 H Street, NW 3.69% 8/1/2024 32,000 Weighted Average/Total 3.93% $ 82,000 (1) Includes the effect of mark to market purchase accounting. At December 31, 2018 , the aggregate unamortized basis difference of our unconsolidated joint ventures of $8,442 is primarily attributable to the difference between the amount for which we purchased our interest in the joint ventures, including transaction costs, and the historical carrying value of the net assets of the joint ventures. This difference will be amortized over the remaining useful life of the related properties and included in the reported amount of equity in net earnings (losses) of investees. Other 2017 Acquisition Activities During the year ended December 31, 2017 , we acquired one building located in Manassas, VA with 69,374 rentable square feet. This building was 100% leased to Prince William County on the date of acquisition. This transaction was accounted for as an asset acquisition. The purchase price was $12,657 , including capitalized acquisition costs of $37 . Our allocation of the purchase price of this acquisition is based on the relative estimated fair value of the acquired assets and assumed liabilities is presented in the table below. Acquisition Date Location Number of Office Buildings Square Feet Purchase Price Land Building and Improvements Other Assumed Assets Jan 2017 Manassas, VA 1 69,374 $ 12,657 $ 1,562 $ 8,253 $ 2,842 In September 2017, we acquired transferable development rights that allow us to expand a property we own in Washington, D.C. for a purchase price of $2,030 , excluding acquisition costs. 2016 Acquisition Activities During the year ended December 31, 2016, we acquired five buildings with a combined 830,185 rentable square feet and a land parcel adjacent to one of our existing properties for an aggregate purchase price of $199,304 , excluding acquisition costs. Our allocation of the purchase price of these acquisitions based on the estimated fair value of the acquired assets and assumed liabilities is presented in the table below. Acquisition Date Location Number of Office Buildings Square Feet Purchase Price (1) Land Buildings and Improvements Other Assumed Assets Acquired Leases Acquired Lease Obligations Jan 2016 Sacramento, CA (2) 1 337,811 $ 79,508 $ 4,688 $ 61,995 $ 2,167 $ 11,245 $ (587 ) Jul 2016 Atlanta, GA (3) — — 1,670 1,670 — — — — Dec 2016 Rancho Cordova, CA (2) 1 82,896 13,943 1,466 8,797 — 3,680 — Dec 2016 Chantilly, VA (2) 3 409,478 104,183 6,966 74,214 — 23,003 — 5 830,185 $ 199,304 $ 14,790 $ 145,006 $ 2,167 $ 37,928 $ (587 ) (1) Excludes acquisition related costs. (2) Accounted for as a business combination. (3) On July 6, 2016, we acquired a land parcel adjacent to one of our existing properties for $1,623 . We accounted for this transaction as an asset acquisition and capitalized acquisition related costs of $47 . 2018 Disposition Activities During the year ended December 31, 2018 , we sold 19 buildings with a combined 2,174,637 rentable square feet for an aggregate purchase price of $320,255 , excluding closing costs, in five separate transactions. The sales of these properties, as presented in the table below, do not represent significant dispositions individually or in the aggregate nor do they represent a strategic shift. As a result, the results of operations of these properties are included in continuing operations through the date of sale in our consolidated statements of income (loss). Date of Sale Number of Office Buildings Location Square Feet Gross Sale Price (1) Mar 2018 (2) 1 Minneapolis, MN 193,594 $ 20,000 May 2018 (3) 1 New York, NY 187,060 118,500 May 2018 (4) 1 Sacramento, CA 110,500 10,755 Nov 2018 (5) 1 Golden, CO 43,231 4,000 Dec 2018 (6) 15 Southern Virginia 1,640,252 167,000 19 2,174,637 $ 320,255 (1) Gross sale price includes purchase price adjustments, if any, excludes closing costs. (2) We recorded a $640 loss on impairment of real estate to reduce the carrying value of this property to its estimated fair value less costs to sell during the year ended December 31, 2018 . (3) We recorded a $17,249 gain on sale of real estate during the year ended December 31, 2018 as a result of this sale. (4) We recorded a loss on impairment of real estate of $3,029 to reduce the carrying value of this property to its estimated fair value less costs to sell during the year ended December 31, 2018 . (5) We recorded a $54 gain on sale of real estate during the year ended December 31, 2018 as a result of this sale. (6) We recorded a $3,358 gain on sale of real estate during the year ended December 31, 2018 as a result of this sale. In February 2018, we entered an agreement to sell an office building located in Safford, AZ with 36,139 rentable square feet for $8,250 . We recorded a $2,453 loss on impairment of real estate to reduce the carrying value of the property to its estimated fair value less costs to sell in the three months ended March 31, 2018. In April 2018, the buyer terminated the sale agreement and we removed this property from held for sale status. We recorded a $322 adjustment to impairment of real estate to increase the carrying value of the property to its estimated fair value during the year ended December 31, 2018 . As of December 31, 2018 , we had 36 buildings with an aggregate undepreciated carrying value of $216,955 under agreement to sell in three separate transactions, as presented in the table below. We have classified these properties as held for sale in our consolidated balance sheet at December 31, 2018 . Date of Sale Agreement Number of Office Buildings Location Square Feet Gross Sale Price (1) Aug 2018 (2) 1 Washington, D.C. 129,035 $ 70,000 Sep 2018 (3) 34 Northern Virginia and Maryland 1,635,868 198,500 Nov 2018 (2)(4) 1 Kapolei, HI 416,956 7,100 36 2,181,859 $ 275,600 (1) Gross sale price includes purchase price adjustments, if any, excludes closing costs. (2) These pending sales are subject to conditions; accordingly, we cannot be sure that we will complete these sales or that these sales will not be delayed or their terms will not change. (3) We recorded a $2,830 loss on impairment of real estate to reduce the carrying value of these buildings to their estimated fair value less costs to sell during the year ended December 31, 2018 . On February 8, 2019, we completed the sale of these buildings. (4) Represents a land parcel acquired from SIR in the SIR Merger. In addition to the properties in the table above, we are currently marketing for sale 34 buildings, including properties acquired in the SIR Merger containing approximately 5.3 million square feet as of December 31, 2018 . We have determined that these properties did not meet the held for sale criteria as of December 31, 2018 . We cannot be sure we will sell any of our properties that we are currently marketing or plan to market for sale or sell them for prices in excess of our carrying values or that we will not recognize impairment losses with respect to these properties. 2017 Disposition Activities - Continuing Operations In October 2017, we sold one vacant office building located in Albuquerque, NM with 29,045 rentable square feet and a net book value of $1,885 as of the date of sale, for $2,000 , excluding closing costs. During the year ended December 31, 2017 , we recorded a $230 loss on impairment of real estate to reduce the carrying value of this property to its estimated fair value. 2017 Disposition Activities – Discontinued Operations In August 2017, we sold one vacant office building in Falls Church, VA with 164,746 rentable square feet and a net book value of $12,901 as of the date of sale for $13,523 , excluding closing costs. Results of operations for this property, which qualified as held for sale prior to our adoption in 2014 of ASU No. 2014-8, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity , are classified as discontinued operations in our consolidated financial statements. During the year ended December 31, 2017 , we recorded an adjustment of $619 to increase the carrying value of this property to its estimated fair value less costs to sell. Summarized income statement information for this property is as follows: Statements of Income (Loss) Year Ended December 31, 2017 2016 Rental income $ 17 $ 68 Real estate taxes (88 ) (97 ) Utility expenses (97 ) (146 ) Other operating expenses (202 ) (300 ) General and administrative (76 ) (114 ) Increase in carrying value of property included in discontinued operations 619 — Income (loss) from discontinued operations $ 173 $ (589 ) 2016 Disposition Activities In July 2016, we sold an office building in Savannah, GA with 35,228 rentable square feet that had a net book value of $2,986 for $4,000 , excluding closing costs. In connection with this sale, we provided $3,600 of mortgage financing to the buyer. The mortgage note requires interest to be paid at an annual rate of LIBOR plus 4.0% , subject to a minimum annual interest rate of 5.0% , and requires monthly payments of interest only until maturity on June 30, 2021. When this sale was completed, this transaction did not qualify for full gain recognition under GAAP and was accounted for under the installment method. Accordingly, we recognized a gain on sale of real estate of $79 during the year ended December 31, 2016 and recorded a deferred gain of $712 . As disclosed in Note 4, on January 1, 2018, we adopted ASU No. 2014-09, which resulted in an adjustment to reclassify the deferred gain on sale of real estate of $712 from accounts payable and other liabilities to cumulative net income. The mortgage note receivable of $3,600 is included in other assets in our consolidated balance sheets at December 31, 2018 and 2017 . Operating leases Our future minimum lease payments related to our consolidated properties and estimated real estate tax and other expense reimbursements scheduled to be received during the current terms of the existing leases as of December 31, 2018 , including the properties acquired in the SIR Merger, are as follows: Year Minimum Lease Payments 2019 $ 569,874 2020 514,551 2021 479,401 2022 434,135 2023 383,695 Thereafter 1,236,540 $ 3,618,196 Certain of our tenants have the right to terminate their leases before the lease term expires. As of December 31, 2018 , tenants who currently represent approximately 5.6% of our total future minimum lease payments have currently exercisable rights to terminate their leases before the stated terms of their leases expire. In 2019 , 2020 , 2021 , 2022 , 2023 , 2024 , 2025 , 2026 and 2028 , early termination rights become exercisable by other government tenants who currently represent an additional approximately 2.1% , 6.4% , 1.9% , 2.7% , 0.6% , 1.4% , 4.7% , 2.0% and 1.9% of our total future minimum lease payments, respectively. In addition, as of December 31, 2018 , 22 of our tenants have the currently exercisable right to terminate their leases if the respective legislature or other funding authority does not appropriate the funding necessary for the tenant to meet its obligation. These 22 tenants represent approximately 5.8% of our total future minimum lease payments as of December 31, 2018 . As part of the FPO Transaction, we assumed the lease for FPO's former corporate headquarters, which expires on January 31, 2021. We sublease a portion of the space, which sublease expires on January 31, 2021. Rent expense incurred under the lease, net of sublease revenue, was $1,707 and $374 for the years ended December 31, 2018 and 2017 , respectively. Future minimum rental payments due under the lease, net of subleased revenue, as of December 31, 2018 are summarized as follows: Year Minimum Rental Payments 2019 $ 1,584 2020 1,627 2021 139 $ 3,350

Business and Property Managemen

Business and Property Management Agreements with RMR LLC	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Business and Property Management Agreements with RMR LLC	Business and Property Management Agreements with RMR LLC We have no employees. The personnel and various services we require to operate our business are provided to us by RMR LLC. We have two agreements with RMR LLC to provide management services to us: (1) a business management agreement, which relates to our business generally, and (2) a property management agreement, which relates to our property level operations. Prior to the consummation of the SIR Merger, SIR had similar business and property management agreements with RMR LLC on substantially similar terms, which agreements were terminated in connection with the SIR Merger. See Notes 1 and 7 for further information regarding our relationship, agreements and transactions with SIR and RMR LLC. Management Agreements with RMR LLC . Our management agreements with RMR LLC provide for an annual base management fee, an annual incentive management fee and property management and construction supervision fees, payable in cash, among other terms: • Base Management Fee. The annual base management fee payable to RMR LLC by us for each applicable period is equal to the lesser of: • the sum of (a) 0.5% of the average aggregate historical cost of the real estate assets acquired from a REIT to which RMR LLC provided business management or property management services, or the Transferred Assets, plus (b) 0.7% of the average aggregate historical cost of our real estate investments excluding the Transferred Assets up to $250,000 , plus (c) 0.5% of the average aggregate historical cost of our real estate investments excluding the Transferred Assets exceeding $250,000 ; and • the sum of (a) 0.7% of the average closing price per share of our common shares on the stock exchange on which such shares are principally traded 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 $250,000 , plus (b) 0.5% of our Average Market Capitalization exceeding $250,000 . The average aggregate historical cost of our real estate investments includes 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 may be allocated to intangibles or are unallocated), all before reserves for depreciation, amortization, impairment charges or bad debts or other similar non-cash reserves; provided, however, our ownership of SIR common shares was not included as part of our real estate investments for purposes of calculating our base management fee due to RMR LLC since SIR paid separate business management fees to RMR LLC. • Incentive Management Fee . The incentive management fee which may be earned by RMR LLC for an annual period is calculated as follows: • An amount, subject to a cap based on the value of our common shares outstanding, equal to 12% of the product of: • our equity market capitalization on the last trading day of the year immediately prior to the relevant three year measurement period, and • the amount (expressed as a percentage) by which the total return per share, as defined in the business management agreement and further described below, of our common shareholders (i.e., share price appreciation plus dividends) exceeds the total shareholder return of the applicable index, or the benchmark return per share, for the relevant measurement period. Effective as of January 1, 2019, we amended our business management agreement with RMR LLC so that the SNL U.S. Office REIT Index will be used for periods beginning on and after January 1, 2019, with the SNL U.S. REIT Equity Index for periods ending on or prior to December 31, 2018. For purposes of the total return per share of our common shareholders, share price appreciation for a measurement period is determined by subtracting (1) the closing price of our common shares on the Nasdaq on the last trading day of the year immediately before the first year of the applicable measurement period, or the initial share price, from (2) the average closing price of our common shares on the 10 consecutive trading days having the highest average closing prices during the final 30 trading days in the last year of the measurement period. • The calculation of the incentive management fee (including the determinations of our equity market capitalization, initial share price and the total return per share of our common shareholders) is subject to adjustments if additional common shares are issued during the measurement period. • No incentive management fee is payable by us unless our total return per share during the measurement period is positive. • The measurement periods are three year periods ending with the year for which the incentive management fee is being calculated. • If our total return per share exceeds 12% per year in any measurement period, the benchmark return per share is adjusted to be the lesser of the total shareholder return of the applicable index for such measurement period and 12% per year, or the adjusted benchmark return per share. In instances where the adjusted benchmark return per share applies, the incentive management fee will be reduced if our total return per share is between 200 basis points and 500 basis points below the applicable index by a low return factor, as defined in the business management agreement, and there will be no incentive management fee paid if, in these instances, our total return per share is more than 500 basis points below the applicable index. • The incentive management fee is subject to a cap. The cap is equal to the value of the number of our common shares which would, after issuance, represent 1.5% of the number of our common shares then outstanding multiplied by the average closing price of our common shares during the 10 consecutive trading days having the highest average closing prices during the final 30 trading days of the relevant measurement period. • Incentive management fees we paid to RMR LLC for any period may be subject to “clawback” if our financial statements for that period are restated due to material non-compliance with any financial reporting requirements under the securities laws as a result of the bad faith, fraud, willful misconduct or gross negligence of RMR LLC and the amount of the incentive management fee we paid was greater than the amount we would have paid based on the restated financial statements. Pursuant to our business management agreement with RMR LLC, we recognized net business management fees of $16,381 , $12,464 and $10,222 for the years ended December 31, 2018, 2017 and 2016, respectively. The net business management fees we recognized are included in general and administrative expenses in our consolidated statements of comprehensive income (loss) for these periods. The net business management fees we recognized for each of the years ended December 31, 2018, 2017 and 2016 reflect a reduction of $603 , for the amortization of the liability we recorded in connection with our investment in RMR Inc., as further described in Note 2. No incentive management fee was payable to RMR LLC under our business management agreement for the years ended December 31, 2018, 2017 or 2016. • Property Management and Construction Supervision Fees . The property management fees payable to RMR LLC by us for each applicable period are equal to 3.0% of gross collected rents and the construction supervision fees payable to RMR LLC by us for each applicable period are equal to 5.0% of construction costs. Pursuant to our property management agreement with RMR LLC, we recognized aggregate net property management and construction supervision fees of $13,989 , $11,566 and $8,949 for each of the years ended December 31, 2018, 2017 and 2016, respectively. The net property management and construction supervision fees we recognized for the years ended December 31, 2018, 2017 and 2016 reflect a reduction of $484 , for the amortization of the liability we recorded in connection with our investment in RMR Inc., as further described in Note 2. These amounts are included in other operating expenses or have been capitalized, as appropriate, in our consolidated financial statements. Prior to the SIR Merger, SIR was party to business and property management agreements with RMR LLC. The terms of those agreements were substantially similar to the terms of our business and property management agreements with RMR LLC, including the determination of the fees payable to RMR LLC. Pursuant to its business management agreement with RMR LLC, SIR incurred an incentive management fee of $25,817 for the year ended December 31, 2018, payable in January 2019. In addition, SIR had incurred, in the ordinary course, but not paid, aggregate business management, property management and construction supervision fees of $2,185 at December 31, 2018. As successor to SIR as a result of the SIR Merger, we assumed the obligations to pay SIR’s 2018 incentive management fee and the business management, property management and construction supervision fees it had accrued, but not paid, as of December 31, 2018. We paid these fees to RMR LLC in January 2019. In calculating the incentive management fee payable by SIR for the year ended December 31, 2018, SIR’s total shareholder return per share was adjusted in accordance with its business management agreement to reflect aggregate net increases in the number of SIR common shares outstanding as a result of certain share issuances and repurchases by SIR during the three year measurement period, and compared to the SNL U.S. REIT Equity Index. In addition, the calculation of SIR’s benchmark return per share was also adjusted for these issuances and repurchases in accordance with its business management agreement. Upon consummation of the SIR Merger, SIR’s separate business and property management agreements with RMR LLC were terminated for convenience and RMR LLC waived its right to receive payment of the termination fees due on account of that termination. Expense Reimbursement . We are generally responsible for all of our operating expenses, including certain expenses incurred or arranged by RMR LLC on our behalf. We are generally not responsible for payment of RMR LLC’s employment, office or administrative expenses incurred to provide management services to us, except for the employment and related expenses of RMR LLC’s employees assigned to work exclusively or partly at our properties, our share of the wages, benefits and other related costs of RMR LLC’s centralized accounting personnel, our share of RMR LLC’s costs for providing our internal audit function and as otherwise agreed. Our property level operating expenses are generally incorporated into rents charged to our tenants, including certain payroll and related costs incurred by RMR LLC. We reimbursed RMR LLC $21,042 , $15,045 and $12,276 for property management related expenses for each of the years ended December 31, 2018, 2017 and 2016, respectively. These amounts are included in other operating expenses in our consolidated statements of comprehensive income (loss) for these periods. We assumed the obligation to reimburse RMR LLC for similar expenses that RMR LLC had incurred on behalf of SIR in the ordinary course but which SIR had not paid as of December 31, 2018. We reimbursed RMR LLC $462 in January 2019 for these expenses. Our Audit Committee appoints our Director of Internal Audit and our Compensation Committee approves the costs of our internal audit function. The amounts we recognized as expense for internal audit costs were $237 , $276 and $235 for the years ended December 31, 2018, 2017 and 2016, respectively. These amounts are included in general and administrative expenses in our consolidated statements of comprehensive income (loss) for these periods. • Term . Our management agreements with RMR LLC have terms that end on December 31, 2038, and automatically extend on December 31st of each year for an additional year, so that the terms of our management agreements thereafter end on the 20th anniversary of the date of the extension. • Termination Rights . We have the right to terminate one or both of our management agreements with RMR LLC: (i) at any time on 60 days’ written notice for convenience, (ii) immediately on written notice for cause, as defined therein, (iii) on written notice given within 60 days after the end of an applicable calendar year for a performance reason, as defined therein, and (iv) by written notice during the 12 months following a change of control of RMR LLC, as defined therein. RMR LLC has the right to terminate the management agreements for good reason, as defined therein. • Termination Fee. If we terminate one or both of our management agreements with RMR LLC for convenience, or if RMR LLC terminates one or both of our management agreements for good reason, we have agreed to pay RMR LLC a termination fee in an amount equal to the sum of the present values of the monthly future fees, as defined therein, for the terminated management agreement(s) for the term that was remaining prior to such termination, which, depending on the time of termination, would be between 19 and 20 years. If we terminate one or both of our management agreements with RMR LLC for a performance reason, we have agreed to pay RMR LLC the termination fee calculated as described above, but assuming a 10 year term was remaining prior to the termination. We are not required to pay any termination fee if we terminate our management agreements with RMR LLC for cause or as a result of a change of control of RMR LLC. • Transition Services. RMR LLC has agreed to provide certain transition services to us for 120 days following an applicable termination by us or notice of termination by RMR LLC, including cooperating with us and using commercially reasonable efforts to facilitate the orderly transfer of the management and real estate investment services provided under our business management agreement and to facilitate the orderly transfer of the management of the managed properties under our property management agreement, as applicable. • Vendors. Pursuant to our management agreements with RMR LLC, RMR LLC may from time to time negotiate on our behalf with certain third party vendors and suppliers for the procurement of goods and services to us. As part of this arrangement, we may enter agreements with RMR LLC and other companies to which RMR LLC or its subsidiaries provide management services for the purpose of obtaining more favorable terms from such vendors and suppliers. • Investment Opportunities . Under our business management agreement with RMR LLC, we acknowledge that RMR LLC may engage in other activities or businesses and act as the manager to any other person or entity (including other REITs) even though such person or entity has investment policies and objectives similar to ours and we are not entitled to preferential treatment in receiving information, recommendations and other services from RMR LLC.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Person Transactions We have relationships and historical and continuing transactions with SIR (prior to the SIR Merger), RMR LLC, RMR Inc., AIC and others related to them, including other companies to which RMR LLC or its subsidiaries provide management services and some of which have trustees, directors or officers who are also our Trustees or officers. One of our Managing Trustees, Adam D. Portnoy, as the sole trustee of ABP Trust, is the controlling shareholder of RMR Inc. and is a managing director and the president and chief executive officer of RMR Inc. and an officer and employee of RMR LLC. Barry M. Portnoy was our other Managing Trustee and a managing director and an officer of RMR Inc. and an officer and employee of RMR LLC until his death on February 25, 2018. Mr. Mark L. Kleifges, was our other Managing Trustee and our Chief Financial Officer and Treasurer until he resigned from his positions with us effective December 31, 2018 and was an officer of, and will remain an employee of, RMR LLC until June 30, 2019. David M. Blackman, our other Managing Trustee and our President and Chief Executive Officer, and each of our other officers is also an officer and employee of RMR LLC. RMR LLC provides management services to us and provided management services to SIR until it ceased to exist. Our Managing Trustees also served as the managing trustees of SIR until it ceased to exist. David M. Blackman, our President and Chief Executive Officer, and Jeffrey C. Leer, our Chief Financial Officer and Treasurer, also served as president and chief executive officer and chief financial officer and treasurer, respectively, of SIR until it ceased to exist. Each of SIR’s officers was also an officer and employee of RMR LLC. Our Independent Trustees also serve as independent directors or independent trustees of other public companies to which RMR LLC or its subsidiaries provide management services, including SIR (until it ceased to exist). Adam Portnoy serves, and, until his death, Barry Portnoy served, as a managing director or managing trustee of these companies and other officers of RMR LLC serve as managing trustees or managing directors of certain of these companies. In addition, officers of RMR LLC and RMR Inc. serve as our officers and officers of other companies to which RMR LLC or its subsidiaries provide management services. Our Manager, RMR LLC . We have two agreements with RMR LLC to provide management services to us: (1) a business management agreement, which relates to our business generally, and (2) a property management agreement, which relates to our property level operations. SIR had similar agreements with RMR LLC until it ceased to exist. See Note 6 for further information regarding these management agreements with RMR LLC. Leases with RMR LLC . We lease office space to RMR LLC in certain of our properties for RMR LLC’s property management offices. Pursuant to our lease agreements with RMR LLC, we recognized rental income from RMR LLC for leased office space of $1,026 , $303 and $366 for the years ended December 31, 2018, 2017 and 2016, respectively. Our office space leases with RMR LLC are terminable by RMR LLC if our management agreements with RMR LLC are terminated. Share Awards to RMR LLC Employees . As described further in Note 11, we award shares to our officers and other employees of RMR LLC annually. Generally, one fifth of these awards vest on the grant date and one fifth vests on each of the next four anniversaries of the grant dates. In certain instances, we may accelerate the vesting of an award, such as in connection with the award holder’s retirement as an officer of us or an officer or employee of RMR LLC. These awards to RMR LLC employees are in addition to the share awards granted to our current and former Managing Trustees, as Trustee compensation, and the fees we paid to RMR LLC. See Note 11 for information regarding our share awards and activity as well as certain share purchases we made in connection with share award recipients satisfying tax withholding obligations on vesting share awards. Prior to the SIR Merger, SIR historically made share awards to certain RMR LLC employees under its equity compensation plan and during the years ended December 31, 2018, 2017 and 2016, SIR awarded to its officers and other employees of RMR LLC annual share awards of 58,700 , 57,850 and 53,400 of its common shares, respectively, valued at $1,183 , $1,337 and $1,397 , in aggregate, respectively. During these periods, SIR repurchased some common shares awarded to certain of its trustees and officers and employees of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares. During the years ended December 31, 2018, 2017 and 2016 SIR accelerated the vesting of its common shares previously awarded to certain of its officers and employees of RMR LLC in connection with their termination of employment from RMR LLC. Ownership Interest in RMR Inc. and Registration and Lock-up Agreements . We currently hold 2,801,061 shares of class A common stock of RMR Inc. which we and SIR acquired in June 2015 in a transaction pursuant to which, among other things, we, SIR and two other REITs managed by RMR LLC acquired class A common stock of RMR Inc. and entered into amended and restated business and property management agreements with RMR LLC. We are party to a registration rights agreement with RMR Inc. covering the shares of class A common stock of RMR Inc. issued to us in this transaction, pursuant to which we have demand and piggyback registration rights, subject to certain limitations. We are also party to a lock up and registration rights agreement with ABP Trust, Adam Portnoy and Barry Portnoy pursuant to which they (on behalf of themselves and their permitted transferees) agreed not to transfer the 175,000 of our common shares (after giving effect to the Reverse Share Split) ABP Trust received in this transaction for a 10 year period ending on June 5, 2025 and they have certain registration rights, subject, in each case, to certain exceptions. Prior to the SIR Merger, SIR was party to similar agreements which we assumed in the SIR Merger. SIR . Until October 9, 2018, we owned 24,918,421 SIR common shares, or approximately 27.8% of its then outstanding common shares. As described further in Note 1, we completed the SIR Merger effective December 31, 2018 pursuant to the SIR Merger Agreement we and SIR entered into on September 14, 2018. On October 9, 2018, we sold all of these shares in the Secondary Sale. During 2018, our Managing Trustees also served as managing trustees of SIR, our President and Chief Executive Officer also served as SIR’s president and chief executive officer and Jeffrey C. Leer, our Chief Financial Officer and Treasurer, served as SIR’s chief financial officer and treasurer. During 2018, each of SIR’s officers was also an officer and employee of RMR LLC. RMR LLC provides management services to us and provided management services to SIR until it ceased to exist. See Note 1 for further information regarding the SIR Merger Agreement and the Secondary Sale and Notes 12 and 13 for further information regarding our investment in SIR. AIC. We, ABP Trust, ILPT and four other companies to which RMR LLC provides management services currently own AIC, an Indiana insurance company, in equal amounts and are parties to a shareholders agreement regarding AIC. All our Trustees (other than David M. Blackman) and all the independent trustees and independent directors of the other AIC shareholders currently serve on the board of directors of AIC. On December 28, 2018, SIR and ILPT entered a stock purchase agreement, or the AIC Stock Purchase Agreement, pursuant to which ILPT purchased all of SIR’s shares of common stock of AIC, effective December 31, 2018 for a purchase price of $8,632 . RMR LLC provides management and administrative services to AIC pursuant to a management and administrative services agreement with AIC. Pursuant to this agreement, AIC pays to RMR LLC a service fee equal to 3.0% of the total annual net earned premiums payable under then active policies issued or underwritten by AIC or by a vendor or an agent of AIC on its behalf or in furtherance of AIC’s business. We and the other AIC shareholders participate in a combined property insurance program arranged and insured or reinsured in part by AIC. We paid aggregate annual premiums, including taxes and fees, of $1,211 , $757 and $1,032 in connection with this insurance program for the policy years ending June 30, 2019, 2018 and 2017, respectively, which amount for the current policy year ending June 30, 2019 may be adjusted from time to time as we acquire or dispose of properties that are included in this insurance program. Properties we acquired as a result of the SIR Merger were already previously included in this insurance program because SIR was a participant in the program. SIR paid an annual premium, including taxes and fees, of $1,666 in connection with this insurance program for the policy year ending June 30, 2019. As of December 31, 2018, 2017 and 2016, our investment in AIC had a carrying value of $8,751 , $8,304 and $7,235 , respectively. These amounts are included in other assets in our consolidated balance sheets. We recognized income of $516 , $608 and $137 related to our investment in AIC for the years ended December 31, 2018, 2017 and 2016, respectively. These amounts are presented as equity in net earnings (losses) of investees in our consolidated statements of comprehensive income (loss). Our other comprehensive income (loss) includes our proportionate part of unrealized gains on securities which are owned and held for sale by AIC of ($69) , $461 and $152 related to our investment in AIC for the years ended December 31, 2018, 2017 and 2016, respectively. Directors’ and Officers’ Liability Insurance. We, RMR Inc., RMR LLC and certain other companies to which RMR LLC or its subsidiaries provide management services, including SIR (until it ceased to exist), participate in a combined directors’ and officers’ liability insurance policy. The current combined policy expires in September 2020. We paid aggregate premiums of $198 , $91 and $106 in 2018, 2017 and 2016, respectively, for these policies.

Concentration

Concentration	12 Months Ended
	Dec. 31, 2018
Risks and Uncertainties [Abstract]
Concentration	Concentration Tenant and Credit Concentration We define annualized rental income as the annualized contractual base rents from our tenants pursuant to our lease agreements as of the measurement date, plus straight line rent adjustments and estimated recurring expense reimbursements to be paid to us, and excluding lease value amortization. The U.S. Government, 13 state governments, and three other government tenants combined were responsible for approximately 35.4% , 62.6% and 87.9% of our annualized rental income as of December 31, 2018 , 2017 and 2016 , respectively. The U.S. Government is our largest tenant by annualized rental income and represents approximately 25.6% , 43.5% and 60.6% of our annualized rental income as of December 31, 2018 , 2017 and 2016 , respectively. Geographic Concentration At December 31, 2018 , our 247 wholly owned buildings were located in 38 states and the District of Columbia. Consolidated properties located in Virginia, California, Texas, the District of Columbia and Maryland were responsible for approximately 15.4% , 11.3% , 10.9% , 9.8% , 9.4% of our annualized rental income as of December 31, 2018 , respectively. Consolidated properties located in the metropolitan Washington, D.C. market area were responsible for approximately 26.5% of our annualized rental income as of December 31, 2018 .

Indebtedness

Indebtedness	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Indebtedness	At December 31, 2018 and 2017 , our outstanding indebtedness consisted of the following: December 31, 2018 2017 Revolving credit facility, due in 2023 $ 175,000 $ 570,000 Unsecured term loan, due in 2020 300,000 300,000 Unsecured term loan, due in 2022 (1) 88,000 250,000 Senior unsecured notes, 3.750% interest rate, due in 2019 350,000 350,000 Senior unsecured notes, 3.600% interest rate, due in 2020 (2) 400,000 — Senior unsecured notes, 4.000% interest rate, due in 2022 300,000 300,000 Senior unsecured notes, 4.150% interest rate, due in 2022 (2) 300,000 — Senior unsecured notes, 4.250% interest rate, due in 2024 (2) 350,000 — Senior unsecured notes, 4.500% interest rate, due in 2025 (2) 400,000 — Senior unsecured notes, 5.875% interest rate, due in 2046 310,000 310,000 Mortgage note payable, 7.000% interest rate, due in 2019 (3) 7,939 8,221 Mortgage note payable, 5.720% interest rate, due in 2020 (3) 33,703 34,474 Mortgage note payable, 4.260% interest rate, due in 2020 (3)(4) — 3,173 Mortgage note payable, 4.160% interest rate, due in 2020 (2)(3) 40,772 — Mortgage note payable, 8.150% interest rate, due in 2021 (3) 2,912 4,045 Mortgage note payable, 5.877% interest rate, due in 2021 (3) 13,437 13,693 Mortgage note payable, 4.220% interest rate, due in 2022 (3) 27,210 27,870 Mortgage note payable, 3.550% interest rate, due in 2023 (2)(3) 71,000 — Mortgage note payable, 3.700% interest rate, due in 2023 (2)(3) 50,000 — Mortgage note payable, 4.800% interest rate, due in 2023 (3) 24,509 24,891 Mortgage note payable, 4.050% interest rate, due in 2030 (3) 66,780 66,780 3,311,262 2,263,147 Unamortized debt premiums, discounts and issuance costs (56,372 ) (18,055 ) $ 3,254,890 $ 2,245,092 (1) On December 18, 2018, we made a partial principal payment of $162,000 without penalty using proceeds from the sale of a property portfolio of 15 office buildings located in southern Virginia. As a result of this repayment, we recognized a loss on early extinguishment of debt of $625 for the year ended December 31, 2018 to write off a proportionate amount of unamortized debt issuance costs. On February 11, 2019, we repaid the remaining outstanding principal balance of $88,000 without penalty using proceeds from the sale of a property portfolio located in Northern Virginia and Maryland. (2) As described in Notes 1 and 5, in connection with the SIR Merger, we assumed all of SIR's outstanding senior unsecured notes and mortgage notes on December 31, 2018. (3) We assumed these mortgage notes in connection with our acquisitions of the encumbered properties. The stated interest rates for these mortgage debts are the contractually stated rates; we recorded the assumed mortgages at estimated fair value on the dates of acquisition, and we amortize the fair value premiums to interest expense over the respective terms of the mortgage notes to reduce interest expense to the estimated market interest rates as of the dates of acquisition. (4) This mortgage note was secured by a property in southern Virginia that was sold on December 14, 2018. The mortgage note was repaid at closing and we recognized a loss on early extinguishment of debt of $60 for the year ended December 31, 2018 . Our $750,000 revolving credit facility and our term loans are governed by a credit agreement, or our credit agreement, with a syndicate of institutional lenders that includes a number of features common to all of these credit arrangements. Our credit agreement also includes a feature under which the maximum aggregate borrowing availability may be increased to up to $2,500,000 on a combined basis in certain circumstances. Our $750,000 revolving credit facility is available for general business purposes, including acquisitions. We can borrow, repay and reborrow funds available under our revolving credit facility until maturity and no principal repayment is due until maturity. On December 13, 2018, we amended and restated the credit agreement governing our $750,000 revolving credit facility and $300,000 and $250,000 term loans. As a result of the amendments, the stated maturity date of our revolving credit facility was extended from January 31, 2019 to January 31, 2023. Subject to the payment of an extension fee and meeting certain other conditions, we also have an option to further extend the stated maturity date of our revolving credit facility by two additional six month periods. Also, as a result of the amendments, the interest rate payable on borrowings under our revolving credit facility was reduced from LIBOR plus a premium of 125 basis points per annum to LIBOR plus a premium of 110 basis points per annum. The facility fee remained unchanged at 25 basis points per annum on the total amount of lending commitments under the facility. Both the interest rate premium and facility fee are subject to adjustment based upon changes to our credit ratings. As a result of these amendments, we recognized a loss on early extinguishment of debt related to the revolving credit facility of $24 during the year ended December 31, 2018 to write off unamortized debt issuance costs. As of December 31, 2018 and 2017 , the annual interest rate payable on borrowings under our revolving credit facility was 3.6% and 2.7% , respectively. The weighted average annual interest rate for borrowings under our revolving credit facility was 3.0% , 2.4% and 1.7% , for the years ended December 31, 2018 , 2017 and 2016 , respectively. As of December 31, 2018 and February 25, 2019 , we had $175,000 and $110,000 outstanding under our revolving credit facility, and $575,000 and $640,000 , respectively, available for borrowing under our revolving credit facility. One of our term loans, which matures on March 31, 2020, is prepayable without penalty at any time. We are required to pay interest at a rate of LIBOR plus a premium, which was 140 basis points per annum at December 31, 2018 , on the amount outstanding under this term loan. The interest rate premium is subject to adjustment based upon changes to our credit ratings. As of December 31, 2018 and 2017 , the annual interest rate for the amount outstanding under this term loan was 3.9% and 3.0% , respectively. The weighted average annual interest rate under this term loan was 3.4% , 2.5% and 1.9% , for the years ended December 31, 2018 , 2017 and 2016 , respectively. Our other term loan, which matures on March 31, 2022, is prepayable without penalty at any time. We are required to pay interest at a rate of LIBOR plus a premium, which was 180 basis points per annum as of December 31, 2018 , on the amount outstanding under this term loan. The interest rate premium is subject to adjustment based upon changes to our credit ratings. As of December 31, 2018 and 2017 , the annual interest rate for the amount outstanding under this term loan was 4.3% and 3.4% , respectively. The weighted average annual interest rate under this term loan was 3.8% , 2.9% and 2.3% , for the years ended December 31, 2018 , 2017 and 2016 , respectively. Our credit agreement and senior unsecured notes indentures and their supplements provide for acceleration of payment of all amounts due thereunder upon the occurrence and continuation of certain events of default, such as, in the case of our credit agreement, a change of control of us, which includes RMR LLC ceasing to act as our business and property manager. Our credit agreement and our senior unsecured notes indentures and their supplements also contain a number of covenants, including covenants that restrict our ability to incur debts, require us to maintain certain financial ratios and, in the case of our credit agreement, restrict our ability to make distributions under certain circumstances. We believe we were in compliance with the terms and conditions of the respective covenants under our credit agreement and senior unsecured notes indentures and their supplements at December 31, 2018 . On July 20, 2017, we issued $300,000 of 4.000% senior unsecured notes due 2022 in an underwritten public offering. The net proceeds from this offering of $295,399 , after payment of the underwriters' discount and other offering expenses, were used to finance, in part, the FPO Transaction. As described in Note 5, in connection with the SIR Merger, we assumed three mortgage notes with an aggregate principal balance of $161,772 . We recorded these mortgage notes at their estimated fair value aggregating $159,490 on the date of acquisition. These mortgage notes are secured by five buildings. Also as described in Note 5, in connection with the FPO Transaction we assumed five mortgage notes with an aggregate principal balance of $167,548 . We recorded these mortgage notes at their estimated fair value aggregating $167,936 on the date of acquisition. These mortgage notes are secured by five buildings. In November 2017, we repaid $10,000 of principal of one of these mortgage notes as part of our assumption agreement with the lender. In connection with the FPO Transaction, we acquired FPO's 50% and 51% interests in two unconsolidated joint ventures which own three buildings encumbered by two mortgage notes with an aggregate principal balance of $82,000 . Concurrently with our entering into the FPO merger agreement, we entered a commitment letter with a group of institutional lenders for a 364 -day senior unsecured bridge loan facility in an initial aggregate principal amount of up to $750,000 . In July 2017, we and the lenders terminated this commitment letter and bridge loan facility as a result of our issuance of the senior unsecured notes described above and the proceeds from the sale of our common shares in July 2017 (see Note 11 for more information regarding this sale), and we recognized a loss on extinguishment of debt of $1,715 . At December 31, 2018 , 12 of our consolidated buildings with an aggregate net book value of $627,173 are encumbered by mortgage notes with an aggregate principal amount of $338,262 . Our mortgage notes are non-recourse, subject to certain limited exceptions and do not contain any material financial covenants. None of our unsecured debt obligations require sinking fund payments prior to their maturity dates. The required principal payments due during the next five years and thereafter under all our outstanding consolidated debt as of December 31, 2018 are as follows: Year Principal Payment 2019 $ 362,054 2020 775,707 2021 14,420 2022 713,518 2023 318,783 Thereafter 1,126,780 $ 3,311,262 (1) (1) Total consolidated debt outstanding as of December 31, 2018 , net of unamortized premiums, discounts and issuance costs totaling $56,372 was $3,254,890 .

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities	Fair Value of Assets and Liabilities The table below presents certain of our assets measured at fair value at December 31, 2018 , categorized by the level of inputs, as defined in the fair value hierarchy under GAAP, used in the valuation of each asset: Fair Value at Reporting Date 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 Assets: Investment in RMR Inc. (1) $ 148,680 $ 148,680 $ — $ — Non-Recurring Fair Value Measurements Assets: Assets of properties held for sale (2) $ 195,107 $ — $ 195,107 $ — (1) As of December 31, 2018, we owned 2,801,061 shares of class A common stock of RMR Inc., including 1,214,225 shares acquired in 2015 with a historical cost basis of $26,888 , and 1,586,836 shares acquired from SIR in the SIR Merger with a cost basis of $84,229 . Our shares of class A common stock of RMR Inc. are included in other assets in our consolidated balance sheets and are reported at fair value based on quoted market prices (Level 1 inputs as defined in the fair value hierarchy under GAAP). During the year ended December 31, 2018 , we recorded an unrealized loss of $7,552 for the shares acquired in 2015 to adjust our investment in RMR Inc. to its fair value. As discussed in Note 5, the shares we acquired from SIR in the SIR Merger were recorded at fair value on December 31, 2018. (2) We estimated the fair value of a property portfolio consisting of 34 buildings we agreed to sell located in Northern Virginia and Maryland at December 31, 2018 based on the selling price agreed to with a third party (Level 2 inputs as defined in the fair value hierarchy under GAAP). See Note 5 for further details. In addition to the assets described in the table above, our financial instruments include our cash and cash equivalents, restricted cash, rents receivable, mortgage note receivable, accounts payable, a revolving credit facility, unsecured term loans, senior unsecured notes, mortgage notes payable, amounts due to related persons, other accrued expenses and security deposits. At December 31, 2018 and 2017, the fair values of our financial instruments approximated their carrying values in our consolidated financial statements, due to their short term nature or floating interest rates, except as follows: As of December 31, 2018 As of December 31, 2017 Financial Instrument Carrying Value (1) Fair Value Carrying Value (1) Fair Value Senior unsecured notes, 3.750% interest rate, due in 2019 $ 349,239 $ 348,903 $ 348,096 $ 354,993 Senior unsecured notes, 3.60% interest rate, due in 2020 399,146 399,146 — — Senior unsecured notes, 4.00% interest rate, due in 2022 296,735 295,047 295,812 302,655 Senior unsecured notes, 4.15% interest rate, due in 2022 296,736 296,736 — — Senior unsecured notes, 4.25% interest rate, due in 2024 337,736 337,736 — — Senior unsecured notes, 4.50% interest rate, due in 2025 377,329 377,329 — — Senior unsecured notes, 5.875% interest rate, due in 2046 300,576 274,288 300,232 320,416 Mortgage notes payable 335,241 336,365 183,100 186,542 Total $ 2,692,738 $ 2,665,550 $ 1,127,240 $ 1,164,606 (1) Includes unamortized debt premiums, discounts and issuance costs. We estimated the fair value of our senior unsecured notes (except for our senior unsecured notes due in 2046) using an average of the bid and ask price of the notes as of the measurement date (Level 2 inputs as defined in the fair value hierarchy under GAAP). We estimated the fair value of our senior unsecured notes due in 2046 based on the closing price on Nasdaq (Level 1 inputs as defined in the fair value hierarchy under GAAP) as of the measurement date. We estimated the fair values of our mortgage notes payable using discounted cash flow analyses and currently prevailing market rates as of the measurement date (Level 3 inputs as defined in the fair value hierarchy under GAAP). Because Level 3 inputs are unobservable, our estimated fair value may differ materially from the actual fair value.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Shareholders' Equity	Shareholders’ Equity Share Awards: We have common shares available for issuance under the terms of the 2009 Plan. During the years ended December 31, 2018, 2017 and 2016, we granted to our officers and other employees of RMR LLC annual share awards of 14,675 , 14,337 and 13,350 of our common shares, respectively, valued at $995 , $1,067 and $1,183 , in aggregate, respectively. We also granted each of our then six Trustees 750 of our common shares in 2018 with an aggregate value of $254 ( $42 per Trustee), each of our then six Trustees 750 common shares in 2017 with an aggregate value of $392 ( $65 per Trustee) and each of our then five Trustees 625 common shares in 2016 with an aggregate value of $244 ( $49 per Trustee) as part of their annual compensation. In addition, we granted 750 of our common shares, with a value of $41 in connection with the election of one of our Managing Trustees in 2018. The values of the share grants were based upon the closing price of our common shares trading on Nasdaq or the New York Stock Exchange, as applicable, on the date of grant. The common shares awarded to our Trustees vested immediately. The common shares granted to our officers and certain other employees of RMR LLC vest in five equal annual installments beginning on the date of grant. We include the value of granted shares in general and administrative expenses ratably over the vesting period. A summary of shares granted, forfeited, vested and unvested under the terms of the 2009 Plan for the years ended December 31, 2018 , 2017 and 2016 , is as follows: 2018 2017 2016 Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Unvested at beginning of year 26,062 $78.24 24,743 $82.36 24,181 $80.44 Granted 19,925 $64.73 18,837 $77.44 16,475 $86.64 Forfeited (255 ) $52.96 — $— — $— Vested (18,634 ) $63.80 (17,518 ) $83.20 (15,913 ) $83.88 Unvested acquired in the SIR Merger (1) 28,223 $27.48 — $— — $— Unvested at end of year 55,321 $73.25 26,062 $78.24 24,743 $82.36 (1) Represents unvested shares granted under SIR's equity compensation plan that were converted at the Exchange Ratio into shares under the 2009 Plan, and which will have similar vesting requirements as shares granted under the 2009 Plan, as described in Note 1. The 55,321 unvested shares as of December 31, 2018 are scheduled to vest as follows: 27,998 shares in 2019, 13,259 shares in 2020, 9,232 shares in 2021 and 4,832 shares in 2022. As of December 31, 2018 , the estimated future compensation expense for the unvested shares was $984 . The weighted average period over which the compensation expense will be recorded is approximately 22 months. During the years ended December 31, 2018 , 2017 and 2016 , we recorded $ 1,337 , $1,377 and $1,371 , respectively, of compensation expense related to the 2009 Plan. At December 31, 2018 , 330,372 of our common shares remained available for issuance under the 2009 Plan. 2018 Share Purchases On January 1, 2018, we purchased 154 of our common shares valued at $74.16 per share, the closing price of our common shares on Nasdaq on December 29, 2017, from a former employee of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares. On May 24, 2018, we purchased 112 of our common shares valued at $56.40 per share, the closing price of our common shares on Nasdaq on that day, from one of our Trustees in satisfaction of tax withholding and payment obligations in connection with the vesting of an award of our common shares. On September 24, 2018, we purchased an aggregate of 4,718 of our common shares, valued at $45.40 per share, the closing price of our common shares on Nasdaq on that day, from our officers and certain other employees of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares. 2017 Share Purchases On May 17, 2017, we purchased 112 of our common shares, valued at $87.00 per share, the closing price of our common shares on Nasdaq on that day, from one of our Trustees to fund that Trustee's resulting minimum required tax withholding obligation. During 2017, we purchased 3,478 of our common shares, valued at a weighted average price per share of $73.20 , based on the closing price of our common shares on Nasdaq, on the date of purchase, from our officers and certain other employees of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares. Distributions During the years ended December 31, 2018 , 2017 and 2016, we paid distributions on our common shares as follows: Annual Per Share Distribution Total Distribution Characterization of Distribution Year Return of Capital Ordinary Income Qualified Dividend 2018 $6.88 $ 170,566 68.60% 31.40% —% 2017 $6.88 $ 145,209 49.35% 50.65% —% 2016 $6.88 $ 122,366 36.21% 62.74% 1.05% On January 18, 2019, we declared a dividend payable to common shareholders of record on January 28, 2019 in the amount of $0.55 per share, or $26,446 . We paid this distribution on February 21, 2019. 2017 Sale of Shares On July 5, 2017, we sold 6,250,000 of our common shares at a price of $74.00 per share in an underwritten public offering. On August 3, 2017, we sold 726,757 of our common shares at a price of $74.00 per share pursuant to an overallotment option granted to the underwriters for the July offering. The aggregate net proceeds from these sales of $493,866 , after payment of the underwriters' discount and other offering expenses, were used to finance, in part, the FPO Transaction. Cumulative Other Comprehensive Income (Loss) Cumulative other comprehensive income (loss) represents our share of the comprehensive income (loss) of our equity method investees, and prior to December 31, 2017, the unrealized gain (loss) on the RMR Inc. shares we own. See Note 4 for further information on ASU No. 2016-01. The following table presents changes in the amounts we recognized in cumulative other comprehensive income (loss) by component for the years ended December 31, 2018 , 2017 and 2016 : Unrealized Gain (Loss) on Investment in Equity Securities Equity in Unrealized Gains (Losses) of Investees (1) Total Balance at December 31, 2015 $ (9,391 ) $ (5,476 ) $ (14,867 ) Other comprehensive income before reclassifications 30,465 11,254 41,719 Amounts reclassified from cumulative other comprehensive income to net income — 105 105 Net current period other comprehensive income 30,465 11,359 41,824 Balance at December 31, 2016 21,074 5,883 26,957 Other comprehensive income before reclassifications 24,042 9,462 33,504 Amounts reclassified from cumulative other comprehensive income to net income — (34 ) (34 ) Net current period other comprehensive income 24,042 9,428 33,470 Balance at December 31, 2017 45,116 15,311 60,427 Amounts reclassified from cumulative other comprehensive income to cumulative net income (45,116 ) (15,165 ) (60,281 ) Balance at January 1, 2018 — 146 146 Other comprehensive income before reclassifications — (3 ) (3 ) Amounts reclassified from cumulative other comprehensive income to net income — (37 ) (37 ) Net current period other comprehensive income — (40 ) (40 ) Balance at December 31, 2018 $ — $ 106 $ 106 (1) Amounts reclassified from cumulative other comprehensive income (loss) to net income (loss) is included in equity in net earnings (losses) of investees in our consolidated statements of comprehensive income (loss). Preferred Units of Limited Partnership On May 1, 2018, one of our subsidiaries redeemed all 1,813,504 of its outstanding 5.5% Series A Cumulative Preferred Units for $11.15 per unit plus accrued and unpaid distributions (an aggregate of $20,310 ).

Equity Investment in Select Inc

Equity Investment in Select Income REIT	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Investment in Select Income REIT	Equity Investment in Select Income REIT Until October 9, 2018, we owned 24,918,421 , or approximately 27.8% , of the then outstanding SIR common shares. As described in Note 1, we completed the Secondary Sale. As a result of the Secondary Sale, we recorded a loss of $18,665 during the year ended December 31, 2018 . We accounted for our investment in SIR under the equity method and had previously reported our investment in SIR as a reportable segment. As a result of the Secondary Sale and the elimination of a reportable segment, our equity method investment in SIR is classified as discontinued operations in our consolidated financial statements. See Note 13 for further information regarding discontinued operations. Under the equity method, we recorded our proportionate share of SIR’s net income as equity in earnings of SIR in our consolidated statements of comprehensive income (loss). During the period from January 1, 2018 to October 9, 2018 and the years ended December 31, 2017 and 2016 , we recorded $24,358 , $21,584 and $35,381 of equity in earnings of SIR, respectively. Our other comprehensive income (loss) includes our proportionate share of SIR’s unrealized gains of $28 , $8,967 and $11,207 for the period from January 1, 2018 to October 9, 2018 and the years ended December 31, 2017 and 2016 , respectively. The adjusted GAAP cost basis of our investment in SIR was less than our proportionate share of SIR’s total shareholders’ equity book value on the dates we acquired the shares. Prior to the Secondary Sale, we were accreting a basis difference to earnings over the estimated remaining useful lives of certain real estate assets and intangible assets and liabilities owned by SIR. This accretion increased our equity in the earnings of SIR by $3,233 , $2,944 and $2,956 for the period from January 1, 2018 to October 9, 2018 and the years ended December 31, 2017 and 2016, respectively. During the period from January 1, 2018 to October 9, 2018 and the years ended December 31, 2017 and 2016 , we received cash distributions from SIR totaling $38,124 , $50,832 and $50,335 , respectively. During the period from January 1, 2018 to October 9, 2018 and the years ended December 31, 2017 and 2016 , SIR issued 63,157 , 59,502 and 65,900 common shares, respectively. We recognized a gain on issuance of shares by SIR of $29 , $72 and $86 during the period from January 1, 2018 to October 9, 2018, and the years ended December 31, 2017 and 2016 , respectively, as a result of the per share issuance price of these SIR common shares being above the then average per share carrying value of our SIR common shares. The following tables present summarized financial data of SIR: Condensed Consolidated Balance Sheet December 31, 2017 Real estate properties, net $ 3,905,616 Properties held for sale 5,829 Acquired real estate leases, net 477,577 Cash and cash equivalents 658,719 Rents receivable, net 127,672 Other assets, net 127,617 Total assets $ 5,303,030 ILPT revolving credit facility $ 750,000 Unsecured term loan, net 348,870 Senior unsecured notes, net 1,777,425 Mortgage notes payable, net 210,785 Assumed real estate lease obligations, net 68,783 Other liabilities 155,348 Total shareholders' equity 1,991,819 Total liabilities and shareholders' equity $ 5,303,030 Consolidated Statements of Income Nine Months Ended September 30, Year Ended December 31, REVENUES: 2018 2017 2016 Rental income $ 298,003 $ 392,285 $ 387,015 Tenant reimbursements and other income 60,514 75,818 74,992 Total revenues 358,517 468,103 462,007 EXPENSES: Real estate taxes 36,748 44,131 42,879 Other operating expenses 43,714 55,567 52,957 Depreciation and amortization 105,326 137,672 133,762 Acquisition and transaction related costs 3,796 1,075 306 General and administrative 47,353 54,909 28,632 Write-off of straight line rents, net 10,626 12,517 — Loss on asset impairment — 4,047 — Loss on impairment of real estate assets 9,706 229 5,484 Total expenses 257,269 310,147 264,020 Gain on sale of real estate 4,075 — — Dividend income 1,190 1,587 1,268 Unrealized gain on equity securities 53,159 — — Interest income 753 91 30 Interest expense (69,446 ) (92,870 ) (82,620 ) Loss on early extinguishment of debt (1,192 ) — — Income before income tax expense and equity in earnings of an investee 89,787 66,764 116,665 Income tax expense (446 ) (466 ) (448 ) Equity in earnings of an investee 882 608 137 Net income 90,223 66,906 116,354 Net income allocated to noncontrolling interest (15,841 ) — (33 ) Net income attributed to SIR $ 74,382 $ 66,906 $ 116,321 Weighted average common shares outstanding (basic) 89,395 89,351 89,304 Weighted average common shares outstanding (diluted) 89,411 89,370 $ 89,324 Net income attributed to SIR per common share (basic and diluted) $ 0.83 $ 0.75 $ 1.30

Discontinued Operations

Discontinued Operations	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Discontinued Operations As described in Notes 1 and 7, on October 9, 2018, we sold all 24,918,421 SIR common shares that we then owned in the Secondary Sale. We recorded a loss of $18,665 during the year ended December 31, 2018 related to this sale. The sale of the SIR common shares qualifies as discontinued operations; accordingly, our equity method investment in SIR is classified as discontinued operations in our consolidated financial statements. As described in Note 5, in August 2017, we sold one vacant office property in Falls Church, VA with 164,746 rentable square feet and a net book value of $12,901 as of the date of sale for $13,523 , excluding closing costs. Results of operations for this property, which qualified as held for sale prior to our adoption in 2014 of ASU No. 2014-8, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity , are classified as discontinued operations in our consolidated financial statements. The table below presents the components of income from discontinued operations for the years ended December 31, 2018, 2017 and 2016: Year Ended December 31, 2018 2017 2016 Equity in earnings of Select Income REIT $ 24,358 $ 21,584 $ 35,381 Net gain on issuance of shares by Select Income REIT 29 72 86 Loss on sale of Select Income REIT shares (18,665 ) — — Income (loss) from property discontinued operations — 173 (589 ) Income from discontinued operations $ 5,722 $ 21,829 $ 34,878

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2018
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 2018 and 2017 . 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Rental income $ 108,717 $ 108,085 $ 106,102 $ 103,656 Net income (loss) available for common shareholders $ 6,287 $ 29,602 $ (449 ) $ (57,695 ) Net income (loss) available for common shareholders per common share (basic and diluted) $ 0.25 $ 1.20 $ (0.02 ) $ (2.31 ) Common distributions declared $ 1.72 $ 1.72 $ 1.72 $ 1.72 2017 First Second Third Fourth Rental income $ 69,296 $ 69,887 $ 70,179 $ 107,170 Net income (loss) available for common shareholders $ 7,415 $ 11,677 $ 10,989 $ (18,266 ) Net income (loss) available for common shareholders per common share (basic and diluted) $ 0.42 $ 0.66 $ 0.45 $ (0.74 ) Common distributions declared $ 1.72 $ 1.72 $ 1.72 $ 1.72

SCHEDULE III REAL ESTATE AND AC

SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION	Initial Cost to Company Costs Capitalized Subsequent to Acquisition Cost amount carried at Close of Period Property Location Number of Buildings Encumbrances (1) Land Buildings Impairments/ Land Buildings Total (2) Accumulated (3) Date(s) Original Inverness Center Birmingham, AL 3 $ — $ 5,954 $ 11,664 $ — $ — $ 5,954 $ 11,664 $ 17,618 $ — 12/31/2018 1984; 1985 445 Jan Davis Drive Huntsville, AL 1 — 1,513 1,503 — — 1,513 1,503 3,016 — 12/31/2018 2007 4905 Moores Mill Road Huntsville, AL 1 — 4,628 36,612 — — 4,628 36,612 41,240 — 12/31/2018 1979 131 Clayton Street Montgomery, AL 1 — 920 9,084 48 — 920 9,132 10,052 (1,708 ) 6/22/2011 2007 4344 Carmichael Road Montgomery, AL 1 — 1,374 11,658 10 — 1,374 11,668 13,042 (1,458 ) 12/17/2013 2009 15451 North 28th Avenue Phoenix, AZ 1 — 1,917 7,416 499 — 1,917 7,915 9,832 (836 ) 9/10/2014 1996 16001 North 28th Avenue Phoenix, AZ 1 — 3,382 416 — — 3,382 416 3,798 — 12/31/2018 1998 2149 West Dunlap Avenue Phoenix, AZ 1 — 6,606 218 — — 6,606 218 6,824 — 12/31/2018 1983 711 S 14th Avenue Safford, AZ 1 — 460 11,708 484 (4,440 ) 364 7,848 8,212 (190 ) 6/16/2010 1992 Regents Center Tempe, AZ 2 — 4,154 3,066 — — 4,154 3,066 7,220 — 12/31/2018 1988 Campbell Place Carlsbad, CA 2 — 5,815 3,902 — — 5,815 3,902 9,717 — 12/31/2018 2007 Folsom Corporate Center Folsom, CA 1 — 2,927 5,628 — — 2,927 5,628 8,555 — 12/31/2018 2008 Bayside Technology Park Fremont, CA 1 — 10,869 653 — — 10,869 653 11,522 — 12/31/2018 1990 5045 East Butler Street Fresno, CA 1 — 7,276 61,118 139 — 7,276 61,257 68,533 (25,031 ) 8/29/2002 1971 10949 N. Mather Boulevard Rancho Cordova, CA 1 — 562 16,923 359 — 562 17,282 17,844 (2,201 ) 10/30/2013 2012 11020 Sun Center Drive Rancho Cordova, CA 1 64,490 1,466 8,797 671 — 1,466 9,468 10,934 (513 ) 12/20/2016 1983 100 Redwood Shores Parkway Redwood City, CA 1 — 14,568 7,783 — — 14,568 7,783 22,351 — 12/31/2018 1993 3875 Atherton Road Rocklin, CA 1 — 178 860 — — 178 860 1,038 — 12/31/2018 1991 801 K Street Sacramento, CA 1 — 4,688 61,995 6,275 — 4,688 68,270 72,958 (5,922 ) 1/29/2016 1989 9815 Goethe Road Sacramento, CA 1 — 1,450 9,465 1,523 — 1,450 10,988 12,438 (2,019 ) 9/14/2011 1992 Capitol Place Sacramento, CA 1 — 2,290 35,891 7,885 — 2,290 43,776 46,066 (10,059 ) 12/17/2009 1988 4181 Ruffin Road San Diego, CA 1 — 5,250 10,549 5,076 — 5,250 15,625 20,875 (3,914 ) 7/16/2010 1981 4560 Viewridge Road San Diego, CA 1 — 4,269 18,316 4,319 — 4,347 22,557 26,904 (10,672 ) 3/31/1997 1996 9174 Sky Park Centre San Diego, CA 1 7,983 685 5,530 2,708 — 685 8,238 8,923 (3,246 ) 6/24/2002 1986 2090 Fortune Drive San Jose, CA 1 — 9,074 — — — 9,074 — 9,074 — 12/31/2018 1996 2115 O’Nel Drive San Jose, CA 1 — 12,402 5,103 — — 12,402 5,103 17,505 — 12/31/2018 1984 6448-6450 Via Del Oro San Jose, CA 1 — 4,747 2,027 — — 4,747 2,027 6,774 — 12/31/2018 1983 North First Street San Jose, CA 1 — 8,377 4,035 — — 8,377 4,035 12,412 — 12/31/2018 1984 Rio Robles Drive San Jose, CA 3 — 23,874 13,806 — — 23,874 13,806 37,680 — 12/31/2018 1984 2450 and 2500 Walsh Avenue Santa Clara, CA 2 — 13,480 16,783 — — 13,480 16,783 30,263 — 12/31/2018 1982 Initial Cost to Company Costs Capitalized Subsequent to Acquisition Cost amount carried at Close of Period Property Location Number of Buildings Encumbrances (1) Land Buildings Impairments/ Land Buildings Total (2) Accumulated (3) Date(s) Original 3250 and 3260 Jay Street Santa Clara, CA 2 — 20,056 14,163 — — 20,056 14,163 34,219 — 12/31/2018 1982 603 San Juan Avenue Stockton, CA 1 — 563 5,470 — — 563 5,470 6,033 (878 ) 7/20/2012 2012 350 West Java Drive Sunnyvale, CA 1 — 24,804 464 — — 24,804 464 25,268 — 12/31/2018 1984 7958 South Chester Street Centennial, CO 1 — 6,735 7,210 — — 6,735 7,210 13,945 — 12/31/2018 2000 350 Spectrum Loop Colorado Springs, CO 1 — 3,679 7,793 — — 3,679 7,793 11,472 — 12/31/2018 2000 333 Inverness Drive South Englewood, CO 1 — 5,756 4,579 — — 5,756 4,579 10,335 — 12/31/2018 1998 12795 West Alameda Parkway Lakewood, CO 1 — 2,640 23,777 1,094 — 2,640 24,871 27,511 (5,559 ) 1/15/2010 1988 Corporate Center Lakewood, CO 3 — 2,887 27,537 3,889 — 2,887 31,426 34,313 (12,495 ) 10/11/2002 1980 1 Targeting Center Windsor, CT 1 — 1,404 574 — — 1,404 574 1,978 — 12/31/2018 1980 11 Dupont Circle, NW Washington, DC 1 — 28,255 44,743 1,994 — 28,255 46,737 74,992 (1,672 ) 10/2/2017 1974 1211 Connecticut Avenue, NW Washington, DC 1 — 30,388 24,667 1,391 — 30,388 26,058 56,446 (892 ) 10/2/2017 1967 1401 K Street, NW Washington, DC 1 — 29,215 34,656 3,210 — 29,215 37,866 67,081 (1,497 ) 10/2/2017 1929 20 Massachusetts Avenue Washington, DC 1 — 12,009 51,528 21,395 — 12,228 72,704 84,932 (35,137 ) 3/31/1997 1996 440 First Street, NW Washington, DC 1 — 27,903 38,624 1,293 — 27,903 39,917 67,820 (1,264 ) 10/2/2017 1982 625 Indiana Avenue Washington, DC 1 — 26,000 25,955 7,293 — 26,000 33,248 59,248 (7,555 ) 8/17/2010 1989 840 First Street, NE Washington, DC 1 — 42,727 73,249 472 — 42,727 73,721 116,448 (2,290 ) 10/2/2017 2003 10350 NW 112th Avenue Miami, FL 1 — 4,836 2,779 — — 4,836 2,779 7,615 — 12/31/2018 2002 7850 Southwest 6th Court Plantation, FL 1 — 4,800 30,592 383 — 4,800 30,975 35,775 (6,026 ) 5/12/2011 1999 8900 Grand Oak Circle Tampa, FL 1 — 1,100 11,773 288 — 1,100 12,061 13,161 (2,471 ) 10/15/2010 1994 180 Ted Turner Drive SW Atlanta, GA 1 — 5,717 20,017 186 — 5,717 20,203 25,920 (3,229 ) 7/25/2012 2007 Corporate Square Atlanta, GA 5 — 3,996 29,762 27,816 — 3,996 57,578 61,574 (13,371 ) 7/16/2004 1967 Executive Park Atlanta, GA 1 — 1,521 11,826 3,996 — 1,521 15,822 17,343 (5,781 ) 7/16/2004 1972 One Georgia Center Atlanta, GA 1 — 10,250 27,933 6,034 — 10,250 33,967 44,217 (5,419 ) 9/30/2011 1968 One Primerica Parkway Duluth, GA 1 — 6,982 23,132 — — 6,982 23,132 30,114 — 12/31/2018 2013 4712 Southpark Boulevard Ellenwood, GA 1 — 1,390 19,635 88 — 1,390 19,723 21,113 (3,156 ) 7/25/2012 2005 91-209 Kuhela Street Kapolei, HI 1 — 2,008 — — — 2,008 — 2,008 — 12/31/2018 — 8305 NW 62nd Avenue Johnston, IA 1 — 2,670 8,060 — — 2,670 8,060 10,730 — 12/31/2018 2011 1185, 1249 & 1387 S. Vinnell Way Boise, ID 3 — 3,390 29,026 822 — 3,390 29,848 33,238 (4,871 ) 9/11/2012 1996; 1997; 2002 Initial Cost to Company Costs Capitalized Subsequent to Acquisition Cost amount carried at Close of Period Property Location Number of Buildings Encumbrances (1) Land Buildings Impairments/ Land Buildings Total (2) Accumulated (3) Date(s) Original 2020 S. Arlington Heights Arlington Heights, IL 1 — 1,450 13,160 872 — 1,450 14,032 15,482 (3,101 ) 12/29/2009 1988 400 South Jefferson Street Chicago, IL 1 13,384 19,532 20,274 — — 19,532 20,274 39,806 — 12/31/2018 1947 475 Bond Street Lincolnshire, IL 1 — 4,915 574 — — 4,915 574 5,489 — 12/31/2018 2000 1415 West Diehl Road Naperville, IL 1 — 12,431 20,749 — — 12,431 20,749 33,180 — 12/31/2018 2001 440 North Fairway Drive Vernon Hills, IL 1 — 4,500 445 — — 4,500 445 4,945 — 12/31/2018 1992 Intech Park Indianapolis, IN 3 — 4,170 68,888 4,337 — 4,170 73,225 77,395 (13,425 ) 10/14/2011 2000; 2001; 2008 7601 and 7635 Interactive Way Indianapolis, IN 2 — 3,363 14,636 — — 3,363 14,636 17,999 — 12/31/2018 2003; 2008 400 State Street Kansas City, KS 1 49,087 640 9,932 5,265 — 640 15,197 15,837 (3,309 ) 6/16/2010 1971 Capitol Tower Topeka, KS 1 — 1,236 3,115 — — 1,236 3,115 4,351 — 12/31/2018 1983 The Atrium at Circleport II Erlanger, KY 1 — 1,810 1,948 — — 1,810 1,948 3,758 — 12/31/2018 1999 7125 Industrial Road Florence, KY 1 — 1,698 11,722 151 — 1,698 11,873 13,571 (1,766 ) 12/31/2012 1980 251 Causeway Street Boston, MA 1 — 5,100 17,293 2,555 — 5,100 19,848 24,948 (4,061 ) 8/17/2010 1987 300 and 330 Billerica Road Chelmsford, MA 2 — 4,737 — — — 4,737 — 4,737 — 12/31/2018 1984 75 Pleasant Street Malden, MA 1 — 1,050 31,086 271 — 1,050 31,357 32,407 (6,703 ) 5/24/2010 2008 111 Powdermill Road Maynard, MA 1 — 4,432 — — — 4,432 — 4,432 — 12/31/2018 1990 25 Newport Avenue Quincy, MA 1 — 2,700 9,199 1,791 — 2,700 10,990 13,690 (2,021 ) 2/16/2011 1985 One Montvale Avenue Stoneham, MA 1 — 1,670 11,035 2,234 — 1,670 13,269 14,939 (2,693 ) 6/16/2010 1945 314 Littleton Road Westford, MA 1 — 5,736 8,555 — — 5,736 8,555 14,291 — 12/31/2018 2007 Annapolis Commerce Center Annapolis, MD 2 — 4,057 7,665 219 — 4,057 7,884 11,941 (275 ) 10/2/2017 1989 4201 Patterson Avenue Baltimore, MD 1 — 901 8,097 4,085 — 901 12,182 13,083 (4,961 ) 10/15/1998 1989 Hillside Center Columbia, MD 2 — 3,437 4,228 336 — 3,437 4,564 8,001 (131 ) 10/2/2017 2001 TenThreeTwenty Columbia, MD 1 — 3,126 16,361 869 — 3,126 17,230 20,356 (570 ) 10/2/2017 1982 7001 Columbia Gateway Drive Columbia, MD 1 — 5,687 10,433 — — 5,687 10,433 16,120 — 12/31/2018 2008 3300 75th Avenue Landover, MD 1 — 4,110 36,371 1,346 — 4,110 37,717 41,827 (8,281 ) 2/26/2010 1985 1401 Rockville Pike Rockville, MD 1 25,019 3,248 29,258 16,481 — 3,248 45,739 48,987 (19,266 ) 2/2/1998 1986 2115 East Jefferson Street Rockville, MD 1 — 3,349 11,152 385 — 3,349 11,537 14,886 (1,521 ) 8/27/2013 1981 Redland 520/530 Rockville, MD 3 — 12,714 61,377 1,498 — 12,714 62,875 75,589 (1,945 ) 10/2/2017 2008 Redland 540 Rockville, MD 1 — 10,740 17,714 2,896 — 10,740 20,610 31,350 (879 ) 10/2/2017 2003 Initial Cost to Company Costs Capitalized Subsequent to Acquisition Cost amount carried at Close of Period Property Location Number of Buildings Encumbrances (1) Land Buildings Impairments/ Land Buildings Total (2) Accumulated (3) Date(s) Original Rutherford Business Park Windsor Mill, MD 1 — 1,598 10,219 330 — 1,598 10,549 12,147 (1,557 ) 11/16/2012 1972 Meadows Business Park Woodlawn, MD 2 — 3,735 21,509 2,268 — 3,735 23,777 27,512 (4,701 ) 2/15/2011 1973 3550 Green Court Ann Arbor, MI 1 69,304 3,659 4,896 — — 3,659 4,896 8,555 — 12/31/2018 1998 11411 E. Jefferson Avenue Detroit, MI 1 — 630 18,002 438 — 630 18,440 19,070 (3,930 ) 4/23/2010 2009 Rosedale Corporate Plaza Roseville, MN 1 — 672 6,045 1,505 — 672 7,550 8,222 (3,474 ) 12/1/1999 1987 1300 Summit Street Kansas City, MO 1 2,933 2,776 12,070 915 — 2,776 12,985 15,761 (1,939 ) 9/27/2012 1998 4241-4300 NE 34th Street Kansas City, MO 1 — 1,443 6,193 3,992 — 1,780 9,848 11,628 (4,199 ) 3/31/1997 1995 2555 Grand Boulevard Kansas City, MO 1 — 4,243 51,931 — — 4,243 51,931 56,174 — 12/31/2018 2003 1220 Echelon Parkway Jackson, MS 1 — 440 25,458 238 — 440 25,696 26,136 (4,100 ) 7/25/2012 2009 2300 and 2400 Yorkmont Road Charlotte, NC 2 — 1,345 19,226 — — 1,345 19,226 20,571 — 12/31/2018 1995 18010 and 18020 Burt Street Omaha, NE 2 — 7,032 12,599 — — 7,032 12,599 19,631 — 12/31/2018 2012 10-12 Celina Avenue Nashua, NH 1 — 3,000 14,052 1,569 — 3,000 15,621 18,621 (3,379 ) 8/31/2009 1979 500 Charles Ewing Boulevard Ewing, NJ 1 — 4,846 26,208 — — 4,846 26,208 31,054 — 12/31/2018 2012 299 Jefferson Road Parsippany, NJ 1 — 4,579 2,937 — — 4,579 2,937 7,516 — 12/31/2018 2011 One Jefferson Road Parsippany, NJ 1 — 4,450 5,291 — — 4,450 5,291 9,741 — 12/31/2018 2009 50 West State Street Trenton, NJ 1 — 5,000 38,203 3,313 — 5,000 41,516 46,516 (8,009 ) 12/30/2010 1989 138 Delaware Avenue Buffalo, NY 1 — 4,405 18,899 7,551 — 4,485 26,370 30,855 (11,830 ) 3/31/1997 1994 Airline Corporate Center Colonie, NY 1 — 790 6,400 406 — 790 6,806 7,596 (1,053 ) 6/22/2012 2004 5000 Corporate Court Holtsville, NY 1 — 6,530 17,711 2,734 — 6,530 20,445 26,975 (3,811 ) 8/31/2011 2000 8687 Carling Road Liverpool, NY 1 — 571 — — — 571 — 571 — 12/31/2018 1997 1212 Pittsford - Victor Road Pittsford, NY 1 27,238 613 79 — — 613 79 692 — 12/31/2018 1965 500 Canal View Boulevard Rochester, NY 1 — 2,077 376 — — 2,077 376 2,453 — 12/31/2018 1996 2231 Schrock Road Columbus, OH 1 — 722 218 — — 722 218 940 — 12/31/2018 1999 4600 25th Avenue Salem, OR 1 — 6,510 17,973 5,165 — 6,510 23,138 29,648 (4,898 ) 12/20/2011 1957 501 Ridge Avenue Hanover, PA 1 — 3,452 5,152 — — 3,452 5,152 8,604 — 12/31/2018 1948 8800 Tinicum Boulevard Philadelphia, PA 1 — 5,617 22,866 — — 5,617 22,866 28,483 — 12/31/2018 2000 Synergy Business Park Columbia, SC 3 — 1,439 11,143 5,178 — 1,439 16,321 17,760 (4,335 ) 5/10/2006;9/17/2010 1982; 1985 9680 Old Bailes Road Fort Mill, SC 1 — 841 2,967 — — 841 2,967 3,808 — 12/31/2018 2007 One Memphis Place Memphis, TN 1 — 1,630 5,645 3,290 — 1,630 8,935 10,565 (1,742 ) 9/17/2010 1985 16001 North Dallas Parkway Addison, TX 2 — 10,364 63,661 — — 10,364 63,661 74,025 — 12/31/2018 1987 Initial Cost to Company Costs Capitalized Subsequent to Acquisition Cost amount carried at Close of Period Property Location Number of Buildings Encumbrances (1) Land Buildings Impairments/ Land Buildings Total (2) Accumulated (3) Date(s) Original 2115-2116 East Randol Mill Road Arlington, TX 1 — 2,146 5,469 — — 2,146 5,469 7,615 — 12/31/2018 1989 Research Park Austin, TX 2 — 4,292 13,856 — — 4,292 13,856 18,148 — 12/31/2018 1999 1001 Noble Energy Way Houston, TX 1 — 5,222 29,392 — — 5,222 29,392 34,614 — 12/31/2018 1998 10451 Clay Road Houston, TX 1 — 5,538 10,335 — — 5,538 10,335 15,873 — 12/31/2018 2013 202 North Castlegory Road Houston, TX 1 — 870 5,064 — — 870 5,064 5,934 — 12/31/2018 2016 6380 Rogerdale Road Houston, TX 1 — 12,728 6,161 — — 12,728 6,161 18,889 — 12/31/2018 2006 4221 W. John Carpenter Freeway Irving, TX 1 — 1,424 2,384 — — 1,424 2,384 3,808 — 12/31/2018 1995 8675,8701-8711 Freeport Pkwy and 8901 Esters Boulevard Irving, TX 3 — 10,266 31,815 — — 10,266 31,815 42,081 — 12/31/2018 1990 1511 East Common Street New Braunfels, TX 1 — 5,004 1,276 — — 5,004 1,276 6,280 — 12/31/2018 2005 2900 West Plano Parkway Plano, TX 1 — 6,873 8,901 — — 6,873 8,901 15,774 — 12/31/2018 1998 3400 West Plano Parkway Plano, TX 1 — 4,579 16,091 — — 4,579 16,091 20,670 — 12/31/2018 1994 19100 Ridgewood Parkway San Antonio, TX 1 — 4,223 144,519 — — 4,223 144,519 148,742 — 12/31/2018 2008 3600 Wiseman Boulevard San Antonio, TX 1 — 3,521 6,715 — — 3,521 6,715 10,236 — 12/31/2018 2004 701 Clay Road Waco, TX 1 — 2,030 8,708 3,584 — 2,060 12,262 14,322 (5,020 ) 12/23/1997 1997 1800 Novell Place Provo, UT 1 — 7,546 43,831 — — 7,546 43,831 51,377 — 12/31/2018 2000 4885-4931 North 300 West Provo, UT 2 — 3,946 9,504 — — 3,946 9,504 13,450 — 12/31/2018 2009 14660, 14672 & 14668 Lee Road Chantilly, VA 3 — 6,966 74,214 2,038 — 6,966 76,252 83,218 (3,757 ) 12/22/2016 1998; 2002; 2006 1434 Crossways Chesapeake, VA 2 — 3,617 19,527 1,817 — 3,617 21,344 24,961 (840 ) 10/2/2017 1998 Greenbrier Towers Chesapeake, VA 2 — 3,437 11,241 700 — 3,437 11,941 15,378 (507 ) 10/2/2017 1985 Enterchange at Meadowville Chester, VA 1 — 1,478 9,594 283 — 1,478 9,877 11,355 (1,309 ) 8/28/2013 1999 Three Flint Hill Fairfax, VA 1 — 5,991 25,619 1,515 — 5,991 27,134 33,125 (1,075 ) 10/2/2017 1984 3920 Pender Drive Fairfax, VA 1 — 2,963 12,840 231 — 2,963 13,071 16,034 (1,529 ) 3/21/2014 1981 Pender Business Park Fairfax, VA 4 — 2,529 21,386 636 — 2,529 22,022 24,551 (2,873 ) 11/4/2013 2000 7987 Ashton Avenue Manassas, VA 1 — 1,562 8,253 623 — 1,562 8,876 10,438 (439 ) 1/3/2017 1989 Two Commercial Place Norfolk, VA 1 — 4,530 21,678 — — 4,530 21,678 26,208 — 12/31/2018 1974 1759 & 1760 Business Center Drive Reston, VA 2 — 9,066 78,658 2,723 — 9,066 81,381 90,447 (9,273 ) 5/28/2014 1987 1775 Wiehle Avenue Reston, VA 1 — 4,138 26,120 756 — 4,138 26,876 31,014 (828 ) 10/2/2017 2001 9960 Mayland Drive Richmond, VA 1 — 2,614 15,930 1,891 — 2,614 17,821 20,435 (2,055 ) 5/20/2014 1994 501 South 5th Street Richmond, VA 1 — 14,884 39,411 — — 14,884 39,411 54,295 — 12/31/2018 2009 9201 Forest Hill Avenue Richmond, VA 1 — 1,355 376 — — 1,355 376 1,731 — 12/31/2018 1985 Initial Cost to Company Costs Capitalized Subsequent to Acquisition Cost amount carried at Close of Period Property Location Number of Buildings Encumbrances (1) Land Buildings Impairments/ Land Buildings Total (2) Accumulated (3) Date(s) Original Parham Place Richmond, VA 3 — 920 1,107 — — 920 1,107 2,027 — 12/31/2018 1989; 2012 1751 Blue Hills Drive Roanoke, VA 1 — 2,710 7,823 — — 2,710 7,823 10,533 — 12/31/2018 2003 Aquia Commerce Center Stafford, VA 2 — 2,090 7,465 768 — 2,090 8,233 10,323 (1,549 ) 6/22/2011 1988; 1999 Atlantic Corporate Park Sterling, VA 2 — 5,752 29,323 178 — 5,752 29,501 35,253 (931 ) 10/2/2017 2008 Sterling Business Park Lots 8 and 9 Sterling, VA 1 — 9,177 44,375 — — 9,177 44,375 53,552 (1,385 ) 10/2/2017 2016 Orbital Sciences Campus Sterling, VA 3 — 12,372 19,473 — — 12,372 19,473 31,845 — 12/31/2018 2000; 2001 65 Bowdoin Street S. Burlington, VT 1 — 700 8,416 140 — 700 8,556 9,256 (1,873 ) 4/9/2010 2009 840 North Broadway Everett, WA 2 34,704 3,360 15,376 2,116 — 3,360 17,492 20,852 (3,099 ) 6/28/2012 1985 Stevens Center Richland, WA 2 — 3,970 17,035 4,137 — 4,045 21,097 25,142 (9,854 ) 3/31/1997 1995 351, 401, 501 Elliott Ave West Seattle, WA 3 — 26,851 53,157 — — 26,851 53,157 80,008 — 12/31/2018 2000 11050 West Liberty Drive Milwaukee, WI 1 — 945 4,539 103 — 945 4,642 5,587 (881 ) 6/9/2011 2006 882 TJ Jackson Drive Falling Waters, WV 1 41,099 906 3,886 270 — 922 4,140 5,062 (2,215 ) 3/31/1997 1993 5353 Yellowstone Road Cheyenne, WY 1 — 1,915 8,217 765 — 1,950 8,947 10,897 (4,658 ) 3/31/1997 1995 211 $ 335,241 $ 923,390 $ 2,804,289 $ 221,397 $ (4,440 ) $ 924,164 $ 3,020,472 $ 3,944,636 $ (375,147 ) Properties Held for Sale — — — — 500 First Street, NW Washington, DC 1 — 30,478 15,660 44 — 30,478 15,704 46,182 (448 ) 10/2/2017 1969 91-008 Hanua Street Kapolei, HI 1 — 6,846 — — — 6,846 — 6,846 — 12/31/2018 — Ammendale Commerce Center Beltsville, MD 3 — 4,879 9,498 99 — 4,879 9,597 14,476 (279 ) 10/2/2017 1987 Indian Creek Technology Park Beltsville, MD 4 — 8,796 12,093 394 (2,830 ) 8,796 9,657 18,453 (363 ) 10/2/2017 1988 Gateway 270 West Clarksburg, MD 6 — 12,104 9,688 516 — 12,104 10,204 22,308 (257 ) 10/2/2017 2002 Snowden Center Columbia, MD 5 — 7,955 10,128 119 — 7,955 10,247 18,202 (258 ) 10/2/2017 1982 20400 Century Boulevard Germantown, MD 1 — 2,305 9,890 1,304 — 2,347 11,152 13,499 (5,520 ) 3/31/1997 1995 Cloverleaf Center Germantown, MD 4 — 11,890 4,639 481 — 11,890 5,120 17,010 (167 ) 10/2/2017 2000 Metro Park North Rockville, MD 4 — 11,159 7,624 235 — 11,159 7,859 19,018 (236 ) 10/2/2017 2001 Sterling Park Business Center Sterling, VA 7 — 18,935 21,191 835 — 18,935 22,026 40,961 (643 ) 10/2/2017 1990 36 — 115,347 100,411 4,027 (2,830 ) 115,389 101,566 216,955 (8,171 ) 247 $ 335,241 $ 1,038,737 $ 2,904,700 $ 225,424 $ (7,270 ) $ 1,039,553 $ 3,122,038 $ 4,161,591 $ (383,318 ) ____________________ (1) Represents mortgage debt, net of the unamortized balance of the fair value adjustments and debt issuance costs totaling $3,021 . (2) Excludes value of real estate intangibles. Aggregate cost for federal income tax purposes is approximately $7,126,328 . (3) Depreciation on building and improvements is provided for periods ranging up to 40 years and on equipment up to 12 years . Analysis of the carrying amount of real estate properties and accumulated depreciation: Real Estate Properties Accumulated Depreciation Balance at December 31, 2015 $ 1,696,132 $ 255,879 Additions 194,107 42,404 Disposals (1,479 ) (1,479 ) Balance at December 31, 2016 1,888,760 296,804 Additions 1,100,138 45,315 Loss on asset impairment (9,490 ) — Disposals (3,687 ) (271 ) Balance at December 31, 2017 2,975,721 341,848 Additions 1,486,342 65,215 Loss on asset impairment (8,630 ) — Disposals (286,837 ) (18,740 ) Cost basis adjustment (1) (5,005 ) (5,005 ) Reclassification of assets of properties held for sale (216,955 ) (8,171 ) Balance at December 31, 2018 $ 3,944,636 $ 375,147 (1) Represents the reclassification between accumulated depreciation and building made to certain properties reclassified as assets of properties held for sale at fair value in accordance with GAAP.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation. These consolidated financial statements include the accounts of us and our subsidiaries, all of which are wholly owned directly or indirectly by us. All intercompany transactions and balances with or among our consolidated subsidiaries have been eliminated.
Real Estate Properties	We regularly evaluate whether events or changes in circumstances have occurred that could indicate an impairment in the value of long lived assets. If there is an indication that the carrying value of an asset is not recoverable, we estimate the projected undiscounted cash flows to determine if an impairment loss should be recognized. We determine the amount of any impairment loss by comparing the historical carrying value to estimated fair value. We estimate fair value through an evaluation of recent financial performance and projected discounted cash flows using standard industry valuation techniques. In addition to consideration of impairment upon the events or changes in circumstances described above, we regularly evaluate the remaining lives of our long lived assets. If we change our estimate of the remaining lives, we allocate the carrying value of the affected assets over their revised remaining lives. Real Estate Properties. We record our properties at cost and provide depreciation on real estate investments on a straight line basis over estimated useful lives generally ranging from 7 to 40 years. In some circumstances, we engage independent real estate appraisal firms to provide market information and evaluations which are relevant to our purchase price allocations and determinations of useful lives; however, we are ultimately responsible for the purchase price allocations and determinations of useful lives. We allocate the purchase prices of our properties to land, building and improvements based on determinations of the relative fair values of these assets assuming the properties are vacant. We determine the fair value of each property using methods similar to those used by independent appraisers. We allocate a portion of the purchase price of our properties to above market and below market leases based on the present value (using an interest rate which reflects the risks associated with acquired in place leases at the time each property was acquired by us) of the difference, if any, between (i) the contractual amounts to be paid pursuant to the acquired in place leases and (ii) our estimates of fair market lease rates for the corresponding leases, measured over a period equal to the terms of the respective leases. We allocate a portion of the purchase price to acquired in place leases and tenant relationships based upon market estimates to lease up the property based on the leases in place at the time of purchase. We allocate this aggregate value between acquired in place lease values and tenant relationships based on our evaluation of the specific characteristics of each tenant’s lease. However, we have not separated the value of tenant relationships from the value of acquired in place leases because such value and related amortization expense is immaterial to the accompanying consolidated financial statements. In making these allocations, we consider factors such as estimated carrying costs during the expected lease up periods, including real estate taxes, insurance and other operating income and expenses and costs, such as leasing commissions, legal and other related expenses, to execute similar leases in current market conditions at the time a property was acquired by us. If the value of tenant relationships becomes material in the future, we may separately allocate those amounts and amortize the allocated amounts over the estimated life of the relationships. For transactions that qualify as business combinations, we allocate the excess, if any, of the consideration over the fair value of the assets acquired to goodwill. We amortize capitalized above market lease values (included in acquired in place real estate leases, net in our consolidated balance sheets) and below market lease values (presented as assumed real estate lease obligations, net in our consolidated balance sheets) as a reduction or increase, respectively, to rental income over the terms of the associated leases. Such amortization resulted in net decreases to rental income of $2,903 , $2,764 and $1,457 during the years ended December 31, 2018 , 2017 and 2016 , respectively. We amortize the value of acquired in place leases (included in acquired real estate leases, net in our consolidated balance sheets), exclusive of the value of above market and below market acquired in place leases, over the terms of the associated leases. Such amortization, which is included in depreciation and amortization expense, amounted to $91,472 , $53,410 , and $27,546 during the years ended December 31, 2018 , 2017 and 2016 , respectively. If a lease is terminated prior to its stated expiration, we write off the unamortized amounts relating to that lease.
Cash and Cash Equivalents	Cash and Cash Equivalents. We consider highly liquid investments with original maturities of three months or less at the date of purchase to be 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 certain of our mortgage debts.
Deferred Leasing Costs	Deferred Leasing Costs . Deferred leasing costs include brokerage, legal and other fees associated with our entering leases and we amortize those costs, which are included in depreciation and amortization expense, on a straight line basis over the terms of the respective leases. Deferred leasing costs, excluding properties classified as held for sale, totaled $38,840 and $32,990 at December 31, 2018 and 2017 , respectively, and accumulated amortization of deferred leasing costs totaled $13,168 and $10,013 at December 31, 2018 and 2017 , respectively. Future amortization of deferred leasing costs to be recognized during the current terms of our existing leases as of December 31, 2018 are estimated to be $4,925 in 2019 , $4,215 in 2020 , $3,599 in 2021 , $2,902 in 2022 , $2,363 in 2023 and $7,668 thereafter.
Debt Issuance Costs	Debt Issuance Costs . Debt issuance costs include capitalized issuance or assumption costs related to borrowings, which are amortized to interest expense over the terms of the respective loans. Debt issuance costs, net of accumulated amortization, for our revolving credit facility are included in other assets in our consolidated balance sheets. As of December 31, 2018 and 2017 , debt issuance costs for our revolving credit facility were $4,125 and $5,234 and accumulated amortization of debt issuance costs for our revolving credit facility were $49 and $3,849 , respectively. Debt issuance costs, net of accumulated amortization, for our unsecured term loans, senior unsecured notes and mortgage notes payable are presented as a direct deduction from the associated debt liability in our consolidated balance sheets. As of December 31, 2018 and 2017 , debt issuance costs, net of accumulated amortization, for our unsecured term loans, senior unsecured notes, and mortgage notes payable totaled $12,888 and $15,750 , respectively. Future amortization of debt issuance costs to be recognized with respect to our revolving credit facility, unsecured term loans, senior unsecured notes and mortgage notes as of December 31, 2018 are estimated to be $2,890 in 2019 , $2,189 in 2020 , $2,049 in 2021 , $1,725 in 2022 , $406 in 2023 and $7,705 thereafter.
Equity Securities	Equity Securities. As of December 31, 2018 , we owned 2,801,061 common shares of class A common stock of RMR Inc., including 1,586,836 common shares acquired from SIR on December 31, 2018 in connection with the SIR Merger. Our equity securities are recorded at fair value based on their quoted market price at the end of each reporting period. Effective January 1, 2018, changes in the fair value of our equity securities are recorded through earnings in accordance with the Financial Accounting Standards Board, or FASB, Accounting Standards Update, or ASU, No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities . Prior to January 1, 2018, unrealized gains and losses on equity securities were recorded as a component of cumulative comprehensive income (loss) in shareholders' equity. As further described in Note 7 , we initially acquired 1,541,201 shares of class A common stock of RMR Inc. on June 5, 2015 for cash and share consideration of $17,462 . We concluded, for accounting purposes, that the cash and share consideration we paid for our investment in these shares represented a discount to the fair value of these shares. We initially accounted for this investment under the cost method of accounting and recorded this investment at its estimated fair value of $39,833 as of June 5, 2015 using Level 3 inputs, as defined in the fair value hierarchy under U.S. generally accepted accounting principles, or GAAP. As a result, we recorded a liability for the amount by which the estimated fair value of these shares exceeded the price we paid for these shares. This liability is included in accounts payable and other liabilities in our consolidated balance sheets. This liability is being amortized on a straight line basis through December 31, 2035 as an allocated reduction to our business management and property management fee expense. We amortized $1,087 of this liability during each of the years ended December 31, 2018 , 2017 and 2016 . These amounts are included in the net business management and property management fee amounts for such periods. As of December 31, 2018 , the remaining unamortized amount of this liability was $18,493 . Future amortization of this liability as of December 31, 2018 is estimated to be $1,087 in 2019 through 2023 and $13,058 thereafter.
Equity Method Investments	Equity Method Investments. We account for our investments in Affiliates Insurance Company, or AIC, and SIR, until we sold the SIR common shares we owned as described in Note 1, using the equity method of accounting. Significant influence is present through common representation on the boards of trustees or directors of us, AIC and, until December 31, 2018, SIR. One of our Managing Trustees, Adam D. Portnoy, as the sole trustee of ABP Trust, is the controlling shareholder of The RMR Group Inc., or RMR Inc. He is also a director and officer of RMR Inc. Substantially all of the business of RMR Inc. is conducted by its majority owned subsidiary, RMR LLC, which is our manager, the manager of AIC and, until December 31, 2018, SIR. Most of our Trustees are directors of AIC. See Notes 7, 12 and 13 for further information of our investments in AIC and SIR. In connection with our acquisition of First Potomac Realty Trust, or FPO, in 2017, we acquired 50% and 51% interests in two unconsolidated joint ventures which own three buildings. The buildings owned by these joint ventures are encumbered by an aggregate $82,000 of mortgage indebtedness. We do not control the activities that are most significant to these joint ventures and, as a result, we account for our investment in these joint ventures under the equity method of accounting. See Note 5 for further information regarding our unconsolidated joint ventures. We periodically evaluate our equity method investments for possible indicators of other than temporary impairment whenever events or changes in circumstances indicate the carrying amount of the investment might not be recoverable. These indicators may include the length of time and the extent to which the market value of our investment is below our carrying value, the financial condition of our investees, our intent and ability to be a long term holder of the investment and other considerations. If the decline in fair value is judged to be other than temporary, we record an impairment charge to adjust the basis of the investment to its estimated fair value.
Revenue Recognition	Revenue Recognition. We recognize rental income from operating leases that contain fixed contractual rent changes on a straight line basis over the term of the lease agreements. We increased rental income by $10,164 , $5,582 and $2,691 to record revenue on a straight line basis during the years ended December 31, 2018 , 2017 and 2016 , respectively. Rents receivable, excluding properties classified as held for sale, include $34,006 and $27,267 of straight line rent receivables at December 31, 2018 and 2017 , respectively. Certain of our leases with government tenants provide the tenant the right to terminate its lease if its respective legislature or other funding authority does not appropriate the funding necessary for the government tenant to meet its lease obligations; we have determined the fixed non-cancelable lease term of these leases to be the fully executed term of the lease because we believe the occurrence of termination to be a remote contingency based on both our historical experience and our assessment of the likelihood of lease cancellation on a separate lease basis.
Income Taxes	Income Taxes. We have elected to be taxed as a REIT under the United States Internal Revenue Code of 1986, as amended, or the IRC, and, accordingly, we generally will not be subject to federal income taxes provided we distribute our taxable income and meet certain other requirements to qualify as a REIT. We are, however, subject to certain state and local taxes.
Cumulative Other Comprehensive Income	Cumulative Other Comprehensive Income. Cumulative other comprehensive income represents our share of the cumulative comprehensive income of our equity method investees and, prior to the adoption of FASB ASU No. 2016-01 on January 1, 2018, unrealized gains and losses related to our investment in RMR Inc. See Notes 5 and 7 for further information regarding these investments.
Per Common Share Amounts	Per Common Share Amounts. We calculate basic earnings per common share by dividing net income (loss) available for common shareholders by the weighted average number of our common shares of beneficial ownership, $.01 par value, or our common shares, outstanding during the period. We calculate diluted earnings per share using the more dilutive of the two class method or the treasury stock method. Unvested share awards and other potentially dilutive common shares and the related impact on earnings, are considered when calculating diluted earnings per share.
Use of Estimates	Use of Estimates. Preparation of these financial statements in conformity with GAAP requires us to make estimates and assumptions that may affect the amounts reported in these consolidated financial statements and related notes. The actual results could differ from these estimates.
Reclassifications	Reclassifications. Reclassifications have been made to the prior years’ consolidated financial statements to conform to the current year’s presentation.
Segment Reporting	Segment Reporting. We operate in one business segment: direct ownership of real estate properties.
Recent Accounting Pronouncements	New Accounting Pronouncements On January 1, 2018, we adopted FASB ASU No. 2014-09 (and related clarifying guidance issued by the FASB), Revenue From Contracts With Customers , which outlines a comprehensive model for entities to use in accounting for revenue arising from contracts with customers. ASU No. 2014-09 states that “an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services.” While ASU No. 2014-09 specifically references contracts with customers, it may apply to certain other transactions such as the sale of real estate or equipment. A substantial portion of our revenue consists of rental income from leasing arrangements, which is specifically excluded from ASU No. 2014-09. We have adopted ASU No. 2014-09 using the modified retrospective approach, which resulted in an adjustment to reclassify a previous deferred gain on sale of real estate of $712 from accounts payable and other liabilities to cumulative net income. The adoption of ASU No. 2014-09 did not have a material impact on the amount or timing of our revenue recognition in our consolidated financial statements except for profit recognition on real estate sales. On January 1, 2018, we adopted FASB ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities , which changes how entities measure certain equity investments and present changes in the fair value of financial liabilities measured under the fair value option that are attributable to their own credit. The implementation of ASU No. 2016-01 resulted in the reclassification of historical changes in the fair value of our equity securities of $45,116 from cumulative other comprehensive income to cumulative net income. We also reclassified $15,165 from cumulative other comprehensive income to cumulative net income for our share of cumulative other comprehensive income of certain of our equity method investees. Effective January 1, 2018, changes in the fair value of our equity securities are recorded through earnings in accordance with ASU No. 2016-01. On January 1, 2018, we adopted FASB ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments , which clarifies how companies present and classify certain cash receipts and cash payments in the statements of cash flows. The implementation of this update resulted in the reclassification of $2,944 and $2,956 of accretion recorded in our equity in the earnings of SIR from cash flow from investing activities to cash flow from operating activities for the year ended December 31, 2017 and 2016 , respectively. See Note 12 for further information regarding our investment in SIR. On January 1, 2018, we adopted FASB ASU No. 2016-18, Restricted Cash , which requires companies to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. The implementation of ASU No. 2016-18 resulted in a decrease of $1,563 and an increase of $492 of net cash provided by operating activities for the years ended December 31, 2017 and 2016 , respectively. This update also requires a reconciliation of the totals in the statements of cash flows to the related captions in the balance sheets. As a result, amounts included in restricted cash on our consolidated balance sheets are included with cash and cash equivalents on the consolidated statements of cash flows. The adoption of this update did not change our balance sheet presentation. On October 1, 2018, we adopted FASB ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting , which aligns the measurement and classification guidance for share based payments to nonemployees with the guidance for share based payments to employees, with certain exceptions. The adoption of this standard did not have a material impact in our consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases . In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements . In December 2018, the FASB issued ASU No. 2018-20 Leases (Topic 842), Narrow-Scope Improvements for Lessors . Collectively, these standards set out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). ASU No. 2016-02 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase of the leased asset by the lessee. This classification will determine whether the lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales type leases, direct financing leases and operating leases. These standards are effective as of January 1, 2019. Upon adoption, we applied the package of practical expedients that allows an entity to not reassess (i) whether any expired or existing contracts are or contain leases, (ii) lease classification for any expired or existing leases and (iii) initial direct costs for any expired or existing leases. Furthermore, we applied the optional transition method in ASU No. 2018-11 which allows entities to initially apply the new leases standard at the adoption date and recognize a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption, if any. Additionally, our leases met the criteria in ASU No. 2018-11 to not separate non-lease components from the related lease component; therefore, the accounting for these leases remained largely unchanged from the previous standard. The adoption of ASU No. 2016-02 and the related improvements did not have a material impact in our consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which requires that entities use a new forward looking “expected loss” model that generally will result in the earlier recognition of allowance for credit losses. The measurement of expected credit losses is based upon historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. ASU No. 2016-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. We are currently assessing the potential impact the adoption of ASU No. 2016-13 will have in our consolidated financial statements. We currently expect to adopt the standard using the modified retrospective approach.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of Real Estate Properties	As of December 31, 2018 and 2017 , our acquired real estate leases and assumed real estate obligations, excluding properties classified as held for sale, were as follows: December 31, 2018 2017 Acquired real estate leases: Capitalized above market lease values $ 62,260 $ 46,096 Less: accumulated amortization (20,956 ) (27,259 ) Capitalized above market lease values, net 41,304 18,837 Lease origination value 1,168,979 472,928 Less: accumulated amortization (153,725 ) (139,893 ) Lease origination value, net 1,015,254 333,035 Acquired real estate leases, net $ 1,056,558 $ 351,872 Assumed real estate lease obligations: Capitalized below market lease values $ 31,091 $ 25,973 Less: accumulated amortization (11,060 ) (12,338 ) Assumed real estate lease obligations, net $ 20,031 $ 13,635

Weighted Average Common Shares

Weighted Average Common Shares (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share, Basic and Diluted [Abstract]
Weighted Average Common Share Amounts	The following table provides a reconciliation of the weighted average number of common shares used in the calculation of basic and diluted earnings per share (in thousands): For the Year Ended December 31, 2018 2017 2016 Weighted average common shares for basic earnings per share 24,830 21,158 17,763 Effect of dilutive securities: unvested share awards — — 5 Weighted average common shares for diluted earnings per share (1) 24,830 21,158 17,768 (1) For the years ended December 31, 2018 and 2017, four and five unvested common shares, respectively, were not included in the calculation of diluted earnings per share because to do so would have been antidilutive.

Real Estate Properties (Tables)

Real Estate Properties (Tables)	12 Months Ended
	Dec. 31, 2018
Real Estate [Abstract]
Schedule of allocation of purchase price	Our allocation of the purchase price of this acquisition is based on the relative estimated fair value of the acquired assets and assumed liabilities is presented in the table below. Acquisition Date Location Number of Office Buildings Square Feet Purchase Price Land Building and Improvements Other Assumed Assets Jan 2017 Manassas, VA 1 69,374 $ 12,657 $ 1,562 $ 8,253 $ 2,842 The following table summarizes the estimated consideration transferred and liabilities assumed: Total Purchase Price (excluding acquisition costs): OPI common shares issued 23,282,704 Closing price of OPI common shares on December 31, 2018 $ 27.48 Value of consideration transferred $ 639,809 Cash consideration for fractional shares 8 Equity issuance costs (239 ) Value of consideration transferred $ 639,578 Assumed working capital 55,703 Assumed senior unsecured notes, principal balance 1,450,000 Assumed mortgage notes payable, principal balance 161,772 SIR unsecured revolving credit facility repaid at closing 108,000 Non-cash portion of purchase price 1,775,475 Total consideration transferred and liabilities assumed $ 2,415,053 The following table summarizes the preliminary purchase price allocation for SIR based on estimated fair values as of the December 31, 2018: Preliminary Purchase Price Allocation: Land $ 475,893 Buildings and improvements 960,286 Assets of properties held for sale 7,022 Acquired real estate leases 858,121 Cash 24,744 Restricted cash 476 Rents receivable, net 11,389 Other assets (1) 89,188 Total assets 2,427,119 Unsecured revolving credit facility (2) (108,000 ) Senior unsecured notes (3) (1,410,947 ) Mortgage notes payable (4) (159,490 ) Accounts payable and other liabilities (67,151 ) Assumed real estate lease obligations (11,833 ) Due to related persons (30,120 ) Net assets acquired 639,578 Assumed working capital 55,703 SIR unsecured revolving credit facility repaid at closing (2) 108,000 Assumed senior unsecured notes, principal balance 1,450,000 Assumed mortgage notes payable, principal balance 161,772 Consideration transferred and liabilities assumed (5) $ 2,415,053 (1) Other assets includes $84,229 for SIR's investment in shares of class A common stock of RMR Inc. which was recorded at fair value as of December 31, 2018 . (2) We repaid the outstanding balance under SIR's revolving credit facility at the closing of the SIR Merger with borrowings under our revolving credit facility. (3) The aggregate principal balance of the senior unsecured notes was $1,450,000 as of December 31, 2018 . (4) The aggregate principal balance of the mortgage notes payable was $161,772 as of December 31, 2018 . (5) The allocation of purchase price is based on preliminary estimates and may change significantly following the completion of (i) third party appraisals and (ii) our analysis of intangibles and building valuations. Purchase price excludes acquisition related costs. Our allocation of the purchase price of these acquisitions based on the estimated fair value of the acquired assets and assumed liabilities is presented in the table below. Acquisition Date Location Number of Office Buildings Square Feet Purchase Price (1) Land Buildings and Improvements Other Assumed Assets Acquired Leases Acquired Lease Obligations Jan 2016 Sacramento, CA (2) 1 337,811 $ 79,508 $ 4,688 $ 61,995 $ 2,167 $ 11,245 $ (587 ) Jul 2016 Atlanta, GA (3) — — 1,670 1,670 — — — — Dec 2016 Rancho Cordova, CA (2) 1 82,896 13,943 1,466 8,797 — 3,680 — Dec 2016 Chantilly, VA (2) 3 409,478 104,183 6,966 74,214 — 23,003 — 5 830,185 $ 199,304 $ 14,790 $ 145,006 $ 2,167 $ 37,928 $ (587 ) (1) Excludes acquisition related costs. (2) Accounted for as a business combination. (3) On July 6, 2016, we acquired a land parcel adjacent to one of our existing properties for $1,623 . We accounted for this transaction as an asset acquisition and capitalized acquisition related costs of $47 . The following table summarizes the total consideration paid and the estimated fair values of the assets acquired and liabilities assumed in the FPO Transaction: Total Purchase Price: Cash consideration $ 1,175,140 Acquisition related costs 9,575 Total cash consideration 1,184,715 Preferred units of limited partnership issued (1) 20,221 Acquired net working capital (1,596 ) Assumed mortgage notes 167,548 Non-cash portion of purchase price 186,173 Gross purchase price $ 1,370,888 Purchase Price Allocation: Land $ 360,909 Buildings and improvements 681,340 Acquired real estate leases (2) 283,498 Investment in unconsolidated joint ventures 51,305 Cash 11,191 Restricted cash 1,018 Rents receivable 2,672 Other assets 3,640 Total assets 1,395,573 Mortgage notes payable (3) (167,936 ) Assumed real estate lease obligations (2) (5,776 ) Accounts payable and accrued expenses (10,640 ) Rents collected in advance (1,436 ) Security deposits (4,849 ) Net assets acquired 1,204,936 Assumed working capital (1,596 ) Assumed principal balance of debt 167,548 Gross purchase price $ 1,370,888 (1) Pursuant to the terms of the FPO Transaction, each unit of limited partnership interest in FPO's operating partnership that was not liquidated on the closing date was exchanged on a one-for-one basis for 5.5% Series A Cumulative Preferred Units of the surviving subsidiary. As of December 31, 2017, the carrying value of these Series A Cumulative Preferred Units was $20,496 and was recorded as temporary equity on our consolidated balance sheet. On May 1, 2018, we redeemed all 1,813,504 of the outstanding 5.5% Series A Cumulative Preferred Units for $11.15 per unit (plus accrued and unpaid distributions) for an aggregate of $20,310 . (2) As of the date acquired, the weighted average amortization periods for capitalized above market lease values, lease origination value and capitalized below market lease values were 3.2 years , 3.1 years and 3.8 years , respectively. (3) Includes fair value adjustments totaling $388 on $167,936 principal amount of mortgage notes we assumed in connection with the FPO Transaction.
Schedule of Pro Forma Information	The following table presents our pro forma results of operations for the years ended December 31, 2018 and 2017 as if the SIR Transactions and the FPO Transaction and related financing activities, had occurred on January 1, 2017. The SIR results of operations included in this pro forma financial information have been adjusted to remove ILPT's results of operations for the years ended December 31, 2018 and 2017 . The effect of these adjustments was to decrease pro forma rental income $152,735 and $156,506 for the years ended December 31, 2018 and 2017 , respectively, and to decrease net income $46,237 and $64,661 for the years ended December 31, 2018 and 2017 , respectively. The FPO results of operations included in this pro forma financial information have been adjusted to remove the results of operations of properties and joint venture interests FPO sold from January 1, 2017 to October 2, 2017, the closing date of the FPO Transaction. The effect of these adjustments was to decrease pro forma rental income $804 for the year ended December 31, 2017 and to decrease net loss $47,019 for the year ended December 31, 2017. This pro forma financial information is not necessarily indicative of what our actual financial position or results of operations would have been for the periods presented or for any future period. Differences could result from numerous factors, including future changes in our portfolio of investments, capital structure, property level operating expenses and revenues, including rents expected to be received on our existing leases or leases we may enter during and after 2019, changes in interest rates and other reasons. Actual future results are likely to be different from amounts presented in this pro forma financial information and such differences could be significant. Year Ended December 31, 2018 2017 Rental income $ 758,596 $ 746,801 Net loss $ (87,240 ) $ (74,556 ) Net loss per common share $ (1.82 ) $ (1.55 )
Schedule of Joint Ventures	As of December 31, 2018 and 2017 , our investment in unconsolidated joint ventures consisted of the following: OPI Ownership OPI Carrying Value of Investment at December 31, Number of Office Buildings Location Square Feet Joint Venture 2018 2017 Prosperity Metro Plaza 51% $ 23,969 $ 27,888 2 Fairfax, VA 328,456 1750 H Street, NW 50% 19,696 22,314 1 Washington, D.C. 115,411 Total $ 43,665 $ 50,202 3 443,867 The following table provides a summary of the mortgage debt of our unconsolidated joint ventures: Joint Venture Interest Rate (1) Maturity Date Principal Balance at December 31, 2018 and 2017 Prosperity Metro Plaza 4.09% 12/1/2029 $ 50,000 1750 H Street, NW 3.69% 8/1/2024 32,000 Weighted Average/Total 3.93% $ 82,000 (1) Includes the effect of mark to market purchase accounting.
Schedule of disposal groups	Summarized income statement information for this property is as follows: Statements of Income (Loss) Year Ended December 31, 2017 2016 Rental income $ 17 $ 68 Real estate taxes (88 ) (97 ) Utility expenses (97 ) (146 ) Other operating expenses (202 ) (300 ) General and administrative (76 ) (114 ) Increase in carrying value of property included in discontinued operations 619 — Income (loss) from discontinued operations $ 173 $ (589 ) As of December 31, 2018 , we had 36 buildings with an aggregate undepreciated carrying value of $216,955 under agreement to sell in three separate transactions, as presented in the table below. We have classified these properties as held for sale in our consolidated balance sheet at December 31, 2018 . Date of Sale Agreement Number of Office Buildings Location Square Feet Gross Sale Price (1) Aug 2018 (2) 1 Washington, D.C. 129,035 $ 70,000 Sep 2018 (3) 34 Northern Virginia and Maryland 1,635,868 198,500 Nov 2018 (2)(4) 1 Kapolei, HI 416,956 7,100 36 2,181,859 $ 275,600 (1) Gross sale price includes purchase price adjustments, if any, excludes closing costs. (2) These pending sales are subject to conditions; accordingly, we cannot be sure that we will complete these sales or that these sales will not be delayed or their terms will not change. (3) We recorded a $2,830 loss on impairment of real estate to reduce the carrying value of these buildings to their estimated fair value less costs to sell during the year ended December 31, 2018 . On February 8, 2019, we completed the sale of these buildings. (4) Represents a land parcel acquired from SIR in the SIR Merger. As a result, the results of operations of these properties are included in continuing operations through the date of sale in our consolidated statements of income (loss). Date of Sale Number of Office Buildings Location Square Feet Gross Sale Price (1) Mar 2018 (2) 1 Minneapolis, MN 193,594 $ 20,000 May 2018 (3) 1 New York, NY 187,060 118,500 May 2018 (4) 1 Sacramento, CA 110,500 10,755 Nov 2018 (5) 1 Golden, CO 43,231 4,000 Dec 2018 (6) 15 Southern Virginia 1,640,252 167,000 19 2,174,637 $ 320,255 (1) Gross sale price includes purchase price adjustments, if any, excludes closing costs. (2) We recorded a $640 loss on impairment of real estate to reduce the carrying value of this property to its estimated fair value less costs to sell during the year ended December 31, 2018 . (3) We recorded a $17,249 gain on sale of real estate during the year ended December 31, 2018 as a result of this sale. (4) We recorded a loss on impairment of real estate of $3,029 to reduce the carrying value of this property to its estimated fair value less costs to sell during the year ended December 31, 2018 . (5) We recorded a $54 gain on sale of real estate during the year ended December 31, 2018 as a result of this sale. (6) We recorded a $3,358 gain on sale of real estate during the year ended December 31, 2018 as a result of this sale. The table below presents the components of income from discontinued operations for the years ended December 31, 2018, 2017 and 2016: Year Ended December 31, 2018 2017 2016 Equity in earnings of Select Income REIT $ 24,358 $ 21,584 $ 35,381 Net gain on issuance of shares by Select Income REIT 29 72 86 Loss on sale of Select Income REIT shares (18,665 ) — — Income (loss) from property discontinued operations — 173 (589 ) Income from discontinued operations $ 5,722 $ 21,829 $ 34,878
Schedule of future minimum lease payments related properties (excluding real estate tax and other expense reimbursements)	Our future minimum lease payments related to our consolidated properties and estimated real estate tax and other expense reimbursements scheduled to be received during the current terms of the existing leases as of December 31, 2018 , including the properties acquired in the SIR Merger, are as follows: Year Minimum Lease Payments 2019 $ 569,874 2020 514,551 2021 479,401 2022 434,135 2023 383,695 Thereafter 1,236,540 $ 3,618,196
Schedule of minimum rental payments	Future minimum rental payments due under the lease, net of subleased revenue, as of December 31, 2018 are summarized as follows: Year Minimum Rental Payments 2019 $ 1,584 2020 1,627 2021 139 $ 3,350

Indebtedness (Tables)

Indebtedness (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	At December 31, 2018 and 2017 , our outstanding indebtedness consisted of the following: December 31, 2018 2017 Revolving credit facility, due in 2023 $ 175,000 $ 570,000 Unsecured term loan, due in 2020 300,000 300,000 Unsecured term loan, due in 2022 (1) 88,000 250,000 Senior unsecured notes, 3.750% interest rate, due in 2019 350,000 350,000 Senior unsecured notes, 3.600% interest rate, due in 2020 (2) 400,000 — Senior unsecured notes, 4.000% interest rate, due in 2022 300,000 300,000 Senior unsecured notes, 4.150% interest rate, due in 2022 (2) 300,000 — Senior unsecured notes, 4.250% interest rate, due in 2024 (2) 350,000 — Senior unsecured notes, 4.500% interest rate, due in 2025 (2) 400,000 — Senior unsecured notes, 5.875% interest rate, due in 2046 310,000 310,000 Mortgage note payable, 7.000% interest rate, due in 2019 (3) 7,939 8,221 Mortgage note payable, 5.720% interest rate, due in 2020 (3) 33,703 34,474 Mortgage note payable, 4.260% interest rate, due in 2020 (3)(4) — 3,173 Mortgage note payable, 4.160% interest rate, due in 2020 (2)(3) 40,772 — Mortgage note payable, 8.150% interest rate, due in 2021 (3) 2,912 4,045 Mortgage note payable, 5.877% interest rate, due in 2021 (3) 13,437 13,693 Mortgage note payable, 4.220% interest rate, due in 2022 (3) 27,210 27,870 Mortgage note payable, 3.550% interest rate, due in 2023 (2)(3) 71,000 — Mortgage note payable, 3.700% interest rate, due in 2023 (2)(3) 50,000 — Mortgage note payable, 4.800% interest rate, due in 2023 (3) 24,509 24,891 Mortgage note payable, 4.050% interest rate, due in 2030 (3) 66,780 66,780 3,311,262 2,263,147 Unamortized debt premiums, discounts and issuance costs (56,372 ) (18,055 ) $ 3,254,890 $ 2,245,092 (1) On December 18, 2018, we made a partial principal payment of $162,000 without penalty using proceeds from the sale of a property portfolio of 15 office buildings located in southern Virginia. As a result of this repayment, we recognized a loss on early extinguishment of debt of $625 for the year ended December 31, 2018 to write off a proportionate amount of unamortized debt issuance costs. On February 11, 2019, we repaid the remaining outstanding principal balance of $88,000 without penalty using proceeds from the sale of a property portfolio located in Northern Virginia and Maryland. (2) As described in Notes 1 and 5, in connection with the SIR Merger, we assumed all of SIR's outstanding senior unsecured notes and mortgage notes on December 31, 2018. (3) We assumed these mortgage notes in connection with our acquisitions of the encumbered properties. The stated interest rates for these mortgage debts are the contractually stated rates; we recorded the assumed mortgages at estimated fair value on the dates of acquisition, and we amortize the fair value premiums to interest expense over the respective terms of the mortgage notes to reduce interest expense to the estimated market interest rates as of the dates of acquisition. (4) This mortgage note was secured by a property in southern Virginia that was sold on December 14, 2018. The mortgage note was repaid at closing and we recognized a loss on early extinguishment of debt of $60 for the year ended December 31, 2018 .
Schedule of required principal payments	The required principal payments due during the next five years and thereafter under all our outstanding consolidated debt as of December 31, 2018 are as follows: Year Principal Payment 2019 $ 362,054 2020 775,707 2021 14,420 2022 713,518 2023 318,783 Thereafter 1,126,780 $ 3,311,262 (1) (1) Total consolidated debt outstanding as of December 31, 2018 , net of unamortized premiums, discounts and issuance costs totaling $56,372 was $3,254,890 .

Fair Value of Assets and Liab_2

Fair Value of Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of assets measured on a non-recurring basis at fair value, categorized by the level of inputs used in the valuation assets	The table below presents certain of our assets measured at fair value at December 31, 2018 , categorized by the level of inputs, as defined in the fair value hierarchy under GAAP, used in the valuation of each asset: Fair Value at Reporting Date 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 Assets: Investment in RMR Inc. (1) $ 148,680 $ 148,680 $ — $ — Non-Recurring Fair Value Measurements Assets: Assets of properties held for sale (2) $ 195,107 $ — $ 195,107 $ — (1) As of December 31, 2018, we owned 2,801,061 shares of class A common stock of RMR Inc., including 1,214,225 shares acquired in 2015 with a historical cost basis of $26,888 , and 1,586,836 shares acquired from SIR in the SIR Merger with a cost basis of $84,229 . Our shares of class A common stock of RMR Inc. are included in other assets in our consolidated balance sheets and are reported at fair value based on quoted market prices (Level 1 inputs as defined in the fair value hierarchy under GAAP). During the year ended December 31, 2018 , we recorded an unrealized loss of $7,552 for the shares acquired in 2015 to adjust our investment in RMR Inc. to its fair value. As discussed in Note 5, the shares we acquired from SIR in the SIR Merger were recorded at fair value on December 31, 2018. (2) We estimated the fair value of a property portfolio consisting of 34 buildings we agreed to sell located in Northern Virginia and Maryland at December 31, 2018 based on the selling price agreed to with a third party (Level 2 inputs as defined in the fair value hierarchy under GAAP). See Note 5 for further details.
Schedule of fair value and carrying value of financial instruments	At December 31, 2018 and 2017, the fair values of our financial instruments approximated their carrying values in our consolidated financial statements, due to their short term nature or floating interest rates, except as follows: As of December 31, 2018 As of December 31, 2017 Financial Instrument Carrying Value (1) Fair Value Carrying Value (1) Fair Value Senior unsecured notes, 3.750% interest rate, due in 2019 $ 349,239 $ 348,903 $ 348,096 $ 354,993 Senior unsecured notes, 3.60% interest rate, due in 2020 399,146 399,146 — — Senior unsecured notes, 4.00% interest rate, due in 2022 296,735 295,047 295,812 302,655 Senior unsecured notes, 4.15% interest rate, due in 2022 296,736 296,736 — — Senior unsecured notes, 4.25% interest rate, due in 2024 337,736 337,736 — — Senior unsecured notes, 4.50% interest rate, due in 2025 377,329 377,329 — — Senior unsecured notes, 5.875% interest rate, due in 2046 300,576 274,288 300,232 320,416 Mortgage notes payable 335,241 336,365 183,100 186,542 Total $ 2,692,738 $ 2,665,550 $ 1,127,240 $ 1,164,606 (1) Includes unamortized debt premiums, discounts and issuance costs.

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Summary of shares granted and vested under the terms of the entity's 2009 Plan	A summary of shares granted, forfeited, vested and unvested under the terms of the 2009 Plan for the years ended December 31, 2018 , 2017 and 2016 , is as follows: 2018 2017 2016 Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Unvested at beginning of year 26,062 $78.24 24,743 $82.36 24,181 $80.44 Granted 19,925 $64.73 18,837 $77.44 16,475 $86.64 Forfeited (255 ) $52.96 — $— — $— Vested (18,634 ) $63.80 (17,518 ) $83.20 (15,913 ) $83.88 Unvested acquired in the SIR Merger (1) 28,223 $27.48 — $— — $— Unvested at end of year 55,321 $73.25 26,062 $78.24 24,743 $82.36 (1) Represents unvested shares granted under SIR's equity compensation plan that were converted at the Exchange Ratio into shares under the 2009 Plan, and which will have similar vesting requirements as shares granted under the 2009 Plan, as described in Note 1.
Schedule of dividends	During the years ended December 31, 2018 , 2017 and 2016, we paid distributions on our common shares as follows: Annual Per Share Distribution Total Distribution Characterization of Distribution Year Return of Capital Ordinary Income Qualified Dividend 2018 $6.88 $ 170,566 68.60% 31.40% —% 2017 $6.88 $ 145,209 49.35% 50.65% —% 2016 $6.88 $ 122,366 36.21% 62.74% 1.05%
Schedule of changes in each component of cumulative other comprehensive income (loss)	The following table presents changes in the amounts we recognized in cumulative other comprehensive income (loss) by component for the years ended December 31, 2018 , 2017 and 2016 : Unrealized Gain (Loss) on Investment in Equity Securities Equity in Unrealized Gains (Losses) of Investees (1) Total Balance at December 31, 2015 $ (9,391 ) $ (5,476 ) $ (14,867 ) Other comprehensive income before reclassifications 30,465 11,254 41,719 Amounts reclassified from cumulative other comprehensive income to net income — 105 105 Net current period other comprehensive income 30,465 11,359 41,824 Balance at December 31, 2016 21,074 5,883 26,957 Other comprehensive income before reclassifications 24,042 9,462 33,504 Amounts reclassified from cumulative other comprehensive income to net income — (34 ) (34 ) Net current period other comprehensive income 24,042 9,428 33,470 Balance at December 31, 2017 45,116 15,311 60,427 Amounts reclassified from cumulative other comprehensive income to cumulative net income (45,116 ) (15,165 ) (60,281 ) Balance at January 1, 2018 — 146 146 Other comprehensive income before reclassifications — (3 ) (3 ) Amounts reclassified from cumulative other comprehensive income to net income — (37 ) (37 ) Net current period other comprehensive income — (40 ) (40 ) Balance at December 31, 2018 $ — $ 106 $ 106 (1) Amounts reclassified from cumulative other comprehensive income (loss) to net income (loss) is included in equity in net earnings (losses) of investees in our consolidated statements of comprehensive income (loss).

Equity Investment in Select I_2

Equity Investment in Select Income REIT (Tables)	12 Months Ended
	Dec. 31, 2018
SIR
Summarized Financial Data of Select Income Realty (SIR)	The following tables present summarized financial data of SIR: Condensed Consolidated Balance Sheet December 31, 2017 Real estate properties, net $ 3,905,616 Properties held for sale 5,829 Acquired real estate leases, net 477,577 Cash and cash equivalents 658,719 Rents receivable, net 127,672 Other assets, net 127,617 Total assets $ 5,303,030 ILPT revolving credit facility $ 750,000 Unsecured term loan, net 348,870 Senior unsecured notes, net 1,777,425 Mortgage notes payable, net 210,785 Assumed real estate lease obligations, net 68,783 Other liabilities 155,348 Total shareholders' equity 1,991,819 Total liabilities and shareholders' equity $ 5,303,030 Consolidated Statements of Income Nine Months Ended September 30, Year Ended December 31, REVENUES: 2018 2017 2016 Rental income $ 298,003 $ 392,285 $ 387,015 Tenant reimbursements and other income 60,514 75,818 74,992 Total revenues 358,517 468,103 462,007 EXPENSES: Real estate taxes 36,748 44,131 42,879 Other operating expenses 43,714 55,567 52,957 Depreciation and amortization 105,326 137,672 133,762 Acquisition and transaction related costs 3,796 1,075 306 General and administrative 47,353 54,909 28,632 Write-off of straight line rents, net 10,626 12,517 — Loss on asset impairment — 4,047 — Loss on impairment of real estate assets 9,706 229 5,484 Total expenses 257,269 310,147 264,020 Gain on sale of real estate 4,075 — — Dividend income 1,190 1,587 1,268 Unrealized gain on equity securities 53,159 — — Interest income 753 91 30 Interest expense (69,446 ) (92,870 ) (82,620 ) Loss on early extinguishment of debt (1,192 ) — — Income before income tax expense and equity in earnings of an investee 89,787 66,764 116,665 Income tax expense (446 ) (466 ) (448 ) Equity in earnings of an investee 882 608 137 Net income 90,223 66,906 116,354 Net income allocated to noncontrolling interest (15,841 ) — (33 ) Net income attributed to SIR $ 74,382 $ 66,906 $ 116,321 Weighted average common shares outstanding (basic) 89,395 89,351 89,304 Weighted average common shares outstanding (diluted) 89,411 89,370 $ 89,324 Net income attributed to SIR per common share (basic and diluted) $ 0.83 $ 0.75 $ 1.30

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Schedule of discontinued operations	Summarized income statement information for this property is as follows: Statements of Income (Loss) Year Ended December 31, 2017 2016 Rental income $ 17 $ 68 Real estate taxes (88 ) (97 ) Utility expenses (97 ) (146 ) Other operating expenses (202 ) (300 ) General and administrative (76 ) (114 ) Increase in carrying value of property included in discontinued operations 619 — Income (loss) from discontinued operations $ 173 $ (589 ) As of December 31, 2018 , we had 36 buildings with an aggregate undepreciated carrying value of $216,955 under agreement to sell in three separate transactions, as presented in the table below. We have classified these properties as held for sale in our consolidated balance sheet at December 31, 2018 . Date of Sale Agreement Number of Office Buildings Location Square Feet Gross Sale Price (1) Aug 2018 (2) 1 Washington, D.C. 129,035 $ 70,000 Sep 2018 (3) 34 Northern Virginia and Maryland 1,635,868 198,500 Nov 2018 (2)(4) 1 Kapolei, HI 416,956 7,100 36 2,181,859 $ 275,600 (1) Gross sale price includes purchase price adjustments, if any, excludes closing costs. (2) These pending sales are subject to conditions; accordingly, we cannot be sure that we will complete these sales or that these sales will not be delayed or their terms will not change. (3) We recorded a $2,830 loss on impairment of real estate to reduce the carrying value of these buildings to their estimated fair value less costs to sell during the year ended December 31, 2018 . On February 8, 2019, we completed the sale of these buildings. (4) Represents a land parcel acquired from SIR in the SIR Merger. As a result, the results of operations of these properties are included in continuing operations through the date of sale in our consolidated statements of income (loss). Date of Sale Number of Office Buildings Location Square Feet Gross Sale Price (1) Mar 2018 (2) 1 Minneapolis, MN 193,594 $ 20,000 May 2018 (3) 1 New York, NY 187,060 118,500 May 2018 (4) 1 Sacramento, CA 110,500 10,755 Nov 2018 (5) 1 Golden, CO 43,231 4,000 Dec 2018 (6) 15 Southern Virginia 1,640,252 167,000 19 2,174,637 $ 320,255 (1) Gross sale price includes purchase price adjustments, if any, excludes closing costs. (2) We recorded a $640 loss on impairment of real estate to reduce the carrying value of this property to its estimated fair value less costs to sell during the year ended December 31, 2018 . (3) We recorded a $17,249 gain on sale of real estate during the year ended December 31, 2018 as a result of this sale. (4) We recorded a loss on impairment of real estate of $3,029 to reduce the carrying value of this property to its estimated fair value less costs to sell during the year ended December 31, 2018 . (5) We recorded a $54 gain on sale of real estate during the year ended December 31, 2018 as a result of this sale. (6) We recorded a $3,358 gain on sale of real estate during the year ended December 31, 2018 as a result of this sale. The table below presents the components of income from discontinued operations for the years ended December 31, 2018, 2017 and 2016: Year Ended December 31, 2018 2017 2016 Equity in earnings of Select Income REIT $ 24,358 $ 21,584 $ 35,381 Net gain on issuance of shares by Select Income REIT 29 72 86 Loss on sale of Select Income REIT shares (18,665 ) — — Income (loss) from property discontinued operations — 173 (589 ) Income from discontinued operations $ 5,722 $ 21,829 $ 34,878

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The following is a summary of our unaudited quarterly results of operations for 2018 and 2017 . 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Rental income $ 108,717 $ 108,085 $ 106,102 $ 103,656 Net income (loss) available for common shareholders $ 6,287 $ 29,602 $ (449 ) $ (57,695 ) Net income (loss) available for common shareholders per common share (basic and diluted) $ 0.25 $ 1.20 $ (0.02 ) $ (2.31 ) Common distributions declared $ 1.72 $ 1.72 $ 1.72 $ 1.72 2017 First Second Third Fourth Rental income $ 69,296 $ 69,887 $ 70,179 $ 107,170 Net income (loss) available for common shareholders $ 7,415 $ 11,677 $ 10,989 $ (18,266 ) Net income (loss) available for common shareholders per common share (basic and diluted) $ 0.42 $ 0.66 $ 0.45 $ (0.74 ) Common distributions declared $ 1.72 $ 1.72 $ 1.72 $ 1.72

Organization (Details)

Organization (Details) $ / shares in Units, $ in Thousands	Dec. 31, 2018USD ($)ft²buildingstateproperty$ / sharesshares	Dec. 27, 2018shares	Oct. 09, 2018USD ($)$ / sharesshares	Sep. 14, 2018ft²	Oct. 02, 2017USD ($)ft²	Jul. 05, 2017$ / sharesshares	Dec. 31, 2018USD ($)ft²buildingstateproperty$ / sharesshares	Dec. 30, 2018$ / sharesshares	Dec. 31, 2017$ / sharesshares	Dec. 31, 2016ft²
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²										830,185
Number of properties, noncontrolling interest | property							2
Number of buildings, noncontrolling interest | building							3
Common shares of beneficial interest, par value (in dollars per share) | $ / shares	$ 0.01						$ 0.01	$ 0.04	$ 0.01
Reverse stock split ratio				0.25
Common shares of beneficial interest, shares outstanding | shares	48,082,903						48,082,903	192,331,612	24,786,479
Continuing operations
Real Estate Properties [Line Items]
Number of buildings | building	247						247
Number of states in which owned properties located | state	38						38
Rentable area of properties (in square feet) | ft²	31,900,000						31,900,000
First Potomac Realty Trust
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²	400,000				6,000,000		400,000
Number of properties, noncontrolling interest | property							2
Number of buildings, noncontrolling interest | building							3
Long term debt acquired					$ 167,936
Purchase price					1,370,888
Liabilities assumed					$ 483,000
SIR
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²	16,500,000			16,500,000			16,500,000
Share conversion ratio | shares	1.04						1.04
Common shares of beneficial interest, par value (in dollars per share) | $ / shares	$ 0.01						$ 0.01
Share price (in dollars per share) | $ / shares	$ 6.87						$ 6.87
Purchase price							$ 2,415,053
Transaction costs	$ 27,497						27,497
Payment transaction costs	$ 14,508
Liabilities assumed							$ 1,719,772
Number of properties acquired | property	99						99
Common Shares | SIR
Real Estate Properties [Line Items]
Share price (in dollars per share) | $ / shares	$ 27.48						$ 27.48
Underwritten Public Offering
Real Estate Properties [Line Items]
Number of shares sold (in shares) | shares						6,250,000
Sale of stock (in dollars per share) | $ / shares						$ 74
Underwritten Public Offering | Common Shares
Real Estate Properties [Line Items]
Number of shares sold (in shares) | shares			24,918,421
Sale of stock (in dollars per share) | $ / shares			$ 18.25
Proceeds from sale fo stock			$ 435,125
SIR | SIR
Real Estate Properties [Line Items]
Payment transaction costs	$ 12,989
Industrial Logistics Properties Trust | SIR
Real Estate Properties [Line Items]
Shares owned (in shares) | shares		45,000,000
Senior unsecured notes | SIR
Real Estate Properties [Line Items]
Long term debt acquired	$ 1,410,947						$ 1,410,947
3.60% Senior Notes Due 2020
Real Estate Properties [Line Items]
Interest rate (as a percent)	3.60%						3.60%
3.60% Senior Notes Due 2020 | Senior unsecured notes
Real Estate Properties [Line Items]
Interest rate (as a percent)	3.60%						3.60%
3.60% Senior Notes Due 2020 | Senior unsecured notes | SIR
Real Estate Properties [Line Items]
Long term debt acquired	$ 400,000						$ 400,000
Interest rate (as a percent)	3.60%						3.60%
4.15% Senior Notes Due 2022
Real Estate Properties [Line Items]
Interest rate (as a percent)	4.15%						4.15%
4.15% Senior Notes Due 2022 | Senior unsecured notes
Real Estate Properties [Line Items]
Interest rate (as a percent)	4.15%						4.15%
4.15% Senior Notes Due 2022 | Senior unsecured notes | SIR
Real Estate Properties [Line Items]
Long term debt acquired	$ 300,000						$ 300,000
Interest rate (as a percent)	4.15%						4.15%
4.25% Senior Notes Due 2024
Real Estate Properties [Line Items]
Interest rate (as a percent)	4.25%						4.25%
4.25% Senior Notes Due 2024 | Senior unsecured notes
Real Estate Properties [Line Items]
Interest rate (as a percent)	4.25%						4.25%
4.25% Senior Notes Due 2024 | Senior unsecured notes | SIR
Real Estate Properties [Line Items]
Long term debt acquired	$ 350,000						$ 350,000
Interest rate (as a percent)	4.25%						4.25%
4.50% Senior Notes Due 2025
Real Estate Properties [Line Items]
Interest rate (as a percent)	4.50%						4.50%
4.50% Senior Notes Due 2025 | Senior unsecured notes
Real Estate Properties [Line Items]
Interest rate (as a percent)	4.50%						4.50%
4.50% Senior Notes Due 2025 | Senior unsecured notes | SIR
Real Estate Properties [Line Items]
Long term debt acquired	$ 400,000						$ 400,000
Interest rate (as a percent)	4.50%						4.50%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Real Estate Properties (Details) - USD ($) $ in Thousands	Oct. 02, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Real Estate [Line Items]
Net decreases to rental income from amortization of capitalized above market and below market leases		$ 2,903	$ 2,764	$ 1,457
Amortization of the value of leases		$ 94,375	56,174	29,003
Below market, acquired lease amortization period	3 years 9 months 18 days	5 years 8 months
Minimum | Buildings and improvements
Real Estate [Line Items]
Estimated useful lives		7 years
Maximum | Buildings and improvements
Real Estate [Line Items]
Estimated useful lives		40 years
Weighted Average
Real Estate [Line Items]
Below market, acquired lease amortization period		5 years 9 months 18 days
Original value lease
Real Estate [Line Items]
Amortization of the value of leases		$ 91,472	$ 53,410	$ 27,546
Original value lease | Weighted Average
Real Estate [Line Items]
Acquired lease amortization period		6 years 10 months 24 days
Above market lease | Weighted Average
Real Estate [Line Items]
Acquired lease amortization period		5 years 4 months 24 days
Continuing operations
Projected future amortization of net intangible lease assets and liabilities, excluding those classified as discontinued operations
2,019		$ 203,554
2,020		180,025
2,021		153,089
2,022		136,515
2,023		112,524
Thereafter		$ 250,820

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Real Estate Assets and Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Real Estate [Line Items]
Acquired real estate leases, net	$ 1,056,558	$ 351,872
Capitalized below market lease values	31,091	25,973
Less: accumulated amortization	(11,060)	(12,338)
Assumed real estate lease obligations, net	20,031	13,635
Above market lease
Real Estate [Line Items]
Real estate leases	62,260	46,096
Less: accumulated amortization	(20,956)	(27,259)
Acquired real estate leases, net	41,304	18,837
Original value lease
Real Estate [Line Items]
Real estate leases	1,168,979	472,928
Less: accumulated amortization	(153,725)	(139,893)
Acquired real estate leases, net	$ 1,015,254	$ 333,035

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Leasing and Financing Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Future amortization of deferred leasing costs, excluding those classified as discontinued operations
Deferred financing fees, net	$ 12,888	$ 15,750
Future amortization of deferred financing fees
2,019	2,890
2,020	2,189
2,021	2,049
2,022	1,725
2,023	406
Thereafter	7,705
Continuing operations
Debt Instrument [Line Items]
Deferred leasing costs, gross	38,840	32,990
Accumulated amortization of deferred leasing costs	13,168	10,013
Future amortization of deferred leasing costs, excluding those classified as discontinued operations
2,019	4,925
2,020	4,215
2,021	3,599
2,022	2,902
2,023	2,363
Thereafter	7,668
Unsecured revolving credit facility
Debt Instrument [Line Items]
Deferred financing fees, gross	4,125	5,234
Future amortization of deferred leasing costs, excluding those classified as discontinued operations
Accumulated amortization of deferred financing fees	$ 49	$ 3,849

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Equity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 05, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015
Related Party Transaction [Line Items]
Common shares owned in RMR Inc.	2,801,061		2,801,061		1,214,225
SIR
Related Party Transaction [Line Items]
Shares acquired (in shares)			1,586,836
Purchase price			$ 2,415,053
RMR Inc
Related Party Transaction [Line Items]
Purchase price		$ 17,462
Initial other liabilities				$ 18,493
Class A common shares | SIR
Related Party Transaction [Line Items]
Shares acquired (in shares)	1,586,836
Class A common shares | RMR Inc
Related Party Transaction [Line Items]
Shares acquired (in shares)		1,541,201
Cost method investment		$ 39,833
RMR Inc
Related Party Transaction [Line Items]
Recognized amortization of the liability			1,087
Amortization of liability, 2019			1,087
Amortization of liability, 2020			1,087
Amortization of liability, 2021			1,087
Amortization of liability, 2022			1,087
Amortization of liability, 2023			1,087
Amortization of liability, thereafter			$ 13,058

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, $ in Thousands	Oct. 02, 2017buildingjoint_venture	Dec. 31, 2018USD ($)segmentbuildingjoint_venture$ / shares	Dec. 31, 2017USD ($)joint_venture$ / shares	Dec. 31, 2016USD ($)	Dec. 30, 2018$ / shares
Schedule of Equity Method Investments [Line Items]
Number of joint ventures | joint_venture		2
Increase in rental income to record revenue on straight line basis		$ 10,164	$ 5,582	$ 2,691
Common shares of beneficial interest, par value (in dollars per share) | $ / shares		$ 0.01	$ 0.01		$ 0.04
Number of business segments | segment		1
First Potomac Realty Trust
Schedule of Equity Method Investments [Line Items]
Number of joint ventures | joint_venture	2		2
Number of buildings | building	3	3
Joint Venture Property 1 | First Potomac Realty Trust
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest	50.00%	50.00%
Joint Venture Property 2 | First Potomac Realty Trust
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest	51.00%	51.00%
Unconsolidated Joint Ventures
Schedule of Equity Method Investments [Line Items]
Number of buildings | building		3
Mortgage indebtedness		$ 82,000
Continuing operations
Schedule of Equity Method Investments [Line Items]
Number of buildings | building		247
Increase in rental income to record revenue on straight line basis		$ 10,164	$ 5,582	$ 2,691
Straight line rent receivables		$ 34,006	$ 27,267

Weighted Average Common Share A

Weighted Average Common Share Amounts (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Basic and Diluted [Abstract]
Weighted average common shares for basic earnings per share (in shares)	24,830	21,158	17,763
Effect of dilutive securities: unvested share awards (in shares)	0	0	5
Weighted average common shares for diluted earnings per share (in shares)	24,830	21,158	17,768
Antidilutive securities	4	5

New Accounting Pronouncements (

New Accounting Pronouncements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred gain on sale of real estate		$ 712
Unrealized gain on investment in available for sale securities	$ 0	24,042	$ 30,465
Equity in net earnings (losses) of investees	(2,269)	(13)	137
Increase (decrease) in cash from operating activities	$ 144,916	137,554	126,722
ASU 2016-01 | Cumulative Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unrealized gain on investment in available for sale securities		45,116
ASU 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accretion of equity in earnings		(2,944)	(2,956)
ASU 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in cash from operating activities		(1,563)	$ 492
SIR and AIC | ASU 2016-01 | Cumulative Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity in net earnings (losses) of investees		$ 15,165

Real Estate Properties - Additi

Real Estate Properties - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)ft²leasebuildingproperty
Real Estate Properties [Line Items]
Number of properties, noncontrolling interest | property	2
Number of buildings, noncontrolling interest | building	3
Number of leases entered | lease	128
Rentable square feet (in sqft) | ft²	1,382,821
Weighted average lease term	6 years 10 months
Expenditures committed on leases	$ 37,135
Committed but unspent tenant related obligations estimated	$ 58,380
Continuing operations
Real Estate Properties [Line Items]
Number of buildings | building	247
Carrying value	$ 4,161,591

Real Estate Properties - Merger

Real Estate Properties - Merger with Select Income REIT (Details) $ in Thousands	Oct. 02, 2017	Dec. 31, 2018USD ($)ft²property	Sep. 14, 2018ft²	Dec. 31, 2016ft²
Business Acquisition [Line Items]
Rentable area of properties (in square feet) | ft²				830,185
Below market, acquired lease amortization period	3 years 9 months 18 days	5 years 8 months
SIR
Business Acquisition [Line Items]
Number of properties acquired | property		99
Rentable area of properties (in square feet) | ft²		16,500,000	16,500,000
Purchase price | $		$ 2,415,053
Liabilities assumed | $		$ 1,719,772
Above market lease
Business Acquisition [Line Items]
Weighted average amortization period, assets acquired	3 years 2 months 12 days	5 years 9 months
Lease origination value
Business Acquisition [Line Items]
Weighted average amortization period, assets acquired	3 years 1 month 6 days	7 years 2 months

Real Estate Properties - Assets

Real Estate Properties - Assets and Liabilities (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 02, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total Purchase Price:
Acquisition related costs		$ (14,508)	$ 0	$ (1,191)
Acquired net working capital		30,483	(1,596)	0
Purchase Price Allocation:
Land				14,790
Acquired net working capital		$ 30,483	$ (1,596)	$ 0
SIR
Total Purchase Price:
Closing price of OPI common shares on December 31, 2018 (in dollars per share)		$ 6.87
Cash consideration		$ 8
Equity issuance costs		(239)
Total cash consideration		639,578
Acquired net working capital		55,703
SIR unsecured revolving credit facility repaid at closing		108,000
Non-cash portion of purchase price		1,775,475
Gross purchase price		2,415,053
Purchase Price Allocation:
Land		475,893
Buildings and improvements		960,286
Assets of properties held for sale		7,022
Acquired real estate leases		858,121
Cash		24,744
Restricted cash		476
Rents receivable, net		11,389
Other assets		89,188
Total assets		2,427,119
Assumed real estate lease obligations		(11,833)
Due to related persons		(30,120)
Accounts payable and accrued expenses		(67,151)
Net assets acquired		639,578
Acquired net working capital		55,703
Gross purchase price		2,415,053
First Potomac Realty Trust
Total Purchase Price:
Cash consideration	$ 1,175,140
Acquisition related costs	9,575
Total cash consideration	1,184,715
Preferred units of limited partnership issued	20,221
Acquired net working capital	(1,596)
Assumed mortgage notes	167,548
Non-cash portion of purchase price	186,173
Gross purchase price	1,370,888
Purchase Price Allocation:
Land	360,909
Buildings and improvements	681,340
Acquired real estate leases	283,498
Investment in unconsolidated joint ventures	51,305
Cash	11,191
Restricted cash	1,018
Rents receivable	2,672
Other assets	3,640
Total assets	1,395,573
Long term debt acquired	(167,936)
Assumed real estate lease obligations	(5,776)
Accounts payable and accrued expenses	(10,640)
Rents collected in advance	(1,436)
Security deposits	(4,849)
Net assets acquired	1,204,936
Acquired net working capital	(1,596)
Assumed mortgage notes	167,548
Gross purchase price	$ 1,370,888
Unsecured revolving credit facility | SIR
Purchase Price Allocation:
Long term debt acquired		(108,000)
Senior unsecured notes | SIR
Total Purchase Price:
Assumed mortgage notes		1,450,000
Purchase Price Allocation:
Long term debt acquired		(1,410,947)
Assumed mortgage notes		1,450,000
Face amount		1,450,000
Mortgage note payable | SIR
Total Purchase Price:
Assumed mortgage notes		161,772
Purchase Price Allocation:
Long term debt acquired		(159,490)
Assumed mortgage notes		161,772
Face amount		$ 161,772
Common Shares | SIR
Total Purchase Price:
OPI common shares issued		23,282,704
Closing price of OPI common shares on December 31, 2018 (in dollars per share)		$ 27.48
Value of consideration transferred		$ 639,809
RMR LLC | SIR
Purchase Price Allocation:
Investment at fair value		$ 84,229

Real Estate Properties - FPO Tr

Real Estate Properties - FPO Transaction (Details) $ / shares in Units, $ in Thousands	Oct. 02, 2017USD ($)ft²buildingjoint_ventureproperty	Dec. 31, 2018ft²buildingjoint_venture	Dec. 31, 2017USD ($)joint_venture	May 01, 2018USD ($)$ / sharesshares	Dec. 31, 2016ft²
Business Acquisition [Line Items]
Rentable area of properties (in square feet) | ft²					830,185
Number of joint ventures | joint_venture		2
Below market, acquired lease amortization period	3 years 9 months 18 days	5 years 8 months
First Potomac Realty Trust
Business Acquisition [Line Items]
Number of buildings acquired | building	72
Rentable area of properties (in square feet) | ft²	6,000,000	400,000
Number of joint ventures | joint_venture	2
Purchase price	$ 1,370,888
Cash consideration	1,175,140
Repayment of debt assumed	483,000
Mortgage notes payable	$ 167,936
First Potomac Realty Trust
Business Acquisition [Line Items]
Number of joint ventures | joint_venture	2		2
Number of buildings | building	3	3
First Potomac Realty Trust | First Potomac Realty Trust
Business Acquisition [Line Items]
Rentable area of properties (in square feet) | ft²	400,000
Joint Venture Property 1 | First Potomac Realty Trust
Business Acquisition [Line Items]
Percentage of ownership interest	50.00%	50.00%
Joint Venture Property 2 | First Potomac Realty Trust
Business Acquisition [Line Items]
Percentage of ownership interest	51.00%	51.00%
Mortgage note payable | FPO Mortgage | First Potomac Realty Trust
Business Acquisition [Line Items]
Mortgage notes payable	$ 167,548
Fair value adjustment	388
Fair value of debt	167,936
Mortgage note payable | Joint Venture Mortgage | First Potomac Realty Trust
Business Acquisition [Line Items]
Mortgage notes payable	$ 82,000
Number of properties collateralized | property	2
FPO Shareholders | First Potomac Realty Trust
Business Acquisition [Line Items]
Cash consideration	$ 651,696
Above market lease
Business Acquisition [Line Items]
Weighted average amortization period, assets acquired	3 years 2 months 12 days	5 years 9 months
Lease origination value
Business Acquisition [Line Items]
Weighted average amortization period, assets acquired	3 years 1 month 6 days	7 years 2 months
Series A Cumulative Preferred Units
Business Acquisition [Line Items]
Preferred stock percentage			5.50%
Preferred stock carrying value			$ 20,496
Shares outstanding (in units) | shares				1,813,504
Redemption percentage			5.50%
Redemption price (in dollars per share) | $ / shares				$ 11.15
Redemption amount				$ 20,310

Real Estate Properties - Pro Fo

Real Estate Properties - Pro Forma (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Rental income	$ 758,596	$ 746,801
Net loss	$ (87,240)	$ (74,556)
Net income per share (in dollars per share)	$ (1.82)	$ (1.55)
Equity in losses from our unconsolidated joint ventures	$ (2,269)	$ (13)	$ 137
Acquisition-related costs
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Decrease revenues	152,735	156,506
Decrease (increase) net income (loss)	$ 46,237	64,661
FPO Transaction
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenue since acquisition		36,722
Operating income since acquisition		3,230
Equity in losses from our unconsolidated joint ventures		(621)
FPO Transaction | Acquisition-related costs
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Decrease revenues		804
Decrease (increase) net income (loss)		$ 47,019

Real Estate Properties - Schedu

Real Estate Properties - Schedule of Joint Ventures (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)ft²buildingjoint_venture	Dec. 31, 2017USD ($)	Dec. 31, 2016ft²
Real Estate [Line Items]
Number of joint ventures | joint_venture	2
Square Feet (in square feet) | ft²			830,185
Unconsolidated Joint Ventures
Real Estate [Line Items]
Investment at carrying value	$ 43,665	$ 50,202
Number of Office Buildings | building	3
Square Feet (in square feet) | ft²	443,867
Interest rate (as a percent)	3.93%
Principal Balance	$ 82,000
Unamortized basis difference	$ 8,442
Unconsolidated Joint Ventures | Prosperity Metro Plaza
Real Estate [Line Items]
OPI Ownership	51.00%
Investment at carrying value	$ 23,969	27,888
Number of Office Buildings | building	2
Square Feet (in square feet) | ft²	328,456
Interest rate (as a percent)	4.09%
Principal Balance	$ 50,000
Unconsolidated Joint Ventures | 1750 H Street, NW
Real Estate [Line Items]
OPI Ownership	50.00%
Investment at carrying value	$ 19,696	$ 22,314
Number of Office Buildings | building	1
Square Feet (in square feet) | ft²	115,411
Interest rate (as a percent)	3.69%
Principal Balance	$ 32,000

Real Estate Properties - Acquis

Real Estate Properties - Acquisition Activities (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)	Jan. 31, 2017USD ($)ft²	Dec. 31, 2017USD ($)ft²building	Dec. 31, 2016USD ($)ft²building
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²				830,185
Purchase price				$ 199,304
Land				14,790
Buildings and Improvements				145,006
Other Assumed Assets				$ 2,167
Manassas, VA
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²		69,374	69,374
Percentage of property lease			100.00%
Capitalized transaction costs			$ 37
Purchase price		$ 12,657	$ 12,657
Land		1,562
Buildings and Improvements		8,253
Other Assumed Assets		$ 2,842
Office Building
Real Estate Properties [Line Items]
Number of buildings acquired | building				5
Office Building | Manassas, VA
Real Estate Properties [Line Items]
Number of buildings acquired | building			1
Transferable Development Rights | Washington, D.C.
Real Estate Properties [Line Items]
Payments to acquire transferable development rights	$ 2,030

Real Estate Properties - 2016 A

Real Estate Properties - 2016 Acquisition Activities (Details) $ in Thousands	Jul. 06, 2016USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)ft²building
Business Acquisition [Line Items]
Rentable area of properties (in square feet) | ft²				830,185
Purchase price				$ 199,304
Land				14,790
Buildings and Improvements				145,006
Other Assumed Assets				2,167
Acquired Leases				37,928
Acquired Lease Obligations				587
Acquisition and transaction related costs		$ 14,508	$ 0	$ 1,191
Office Building
Business Acquisition [Line Items]
Number of buildings acquired | building				5
Sacramento, CA
Business Acquisition [Line Items]
Number of buildings acquired | building				1
Rentable area of properties (in square feet) | ft²				337,811
Purchase price				$ 79,508
Land				4,688
Buildings and Improvements				61,995
Other Assumed Assets				2,167
Acquired Leases				11,245
Acquired Lease Obligations				587
Atlanta, GA
Business Acquisition [Line Items]
Purchase price				1,670
Land				$ 1,670
Atlanta, GA | Land
Business Acquisition [Line Items]
Purchase price	$ 1,623
Acquisition and transaction related costs	$ 47
Rancho Cordova, CA
Business Acquisition [Line Items]
Number of buildings acquired | building				1
Rentable area of properties (in square feet) | ft²				82,896
Purchase price				$ 13,943
Land				1,466
Buildings and Improvements				8,797
Acquired Leases				$ 3,680
Chantilly, VA
Business Acquisition [Line Items]
Number of buildings acquired | building				3
Rentable area of properties (in square feet) | ft²				409,478
Purchase price				$ 104,183
Land				6,966
Buildings and Improvements				74,214
Acquired Leases				23,003
Acquired Lease Obligations				$ 0

Real Estate Properties - 2018_2

Real Estate Properties - 2018/2017 Disposition Activities (Details) $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Oct. 31, 2017USD ($)ft²property	Aug. 31, 2017USD ($)ft²property	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)ft²building	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)ft²	Feb. 28, 2018ft²property
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²							830,185
Net book value					$ 3,569,489	$ 2,633,873
Loss on impairment of real estate					8,630	9,490	$ 0
Gain on sale of real estate					20,661	0	$ 79
Properties held for sale					$ 253,501	0
Sacramento, CA
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²							337,811
Discontinued Operations, Held-for-sale
Real Estate Properties [Line Items]
Number of buildings | building					36
Rentable area of properties (in square feet) | ft²					2,181,859
Aggregate sale price of properties sold, excluding closing costs					$ 275,600
Properties held for sale					$ 216,955
Discontinued Operations, Held-for-sale | District of Columbia
Real Estate Properties [Line Items]
Number of buildings | building					1
Rentable area of properties (in square feet) | ft²					129,035
Aggregate sale price of properties sold, excluding closing costs					$ 70,000
Discontinued Operations, Held-for-sale | Northern Virginia and Maryland
Real Estate Properties [Line Items]
Number of buildings | building					34
Rentable area of properties (in square feet) | ft²					1,635,868
Aggregate sale price of properties sold, excluding closing costs					$ 198,500
Loss on impairment of real estate					$ 2,830
Discontinued Operations, Held-for-sale | Kapolei, HI
Real Estate Properties [Line Items]
Number of buildings | building					1
Rentable area of properties (in square feet) | ft²					416,956
Aggregate sale price of properties sold, excluding closing costs					$ 7,100
Discontinued operations | Falls Church, VA
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²		164,746
Net book value		$ 12,901
Number of properties | property		1
Office Building | Disposal Group, Disposed of by Sale | One building
Real Estate Properties [Line Items]
Number of buildings | building					19
Rentable area of properties (in square feet) | ft²					2,174,637
Aggregate sale price of properties sold, excluding closing costs					$ 320,255
Office Building | Disposal Group, Disposed of by Sale | Minneapolis, NM | One building
Real Estate Properties [Line Items]
Number of buildings | building					1
Rentable area of properties (in square feet) | ft²					193,594
Aggregate sale price of properties sold, excluding closing costs					$ 20,000
Loss on impairment of real estate				$ 640
Number of properties | property								1
Office Building | Disposal Group, Disposed of by Sale | New York, NY | One building
Real Estate Properties [Line Items]
Number of buildings | building					1
Rentable area of properties (in square feet) | ft²					187,060
Aggregate sale price of properties sold, excluding closing costs					$ 118,500
Gain on sale of real estate					$ 17,249
Office Building | Disposal Group, Disposed of by Sale | Sacramento, CA | One building
Real Estate Properties [Line Items]
Number of buildings | building					1
Rentable area of properties (in square feet) | ft²					110,500
Aggregate sale price of properties sold, excluding closing costs					$ 10,755
Loss on impairment of real estate					$ 3,029
Number of properties | property								1
Office Building | Disposal Group, Disposed of by Sale | Golden, CO | One building
Real Estate Properties [Line Items]
Number of buildings | building					1
Rentable area of properties (in square feet) | ft²					43,231
Aggregate sale price of properties sold, excluding closing costs					$ 4,000
Gain on sale of real estate					$ 54
Office Building | Disposal Group, Disposed of by Sale | Southern Virginia | One building
Real Estate Properties [Line Items]
Number of buildings | building					15
Rentable area of properties (in square feet) | ft²					1,640,252
Aggregate sale price of properties sold, excluding closing costs					$ 167,000
Gain on sale of real estate					$ 3,358
Office Building | Disposal Group, Disposed of by Sale | Safford, AZ | One building
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²								36,139
Aggregate sale price of properties sold, excluding closing costs				8,250
Loss on impairment of real estate				$ 2,453
Number of properties | property								1
Fair value adjustment			$ 322
Office Building | Disposal Group, Disposed of by Sale | Albuquerque, NM | One building
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²	29,045
Aggregate sale price of properties sold, excluding closing costs	$ 2,000
Net book value	$ 1,885
Loss on impairment of real estate						230
Number of properties | property	1
Office Building | Discontinued operations | Falls Church, VA | One building
Real Estate Properties [Line Items]
Rentable area of properties (in square feet) | ft²		164,746
Aggregate sale price of properties sold, excluding closing costs		$ 13,523
Net book value		$ 12,901
Increase the carrying value of property						$ 619
Number of properties | property		1
FPO Transaction | Disposal Group, Disposed of by Sale
Real Estate Properties [Line Items]
Number of buildings | building					34
Rentable area of properties (in square feet) | ft²					5,300,000

Real Estate Properties - Income

Real Estate Properties - Income Statement Information for Disposal of Property (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations	$ 5,722	$ 21,829	$ 34,878
Discontinued Operations, Held-for-sale | Discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rental income		17	68
Real estate taxes		(88)	(97)
Utility expenses		(97)	(146)
Other operating expenses		(202)	(300)
General and administrative		(76)	(114)
Increase in carrying value of property included in discontinued operations		619	0
Income (loss) from discontinued operations		$ 173	$ (589)

Real Estate Properties - 2016 D

Real Estate Properties - 2016 Dispositions (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2016USD ($)ft²property	Dec. 31, 2018USD ($)ft²	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable area of properties (in square feet) | ft²				830,185
Net book value		$ 3,569,489	$ 2,633,873
Gain on sale of real estate		$ 20,661	0	$ 79
Deferred gain on sale of real estate			$ 712
One building | Disposal Group, Held-for-sale | Savannah, GA | Office Building
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties owned | property	1
Rentable area of properties (in square feet) | ft²	35,228
Net book value	$ 2,986
Aggregate sale price of properties sold, excluding closing costs	4,000
Mortgage loan	$ 3,600
One building | Disposal Group, Disposed of by Sale | Office Building
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable area of properties (in square feet) | ft²		2,174,637
Aggregate sale price of properties sold, excluding closing costs		$ 320,255
LIBOR | Disposal Group, Disposed of by Sale | Savannah, GA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Basis spread on variable rate			4.00%
Minimum | LIBOR | Disposal Group, Disposed of by Sale | Savannah, GA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Basis spread on variable rate			5.00%
Other Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred gain on sale of real estate				$ 712
Real Estate Loan | Other Assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Financing receivable		$ 3,600	$ 3,600

Real Estate Properties - Future

Real Estate Properties - Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Real Estate [Abstract]
2,019	$ 569,874
2,020	514,551
2,021	479,401
2,022	434,135
2,023	383,695
Thereafter	1,236,540
Total	$ 3,618,196

Real Estate Properties - Operat

Real Estate Properties - Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)tenant	Dec. 31, 2017USD ($)
Concentration Risk [Line Items]
Number of government tenants | tenant	22
Rent expense, net of subleased revenue | $	$ 1,707	$ 374
Tenant concentration
Concentration Risk [Line Items]
Percentage termination right, 2019	2.10%
Percentage termination right, 2020	6.40%
Percentage termination right, 2021	1.90%
Percentage termination right, 2023	2.70%
Percentage termination right, 2023	0.60%
Percentage termination right, 2024	1.40%
Percentage termination right, 2025	4.70%
Percentage termination right, 2026	2.00%
Percentage termination right, 2027	1.90%
Government Tenants, All Other | Tenant concentration
Concentration Risk [Line Items]
Concentration risk, percentage	5.60%
15 Government Tenants | Tenant concentration
Concentration Risk [Line Items]
Concentration risk, percentage	5.80%

Real Estate Properties - Futu_2

Real Estate Properties - Future Minimum Rental Payments (Details)	Dec. 31, 2018USD ($)
Real Estate [Abstract]
2,019	$ 1,584
2,020	1,627
2,021	139
Total	$ 3,350

Business and Property Managem_2

Business and Property Management Agreements with RMR LLC (Details) - RMR LLC $ in Thousands	Jun. 05, 2015	Jan. 31, 2019USD ($)	Dec. 31, 2018USD ($)employeeagreement	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Related Party Transaction [Line Items]
Number of employees | employee			0
Number of agreements with RMR LLC to provide management services | agreement			2
Management fees as percentage of gross collected rents			3.00%
Construction supervision fees as percentage of construction costs			5.00%
Net business management fees			$ 16,381	$ 12,464	$ 10,222
Recognized amortization of the liability			603	603	603
Reimbursement amounts			21,042	15,045	12,276
Internal audit costs			237	276	235
Net Property Management and Construction Supervision Fees
Related Party Transaction [Line Items]
Transaction amount			13,989	11,566	8,949
Net Property Management and Construction Supervision Fees, Amortization Liability
Related Party Transaction [Line Items]
Transaction amount			$ 484	$ 484	$ 484
Transition Services
Related Party Transaction [Line Items]
Duration of transition services			120 days
Amended And Restate Business Management Agreement
Related Party Transaction [Line Items]
Percentage applied on average historical cost of real estate investment properties acquired			0.50%
Base management fee payable as percentage of average historical cost of real estate investments			0.70%
Percentage of average closing stock price on stock exchange			0.70%
Management fee payable as percentage of average market capitalization exceeding specified amount			0.50%
Measurement period for incentive management fee			3 years
Percentage for limitation and adjustments of incentive management fee payable			12.00%
Percentage for limitation and adjustments of incentive management fee payable, minimum total return per share percentage change			5.00%
Average closing price of our common shares, consecutive trading days			10 days
Highest Average closing price of our common shares, final consecutive trading days			30 days
Percentage of base business management fee payable in common shares			1.50%
Amended And Restate Business Management Agreement | Up C Transaction
Related Party Transaction [Line Items]
Written notice for convenience	60 days
Window of written notice after calendar year	60 days
Window for written notice after change of control	12 months
Remaining termination fee term	10 years
Minimum | Amended And Restate Business Management Agreement
Related Party Transaction [Line Items]
Threshold amount of average market capitalization			$ 250,000
Percentage for limitation and adjustments of incentive management fee payable, total return per share percentage, reduction			2.00%
Minimum | Amended And Restate Business Management Agreement | Up C Transaction
Related Party Transaction [Line Items]
Termination fee term	19 years
Maximum | Amended And Restate Business Management Agreement
Related Party Transaction [Line Items]
Threshold amount of real estate investments			$ 250,000
Base management fee payable average market capitalization			$ 250,000
Percentage for limitation and adjustments of incentive management fee payable, total return per share percentage, reduction			5.00%
Maximum | Amended And Restate Business Management Agreement | Up C Transaction
Related Party Transaction [Line Items]
Termination fee term	20 years
SIR | Net Property Management and Construction Supervision Fees
Related Party Transaction [Line Items]
Transaction amount			$ 2,185
Incentive management fee			$ 25,817
Forecast
Related Party Transaction [Line Items]
Reimbursement amounts		$ 462

Related Party Transactions - RE

Related Party Transactions - REITs, for which RMR LLC provides Management Services (Details) $ in Thousands	6 Months Ended			9 Months Ended		12 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Oct. 09, 2018USD ($)shares	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)agreementcompanyshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015shares
Related Party Transaction [Line Items]
Common shares owned in RMR Inc. | shares						2,801,061			1,214,225
Lock up agreement, transfer of shares (in shares) | shares						175,000
Duration of lock up agreement						10 years
Equity in earnings of Select Income REIT						$ (2,269)	$ (13)	$ 137
SIR
Related Party Transaction [Line Items]
Percentage of ownership interest					27.80%	27.80%
Equity in earnings of Select Income REIT				$ 24,358			$ 21,584	$ 35,381
Shares owned (in shares) | shares						24,918,421
SIR | SIR
Related Party Transaction [Line Items]
Issuance of shares, net (in shares) | shares				63,157			59,502	65,900
Equity in earnings of Select Income REIT					$ 882		$ 608	$ 137
AIC
Related Party Transaction [Line Items]
Number of entities to whom RMR provides management services | company						4
Amount invested in equity investee						$ 8,751	8,304	7,235
Equity in earnings of Select Income REIT						516	608	137
Equity in unrealized gain (loss) of investees						$ (69)	461	152
RMR LLC
Related Party Transaction [Line Items]
Number of agreements with RMR LLC to provide management services | agreement						2
Rental income earned						$ 1,026	303	366
Related party transaction						$ 16,381	12,464	10,222
RMR LLC | AIC
Related Party Transaction [Line Items]
Service fee percentage						3.00%
Property Insurance Premium Expense, June 2018 | AIC
Related Party Transaction [Line Items]
Related party transaction		$ 757
Property Insurance Premium Expense, June 2017 | AIC
Related Party Transaction [Line Items]
Related party transaction			$ 1,032
Property Insurance Premium Expense
Related Party Transaction [Line Items]
Related party transaction						$ 198	$ 91	$ 106
Common Shares
Related Party Transaction [Line Items]
Issuance of shares, net (in shares) | shares						23,281,738	6,976,757
Common Shares | SIR | Industrial Logistics Properties Trust
Related Party Transaction [Line Items]
Payments to acquire shares in investment						$ 8,632
Common Shares | Officers and Other Employees
Related Party Transaction [Line Items]
Issuance of shares, net (in shares) | shares						14,675	14,337	13,350
Aggregate market value of shares awarded						$ 995	$ 1,067	$ 1,183
Common Shares | Officers and Other Employees | SIR
Related Party Transaction [Line Items]
Issuance of shares, net (in shares) | shares						58,700	57,850	53,400
Aggregate market value of shares awarded						$ 1,183	$ 1,337	$ 1,397
Class A common shares
Related Party Transaction [Line Items]
Common shares owned in RMR Inc. | shares						2,801,061
Tranche 1 | 2009 Award Plan | Common Shares | Officers and Other Employees
Related Party Transaction [Line Items]
Vesting percentage						20.00%
Tranche 2 | 2009 Award Plan | Common Shares | Officers and Other Employees
Related Party Transaction [Line Items]
Vesting percentage						20.00%
Tranche 3 | 2009 Award Plan | Common Shares | Officers and Other Employees
Related Party Transaction [Line Items]
Vesting percentage						20.00%
Tranche 4 | 2009 Award Plan | Common Shares | Officers and Other Employees
Related Party Transaction [Line Items]
Vesting percentage						20.00%
Tranche 5 | 2009 Award Plan | Common Shares | Officers and Other Employees
Related Party Transaction [Line Items]
Vesting percentage						20.00%
Forecast | Property Insurance Premium Expense, June 2019 | AIC
Related Party Transaction [Line Items]
Related party transaction	$ 1,211
Forecast | Property Insurance Premium Expense, June 2019 | AIC | SIR
Related Party Transaction [Line Items]
Related party transaction	$ 1,666

Concentration (Details)

Concentration (Details)	12 Months Ended
	Dec. 31, 2018buildingstategovernment_tenantstate_government	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Number of state governments | state_government	13
Number of other governments | government_tenant	3
Annualized rental income, excluding properties classified as discontinued operations | Virginia
Concentration Risk [Line Items]
Annualized Rental income percent	15.40%
Annualized rental income, excluding properties classified as discontinued operations | California
Concentration Risk [Line Items]
Annualized Rental income percent	11.30%
Annualized rental income, excluding properties classified as discontinued operations | Texas
Concentration Risk [Line Items]
Annualized Rental income percent	10.90%
Annualized rental income, excluding properties classified as discontinued operations | District of Columbia
Concentration Risk [Line Items]
Concentration risk, percentage	26.50%
Annualized Rental income percent	9.80%
Annualized rental income, excluding properties classified as discontinued operations | Maryland
Concentration Risk [Line Items]
Annualized Rental income percent	9.40%
Annualized rental income, excluding properties classified as discontinued operations | Tenant concentration | U S Government, State Governments, and Other Governments
Concentration Risk [Line Items]
Concentration risk, percentage	35.40%	62.60%	87.90%
Annualized rental income, excluding properties classified as discontinued operations | Tenant concentration | U.S. Government
Concentration Risk [Line Items]
Concentration risk, percentage	25.60%	43.50%	60.60%
Continuing operations
Concentration Risk [Line Items]
Number of buildings | building	247
Number of states in which acquired properties located | state	38

Indebtedness - Outstanding Debt

Indebtedness - Outstanding Debt (Details) $ in Thousands	Feb. 11, 2019USD ($)	Dec. 18, 2018USD ($)building	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Jul. 20, 2017
Debt Instrument [Line Items]
Long term debt gross			$ 3,311,262	$ 2,263,147
Unamortized debt premiums, discounts and issuance costs			(56,372)	(18,055)
Total debt			3,254,890	2,245,092
Loss on early extinguishment of debt			$ 709	1,715	$ (104)
Senior unsecured notes, 3.60% interest rate, due in 2020
Debt Instrument [Line Items]
Interest rate (as a percent)			3.60%
Senior unsecured notes, 4.00% interest rate, due in 2022
Debt Instrument [Line Items]
Interest rate (as a percent)			4.00%
Senior unsecured notes, 4.15% interest rate, due in 2022
Debt Instrument [Line Items]
Interest rate (as a percent)			4.15%
Senior unsecured notes, 4.25% interest rate, due in 2024
Debt Instrument [Line Items]
Interest rate (as a percent)			4.25%
Senior unsecured notes, 4.50% interest rate, due in 2025
Debt Instrument [Line Items]
Interest rate (as a percent)			4.50%
Unsecured term loan | Unsecured term loan, due in 2020
Debt Instrument [Line Items]
Long term debt gross			$ 300,000	300,000
Unsecured term loan | Unsecured term loan, due in 2022
Debt Instrument [Line Items]
Long term debt gross			88,000	250,000
Repayment of principal		$ 162,000
Number of buildings sold in portfolio | building		15
Loss on early extinguishment of debt			625
Senior unsecured notes | Senior unsecured notes, 3.750% interest rate, due in 2019
Debt Instrument [Line Items]
Long term debt gross			$ 350,000	350,000
Interest rate (as a percent)			3.75%
Senior unsecured notes | Senior unsecured notes, 3.60% interest rate, due in 2020
Debt Instrument [Line Items]
Long term debt gross			$ 400,000	0
Interest rate (as a percent)			3.60%
Senior unsecured notes | Senior unsecured notes, 4.00% interest rate, due in 2022
Debt Instrument [Line Items]
Long term debt gross			$ 300,000	300,000
Interest rate (as a percent)			4.00%			4.00%
Senior unsecured notes | Senior unsecured notes, 4.15% interest rate, due in 2022
Debt Instrument [Line Items]
Long term debt gross			$ 300,000	0
Interest rate (as a percent)			4.15%
Senior unsecured notes | Senior unsecured notes, 4.25% interest rate, due in 2024
Debt Instrument [Line Items]
Long term debt gross			$ 350,000	0
Interest rate (as a percent)			4.25%
Senior unsecured notes | Senior unsecured notes, 4.50% interest rate, due in 2025
Debt Instrument [Line Items]
Long term debt gross			$ 400,000	0
Interest rate (as a percent)			4.50%
Senior unsecured notes | Senior unsecured notes, 5.875% interest rate, due in 2046
Debt Instrument [Line Items]
Long term debt gross			$ 310,000	310,000
Interest rate (as a percent)			5.875%
Mortgage note payable | Mortgage note payable, 7.000% interest rate, due in 2019
Debt Instrument [Line Items]
Long term debt gross			$ 7,939	8,221
Interest rate (as a percent)			7.00%
Mortgage note payable | Mortgage note payable, 5.720% interest rate, due in 2020
Debt Instrument [Line Items]
Long term debt gross			$ 33,703	34,474
Interest rate (as a percent)			5.72%
Mortgage note payable | Mortgage note payable, 4.260% interest rate, due in 2020
Debt Instrument [Line Items]
Long term debt gross			$ 0	3,173
Interest rate (as a percent)			4.26%
Loss on early extinguishment of debt			$ 60
Mortgage note payable | Mortgage note payable, 4.160% interest rate, due in 2020
Debt Instrument [Line Items]
Long term debt gross			$ 40,772	0
Interest rate (as a percent)			4.16%
Mortgage note payable | Mortgage note payable, 8.150% interest rate, due in 2021
Debt Instrument [Line Items]
Long term debt gross			$ 2,912	4,045
Interest rate (as a percent)			8.15%
Mortgage note payable | Mortgage note payable, 5.877% interest rate, due in 2021
Debt Instrument [Line Items]
Long term debt gross			$ 13,437	13,693
Interest rate (as a percent)			5.877%
Mortgage note payable | Mortgage note payable, 4.220% interest rate, due in 2022
Debt Instrument [Line Items]
Long term debt gross			$ 27,210	27,870
Interest rate (as a percent)			4.22%
Mortgage note payable | Mortgage note payable, 3.550% interest rate, due in 2023
Debt Instrument [Line Items]
Long term debt gross			$ 71,000	0
Interest rate (as a percent)			3.55%
Mortgage note payable | Mortgage note payable, 3.700% interest rate, due in 2023
Debt Instrument [Line Items]
Long term debt gross			$ 50,000	0
Interest rate (as a percent)			3.70%
Mortgage note payable | Mortgage note payable, 4.800% interest rate, due in 2023
Debt Instrument [Line Items]
Long term debt gross			$ 24,509	24,891
Interest rate (as a percent)			4.80%
Mortgage note payable | Mortgage note payable, 4.050% interest rate, due in 2030
Debt Instrument [Line Items]
Long term debt gross			$ 66,780	66,780
Interest rate (as a percent)			4.05%
Revolving credit facility, due in 2023 | Line of Credit
Debt Instrument [Line Items]
Long term debt gross			$ 175,000	$ 570,000
Subsequent Event | Unsecured term loan | Unsecured term loan, due in 2022
Debt Instrument [Line Items]
Extinguishment of debt	$ 88,000

Indebtedness - Revolving Credit

Indebtedness - Revolving Credit Facility (Details) - USD ($) $ in Thousands	Dec. 13, 2018	Dec. 12, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 25, 2019
Line of Credit Facility [Line Items]
Maximum borrowing capacity on revolving credit facility			$ 2,500,000
Loss on early extinguishment of debt			709	$ 1,715	$ (104)
Unsecured revolving credit facility			175,000	$ 570,000
Unsecured revolving credit facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity on revolving credit facility			750,000
Commitment fee percentage	0.25%
Loss on early extinguishment of debt			$ 24
Interest rate (as a percent)			3.60%	2.70%
The weighted average annual interest rate (as a percent)			3.00%	2.40%	1.70%
Unsecured revolving credit facility			$ 175,000
Available borrowings			575,000
Unsecured term loan, due in 2020
Line of Credit Facility [Line Items]
Face amount			$ 300,000
Interest rate (as a percent)			3.90%	3.00%
The weighted average annual interest rate (as a percent)			3.40%	2.50%	1.90%
Unsecured term loan, due in 2022
Line of Credit Facility [Line Items]
Face amount			$ 250,000
Interest rate (as a percent)			4.30%	3.40%
The weighted average annual interest rate (as a percent)			3.80%	2.90%	2.30%
Subsequent Event | Unsecured revolving credit facility
Line of Credit Facility [Line Items]
Unsecured revolving credit facility						$ 110,000
Available borrowings						$ 640,000
LIBOR | Unsecured revolving credit facility
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.10%	1.25%
LIBOR | Unsecured term loan, due in 2020
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.40%
LIBOR | Unsecured term loan, due in 2022
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.80%

Indebtedness - Narrative Inform

Indebtedness - Narrative Information (Details) $ in Thousands	Oct. 02, 2017USD ($)buildingjoint_venturemortgage_note	Jul. 20, 2017USD ($)	Nov. 30, 2017USD ($)	Jul. 31, 2017USD ($)	Dec. 31, 2018USD ($)buildingjoint_ventureloan	Dec. 31, 2017USD ($)joint_venture	Dec. 31, 2016USD ($)
Debt Instrument [Line Items]
Gain (loss) on early extinguishment of debt					$ (709)	$ (1,715)	$ 104
Number of Buildings Collateralized | building					12
Number of joint ventures | joint_venture					2
Book value of properties collateralized					$ 627,173
Principal of properties collateralized					$ 338,262
Senior unsecured notes, 4.00% interest rate, due in 2022
Debt Instrument [Line Items]
Interest rate (as a percent)					4.00%
Senior unsecured notes | Senior unsecured notes, 4.00% interest rate, due in 2022
Debt Instrument [Line Items]
Face amount		$ 300,000
Interest rate (as a percent)		4.00%			4.00%
Proceeds from Issuance of Debt		$ 295,399
SIR
Debt Instrument [Line Items]
Number loans assumed in acquisition | loan					3
Long-term Debt, Fair Value					$ 159,490
Number of Buildings Collateralized | building					5
SIR | Senior unsecured notes
Debt Instrument [Line Items]
Face amount					$ 1,450,000
Assumed mortgage notes					1,450,000
Mortgage notes payable					1,410,947
SIR | Mortgage note payable
Debt Instrument [Line Items]
Face amount					161,772
Assumed mortgage notes					161,772
Mortgage notes payable					$ 159,490
First Potomac Realty Trust
Debt Instrument [Line Items]
Number loans assumed in acquisition | mortgage_note	5
Assumed mortgage notes	$ 167,548
Mortgage notes payable	$ 167,936
Number of Buildings Collateralized | building	5
Number of joint ventures | joint_venture	2
Number of mortgage notes securing joint ventures | mortgage_note	2
First Potomac Realty Trust | Mortgage note payable | FPO Mortgage
Debt Instrument [Line Items]
Mortgage notes payable	$ 167,548
Long-term Debt, Fair Value	167,936
Repayment of principal			$ 10,000
First Potomac Realty Trust | Mortgage note payable | Joint Venture Mortgage
Debt Instrument [Line Items]
Mortgage notes payable	$ 82,000
Number of Buildings Collateralized | building	3
First Potomac Realty Trust
Debt Instrument [Line Items]
Number of joint ventures | joint_venture	2					2
Joint Venture Property 1 | First Potomac Realty Trust
Debt Instrument [Line Items]
Percentage of ownership interest	50.00%				50.00%
Joint Venture Property 2 | First Potomac Realty Trust
Debt Instrument [Line Items]
Percentage of ownership interest	51.00%				51.00%
Letter of Credit
Debt Instrument [Line Items]
Gain (loss) on early extinguishment of debt				$ (1,715)
Letter of Credit | Bridge Loan Facility [Member]
Debt Instrument [Line Items]
Face amount		$ 750,000
Debt Instrument, Term		364 days

Indebtedness - Future Principal

Indebtedness - Future Principal Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
2,019	$ 362,054
2,020	775,707
2,021	14,420
2,022	713,518
2,023	318,783
Thereafter	1,126,780
Total	3,311,262	$ 2,263,147
Unamortized premiums, discounts and certain issuance costs	56,372	18,055
Total debt outstanding	$ 3,254,890	$ 2,245,092

Fair Value of Assets and Liab_3

Fair Value of Assets and Liabilities - Asset Measured at Fair Value (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)buildingshares	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)shares
Fair Value of Assets and Liabilities
Common shares owned in RMR Inc. | shares	2,801,061			1,214,225
Historical cost				$ 26,888
Unrealized loss on equity securities	$ 7,552	$ 0	$ 0
Recurring
Fair Value of Assets and Liabilities
Investment in RMR Inc.	148,680
Recurring | Level 1 inputs
Fair Value of Assets and Liabilities
Investment in RMR Inc.	148,680
Recurring | Level 2 inputs
Fair Value of Assets and Liabilities
Investment in RMR Inc.	0
Recurring | Level 3 inputs
Fair Value of Assets and Liabilities
Investment in RMR Inc.	$ 0
Discontinued Operations, Held-for-sale
Fair Value of Assets and Liabilities
Number of buildings | building	36
Discontinued Operations, Held-for-sale | Nonrecurring
Fair Value of Assets and Liabilities
Assets of properties held for sale	$ 195,107
Discontinued Operations, Held-for-sale | Nonrecurring | Level 1 inputs
Fair Value of Assets and Liabilities
Assets of properties held for sale	0
Discontinued Operations, Held-for-sale | Nonrecurring | Level 2 inputs
Fair Value of Assets and Liabilities
Assets of properties held for sale	195,107
Discontinued Operations, Held-for-sale | Nonrecurring | Level 3 inputs
Fair Value of Assets and Liabilities
Assets of properties held for sale	$ 0
SIR
Fair Value of Assets and Liabilities
Historical cost				$ 84,229
Shares acquired (in shares) | shares	1,586,836
Northern Virginia and Maryland | Discontinued Operations, Held-for-sale
Fair Value of Assets and Liabilities
Number of buildings | building	34

Shareholders' Equity - Share Aw

Shareholders' Equity - Share Awards (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)installmenttrusteeshares	Dec. 31, 2017USD ($)trusteeshares	Dec. 31, 2016USD ($)trusteeshares	Dec. 31, 2015shares
Common Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of shares, net (in shares)	23,281,738	6,976,757
Officers and Other Employees | Common Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of shares, net (in shares)	14,675	14,337	13,350
Aggregate market value of shares awarded | $	$ 995	$ 1,067	$ 1,183
2009 Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted to each trustee under the award plan	19,925	18,837	16,475
Number of installments | installment	5
Unvested shares	55,321	26,062	24,743	24,181
Unvested shares 2019	27,998
Unvested shares 2020	13,259
Unvested shares 2021	9,232
Unvested shares 2022	4,832
Share Awards, additional disclosures
Estimated future compensation expense for the unvested shares | $	$ 984
Weighted average period of recognition of compensation expenses (in years)	22 months
Compensation expense | $	$ 1,337	$ 1,377	$ 1,371
Shares available for issuance under the Award Plan	330,372
2009 Award Plan | Trustees | Common Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate market value of shares awarded | $	$ 254	$ 392	$ 244
Number of Trustees | trustee	6	6	5
Number of shares granted to each trustee under the award plan	750	750	625
Market value of common shares awarded to each trustee (in dollars) | $	$ 42	$ 65	$ 49
2009 Award Plan | Managing Trustee | Common Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate market value of shares awarded | $	$ 41
Number of shares granted to each trustee under the award plan	750

Fair Value of Assets and Liab_4

Fair Value of Assets and Liabilities - Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value of Financial Instruments
Senior Notes	$ 2,357,497	$ 944,140
Mortgage notes payable	$ 335,241	183,100
Senior unsecured notes, 3.750% interest rate, due in 2019
Fair Value of Financial Instruments
Interest rate (as a percent)	3.75%
Senior unsecured notes, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Interest rate (as a percent)	3.60%
Senior unsecured notes, 4.00% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)	4.00%
Senior unsecured notes, 4.15% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)	4.15%
Senior unsecured notes, 4.25% interest rate, due in 2024
Fair Value of Financial Instruments
Interest rate (as a percent)	4.25%
Senior unsecured notes, 4.50% interest rate, due in 2025
Fair Value of Financial Instruments
Interest rate (as a percent)	4.50%
Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Interest rate (as a percent)	5.875%
Carrying Amount
Fair Value of Financial Instruments
Mortgage notes payable	$ 335,241	183,100
Fair value of debt	2,692,738	1,127,240
Carrying Amount | Senior unsecured notes, 3.750% interest rate, due in 2019
Fair Value of Financial Instruments
Senior Notes	349,239	348,096
Carrying Amount | Senior unsecured notes, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Senior Notes	399,146	0
Carrying Amount | Senior unsecured notes, 4.00% interest rate, due in 2022
Fair Value of Financial Instruments
Senior Notes	296,735	295,812
Carrying Amount | Senior unsecured notes, 4.15% interest rate, due in 2022
Fair Value of Financial Instruments
Senior Notes	296,736	0
Carrying Amount | Senior unsecured notes, 4.25% interest rate, due in 2024
Fair Value of Financial Instruments
Senior Notes	337,736	0
Carrying Amount | Senior unsecured notes, 4.50% interest rate, due in 2025
Fair Value of Financial Instruments
Senior Notes	377,329	0
Carrying Amount | Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Senior Notes	300,576	300,232
Fair Value
Fair Value of Financial Instruments
Mortgage notes payable	336,365	186,542
Fair value of debt	2,665,550	1,164,606
Fair Value | Senior unsecured notes, 3.750% interest rate, due in 2019
Fair Value of Financial Instruments
Senior Notes	348,903	354,993
Fair Value | Senior unsecured notes, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Senior Notes	399,146	0
Fair Value | Senior unsecured notes, 4.00% interest rate, due in 2022
Fair Value of Financial Instruments
Senior Notes	295,047	302,655
Fair Value | Senior unsecured notes, 4.15% interest rate, due in 2022
Fair Value of Financial Instruments
Senior Notes	296,736	0
Fair Value | Senior unsecured notes, 4.25% interest rate, due in 2024
Fair Value of Financial Instruments
Senior Notes	337,736	0
Fair Value | Senior unsecured notes, 4.50% interest rate, due in 2025
Fair Value of Financial Instruments
Senior Notes	377,329	0
Fair Value | Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Senior Notes	$ 274,288	$ 320,416

Shareholders' Equity - Unvested

Shareholders' Equity - Unvested Shares Activity (Details) - 2009 Award Plan - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Unvested shares at the beginning of the period	26,062	24,743	24,181
Shares granted (in shares)	19,925	18,837	16,475
Shared forfeited (in shares)	(255)
Shares Vested (in shares)	(18,634)	(17,518)	(15,913)
Unvested acquired in the SIR Merger (in shares)	28,223
Unvested shares at the end of the period	55,321	26,062	24,743
Weighted Average Grant Date Fair Value
Unvested shares at the beginning of the period (in dollars per share)	$ 78.24	$ 82.36	$ 80.44
Granted (in dollars per share)	64.73	77.44	86.64
Shared forfeited (in dollars per share)	52.96
Vested (in dollars per share)	63.80	83.20	83.88
Unvested acquired in the SIR Merger (in dollars per share)	27.48
Unvested shares at the end of the period (in dollars per share)	$ 73.25	$ 78.24	$ 82.36

Shareholders' Equity - Sale of

Shareholders' Equity - Sale of Shares/Share Repurchases (Details) $ / shares in Units, $ in Thousands	Sep. 24, 2018$ / sharesshares	May 24, 2018trustee$ / sharesshares	Jan. 01, 2018$ / sharesshares	Aug. 03, 2017USD ($)$ / sharesshares	Jul. 05, 2017$ / sharesshares	May 17, 2017trustee$ / sharesshares	Dec. 31, 2017$ / sharesshares
Class of Stock [Line Items]
Consideration received from sale of stock | $				$ 493,866
Former Employee Of RMR LLC
Class of Stock [Line Items]
Shares paid for tax withholding | shares			154
Shares paid for tax withholding (in dollars per share) | $ / shares			$ 74.16
Trustees
Class of Stock [Line Items]
Shares paid for tax withholding | shares		112				112
Shares paid for tax withholding (in dollars per share) | $ / shares		$ 56.4				$ 87
Number of Trustees | trustee		1				1
Officers and Other Employees
Class of Stock [Line Items]
Shares paid for tax withholding | shares	4,718						3,478
Shares paid for tax withholding (in dollars per share) | $ / shares	$ 45.4						$ 73.20
Underwritten Public Offering
Class of Stock [Line Items]
Number of shares sold (in shares) | shares					6,250,000
Sale of stock (in dollars per share) | $ / shares					$ 74
Over-Allotment Option
Class of Stock [Line Items]
Number of shares sold (in shares) | shares				726,757
Sale of stock (in dollars per share) | $ / shares				$ 74

Shareholders' Equity - Distribu

Shareholders' Equity - Distributions (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 18, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Distributions Per Share (in dollars per share)										$ 6.88	$ 6.88	$ 6.88
Total Distributions										$ 170,566	$ 145,209	$ 122,366
Characterization of distributions paid or accrued as a percentage of return of capital										68.60%	49.35%	36.21%
Characterization of distributions paid or accrued as a percentage of ordinary income										31.40%	50.65%	62.74%
Characterization of distributions paid or accrued as a percentage of qualified dividends										0.00%	0.00%	1.05%
Common distributions declared (in dollars per share)		$ 1.72	$ 1.72	$ 1.72	$ 1.72	$ 1.72	$ 1.72	$ 1.72	$ 1.72
Subsequent Event
Class of Stock [Line Items]
Common distributions declared (in dollars per share)	$ 0.55
Dividends payable	$ 26,446

Shareholders' Equity - Cumulati

Shareholders' Equity - Cumulative Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	Jan. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	$ 1,330,043	$ 1,330,043	$ 935,004	$ 956,651
Other comprehensive income (loss)		(40)	33,470	41,824
Balance ending		1,778,968	1,330,043	935,004
Unrealized Gain (Loss) on Investment in Equity Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	45,116	45,116	21,074	(9,391)
Other comprehensive income before reclassifications		0	24,042	30,465
Amounts reclassified from cumulative other comprehensive income to net income (loss)	(45,116)	0	0	0
Other comprehensive income (loss)		0	24,042	30,465
Balance ending	0	0	45,116	21,074
Equity in Unrealized Gains (Losses) of Investees (1)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	15,311	15,311	5,883	(5,476)
Other comprehensive income before reclassifications		(3)	9,462	11,254
Amounts reclassified from cumulative other comprehensive income to net income (loss)	(15,165)	(37)	(34)	105
Other comprehensive income (loss)		(40)	9,428	11,359
Balance ending	146	106	15,311	5,883
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	60,427	60,427	26,957	(14,867)
Other comprehensive income before reclassifications		(3)	33,504	41,719
Amounts reclassified from cumulative other comprehensive income to net income (loss)	(60,281)	(37)	(34)	105
Other comprehensive income (loss)		(40)	33,470	41,824
Balance ending	$ 146	$ 106	$ 60,427	$ 26,957

Shareholders' Equity - Preferre

Shareholders' Equity - Preferred Units of Limited Partnership (Details) - Series A Cumulative Preferred Units - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	May 01, 2018
Class of Stock [Line Items]
Shares outstanding (in units)		1,813,504
Redemption percentage	5.50%
Redemption price (in dollars per share)		$ 11.15
Redemption amount		$ 20,310

Equity Investment in Select I_3

Equity Investment in Select Income REIT (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Oct. 09, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Equity in net earnings (losses) of investees			$ (2,269)	$ (13)	$ 137
Unrealized gain (loss) from investees			(40)	9,428	11,359
Distributions of earnings from Select Income REIT			20,873	21,584	35,381
Loss on impairment of real estate			8,630	9,490	0
Gain (loss) on issuance of shares by Select Income REIT			$ 29	72	86
SIR
Schedule of Equity Method Investments [Line Items]
Equity investments, common shares owned		24,918,421
Percentage of outstanding shares owned		27.80%	27.80%
Equity in net earnings (losses) of investees	$ 24,358			21,584	35,381
Unrealized gain (loss) from investees	28			8,967	11,207
Accretion of equity in earnings	3,233			2,944	2,956
Distributions of earnings from Select Income REIT	$ 38,124			50,832	50,335
SIR | SIR
Schedule of Equity Method Investments [Line Items]
Equity in net earnings (losses) of investees		$ 882		608	137
Loss on impairment of real estate		$ 9,706		$ 229	$ 5,484
Issuance of shares, net (in shares)	63,157			59,502	65,900
Gain (loss) on issuance of shares by Select Income REIT	$ 29			$ 72	$ 86
Secondary Sale
Schedule of Equity Method Investments [Line Items]
Loss on sale of stock			$ 18,665

Equity Investment in Select I_4

Equity Investment in Select Income REIT - Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Real estate properties, net	$ 3,569,489	$ 2,633,873
Properties held for sale	253,501	0
Acquired real estate leases, net	1,056,558	351,872
Cash and cash equivalents	35,349	16,569	$ 29,941
Rents receivable, net	72,051	61,429
Other assets, net	178,704	96,033
Total assets	5,238,583	3,703,565
Unsecured term loan, net	387,152	547,852
Senior unsecured notes, net	2,357,497	944,140
Mortgage notes payable, net	335,241	183,100
Assumed real estate lease obligations, net	20,031	13,635
Other liabilities	145,536	89,440
Total shareholders' equity	1,778,968	1,330,043	$ 935,004	$ 956,651
Total liabilities and shareholders’ equity	$ 5,238,583	3,703,565
SIR | SIR
Schedule of Equity Method Investments [Line Items]
Real estate properties, net		3,905,616
Properties held for sale		5,829
Acquired real estate leases, net		477,577
Cash and cash equivalents		658,719
Rents receivable, net		127,672
Other assets, net		127,617
Total assets		5,303,030
ILPT revolving credit facility		750,000
Unsecured term loan, net		348,870
Senior unsecured notes, net		1,777,425
Mortgage notes payable, net		210,785
Assumed real estate lease obligations, net		68,783
Other liabilities		155,348
Total shareholders' equity		1,991,819
Total liabilities and shareholders’ equity		$ 5,303,030

Equity Investment in Select I_5

Equity Investment in Select Income REIT - Income Statement Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								9 Months Ended		12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Oct. 09, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Rental income	$ 103,656	$ 106,102	$ 108,085	$ 108,717	$ 107,170	$ 70,179	$ 69,887	$ 69,296			$ 426,560	$ 316,532	$ 258,180
Real estate taxes											49,708	37,942	30,703
Other operating expenses											89,610	65,349	54,290
Depreciation and amortization											162,488	109,588	73,153
Acquisition and transaction related costs											14,508	0	1,191
General and administrative											24,922	18,847	14,897
Loss on impairment of real estate assets											8,630	9,490	0
Total expenses											376,291	262,214	191,503
Gain on sale of real estate											20,661	0	79
Dividend income											1,337	1,216	971
Unrealized gain on equity securities											(7,552)	0	0
Interest income											639	1,962	158
Interest expense											(89,865)	(65,406)	(45,060)
Loss on early extinguishment of debt											(709)	(1,715)	104
Income (loss) from continuing operations before income taxes, equity in earnings of investees and gain on sale of real estate											(25,220)	(9,625)	22,929
Income tax expense											(117)	(101)	(101)
Equity in net earnings (losses) of investees											(2,269)	(13)	137
Net income (loss)											$ (21,884)	$ 12,090	$ 57,843
Weighted average common shares outstanding (basic) (in shares)											24,830	21,158	17,763
Weighted average common shares outstanding (diluted) (in shares)											24,830	21,158	17,768
Net income attributed to SIR per common share (basic and diluted) (in dollars per share)	$ (2.31)	$ (0.02)	$ 1.20	$ 0.25	$ (0.74)	$ 0.45	$ 0.66	$ 0.42			$ (0.90)	$ 0.56	$ 3.26
SIR
Schedule of Equity Method Investments [Line Items]
Equity in net earnings (losses) of investees									$ 24,358			$ 21,584	$ 35,381
SIR | SIR
Schedule of Equity Method Investments [Line Items]
Rental income										$ 298,003		392,285	387,015
Tenant reimbursements and other income										60,514		75,818	74,992
Total revenues										358,517		468,103	462,007
Real estate taxes										36,748		44,131	42,879
Other operating expenses										43,714		55,567	52,957
Depreciation and amortization										105,326		137,672	133,762
Acquisition and transaction related costs										3,796		1,075	306
General and administrative										47,353		54,909	28,632
Write-off of straight line rents, net										10,626		12,517	0
Loss on asset impairment										0		4,047	0
Loss on impairment of real estate assets										9,706		229	5,484
Total expenses										257,269		310,147	264,020
Gain on sale of real estate										4,075		0	0
Dividend income										1,190		1,587	1,268
Unrealized gain on equity securities										53,159		0	0
Interest income										753		91	30
Interest expense										(69,446)		(92,870)	(82,620)
Loss on early extinguishment of debt										(1,192)		0	0
Income (loss) from continuing operations before income taxes, equity in earnings of investees and gain on sale of real estate										89,787		66,764	116,665
Income tax expense										(446)		(466)	(448)
Equity in net earnings (losses) of investees										882		608	137
Net income										90,223		66,906	116,354
Net income allocated to noncontrolling interest										(15,841)		0	(33)
Net income (loss)										$ 74,382		$ 66,906	$ 116,321
Weighted average common shares outstanding (basic) (in shares)										89,395		89,351	89,304
Weighted average common shares outstanding (diluted) (in shares)										89,411		89,370	89,324
Net income attributed to SIR per common share (basic and diluted) (in dollars per share)										$ 0.83		$ 0.75	$ 1.30

Discontinued Operations - Addit

Discontinued Operations - Additional Information (Details) $ in Thousands	Oct. 09, 2018shares	Aug. 31, 2017USD ($)ft²property	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on impairment of Select Income REIT investment			$ 15,180	$ 0	$ 0
Rentable area of properties (in square feet) | ft²					830,185
Net book value			3,569,489	2,633,873
Falls Church, VA | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties | property		1
Rentable area of properties (in square feet) | ft²		164,746
Net book value		$ 12,901
Aggregate sale price of properties sold, excluding closing costs		$ 13,523
SIR | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on impairment of Select Income REIT investment			18,665	$ 0	$ 0
SIR | Common Shares | Secondary Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of shares sold (in shares) | shares	24,918,421
Loss on impairment of Select Income REIT investment			$ 18,665

Discontinued Operations - Sched

Discontinued Operations - Schedule of Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity in earnings of Select Income REIT	$ (2,269)	$ (13)	$ 137
Net gain on issuance of shares by Select Income REIT	29	72	86
Loss on sale of Select Income REIT shares	(15,180)	0	0
Income (loss) from discontinued operations	5,722	21,829	34,878
SIR | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity in earnings of Select Income REIT	24,358	21,584	35,381
Net gain on issuance of shares by Select Income REIT	29	72	86
Loss on sale of Select Income REIT shares	(18,665)	0	0
Income (loss) from property discontinued operations	$ 0	$ 173	$ (589)

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Rental income	$ 103,656	$ 106,102	$ 108,085	$ 108,717	$ 107,170	$ 70,179	$ 69,887	$ 69,296	$ 426,560	$ 316,532	$ 258,180
Net income (loss) available for common shareholders	$ (57,695)	$ (449)	$ 29,602	$ 6,287	$ (18,266)	$ 10,989	$ 11,677	$ 7,415	$ (22,255)	$ 11,815	$ 57,843
Net income (loss) available for common shareholders per common share (basic and diluted) (in dollars per share)	$ (2.31)	$ (0.02)	$ 1.20	$ 0.25	$ (0.74)	$ 0.45	$ 0.66	$ 0.42	$ (0.90)	$ 0.56	$ 3.26
Common distributions declared (in dollars per share)	$ 1.72	$ 1.72	$ 1.72	$ 1.72	$ 1.72	$ 1.72	$ 1.72	$ 1.72

SCHEDULE III REAL ESTATE AND _2

SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)building	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Real estate and accumulated depreciation
Number of Buildings | building	211
Encumbrances	$ 335,241
Initial Cost to Company
Land	923,390
Buildings and Equipment	2,804,289
Costs Capitalized Subsequent to Acquisition	221,397
Impairment/ Writedowns	(4,440)
Cost amount carried at Close of Period
Land	924,164
Buildings and Equipment	3,020,472
Total	3,944,636	$ 2,975,721	$ 1,888,760	$ 1,696,132
Accumulated Depreciation	$ (375,147)	$ (341,848)	$ (296,804)	$ (255,879)
Inverness Center, Birmingham, AL
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 5,954
Buildings and Equipment	11,664
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	5,954
Buildings and Equipment	11,664
Total	17,618
Accumulated Depreciation	$ 0
445 Jan Davis Drive, Huntsville, AL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,513
Buildings and Equipment	1,503
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	1,513
Buildings and Equipment	1,503
Total	3,016
Accumulated Depreciation	$ 0
4905 Moores Mill Road, Huntsville, AL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,628
Buildings and Equipment	36,612
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,628
Buildings and Equipment	36,612
Total	41,240
Accumulated Depreciation	$ 0
131 Clayton Street, Montgomery, AL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 920
Buildings and Equipment	9,084
Costs Capitalized Subsequent to Acquisition	48
Cost amount carried at Close of Period
Land	920
Buildings and Equipment	9,132
Total	10,052
Accumulated Depreciation	$ (1,708)
4344 Carmichael Road, Montgomery, AL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,374
Buildings and Equipment	11,658
Costs Capitalized Subsequent to Acquisition	10
Cost amount carried at Close of Period
Land	1,374
Buildings and Equipment	11,668
Total	13,042
Accumulated Depreciation	$ (1,458)
15451 North 28th Avenue, Phoenix, AZ
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,917
Buildings and Equipment	7,416
Costs Capitalized Subsequent to Acquisition	499
Cost amount carried at Close of Period
Land	1,917
Buildings and Equipment	7,915
Total	9,832
Accumulated Depreciation	$ (836)
16001 North 28th Avenue, Phoenix, AZ
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 3,382
Buildings and Equipment	416
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	3,382
Buildings and Equipment	416
Total	3,798
Accumulated Depreciation	$ 0
2149 West Dunlap Avenue, Phoenix, AZ
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 6,606
Buildings and Equipment	218
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	6,606
Buildings and Equipment	218
Total	6,824
Accumulated Depreciation	$ 0
711 14th Avenue, Safford, AZ
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 460
Buildings and Equipment	11,708
Costs Capitalized Subsequent to Acquisition	484
Impairment/ Writedowns	(4,440)
Cost amount carried at Close of Period
Land	364
Buildings and Equipment	7,848
Total	8,212
Accumulated Depreciation	$ (190)
Regents Center, Tempe, AZ
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 4,154
Buildings and Equipment	3,066
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,154
Buildings and Equipment	3,066
Total	7,220
Accumulated Depreciation	$ 0
Campbell Place, Carlsbad, CA
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 5,815
Buildings and Equipment	3,902
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	5,815
Buildings and Equipment	3,902
Total	9,717
Accumulated Depreciation	$ 0
Folsom Corporate Center, Folsom, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,927
Buildings and Equipment	5,628
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	2,927
Buildings and Equipment	5,628
Total	8,555
Accumulated Depreciation	$ 0
Bayside Technology Park, Fremont, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 10,869
Buildings and Equipment	653
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	10,869
Buildings and Equipment	653
Total	11,522
Accumulated Depreciation	$ 0
5045 East Butler Street, Fresno, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 7,276
Buildings and Equipment	61,118
Costs Capitalized Subsequent to Acquisition	139
Cost amount carried at Close of Period
Land	7,276
Buildings and Equipment	61,257
Total	68,533
Accumulated Depreciation	$ (25,031)
10949 N. Mather Boulevard, Rancho Cordova, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 562
Buildings and Equipment	16,923
Costs Capitalized Subsequent to Acquisition	359
Cost amount carried at Close of Period
Land	562
Buildings and Equipment	17,282
Total	17,844
Accumulated Depreciation	$ (2,201)
11020 Sun Center Drive, Rancho Cordova, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Encumbrances	$ 64,490
Initial Cost to Company
Land	1,466
Buildings and Equipment	8,797
Costs Capitalized Subsequent to Acquisition	671
Cost amount carried at Close of Period
Land	1,466
Buildings and Equipment	9,468
Total	10,934
Accumulated Depreciation	$ (513)
100 Redwood Shores Parkway, Redwood City, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 14,568
Buildings and Equipment	7,783
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	14,568
Buildings and Equipment	7,783
Total	22,351
Accumulated Depreciation	$ 0
3875 Atherton Road, Rocklin, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 178
Buildings and Equipment	860
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	178
Buildings and Equipment	860
Total	1,038
Accumulated Depreciation	$ 0
801 K Street, Sacramento, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,688
Buildings and Equipment	61,995
Costs Capitalized Subsequent to Acquisition	6,275
Cost amount carried at Close of Period
Land	4,688
Buildings and Equipment	68,270
Total	72,958
Accumulated Depreciation	$ (5,922)
9815 Goethe Road, Sacramento, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,450
Buildings and Equipment	9,465
Costs Capitalized Subsequent to Acquisition	1,523
Cost amount carried at Close of Period
Land	1,450
Buildings and Equipment	10,988
Total	12,438
Accumulated Depreciation	$ (2,019)
Capital Place, Sacramento, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,290
Buildings and Equipment	35,891
Costs Capitalized Subsequent to Acquisition	7,885
Cost amount carried at Close of Period
Land	2,290
Buildings and Equipment	43,776
Total	46,066
Accumulated Depreciation	$ (10,059)
4181 Ruffin Road, San Diego, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,250
Buildings and Equipment	10,549
Costs Capitalized Subsequent to Acquisition	5,076
Cost amount carried at Close of Period
Land	5,250
Buildings and Equipment	15,625
Total	20,875
Accumulated Depreciation	$ (3,914)
4560 Viewridge Road, San Diego, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,269
Buildings and Equipment	18,316
Costs Capitalized Subsequent to Acquisition	4,319
Cost amount carried at Close of Period
Land	4,347
Buildings and Equipment	22,557
Total	26,904
Accumulated Depreciation	$ (10,672)
9174 Sky Park Centre, San Diego, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Encumbrances	$ 7,983
Initial Cost to Company
Land	685
Buildings and Equipment	5,530
Costs Capitalized Subsequent to Acquisition	2,708
Cost amount carried at Close of Period
Land	685
Buildings and Equipment	8,238
Total	8,923
Accumulated Depreciation	$ (3,246)
2090 Fortune Drive, San Jose, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 9,074
Buildings and Equipment	0
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	9,074
Buildings and Equipment	0
Total	9,074
Accumulated Depreciation	$ 0
2115 O'Nel Drive, San Jose, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 12,402
Buildings and Equipment	5,103
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	12,402
Buildings and Equipment	5,103
Total	17,505
Accumulated Depreciation	$ 0
6448-6450 Via Del Oro, San Jose, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,747
Buildings and Equipment	2,027
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,747
Buildings and Equipment	2,027
Total	6,774
Accumulated Depreciation	$ 0
North First Street, San Jose, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 8,377
Buildings and Equipment	4,035
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	8,377
Buildings and Equipment	4,035
Total	12,412
Accumulated Depreciation	$ 0
Rio Robles Drive, San Jose, CA
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 23,874
Buildings and Equipment	13,806
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	23,874
Buildings and Equipment	13,806
Total	37,680
Accumulated Depreciation	$ 0
2450 and 2500 Walsh Avenue, Santa Clara, CA
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 13,480
Buildings and Equipment	16,783
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	13,480
Buildings and Equipment	16,783
Total	30,263
Accumulated Depreciation	$ 0
3250 and 3260 Jay Street, Santa Clara, CA
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 20,056
Buildings and Equipment	14,163
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	20,056
Buildings and Equipment	14,163
Total	34,219
Accumulated Depreciation	$ 0
603 San Juan Avenue, Stockton, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 563
Buildings and Equipment	5,470
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	563
Buildings and Equipment	5,470
Total	6,033
Accumulated Depreciation	$ (878)
350 West Java Drive, Sunnyvale, CA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 24,804
Buildings and Equipment	464
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	24,804
Buildings and Equipment	464
Total	25,268
Accumulated Depreciation	$ 0
7958 South Chester Street, Centennial, CO
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 6,735
Buildings and Equipment	7,210
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	6,735
Buildings and Equipment	7,210
Total	13,945
Accumulated Depreciation	$ 0
350 Spectrum Loop, Colorado Springs, CO
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 3,679
Buildings and Equipment	7,793
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	3,679
Buildings and Equipment	7,793
Total	11,472
Accumulated Depreciation	$ 0
333 Inverness Drive South, Englewood, CO
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,756
Buildings and Equipment	4,579
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	5,756
Buildings and Equipment	4,579
Total	10,335
Accumulated Depreciation	$ 0
12795 West Alameda Parkway, Lakewood, CO
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,640
Buildings and Equipment	23,777
Costs Capitalized Subsequent to Acquisition	1,094
Cost amount carried at Close of Period
Land	2,640
Buildings and Equipment	24,871
Total	27,511
Accumulated Depreciation	$ (5,559)
Corporate Center, Lakewood, CO
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 2,887
Buildings and Equipment	27,537
Costs Capitalized Subsequent to Acquisition	3,889
Cost amount carried at Close of Period
Land	2,887
Buildings and Equipment	31,426
Total	34,313
Accumulated Depreciation	$ (12,495)
1Targeting Center, Windsor, CT
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,404
Buildings and Equipment	574
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	1,404
Buildings and Equipment	574
Total	1,978
Accumulated Depreciation	$ 0
11 Dupont Circle, NW, Washington DC
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 28,255
Buildings and Equipment	44,743
Costs Capitalized Subsequent to Acquisition	1,994
Cost amount carried at Close of Period
Land	28,255
Buildings and Equipment	46,737
Total	74,992
Accumulated Depreciation	$ (1,672)
1211 Connecticut Avenue, NW, Washington DC
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 30,388
Buildings and Equipment	24,667
Costs Capitalized Subsequent to Acquisition	1,391
Cost amount carried at Close of Period
Land	30,388
Buildings and Equipment	26,058
Total	56,446
Accumulated Depreciation	$ (892)
1401 K Street, NW, Washington DC
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 29,215
Buildings and Equipment	34,656
Costs Capitalized Subsequent to Acquisition	3,210
Cost amount carried at Close of Period
Land	29,215
Buildings and Equipment	37,866
Total	67,081
Accumulated Depreciation	$ (1,497)
20 Massachusetts Avenue, Washington, DC
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 12,009
Buildings and Equipment	51,528
Costs Capitalized Subsequent to Acquisition	21,395
Cost amount carried at Close of Period
Land	12,228
Buildings and Equipment	72,704
Total	84,932
Accumulated Depreciation	$ (35,137)
440 First Street, NW, Washington DC
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 27,903
Buildings and Equipment	38,624
Costs Capitalized Subsequent to Acquisition	1,293
Cost amount carried at Close of Period
Land	27,903
Buildings and Equipment	39,917
Total	67,820
Accumulated Depreciation	$ (1,264)
625 Indiana Avenue, Washington, DC
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 26,000
Buildings and Equipment	25,955
Costs Capitalized Subsequent to Acquisition	7,293
Cost amount carried at Close of Period
Land	26,000
Buildings and Equipment	33,248
Total	59,248
Accumulated Depreciation	$ (7,555)
840 First Street, NE, Washington DC
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 42,727
Buildings and Equipment	73,249
Costs Capitalized Subsequent to Acquisition	472
Cost amount carried at Close of Period
Land	42,727
Buildings and Equipment	73,721
Total	116,448
Accumulated Depreciation	$ (2,290)
10350 NW 112th Avenue, Miami, FL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,836
Buildings and Equipment	2,779
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,836
Buildings and Equipment	2,779
Total	7,615
Accumulated Depreciation	$ 0
7850 Southwest 6th Court, Plantation, FL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,800
Buildings and Equipment	30,592
Costs Capitalized Subsequent to Acquisition	383
Cost amount carried at Close of Period
Land	4,800
Buildings and Equipment	30,975
Total	35,775
Accumulated Depreciation	$ (6,026)
8900 Grand Oak Circle, Tampa, FL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,100
Buildings and Equipment	11,773
Costs Capitalized Subsequent to Acquisition	288
Cost amount carried at Close of Period
Land	1,100
Buildings and Equipment	12,061
Total	13,161
Accumulated Depreciation	$ (2,471)
180 Ted Turner Drive SW, Atlanta, GA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,717
Buildings and Equipment	20,017
Costs Capitalized Subsequent to Acquisition	186
Cost amount carried at Close of Period
Land	5,717
Buildings and Equipment	20,203
Total	25,920
Accumulated Depreciation	$ (3,229)
Corporate Square, Atlanta, GA
Real estate and accumulated depreciation
Number of Buildings | building	5
Initial Cost to Company
Land	$ 3,996
Buildings and Equipment	29,762
Costs Capitalized Subsequent to Acquisition	27,816
Cost amount carried at Close of Period
Land	3,996
Buildings and Equipment	57,578
Total	61,574
Accumulated Depreciation	$ (13,371)
Executive Park, Atlanta, GA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,521
Buildings and Equipment	11,826
Costs Capitalized Subsequent to Acquisition	3,996
Cost amount carried at Close of Period
Land	1,521
Buildings and Equipment	15,822
Total	17,343
Accumulated Depreciation	$ (5,781)
One Georgia Center, Atlanta, GA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 10,250
Buildings and Equipment	27,933
Costs Capitalized Subsequent to Acquisition	6,034
Cost amount carried at Close of Period
Land	10,250
Buildings and Equipment	33,967
Total	44,217
Accumulated Depreciation	$ (5,419)
One Primerica Parkway, Duluth, GA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 6,982
Buildings and Equipment	23,132
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	6,982
Buildings and Equipment	23,132
Total	30,114
Accumulated Depreciation	$ 0
4712 Southpark Boulevard, Ellenwood, GA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,390
Buildings and Equipment	19,635
Costs Capitalized Subsequent to Acquisition	88
Cost amount carried at Close of Period
Land	1,390
Buildings and Equipment	19,723
Total	21,113
Accumulated Depreciation	$ (3,156)
91-209 Kuhela Street, Kapolei, HI
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,008
Buildings and Equipment	0
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	2,008
Buildings and Equipment	0
Total	2,008
Accumulated Depreciation	$ 0
8305 NW 62nd Avenue, Johnston, IA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,670
Buildings and Equipment	8,060
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	2,670
Buildings and Equipment	8,060
Total	10,730
Accumulated Depreciation	$ 0
South Vinnell Way, Boise, ID
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 3,390
Buildings and Equipment	29,026
Costs Capitalized Subsequent to Acquisition	822
Cost amount carried at Close of Period
Land	3,390
Buildings and Equipment	29,848
Total	33,238
Accumulated Depreciation	$ (4,871)
2020 S. Arlington Heights, Arlington Heights, IL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,450
Buildings and Equipment	13,160
Costs Capitalized Subsequent to Acquisition	872
Cost amount carried at Close of Period
Land	1,450
Buildings and Equipment	14,032
Total	15,482
Accumulated Depreciation	$ (3,101)
400 South Jefferson Street, Chicago, IL
Real estate and accumulated depreciation
Number of Buildings | building	1
Encumbrances	$ 13,384
Initial Cost to Company
Land	19,532
Buildings and Equipment	20,274
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	19,532
Buildings and Equipment	20,274
Total	39,806
Accumulated Depreciation	$ 0
475 Bond Street, Lincolnshire, IL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,915
Buildings and Equipment	574
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,915
Buildings and Equipment	574
Total	5,489
Accumulated Depreciation	$ 0
1415 West Diehl Road, Naperville, IL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 12,431
Buildings and Equipment	20,749
Costs Capitalized Subsequent to Acquisition	0
Impairment/ Writedowns	0
Cost amount carried at Close of Period
Land	12,431
Buildings and Equipment	20,749
Total	33,180
Accumulated Depreciation	$ 0
440 North Fairway Drive, Vernon Hills, IL
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,500
Buildings and Equipment	445
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,500
Buildings and Equipment	445
Total	4,945
Accumulated Depreciation	$ 0
Intech Park, Indianapolis, IN
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 4,170
Buildings and Equipment	68,888
Costs Capitalized Subsequent to Acquisition	4,337
Cost amount carried at Close of Period
Land	4,170
Buildings and Equipment	73,225
Total	77,395
Accumulated Depreciation	$ (13,425)
7601 and 7635 Interactive Way, Indianapolis, IN
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 3,363
Buildings and Equipment	14,636
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	3,363
Buildings and Equipment	14,636
Total	17,999
Accumulated Depreciation	$ 0
400 State Street, Kansas City, KS
Real estate and accumulated depreciation
Number of Buildings | building	1
Encumbrances	$ 49,087
Initial Cost to Company
Land	640
Buildings and Equipment	9,932
Costs Capitalized Subsequent to Acquisition	5,265
Cost amount carried at Close of Period
Land	640
Buildings and Equipment	15,197
Total	15,837
Accumulated Depreciation	$ (3,309)
Capital Tower, Topeka, KS [Member]
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,236
Buildings and Equipment	3,115
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	1,236
Buildings and Equipment	3,115
Total	4,351
Accumulated Depreciation	$ 0
The Atrium at Circleport II, Erlanger, KY
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,810
Buildings and Equipment	1,948
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	1,810
Buildings and Equipment	1,948
Total	3,758
Accumulated Depreciation	$ 0
7125 Industrial Road, Florence, KY
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,698
Buildings and Equipment	11,722
Costs Capitalized Subsequent to Acquisition	151
Cost amount carried at Close of Period
Land	1,698
Buildings and Equipment	11,873
Total	13,571
Accumulated Depreciation	$ (1,766)
251 Causeway Street, Boston, MA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,100
Buildings and Equipment	17,293
Costs Capitalized Subsequent to Acquisition	2,555
Cost amount carried at Close of Period
Land	5,100
Buildings and Equipment	19,848
Total	24,948
Accumulated Depreciation	$ (4,061)
300 and 330 Billerica Road, Chelmsford, MA
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 4,737
Buildings and Equipment	0
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,737
Buildings and Equipment	0
Total	4,737
Accumulated Depreciation	$ 0
75 Pleasant Street, Malden, MA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,050
Buildings and Equipment	31,086
Costs Capitalized Subsequent to Acquisition	271
Cost amount carried at Close of Period
Land	1,050
Buildings and Equipment	31,357
Total	32,407
Accumulated Depreciation	$ (6,703)
111 Powdermill Road, Maynard, MA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,432
Buildings and Equipment	0
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,432
Buildings and Equipment	0
Total	4,432
Accumulated Depreciation	$ 0
25 Newport Avenue, Quincy, MA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,700
Buildings and Equipment	9,199
Costs Capitalized Subsequent to Acquisition	1,791
Cost amount carried at Close of Period
Land	2,700
Buildings and Equipment	10,990
Total	13,690
Accumulated Depreciation	$ (2,021)
One Montvale Avenue, Stoneham, MA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,670
Buildings and Equipment	11,035
Costs Capitalized Subsequent to Acquisition	2,234
Cost amount carried at Close of Period
Land	1,670
Buildings and Equipment	13,269
Total	14,939
Accumulated Depreciation	$ (2,693)
314 Littleton Road, Westford, MA [Member]
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,736
Buildings and Equipment	8,555
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	5,736
Buildings and Equipment	8,555
Total	14,291
Accumulated Depreciation	$ 0
Annapolis Commerce Center, Annapolis, MD
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 4,057
Buildings and Equipment	7,665
Costs Capitalized Subsequent to Acquisition	219
Cost amount carried at Close of Period
Land	4,057
Buildings and Equipment	7,884
Total	11,941
Accumulated Depreciation	$ (275)
4201 Patterson Avenue, Baltimore, MD
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 901
Buildings and Equipment	8,097
Costs Capitalized Subsequent to Acquisition	4,085
Cost amount carried at Close of Period
Land	901
Buildings and Equipment	12,182
Total	13,083
Accumulated Depreciation	$ (4,961)
Hillside Center, Columbia, MD
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 3,437
Buildings and Equipment	4,228
Costs Capitalized Subsequent to Acquisition	336
Cost amount carried at Close of Period
Land	3,437
Buildings and Equipment	4,564
Total	8,001
Accumulated Depreciation	$ (131)
TenThreeTwenty, Columbia, MD
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 3,126
Buildings and Equipment	16,361
Costs Capitalized Subsequent to Acquisition	869
Cost amount carried at Close of Period
Land	3,126
Buildings and Equipment	17,230
Total	20,356
Accumulated Depreciation	$ (570)
7001 Columbia Gateway Drive, Columbia, MD
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,687
Buildings and Equipment	10,433
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	5,687
Buildings and Equipment	10,433
Total	16,120
Accumulated Depreciation	$ 0
3300 75th Avenue, Landover, MD
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,110
Buildings and Equipment	36,371
Costs Capitalized Subsequent to Acquisition	1,346
Cost amount carried at Close of Period
Land	4,110
Buildings and Equipment	37,717
Total	41,827
Accumulated Depreciation	$ (8,281)
1401 Rockville Pike, Rockville, MD
Real estate and accumulated depreciation
Number of Buildings | building	1
Encumbrances	$ 25,019
Initial Cost to Company
Land	3,248
Buildings and Equipment	29,258
Costs Capitalized Subsequent to Acquisition	16,481
Cost amount carried at Close of Period
Land	3,248
Buildings and Equipment	45,739
Total	48,987
Accumulated Depreciation	$ (19,266)
2115 East Jefferson Street, Rockville, MD
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 3,349
Buildings and Equipment	11,152
Costs Capitalized Subsequent to Acquisition	385
Cost amount carried at Close of Period
Land	3,349
Buildings and Equipment	11,537
Total	14,886
Accumulated Depreciation	$ (1,521)
Redland 520/530, Rockville, MD
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 12,714
Buildings and Equipment	61,377
Costs Capitalized Subsequent to Acquisition	1,498
Cost amount carried at Close of Period
Land	12,714
Buildings and Equipment	62,875
Total	75,589
Accumulated Depreciation	$ (1,945)
Redland 540, Rockville, MD
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 10,740
Buildings and Equipment	17,714
Costs Capitalized Subsequent to Acquisition	2,896
Cost amount carried at Close of Period
Land	10,740
Buildings and Equipment	20,610
Total	31,350
Accumulated Depreciation	$ (879)
Rutherford Business Park, Windsor Mill, MD
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,598
Buildings and Equipment	10,219
Costs Capitalized Subsequent to Acquisition	330
Cost amount carried at Close of Period
Land	1,598
Buildings and Equipment	10,549
Total	12,147
Accumulated Depreciation	$ (1,557)
Meadows Business Park, Woodlawn, MD
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 3,735
Buildings and Equipment	21,509
Costs Capitalized Subsequent to Acquisition	2,268
Cost amount carried at Close of Period
Land	3,735
Buildings and Equipment	23,777
Total	27,512
Accumulated Depreciation	$ (4,701)
3550 Green Court, Ann Arbor, MI
Real estate and accumulated depreciation
Number of Buildings | building	1
Encumbrances	$ 69,304
Initial Cost to Company
Land	3,659
Buildings and Equipment	4,896
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	3,659
Buildings and Equipment	4,896
Total	8,555
Accumulated Depreciation	$ 0
11411 E. Jefferson Avenue, Detroit, MI
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 630
Buildings and Equipment	18,002
Costs Capitalized Subsequent to Acquisition	438
Cost amount carried at Close of Period
Land	630
Buildings and Equipment	18,440
Total	19,070
Accumulated Depreciation	$ (3,930)
Rosedale Corporate Plaza, Roseville, MN
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 672
Buildings and Equipment	6,045
Costs Capitalized Subsequent to Acquisition	1,505
Cost amount carried at Close of Period
Land	672
Buildings and Equipment	7,550
Total	8,222
Accumulated Depreciation	$ (3,474)
1300 Summit Street, Kansas City, MO
Real estate and accumulated depreciation
Number of Buildings | building	1
Encumbrances	$ 2,933
Initial Cost to Company
Land	2,776
Buildings and Equipment	12,070
Costs Capitalized Subsequent to Acquisition	915
Cost amount carried at Close of Period
Land	2,776
Buildings and Equipment	12,985
Total	15,761
Accumulated Depreciation	$ (1,939)
4241-4300 NE 34th Street, Kansas City, MO
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,443
Buildings and Equipment	6,193
Costs Capitalized Subsequent to Acquisition	3,992
Cost amount carried at Close of Period
Land	1,780
Buildings and Equipment	9,848
Total	11,628
Accumulated Depreciation	$ (4,199)
2555 Grand Boulevard, Kansas City, MO
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,243
Buildings and Equipment	51,931
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,243
Buildings and Equipment	51,931
Total	56,174
Accumulated Depreciation	$ 0
1220 Echelon Parkway, Jackson, MS
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 440
Buildings and Equipment	25,458
Costs Capitalized Subsequent to Acquisition	238
Cost amount carried at Close of Period
Land	440
Buildings and Equipment	25,696
Total	26,136
Accumulated Depreciation	$ (4,100)
2300 and 2400 Yorkmont Road, Charlotte, NC
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 1,345
Buildings and Equipment	19,226
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	1,345
Buildings and Equipment	19,226
Total	20,571
Accumulated Depreciation	$ 0
18010 and 18020 Burt Street, Omaha, NE
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 7,032
Buildings and Equipment	12,599
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	7,032
Buildings and Equipment	12,599
Total	19,631
Accumulated Depreciation	$ 0
10-12 Celina Avenue, Nashua, NH
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 3,000
Buildings and Equipment	14,052
Costs Capitalized Subsequent to Acquisition	1,569
Cost amount carried at Close of Period
Land	3,000
Buildings and Equipment	15,621
Total	18,621
Accumulated Depreciation	$ (3,379)
500 Charles Ewing Boulevard, Ewing, NJ
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,846
Buildings and Equipment	26,208
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,846
Buildings and Equipment	26,208
Total	31,054
Accumulated Depreciation	$ 0
299 Jefferson Road, Parsippany, NJ
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,579
Buildings and Equipment	2,937
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,579
Buildings and Equipment	2,937
Total	7,516
Accumulated Depreciation	$ 0
One Jefferson Road, Parsippany, NJ
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,450
Buildings and Equipment	5,291
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,450
Buildings and Equipment	5,291
Total	9,741
Accumulated Depreciation	$ 0
50 West State Street, Trenton, NJ
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,000
Buildings and Equipment	38,203
Costs Capitalized Subsequent to Acquisition	3,313
Cost amount carried at Close of Period
Land	5,000
Buildings and Equipment	41,516
Total	46,516
Accumulated Depreciation	$ (8,009)
138 Delaware Avenue, Buffalo, NY
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,405
Buildings and Equipment	18,899
Costs Capitalized Subsequent to Acquisition	7,551
Cost amount carried at Close of Period
Land	4,485
Buildings and Equipment	26,370
Total	30,855
Accumulated Depreciation	$ (11,830)
Airline Corporate Center, Colonie, NY
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 790
Buildings and Equipment	6,400
Costs Capitalized Subsequent to Acquisition	406
Cost amount carried at Close of Period
Land	790
Buildings and Equipment	6,806
Total	7,596
Accumulated Depreciation	$ (1,053)
5000 Corporate Court, Holtsville, NY
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 6,530
Buildings and Equipment	17,711
Costs Capitalized Subsequent to Acquisition	2,734
Cost amount carried at Close of Period
Land	6,530
Buildings and Equipment	20,445
Total	26,975
Accumulated Depreciation	$ (3,811)
8687 Carling Road, Liverpool, NY
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 571
Buildings and Equipment	0
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	571
Buildings and Equipment	0
Total	571
Accumulated Depreciation	$ 0
1212 Pittsford - Victor Road, Pittsford, NY
Real estate and accumulated depreciation
Number of Buildings | building	1
Encumbrances	$ 27,238
Initial Cost to Company
Land	613
Buildings and Equipment	79
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	613
Buildings and Equipment	79
Total	692
Accumulated Depreciation	$ 0
500 Canal View Boulevard, Rochester, NY
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,077
Buildings and Equipment	376
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	2,077
Buildings and Equipment	376
Total	2,453
Accumulated Depreciation	$ 0
2231 Schrock Road, Columbus, OH
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 722
Buildings and Equipment	218
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	722
Buildings and Equipment	218
Total	940
Accumulated Depreciation	$ 0
4600 25th Avenue, Salem, OR
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 6,510
Buildings and Equipment	17,973
Costs Capitalized Subsequent to Acquisition	5,165
Cost amount carried at Close of Period
Land	6,510
Buildings and Equipment	23,138
Total	29,648
Accumulated Depreciation	$ (4,898)
501 Ridge Avenue, Hanover, PA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 3,452
Buildings and Equipment	5,152
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	3,452
Buildings and Equipment	5,152
Total	8,604
Accumulated Depreciation	$ 0
8800 Tinicum Boulevard, Philadelphia, PA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,617
Buildings and Equipment	22,866
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	5,617
Buildings and Equipment	22,866
Total	28,483
Accumulated Depreciation	$ 0
Synergy Business Park, Columbia, SC
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 1,439
Buildings and Equipment	11,143
Costs Capitalized Subsequent to Acquisition	5,178
Cost amount carried at Close of Period
Land	1,439
Buildings and Equipment	16,321
Total	17,760
Accumulated Depreciation	$ (4,335)
9680 Old Bailes Road, Fort Mill, SC
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 841
Buildings and Equipment	2,967
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	841
Buildings and Equipment	2,967
Total	3,808
Accumulated Depreciation	$ 0
One Memphis Place, Memphis, TN
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,630
Buildings and Equipment	5,645
Costs Capitalized Subsequent to Acquisition	3,290
Cost amount carried at Close of Period
Land	1,630
Buildings and Equipment	8,935
Total	10,565
Accumulated Depreciation	$ (1,742)
16001 North Dallas Parkway, Addison, TX
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 10,364
Buildings and Equipment	63,661
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	10,364
Buildings and Equipment	63,661
Total	74,025
Accumulated Depreciation	$ 0
2115-2116 East Randol Mill Road, Arlington, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,146
Buildings and Equipment	5,469
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	2,146
Buildings and Equipment	5,469
Total	7,615
Accumulated Depreciation	$ 0
Research Park, Austin, TX
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 4,292
Buildings and Equipment	13,856
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,292
Buildings and Equipment	13,856
Total	18,148
Accumulated Depreciation	$ 0
1001 Noble Energy Way, Houston, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,222
Buildings and Equipment	29,392
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	5,222
Buildings and Equipment	29,392
Total	34,614
Accumulated Depreciation	$ 0
10451 Clay Road, Houston, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,538
Buildings and Equipment	10,335
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	5,538
Buildings and Equipment	10,335
Total	15,873
Accumulated Depreciation	$ 0
202 North Castlegory Road, Houston, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 870
Buildings and Equipment	5,064
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	870
Buildings and Equipment	5,064
Total	5,934
Accumulated Depreciation	$ 0
6380 Rogerdale Road, Houston, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 12,728
Buildings and Equipment	6,161
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	12,728
Buildings and Equipment	6,161
Total	18,889
Accumulated Depreciation	$ 0
4221 W. John Carpenter Freeway, Irving, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,424
Buildings and Equipment	2,384
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	1,424
Buildings and Equipment	2,384
Total	3,808
Accumulated Depreciation	$ 0
8675, 8701-8711 Freeport Pkwy and 8901 Esters Boulevard, Irving, TX
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 10,266
Buildings and Equipment	31,815
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	10,266
Buildings and Equipment	31,815
Total	42,081
Accumulated Depreciation	$ 0
1511 East Common Street, New Braunfels, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,004
Buildings and Equipment	1,276
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	5,004
Buildings and Equipment	1,276
Total	6,280
Accumulated Depreciation	$ 0
2900 West Plano Parkway, Plano, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 6,873
Buildings and Equipment	8,901
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	6,873
Buildings and Equipment	8,901
Total	15,774
Accumulated Depreciation	$ 0
3400 West Plano Parkway, Plano, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,579
Buildings and Equipment	16,091
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,579
Buildings and Equipment	16,091
Total	20,670
Accumulated Depreciation	$ 0
19100 Ridgewood Parkway, San Antonio, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,223
Buildings and Equipment	144,519
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,223
Buildings and Equipment	144,519
Total	148,742
Accumulated Depreciation	$ 0
3600 Weismann Boulevard, San Antonio, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 3,521
Buildings and Equipment	6,715
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	3,521
Buildings and Equipment	6,715
Total	10,236
Accumulated Depreciation	$ 0
701 Clay Road, Waco, TX
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,030
Buildings and Equipment	8,708
Costs Capitalized Subsequent to Acquisition	3,584
Cost amount carried at Close of Period
Land	2,060
Buildings and Equipment	12,262
Total	14,322
Accumulated Depreciation	$ (5,020)
1800 Novell Place, Provo, UT
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 7,546
Buildings and Equipment	43,831
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	7,546
Buildings and Equipment	43,831
Total	51,377
Accumulated Depreciation	$ 0
4885-4931 North 300 West, Provo, UT
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 3,946
Buildings and Equipment	9,504
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	3,946
Buildings and Equipment	9,504
Total	13,450
Accumulated Depreciation	$ 0
14660,14672 and 14668 Lee Road, Chantilly, VA
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 6,966
Buildings and Equipment	74,214
Costs Capitalized Subsequent to Acquisition	2,038
Cost amount carried at Close of Period
Land	6,966
Buildings and Equipment	76,252
Total	83,218
Accumulated Depreciation	$ (3,757)
1434 Crossways, Chesapeake, VA
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 3,617
Buildings and Equipment	19,527
Costs Capitalized Subsequent to Acquisition	1,817
Cost amount carried at Close of Period
Land	3,617
Buildings and Equipment	21,344
Total	24,961
Accumulated Depreciation	$ (840)
Greenbrier Towers, Chesapeake, VA
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 3,437
Buildings and Equipment	11,241
Costs Capitalized Subsequent to Acquisition	700
Cost amount carried at Close of Period
Land	3,437
Buildings and Equipment	11,941
Total	15,378
Accumulated Depreciation	$ (507)
Enterchange at Meadowville, Chester, VA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,478
Buildings and Equipment	9,594
Costs Capitalized Subsequent to Acquisition	283
Cost amount carried at Close of Period
Land	1,478
Buildings and Equipment	9,877
Total	11,355
Accumulated Depreciation	$ (1,309)
Three Flint Hill, Fairfax, VA [Member]
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 5,991
Buildings and Equipment	25,619
Costs Capitalized Subsequent to Acquisition	1,515
Cost amount carried at Close of Period
Land	5,991
Buildings and Equipment	27,134
Total	33,125
Accumulated Depreciation	$ (1,075)
3920 Pender Drive, Fairfax, VA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,963
Buildings and Equipment	12,840
Costs Capitalized Subsequent to Acquisition	231
Cost amount carried at Close of Period
Land	2,963
Buildings and Equipment	13,071
Total	16,034
Accumulated Depreciation	$ (1,529)
Pender Business Park, Fairfax, VA
Real estate and accumulated depreciation
Number of Buildings | building	4
Initial Cost to Company
Land	$ 2,529
Buildings and Equipment	21,386
Costs Capitalized Subsequent to Acquisition	636
Cost amount carried at Close of Period
Land	2,529
Buildings and Equipment	22,022
Total	24,551
Accumulated Depreciation	$ (2,873)
7987 Ashton Avenue, Manassas, VA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,562
Buildings and Equipment	8,253
Costs Capitalized Subsequent to Acquisition	623
Cost amount carried at Close of Period
Land	1,562
Buildings and Equipment	8,876
Total	10,438
Accumulated Depreciation	$ (439)
Two Commercial Place, Norfolk, VA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,530
Buildings and Equipment	21,678
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	4,530
Buildings and Equipment	21,678
Total	26,208
Accumulated Depreciation	$ 0
1759 & 1760 Business Park Drive Reston, VA
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 9,066
Buildings and Equipment	78,658
Costs Capitalized Subsequent to Acquisition	2,723
Cost amount carried at Close of Period
Land	9,066
Buildings and Equipment	81,381
Total	90,447
Accumulated Depreciation	$ (9,273)
1775 Wiehle Avenue, Reston, VA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 4,138
Buildings and Equipment	26,120
Costs Capitalized Subsequent to Acquisition	756
Cost amount carried at Close of Period
Land	4,138
Buildings and Equipment	26,876
Total	31,014
Accumulated Depreciation	$ (828)
9960 Mayland Drive, Richmond VA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,614
Buildings and Equipment	15,930
Costs Capitalized Subsequent to Acquisition	1,891
Cost amount carried at Close of Period
Land	2,614
Buildings and Equipment	17,821
Total	20,435
Accumulated Depreciation	$ (2,055)
501 South 5th Street, Richmond, VA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 14,884
Buildings and Equipment	39,411
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	14,884
Buildings and Equipment	39,411
Total	54,295
Accumulated Depreciation	$ 0
9201 Forest Hill Avenue, Richmond, VA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,355
Buildings and Equipment	376
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	1,355
Buildings and Equipment	376
Total	1,731
Accumulated Depreciation	$ 0
Parham Place, Richmond, VA
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 920
Buildings and Equipment	1,107
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	920
Buildings and Equipment	1,107
Total	2,027
Accumulated Depreciation	$ 0
1751 Blue Hills Drive, Roanoke, VA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,710
Buildings and Equipment	7,823
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	2,710
Buildings and Equipment	7,823
Total	10,533
Accumulated Depreciation	$ 0
Aquia Commerce Center, Stafford, VA
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 2,090
Buildings and Equipment	7,465
Costs Capitalized Subsequent to Acquisition	768
Cost amount carried at Close of Period
Land	2,090
Buildings and Equipment	8,233
Total	10,323
Accumulated Depreciation	$ (1,549)
Atlantic Corporate Park, Sterling, VA
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 5,752
Buildings and Equipment	29,323
Costs Capitalized Subsequent to Acquisition	178
Cost amount carried at Close of Period
Land	5,752
Buildings and Equipment	29,501
Total	35,253
Accumulated Depreciation	$ (931)
Sterling Business Park Lots 8 and 9, Sterling, VA
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 9,177
Buildings and Equipment	44,375
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	9,177
Buildings and Equipment	44,375
Total	53,552
Accumulated Depreciation	$ (1,385)
Orbital Sciences Campus, Sterling, VA
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 12,372
Buildings and Equipment	19,473
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	12,372
Buildings and Equipment	19,473
Total	31,845
Accumulated Depreciation	$ 0
65 Bowdoin Street, S. Burlington, VT
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 700
Buildings and Equipment	8,416
Costs Capitalized Subsequent to Acquisition	140
Cost amount carried at Close of Period
Land	700
Buildings and Equipment	8,556
Total	9,256
Accumulated Depreciation	$ (1,873)
840 North Broadway, Everett, WA
Real estate and accumulated depreciation
Number of Buildings | building	2
Encumbrances	$ 34,704
Initial Cost to Company
Land	3,360
Buildings and Equipment	15,376
Costs Capitalized Subsequent to Acquisition	2,116
Cost amount carried at Close of Period
Land	3,360
Buildings and Equipment	17,492
Total	20,852
Accumulated Depreciation	$ (3,099)
Stevens Center, Richland, WA
Real estate and accumulated depreciation
Number of Buildings | building	2
Initial Cost to Company
Land	$ 3,970
Buildings and Equipment	17,035
Costs Capitalized Subsequent to Acquisition	4,137
Cost amount carried at Close of Period
Land	4,045
Buildings and Equipment	21,097
Total	25,142
Accumulated Depreciation	$ (9,854)
351, 401, 501 Elliott Ave West, Seattle, WA
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 26,851
Buildings and Equipment	53,157
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	26,851
Buildings and Equipment	53,157
Total	80,008
Accumulated Depreciation	$ 0
11050 West Liberty Drive, Milwaukee, WI
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 945
Buildings and Equipment	4,539
Costs Capitalized Subsequent to Acquisition	103
Cost amount carried at Close of Period
Land	945
Buildings and Equipment	4,642
Total	5,587
Accumulated Depreciation	$ (881)
882 TJ Jackson Drive, Falling Waters, WV
Real estate and accumulated depreciation
Number of Buildings | building	1
Encumbrances	$ 41,099
Initial Cost to Company
Land	906
Buildings and Equipment	3,886
Costs Capitalized Subsequent to Acquisition	270
Cost amount carried at Close of Period
Land	922
Buildings and Equipment	4,140
Total	5,062
Accumulated Depreciation	$ (2,215)
5353 Yellowstone Road, Cheyenne, WY
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 1,915
Buildings and Equipment	8,217
Costs Capitalized Subsequent to Acquisition	765
Cost amount carried at Close of Period
Land	1,950
Buildings and Equipment	8,947
Total	10,897
Accumulated Depreciation	$ (4,658)
Total Real Estate Assets
Real estate and accumulated depreciation
Number of Buildings | building	247
Encumbrances	$ 335,241
Initial Cost to Company
Land	1,038,737
Buildings and Equipment	2,904,700
Costs Capitalized Subsequent to Acquisition	225,424
Impairment/ Writedowns	(7,270)
Cost amount carried at Close of Period
Land	1,039,553
Buildings and Equipment	3,122,038
Total	4,161,591
Accumulated Depreciation	$ (383,318)
Properties Held for Sale
Real estate and accumulated depreciation
Number of Buildings | building	36
Initial Cost to Company
Land	$ 115,347
Buildings and Equipment	100,411
Costs Capitalized Subsequent to Acquisition	4,027
Impairment/ Writedowns	(2,830)
Cost amount carried at Close of Period
Land	115,389
Buildings and Equipment	101,566
Total	216,955
Accumulated Depreciation	$ (8,171)
Properties Held for Sale | 500 First Street, NW, Washington DC
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 30,478
Buildings and Equipment	15,660
Costs Capitalized Subsequent to Acquisition	44
Cost amount carried at Close of Period
Land	30,478
Buildings and Equipment	15,704
Total	46,182
Accumulated Depreciation	$ (448)
Properties Held for Sale | 91-008 Hanua Street, Kapolei, HI
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 6,846
Buildings and Equipment	0
Costs Capitalized Subsequent to Acquisition	0
Cost amount carried at Close of Period
Land	6,846
Buildings and Equipment	0
Total	6,846
Accumulated Depreciation	$ 0
Properties Held for Sale | Ammendale Commerce Center, Beltsville, MD
Real estate and accumulated depreciation
Number of Buildings | building	3
Initial Cost to Company
Land	$ 4,879
Buildings and Equipment	9,498
Costs Capitalized Subsequent to Acquisition	99
Cost amount carried at Close of Period
Land	4,879
Buildings and Equipment	9,597
Total	14,476
Accumulated Depreciation	$ (279)
Properties Held for Sale | Indian Creek Technology Park, Beltsville, MD
Real estate and accumulated depreciation
Number of Buildings | building	4
Initial Cost to Company
Land	$ 8,796
Buildings and Equipment	12,093
Costs Capitalized Subsequent to Acquisition	394
Impairment/ Writedowns	(2,830)
Cost amount carried at Close of Period
Land	8,796
Buildings and Equipment	9,657
Total	18,453
Accumulated Depreciation	$ (363)
Properties Held for Sale | Gateway 270 West, Clarksburg, MD
Real estate and accumulated depreciation
Number of Buildings | building	6
Initial Cost to Company
Land	$ 12,104
Buildings and Equipment	9,688
Costs Capitalized Subsequent to Acquisition	516
Cost amount carried at Close of Period
Land	12,104
Buildings and Equipment	10,204
Total	22,308
Accumulated Depreciation	$ (257)
Properties Held for Sale | Snowden Center, Columbia, MD
Real estate and accumulated depreciation
Number of Buildings | building	5
Initial Cost to Company
Land	$ 7,955
Buildings and Equipment	10,128
Costs Capitalized Subsequent to Acquisition	119
Cost amount carried at Close of Period
Land	7,955
Buildings and Equipment	10,247
Total	18,202
Accumulated Depreciation	$ (258)
Properties Held for Sale | 20400 Century Boulevard, Germantown, MD
Real estate and accumulated depreciation
Number of Buildings | building	1
Initial Cost to Company
Land	$ 2,305
Buildings and Equipment	9,890
Costs Capitalized Subsequent to Acquisition	1,304
Cost amount carried at Close of Period
Land	2,347
Buildings and Equipment	11,152
Total	13,499
Accumulated Depreciation	$ (5,520)
Properties Held for Sale | Cloverleaf Center, Germantown, MD
Real estate and accumulated depreciation
Number of Buildings | building	4
Initial Cost to Company
Land	$ 11,890
Buildings and Equipment	4,639
Costs Capitalized Subsequent to Acquisition	481
Cost amount carried at Close of Period
Land	11,890
Buildings and Equipment	5,120
Total	17,010
Accumulated Depreciation	$ (167)
Properties Held for Sale | Metro Park North, Rockville, MD
Real estate and accumulated depreciation
Number of Buildings | building	4
Initial Cost to Company
Land	$ 11,159
Buildings and Equipment	7,624
Costs Capitalized Subsequent to Acquisition	235
Cost amount carried at Close of Period
Land	11,159
Buildings and Equipment	7,859
Total	19,018
Accumulated Depreciation	$ (236)
Properties Held for Sale | Sterling Park Business Center, Sterling, VA
Real estate and accumulated depreciation
Number of Buildings | building	7
Initial Cost to Company
Land	$ 18,935
Buildings and Equipment	21,191
Costs Capitalized Subsequent to Acquisition	835
Cost amount carried at Close of Period
Land	18,935
Buildings and Equipment	22,026
Total	40,961
Accumulated Depreciation	$ (643)

SCHEDULE III REAL ESTATE AND _3

SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018USD ($)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Mortgage debt, net	$ 3,021,000
Aggregate cost for federal income tax purposes	$ 7,126,328
Useful life of buildings and improvements	40 years
Useful life of equipment	12 years

SCHEDULE III REAL ESTATE AND _4

SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION - Carrying Amount and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Real Estate Properties
Balance at the beginning of the period	$ 2,975,721	$ 1,888,760	$ 1,696,132
Additions	1,486,342	1,100,138	194,107
Loss on asset impairment	(8,630)	(9,490)
Disposals	(286,837)	(3,687)	(1,479)
Cost basis adjustment	(5,005)
Reclassification of assets of properties held for sale	(216,955)
Balance at the end of the period	3,944,636	2,975,721	1,888,760
Accumulated Depreciation
Balance at the beginning of the period	341,848	296,804	255,879
Additions	65,215	45,315	42,404
Loss on asset impairment	0	0
Disposals	(18,740)	(271)	(1,479)
Cost basis adjustment	(5,005)
Reclassification of assets of properties held for sale	(8,171)
Balance at the end of the period	$ 375,147	$ 341,848	$ 296,804