Office Properties Income Trust (OPI) 10-Q 1 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 30, 2018
Document and Entity Information
Entity Registrant Name	Government Properties Income Trust
Entity Central Index Key	1,456,772
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		99,205,199
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Real estate properties:
Land	$ 448,714	$ 627,108
Buildings and improvements	2,050,365	2,348,613
Total real estate properties, gross	2,499,079	2,975,721
Accumulated depreciation	(363,490)	(341,848)
Total real estate properties, net	2,135,589	2,633,873
Assets of discontinued operations - Equity investment in Select Income REIT	453,275	467,499
Assets of properties held for sale	408,626	0
Investment in unconsolidated joint ventures	45,161	50,202
Acquired real estate leases, net	215,938	351,872
Cash and cash equivalents	9,644	16,569
Restricted cash	2,354	3,111
Rents receivable, net	55,297	61,429
Deferred leasing costs, net	22,181	22,977
Other assets, net	136,360	96,033
Total assets	3,484,425	3,703,565
LIABILITIES AND SHAREHOLDERS’ EQUITY
Unsecured revolving credit facility	467,000	570,000
Unsecured term loans, net	548,363	547,852
Senior unsecured notes, net	945,948	944,140
Mortgage notes payable, net	176,828	183,100
Liabilities of properties held for sale	9,998	0
Accounts payable and other liabilities	64,868	89,440
Due to related persons	23,300	4,859
Assumed real estate lease obligations, net	8,759	13,635
Total liabilities	2,245,064	2,353,026
Commitments and contingencies
Preferred units of limited partnership	0	20,496
Shareholders’ equity:
Common shares of beneficial interest, $.01 par value: 150,000,000 shares authorized, 99,205,199 and 99,145,921 shares issued and outstanding, respectively	992	991
Additional paid in capital	1,969,168	1,968,217
Cumulative net income	204,579	108,144
Cumulative other comprehensive income	265	60,427
Cumulative common distributions	(935,643)	(807,736)
Total shareholders’ equity	1,239,361	1,330,043
Total liabilities and shareholders’ equity	$ 3,484,425	$ 3,703,565

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 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 (in shares)	150,000,000	150,000,000
Common shares of beneficial interest, shares issued (in shares)	99,205,199	99,145,921
Common shares of beneficial interest, shares outstanding (in shares)	99,205,199	99,145,921

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Rental income	$ 106,102	$ 70,179	$ 322,904	$ 209,362
Expenses:
Real estate taxes	12,072	8,862	37,402	24,980
Other operating expenses	21,785	14,867	66,221	44,046
Depreciation and amortization	42,569	20,781	129,444	61,949
Loss on impairment of real estate	0	230	5,800	230
Acquisition and transaction related costs	3,813	0	3,813	0
General and administrative	22,383	3,266	36,438	12,314
Total expenses	110,405	53,414	299,608	157,705
Operating income (loss)	(4,303)	16,765	23,296	51,657
Dividend income	304	304	912	911
Unrealized gain on equity securities	17,425	0	40,677	0
Interest income	140	1,715	405	1,843
Interest expense (including net amortization of debt premiums and discounts and debt issuance costs of $893, $990, $2,749 and $2,605, respectively)	(23,374)	(16,055)	(69,444)	(43,599)
Loss on early extinguishment of debt	0	(1,715)	0	(1,715)
Income (loss) from continuing operations before income taxes, equity in net earnings (losses) of investees and gain on sale of real estate	(9,808)	1,014	(4,154)	9,097
Income tax expense	(9)	(22)	(124)	(65)
Equity in net earnings (losses) of investees	94	31	(1,112)	533
Income (loss) from continuing operations	(9,723)	1,023	(5,390)	9,565
Income from discontinued operations	9,274	9,966	23,872	20,516
Income (loss) before gain on sale of real estate	(449)	10,989	18,482	30,081
Gain on sale of real estate	0	0	17,329	0
Net income (loss)	(449)	10,989	35,811	30,081
Other comprehensive income:
Unrealized gain on investment in equity securities	0	3,279	0	14,389
Equity in unrealized gain of investees	126	1,351	119	5,634
Other comprehensive income	126	4,630	119	20,023
Comprehensive income	(323)	15,619	35,930	50,104
Net income (loss)	(449)	10,989	35,811	30,081
Preferred units of limited partnership distributions	0	0	(371)	0
Net income (loss) available for common shareholders	$ (449)	$ 10,989	$ 35,440	$ 30,081
Weighted average common shares outstanding (basic) (in shares)	99,071	96,883	99,055	79,778
Weighted average common shares outstanding (diluted) (in shares)	99,071	96,958	99,075	79,852
Income from discontinued operations
Income (loss) from continuing operations (in dollars per share)	$ (0.10)	$ 0.01	$ 0.12	$ 0.12
Income from discontinued operations (in dollars per share)	0.09	0.10	0.24	0.26
Net income (loss) available for common shareholders (in dollars per share)	$ 0	$ 0.11	$ 0.36	$ 0.38
Utility expenses
Expenses:
Utility expenses	$ 7,783	$ 5,408	$ 20,490	$ 14,186

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net amortization of debt premiums and discounts and deferred financing fees	$ 893	$ 990	$ 2,749	$ 2,605

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 35,811	$ 30,081
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	51,121	35,460
Net amortization of debt premiums and discounts and debt issuance costs	2,749	2,605
Gain on sale of real estate	(17,329)	0
Loss on early extinguishment of debt	0	1,715
Straight line rental income	(7,825)	(3,115)
Amortization of acquired real estate leases	77,434	25,592
Amortization of deferred leasing costs	3,524	2,790
Other non-cash expenses, net	189	352
Loss on impairment of real estate	5,800	230
Unrealized gain on equity securities	(40,677)	0
Increase in carrying value of asset held for sale	0	(619)
Equity in net (earnings) losses of investees	1,112	(533)
Equity in earnings of Select Income REIT included in discontinued operations	(23,843)	(20,271)
Net gain on issuance of shares by Select Income REIT included in discontinued operations	(29)	(72)
Distributions of earnings from Select Income REIT	23,843	20,271
Change in assets and liabilities:
Deferred leasing costs	(5,937)	(2,846)
Rents receivable	7,535	3,839
Other assets	(1,393)	(7,045)
Accounts payable and other liabilities	(10,361)	6,703
Due to related persons	18,441	777
Net cash provided by operating activities	120,165	95,914
CASH FLOWS FROM INVESTING ACTIVITIES:
Real estate acquisitions and deposits	0	(666,202)
Real estate improvements	(32,625)	(29,377)
Distributions in excess of earnings from Select Income REIT	14,281	17,854
Distributions in excess of earnings from unconsolidated joint ventures	3,046	0
Proceeds from sale of properties, net	142,189	13,198
Net cash provided by (used in) investing activities	126,891	(664,527)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of mortgage notes payable	(2,732)	(1,150)
Proceeds from issuance of senior notes, after discounts	0	297,954
Proceeds from issuance of common shares, net	0	493,936
Borrowings on unsecured revolving credit facility	95,000	610,000
Repayments on unsecured revolving credit facility	(198,000)	(205,000)
Payment of debt issuance costs	0	(2,551)
Repurchase of common shares	(232)	(255)
Redemption of preferred units of limited partnership	(20,221)	0
Preferred units of limited partnership distributions	(646)	0
Distributions to common shareholders	(127,907)	(102,576)
Net cash (used in) provided by financing activities	(254,738)	1,090,358
Increase (decrease) in cash and cash equivalents and restricted cash	(7,682)	521,745
Cash and cash equivalents and restricted cash at beginning of period	19,680	30,471
Cash and cash equivalents and restricted cash at end of period	$ 11,998	$ 552,216

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - Supplemental Cash Flow - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Supplemental cash flow information
Interest paid	$ 72,651	$ 42,019
Income taxes paid	44	100
Supplemental disclosure of cash and cash equivalents and restricted cash
Cash and cash equivalents	9,644	551,707
Restricted cash	2,354	509
Total cash and cash equivalents and restricted cash reported in the statements of cash flows	$ 11,998	$ 552,216

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements of Government Properties Income Trust and its subsidiaries, or the Company, GOV, we, us or our, are unaudited. Certain information and disclosures required by U.S. generally accepted accounting principles, or GAAP, for complete financial statements have been condensed or omitted. We believe the disclosures made are adequate to make the information presented not misleading. However, the accompanying condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes contained in our Annual Report on Form 10-K for the year ended December 31, 2017 , or our Annual Report. In the opinion of management, all adjustments, consisting of normal recurring accruals considered necessary for a fair statement of results for the interim period have been included. All intercompany transactions and balances with or among our consolidated subsidiaries have been eliminated. Our operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. Reclassifications have been made to the prior years' condensed consolidated financial statements to conform to the current year’s presentation. The preparation of these financial statements in conformity with GAAP requires us to make estimates and assumptions that affect reported amounts. Actual results could differ from those estimates. Significant estimates in the condensed consolidated financial statements include purchase price allocations, useful lives of fixed assets, assessment of impairment of real estate and equity method investments and the valuation of intangible assets. Segment Information We operate in one business segment: direct ownership of real estate properties. Our equity method investment in Select Income REIT, or SIR, has been reclassified as a discontinued operation and is no longer a separate business segment. See below for further information about our equity method investment in SIR. Merger with Select Income REIT On September 14, 2018, we and our wholly owned subsidiary, GOV MS REIT, or Merger Sub, entered into an Agreement and Plan of Merger, or the Merger Agreement, with SIR, pursuant to which SIR has agreed to merge with and into Merger Sub, with Merger Sub continuing as the surviving entity in the merger, or the Merger. Pursuant to the terms and subject to the conditions set forth in the Merger Agreement, at the effective time of the Merger, or the Effective Time, each common share of SIR issued and outstanding immediately prior to the Effective Time will be converted into the right to receive 1.04 , or the Exchange Ratio, of our newly issued common shares, subject to adjustment as described in the Merger Agreement, with cash paid in lieu of fractional shares. The Exchange Ratio is fixed and will not be adjusted to reflect changes in the market price of our common shares or SIR common shares prior to the Effective Time. At the Effective Time, any outstanding unvested SIR common share awards under SIR’s equity compensation plan will be converted into an award under our equity compensation 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 the Exchange Ratio (rounded down to the nearest whole number). Also pursuant to the Merger Agreement, we and SIR agreed that, prior to the Effective Time, we would sell, for cash consideration, all 24,918,421 SIR common shares owned by us, or the Secondary Sale, which Secondary Sale was completed on October 9, 2018 as further described below, and further that, subject to the satisfaction of certain conditions, SIR will declare and, at least one business day prior to the closing date of the Merger, pay a pro rata distribution to its shareholders of all 45,000,000 common shares of its majority owned subsidiary, Industrial Logistics Properties Trust that SIR owns, or the ILPT Distribution. Following the ILPT Distribution and upon the closing of the Merger, we will acquire SIR's remaining property portfolio of 99 properties with approximately 16,538,462 rentable square feet. The aggregate transaction value, based on the closing price of our common shares on September 30, 2018 of $11.29 per share, is approximately $2,738,488 , excluding estimated closing costs of $40,000 and including the repayment or assumption of $1,720,000 of SIR debt. The Merger and the other transactions contemplated by the Merger Agreement, including the Secondary Sale and the ILPT Distribution, are collectively referred to herein as the Transactions. We expect that immediately after the Merger is effective, Merger Sub will then merge with and into us, with us as the surviving entity, and we will change our name to “Office Properties Income Trust,” following which our ticker symbol on The Nasdaq Stock Market LLC, or Nasdaq, will be changed to “OPI”. We also expect that immediately following that second merger, the combined company will effect a reverse stock split of its common shares pursuant to which every four common shares of the combined company will be converted into one common share of the combined company. The combined company will continue to be managed by The RMR Group LLC, or RMR LLC, pursuant to our existing business and property management agreements with RMR LLC. The completion of the Merger is subject to the satisfaction or waiver of various conditions, including, among other things, approval by our shareholders of the issuance of our common shares in the Merger and by SIR’s shareholders of the Merger and the other Transactions to which SIR is a party, the absence of any law or order by any governmental authority prohibiting, making illegal, enjoining or otherwise restricting, preventing or prohibiting the consummation of the Merger and the other Transactions, the effectiveness of the registration statement on Form S-4, as amended, or the Form S-4, filed by us with the Securities and Exchange Commission, or SEC, to register our common shares to be issued in the Merger and the approval of Nasdaq for the listing of such shares on Nasdaq, subject to official notice of issuance, and, subject to the satisfaction of certain other conditions, the payment of the ILPT Distribution at least one business day before the completion of the Merger. We and SIR expect to consummate the Merger by December 31, 2018. The Merger Agreement provides that either party may terminate the Merger Agreement if the Merger is not consummated by the outside closing date of June 30, 2019. The Merger Agreement contains certain customary representations, warranties and covenants, including, among others, covenants with respect to the conduct of our and SIR’s respective businesses prior to closing, subject to certain consent rights by SIR and us, respectively, and covenants prohibiting us and SIR from soliciting, providing information or entering into discussions concerning competing proposals (generally defined as proposals for 20% or more of the assets, revenues or earnings or equity of the applicable party), subject to certain exceptions. In addition, because we owned the SIR common shares we sold pursuant to the Secondary Sale as of October 1, 2018, the record date set by SIR's board of trustees for shareholders eligible to vote at SIR’s special meeting of shareholders to approve the Merger and the other Transactions to which SIR is a party, or the Record Date, we are entitled to vote those shares at that meeting, unless the Record Date is changed pursuant to the Merger Agreement, we have agreed to vote those shares at that meeting in favor of approval of the Merger and the other Transactions to which SIR is a party. The Merger Agreement contains certain termination rights for both us and SIR, including that under specified circumstances, either party is entitled to terminate the Merger Agreement to accept a superior proposal (generally defined as proposals for 75% or more of the assets, revenues or earnings or equity of such party, which proposal such party’s board of trustees (or an authorized committee thereof) has determined in good faith, after consultation with outside financial advisors and outside legal counsel, (1) would, if consummated, result in a transaction that is more favorable to the shareholders of such party from a financial point of view than the Merger and the other Transactions, (2) for which the third party has demonstrated that the financing for such offer is fully committed or is reasonably likely to be obtained and (3) which is reasonably likely to receive all required approvals from any governmental authority and otherwise reasonably likely to be consummated on the terms proposed). Neither we nor SIR is entitled to any termination fee under the Merger Agreement. All fees and expenses incurred in connection with the Merger and the other Transactions will be paid by the party incurring those expenses, except that we and SIR will share equally any filing fees incurred in connection with the filing of the Form S-4 and related joint proxy statement/prospectus and, as explained below, we are responsible for all of the costs and expenses incurred in connection with the Secondary Sale, including the costs and expenses of SIR and its affiliates. Contemporaneously with the execution of the Merger Agreement, and in connection with the Secondary Sale, we entered into a registration agreement with SIR, or the Registration Agreement, pursuant to which we received demand registration rights, subject to certain limitations, with respect to the Secondary Sale. The Registration Agreement provides that we will pay all the costs and expenses incurred in connection with the Secondary Sale, including costs and expenses incurred by SIR and its affiliates. On October 9, 2018, pursuant to the terms of the Registration Agreement, we sold all 24,918,421 SIR common shares in the Secondary Sale that we then owned in an underwritten public offering at a price of $18.25 per share, raising net proceeds of approximately $434,700 after deducting underwriting discounts and estimated offering expenses. We used the net proceeds from the Secondary Sale to repay amounts outstanding under our revolving credit facility. The transactions contemplated by the Merger Agreement and the terms thereof were evaluated, negotiated and recommended to each of our and SIR’s board of trustees by a special committee of our and SIR’s board of trustees, respectively, each comprised solely of our and SIR’s disinterested, independent trustees, respectively, and were separately approved and adopted by our and SIR’s independent trustees and by our and SIR’s board of trustees. Citigroup Global Markets Inc. acted as financial advisor to the special committee of our board of trustees, and UBS Securities LLC acted as financial advisor to the special committee of SIR’s board of trustees.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements On January 1, 2018, we adopted the Financial Accounting Standards Board, or FASB, Accounting Standards Update, or 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 condensed 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 available for sale 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 $2,209 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 nine months ended September 30, 2017 . 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 2016-18 resulted in an increase of $21 of net cash provided by operating activities for the nine months ended September 30, 2017 . This update also requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheets. As a result, amounts included in restricted cash on our condensed consolidated balance sheets are included with cash and cash equivalents on the condensed consolidated statements of cash flows. Restricted cash, which 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, totaled $2,354 and $509 as of September 30, 2018 and 2017, respectively. The adoption of this update did not change our balance sheet presentation. In February 2016, the FASB issued ASU No. 2016-02, Leases , which sets 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. A lessee is also required to record a right of use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases today. 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. ASU No. 2016-02 is effective for reporting periods beginning after December 15, 2018, with early adoption permitted. We are currently assessing the potential impact the adoption of ASU No. 2016-02 will have in our condensed 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 condensed consolidated financial statements. We currently expect to adopt the standard using the modified retrospective approach. In June 2018, the FASB issued 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. ASU No. 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We are currently assessing the potential impact the adoption of ASU No. 2018-07 will have in our condensed consolidated financial statements.

Weighted Average Common Shares

Weighted Average Common Shares	9 Months Ended
	Sep. 30, 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 Three Months For the Nine Months Ended September 30, Ended September 30, 2018 2017 2018 2017 Weighted average common shares for basic earnings per share 99,071 96,883 99,055 79,778 Effect of dilutive securities: unvested share awards — 75 20 74 Weighted average common shares for diluted earnings per share (1) 99,071 96,958 99,075 79,852 (1) For the three months ended September 30, 2018 , 35 unvested common shares were not included in the calculation of diluted earnings per share because to do so would have been antidilutive.

Real Estate Properties

Real Estate Properties	9 Months Ended
	Sep. 30, 2018
Real Estate [Abstract]
Real Estate Properties	Real Estate Properties As of September 30, 2018 , we wholly owned 105 properties ( 164 buildings), with an aggregate undepreciated carrying value of $2,854,937 , and had a noncontrolling ownership interest in two unconsolidated joint ventures that owned two properties ( three buildings). We generally lease space at our properties on a gross lease or modified gross lease basis pursuant to fixed term contracts expiring between 2018 and 2038. Our leases generally require us to pay all or some property operating expenses and to provide all or most property management services. During the three months ended September 30, 2018 , we entered into 24 leases for 182,220 rentable square feet, for a weighted (by rentable square feet) average lease term of 8.1 years and we made commitments for $6,479 of leasing related costs. During the nine months ended September 30, 2018 , we entered into 94 leases for 858,998 rentable square feet, for a weighted (by rentable square feet) average lease term of 6.4 years and we made commitments for $21,287 of leasing related costs. As of September 30, 2018 , we have estimated unspent leasing related obligations of $34,048 . We regularly evaluate whether events or changes in circumstances have occurred that could indicate an impairment in the value of our 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 evaluating for 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. Disposition Activities In March 2018, we sold an office property ( one building) located in Minneapolis, MN with 193,594 rentable square feet for $20,000 , excluding closing costs. 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 three months ended March 31, 2018. In February 2018, we entered an agreement to sell an office property ( one 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, we terminated the sales agreement and 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 three months ended June 30, 2018. In May 2018, we sold an office property ( one building) located in New York, NY with 187,060 rentable square feet for $118,500 , excluding closing costs. We recorded a $17,329 gain on sale of real estate during the three months ended June 30, 2018 as a result of this sale. In May 2018, we sold an office property ( one building) located in Sacramento, CA with 110,500 rentable square feet for $10,755 , excluding closing costs. We recorded a loss on impairment of real estate of $3,023 and $6 to reduce the carrying value of this property to its estimated fair value less costs to sell during the three months ended March 31, 2018 and June 30, 2018, respectively. The sales of these properties do not represent significant dispositions individually or in the aggregate. The results of operations of these properties are included in continuing operations through the date of sale in our condensed consolidated statements of comprehensive income. As of September 30, 2018 , we had 20 properties ( 50 buildings) with an aggregate undepreciated carrying value of $355,858 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 condensed consolidated balance sheet at September 30, 2018 . Date of Agreement (1) Number of Properties Number of Buildings Location Square Footage Gross Sale Price (2) August 2018 1 1 Washington D.C. 129,035 $ 70,000 September 2018 8 34 Northern Virginia and Maryland 1,635,868 201,500 October 2018 11 15 Southern Virginia 1,641,109 167,000 20 50 3,406,012 $ 438,500 (1) 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. (2) Gross sale price excludes closing costs. As part of our long term plans to reduce our leverage, we expect to sell additional properties. We are currently marketing or plan to market for sale three properties ( three buildings) with an aggregate carrying value of $24,566 as of September 30, 2018 . We have determined that these properties did not meet the held for sale criteria as of September 30, 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. Pro Forma Financial Information On October 2, 2017, we acquired First Potomac Realty Trust, or FPO, pursuant to a merger transaction, as a result of which we acquired 35 office properties ( 72 buildings) with 6,028,072 rentable square feet and FPO's 50% and 51% interests in two joint ventures that own two properties ( three buildings) with 443,867 rentable square feet, or collectively, the FPO Transaction. The aggregate value we paid at the closing of the FPO Transaction was $1,370,888 . We financed the FPO Transaction with the assumption of certain FPO mortgage debt, borrowings under our revolving credit facility and cash on hand, including net proceeds from our public offerings of common shares and senior unsecured notes. The following table presents our pro forma results of operations for the nine months ended September 30, 2017 as if the FPO Transaction and related financing activities had occurred on January 1, 2017. The historical FPO results of operations included in this pro forma financial information have been adjusted to eliminate the results of operations of FPO properties and joint venture interests that were sold from January 1, 2017 to October 2, 2017, the closing date of the FPO Transaction. The effect of these adjustments was a decrease in pro forma rental income of $804 and a decrease in net income of $47,019 for the nine months ended September 30, 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 pursuant to our existing leases or leases we may enter during the remainder of 2018 and thereafter, 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. Nine Months Ended September 30, 2017 Rental income $ 328,255 Net loss $ (4,733 ) Net loss per share $ (0.05 ) Unconsolidated Joint Ventures We own noncontrolling interests in two joint ventures that own two properties ( three buildings). We account for these investments under the equity method of accounting. As of September 30, 2018 , our investment in unconsolidated joint ventures consisted of the following: Joint Venture GOV Ownership GOV Carrying Value of Investment at September 30, 2018 Property Type Number of Buildings Location Square Feet Prosperity Metro Plaza 51% $ 24,821 Office 2 Fairfax, VA 328,456 1750 H Street, NW 50% 20,340 Office 1 Washington, DC 115,411 Total $ 45,161 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 September 30, 2018 (2) 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. (2) Reflects the entire balance of the debt secured by the properties and is not adjusted to reflect the interests in the joint venture we do not own. None of the debt is recourse to us. At September 30, 2018 , the aggregate $8,565 unamortized basis difference of our unconsolidated joint ventures is primarily attributable to the difference between the amount we paid to purchase our interest in these joint ventures, including transaction costs, and the historical carrying value of the net assets of these joint ventures. This difference is being amortized over the remaining useful life of the properties owned by these joint ventures and the resulting amortization expense is included in equity in net earnings of investees in our condensed consolidated statements of comprehensive income.

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2018
Revenue Recognition [Abstract]
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. Certain of our leases with government tenants provide the tenant the right to terminate before the lease expiration date if the 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 full term of the lease because we believe the occurrence of early terminations to be remote contingencies based on both our historical experience and our assessments of the likelihood of lease cancellation on a separate lease basis. We increased rental income to record revenue on a straight line basis by $1,990 and $711 for the three months ended September 30, 2018 and 2017 , respectively, and $7,825 and $3,115 for the nine months ended September 30, 2018 and 2017 , respectively. Rents receivable include $33,978 (including $1,819 related to properties held for sale) and $27,267 of straight line rent receivables, net of allowance for doubtful accounts of $1,755 (including $976 related to properties held for sale) and $1,503 at September 30, 2018 and December 31, 2017 , respectively.

Concentration

Concentration	9 Months Ended
	Sep. 30, 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 62.5% and 87.5% of our annualized rental income as of September 30, 2018 and 2017 , respectively. The U.S. Government is our largest tenant by annualized rental income and was responsible for approximately 45.6% and 59.8% of our annualized rental income as of September 30, 2018 and 2017 , respectively. Geographic Concentration At September 30, 2018 , our 105 consolidated properties ( 164 buildings) were located in 30 states and the District of Columbia. Consolidated properties located in Virginia, the District of Columbia, Maryland, California and Georgia were responsible for 23.7% , 18.1% , 15.3% , 9.4% and 6.1% of our annualized rental income as of September 30, 2018 , respectively. Consolidated properties located in the metropolitan Washington, D.C. market area were responsible for approximately 44.1% of our annualized rental income as of September 30, 2018 .

Indebtedness

Indebtedness	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Indebtedness	Indebtedness Our principal debt obligations at September 30, 2018 were: (1) $467,000 of outstanding borrowings under our $750,000 unsecured revolving credit facility; (2) $550,000 aggregate outstanding principal amount of unsecured term loans; (3) $960,000 aggregate outstanding principal amount of senior unsecured notes; and (4) $180,416 aggregate outstanding principal amount of mortgage notes. Our $750,000 revolving credit facility, our $300,000 term loan and our $250,000 term loan 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. The maturity date of our revolving credit facility is January 31, 2019 and, subject to the payment of an extension fee and meeting other conditions, we have an option to extend the stated maturity date of our revolving credit facility by one year to January 31, 2020. We can borrow, repay and reborrow funds available under our revolving credit facility until maturity and no principal repayment is due until maturity. We are required to pay interest at a rate of LIBOR plus a premium, which was 125 basis points per annum at September 30, 2018 , on borrowings under our revolving credit facility. We also pay a facility fee on the total amount of lending commitments under our revolving credit facility, which was 25 basis points per annum at September 30, 2018 . Both the interest rate premium and the facility fee are subject to adjustment based upon changes to our credit ratings. As of September 30, 2018 , the annual interest rate payable on borrowings under our revolving credit facility was 3.4% and the weighted average annual interest rate for borrowings under our revolving credit facility was 3.2% and 2.4% for the three months ended September 30, 2018 and 2017 , respectively, and 3.0% and 2.2% for the nine months ended September 30, 2018 and 2017 , respectively. As of September 30, 2018 and October 30, 2018 , we had $467,000 and $32,000 outstanding under our revolving credit facility. Our $300,000 term loan, 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 September 30, 2018 , on the amount outstanding under our $300,000 term loan. The interest rate premium is subject to adjustment based upon changes to our credit ratings. As of September 30, 2018 , the annual interest rate for the amount outstanding under our $300,000 term loan was 3.6% . The weighted average annual interest rate under our $300,000 term loan was 3.5% and 2.6% for the three months ended September 30, 2018 and 2017 , respectively, and 3.3% and 2.4% for the nine months ended September 30, 2018 and 2017 , respectively. Our $250,000 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 September 30, 2018 , on the amount outstanding under our $250,000 term loan. The interest rate premium is subject to adjustment based upon changes to our credit ratings. As of September 30, 2018 , the annual interest rate for the amount outstanding under our $250,000 term loan was 4.0% . The weighted average annual interest rate under our $250,000 term loan was 3.9% and 3.0% for the three months ended September 30, 2018 and 2017 , respectively, and 3.7% and 2.8% for the nine months ended September 30, 2018 and 2017 , 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 September 30, 2018 . At September 30, 2018 , eight of our consolidated properties ( eight buildings) with an aggregate net book value of $417,842 were encumbered by eight mortgages for an aggregate principal amount of $180,416 . Our mortgage notes are non-recourse, subject to certain limited exceptions and do not contain any material financial covenants.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	9 Months Ended
	Sep. 30, 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 September 30, 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 Significant Active Markets for Significant Other Unobservable Identical Assets Observable Inputs Inputs Description Total (Level 1) (Level 2) (Level 3) Recurring Fair Value Measurements Assets: Investment in RMR Inc. (1) $ 112,680 $ 112,680 $ — $ — (1) Our 1,214,225 shares of class A common stock of The RMR Group Inc., or RMR Inc., which are included in other assets in our condensed consolidated balance sheets, are reported at fair value which is based on quoted market prices (Level 1 inputs as defined in the fair value hierarchy under GAAP). Our historical cost basis for these shares is $26,888 as of September 30, 2018 . During the three and nine months ended September 30, 2018 , we recorded an unrealized gain of $17,425 and $40,677 , respectively, to adjust our investment in RMR Inc. to its fair value. In addition to the assets described in the table above, our financial instruments include our cash and cash equivalents, restricted cash, rents receivable, mortgage notes receivable, accounts payable, revolving credit facility, term loans, senior unsecured notes, mortgage notes payable, amounts due to related persons, other accrued expenses and security deposits. At September 30, 2018 and December 31, 2017 , the fair values of our financial instruments approximated their carrying values in our condensed consolidated financial statements due to their short term nature or variable interest rates, except as follows: As of September 30, 2018 As of December 31, 2017 Carrying Amount (1) Fair Value Carrying Amount (1) Fair Value Senior unsecured notes, 3.75% interest rate, due in 2019 $ 348,953 $ 351,468 $ 348,096 $ 354,993 Senior unsecured notes, 5.875% interest rate, due in 2046 300,490 309,380 300,232 320,416 Senior unsecured notes, 4.000% interest rate, due in 2022 296,505 296,609 295,812 302,655 Mortgage note payable, 4.050% interest rate, due in 2030 (2) 64,441 62,363 64,293 65,198 Mortgage note payable, 5.720% interest rate, due in 2020 (2) 35,067 34,877 36,085 36,332 Mortgage note payable, 4.220% interest rate, due in 2022 (2) 27,408 27,422 27,906 28,432 Mortgage note payable, 4.800% interest rate, due in 2023 (2) 25,145 25,220 25,501 25,904 Mortgage note payable, 5.877% interest rate, due in 2021 (2) 13,445 13,978 13,620 14,565 Mortgage note payable, 7.000% interest rate, due in 2019 (2) 8,087 8,129 8,391 8,555 Mortgage note payable, 8.150% interest rate, due in 2021 (2) 3,235 3,360 4,111 4,340 Mortgage note payable, 4.260% interest rate, due in 2020 (2) (3) 3,047 3,028 3,193 3,216 $ 1,125,823 $ 1,135,834 $ 1,127,240 $ 1,164,606 (1) Carrying amount includes certain unamortized debt issuance costs and unamortized premiums and discounts. (2) We assumed these mortgages 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 date of acquisition and we are amortizing the fair value premiums, if any, to interest expense over the respective terms of the mortgages to reduce interest expense to the estimated market interest rates as of the date of acquisition. (3) Secured by one property (one building) that is held for sale at September 30, 2018. We estimated the fair value of our senior unsecured notes due 2019 and due 2022 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 2046 based on the closing price on Nasdaq as of the measurement date (Level 1 inputs as defined in the fair value hierarchy under GAAP). We estimated the fair values of our mortgage notes payable by using discounted cash flow analyses and currently prevailing market terms 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	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Shareholders' Equity	Shareholders’ Equity Share Awards On April 3, 2018, in accordance with our Trustee compensation arrangements, and in connection with the election of one of our Managing Trustees, we granted 3,000 of our common shares, valued at $13.59 per share, the closing price of our common shares on Nasdaq on that day, to the Managing Trustee who was elected as a Managing Trustee that day. On May 24, 2018, in accordance with our Trustee compensation arrangements, we granted 3,000 of our common shares, valued at $14.10 per share, the closing price of our common shares on Nasdaq on that day, to each of our six Trustees as part of their annual compensation. On September 13, 2018, we granted an aggregate of 58,700 of our common shares, valued at $16.95 per share, the closing price of our common shares on Nasdaq on that day, to our officers and certain other employees of RMR LLC under our equity compensation plan. Share Purchases On January 1, 2018, we purchased 617 of our common shares valued at $18.54 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 450 of our common shares valued at $14.10 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 18,875 of our common shares, valued at $11.35 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. Distributions On February 26, 2018, we paid a regular quarterly distribution to common shareholders of record on January 29, 2018 of $0.43 per share, or $42,632 . On May 21, 2018, we paid a regular quarterly distribution to common shareholders of record on April 30, 2018 of $0.43 per share, or $42,634 . On August 20, 2018, we paid a regular quarterly distribution to common shareholders of record on July 30, 2018 of $0.43 per share, or $42,641 . On October 18, 2018, we declared a regular quarterly distribution payable to common shareholders of record on October 29, 2018 of $0.43 per share, or $42,658 . We expect to pay this distribution on or about November 19, 2018. Cumulative Other Comprehensive Income Cumulative other comprehensive income represents our share of the comprehensive income of our equity method investees, SIR and Affiliates Insurance Company, or AIC. See Notes 11 and 12 for further information regarding these investments. The following table presents changes in the amounts we recognized in cumulative other comprehensive income by component for the three and nine months ended September 30, 2018 : Three Months Ended September 30, 2018 Unrealized Gain Equity in on Investment Unrealized in Equity Gain Securities of Investees Total Balance at June 30, 2018 $ — $ 139 $ 139 Other comprehensive income before reclassifications — 143 143 Amounts reclassified from cumulative other comprehensive income to net income (1) — (17 ) (17 ) Net current period other comprehensive income — 126 126 Balance at September 30, 2018 $ — $ 265 $ 265 Nine Months Ended September 30, 2018 Unrealized Gain Equity in on Investment Unrealized in Equity Gain (Loss) Securities of Investees Total 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 ) Other comprehensive income before reclassifications — 155 155 Amounts reclassified from cumulative other comprehensive income to net income (1) — (36 ) (36 ) Net current period other comprehensive income — 119 119 Balance at September 30, 2018 $ — $ 265 $ 265 (1) Amounts reclassified from cumulative other comprehensive income to net income (loss) are included in equity in net earnings of investees in our condensed consolidated statements of comprehensive income. 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 ).

Business and Property Managemen

Business and Property Management Agreements with RMR LLC	9 Months Ended
	Sep. 30, 2018
Property Management Fee [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. Pursuant to our business management agreement with RMR LLC, we recognized net business management fees of $20,575 and $1,891 for the three months ended September 30, 2018 and 2017 , respectively, and $30,059 and $8,241 for the nine months ended September 30, 2018 and 2017 , respectively. The net business management fees payable to RMR LLC include $16,236 and $16,973 of estimated business management incentive fees for the three and nine months ended September 30, 2018 , respectively, based on our common share total return, as defined, as of September 30, 2018 . Although we recognized estimated business management incentive fees in accordance with GAAP, the actual amount of business management incentive fees payable by us to RMR LLC for 2018, if any, will be based on our common share total return, as defined, for the three year period ending December 31, 2018, and will be payable in 2019. The net business management fees recognized for the three months ended September 30, 2017 included the reversal of $893 of previously accrued estimated business management incentive fees as of June 30, 2017. As of September 30, 2017, based on our common share total return, as defined, as of such date, no annual business management incentive fees were estimated to be payable by us to RMR LLC for 2017. No incentive management fee was payable by us to RMR LLC for the year ended December 31, 2017. The net business management fees we recognize are included in general and administrative expenses in our condensed consolidated statements of comprehensive income. Pursuant to our property management agreement with RMR LLC, we recognized aggregate net property management and construction supervision fees of $3,415 and $2,338 for the three months ended September 30, 2018 and 2017 , respectively, and $10,201 and $7,371 for the nine months ended September 30, 2018 and 2017 , respectively. These amounts are included in other operating expenses or have been capitalized, as appropriate, in our condensed consolidated financial statements. We are generally responsible for all our operating expenses, including certain expenses incurred by RMR LLC on our behalf. Our property level operating expenses, including certain payroll and related costs incurred by RMR LLC, are generally incorporated into rents charged to our tenants. We reimbursed RMR LLC $5,100 and $3,436 for property management related expenses for the three months ended September 30, 2018 and 2017 , respectively, and $15,121 and $10,482 for property management related expenses for the nine months ended September 30, 2018 and 2017 , respectively, which amounts are included in other operating expenses in our condensed consolidated statements of comprehensive income. In addition, we are responsible for our share of RMR LLC’s costs for providing our internal audit function. The amounts we recognized as expense for internal audit costs were $50 and $67 for the three months ended September 30, 2018 and 2017 , respectively, and $173 and $202 for the nine months ended September 30, 2018 and 2017 , respectively. These amounts are included in general and administrative expenses in our condensed consolidated statements of comprehensive income.

Related Person Transactions

Related Person Transactions	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related Person Transactions	Related Person Transactions We have relationships and historical and continuing transactions with RMR LLC, RMR Inc., SIR, AIC and others related to them, including other companies to which RMR LLC or its subsidiaries provide management services and which have trustees, directors and officers who are also our Trustees or officers. Our Manager, RMR LLC. We have two agreements with RMR LLC to provide management services to us. See Note 10 for further information regarding our management agreements with RMR LLC. We lease office space to RMR LLC in certain of our properties for RMR LLC's property management offices. We recognized rental income from RMR LLC for leased office space of $263 and $90 for the three months ended September 30, 2018 and 2017, respectively, and $763 and $272 for the nine months ended September 30, 2018 and 2017, respectively. Our office space leases with RMR LLC are terminable by RMR LLC if our management agreements with RMR LLC are terminated. We have historically granted share awards to our officers and other RMR LLC employees under our equity compensation plans. In September 2018 and 2017, we granted annual awards of 58,700 and 57,350 of our common shares, respectively, to our officers and other employees of RMR LLC. In September 2018 and 2017, we purchased 18,875 and 13,636 of our common shares, respectively, valued at the closing price of our common shares on Nasdaq on the applicable date of purchase, in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares to our officers and other employees of RMR LLC. We include amounts recognized as expense for share awards to RMR LLC employees in general and administrative expenses in our condensed consolidated statements of comprehensive income. RMR Inc. RMR LLC is a majority owned subsidiary of RMR Inc. and RMR Inc. is the managing member of RMR LLC. Adam D. Portnoy, one of our Managing Trustees, is the sole trustee, an officer and the controlling shareholder of ABP Trust, which is the controlling shareholder of RMR Inc., a managing director, president and chief executive officer of RMR Inc. and an officer of RMR LLC. Mark L. Kleifges, our other Managing Trustee and our Chief Financial Officer and Treasurer, and David M. Blackman, our President and Chief Executive Officer, also serve as executive officers of RMR LLC. Mr. Kleifges has announced his retirement from his position with us, effective December 31, 2018, and Mr. Blackman has been elected to be our other Managing Trustee, effective January 1, 2019. RMR LLC provides management services to us. As of September 30, 2018 , we owned 1,214,225 shares of class A common stock of RMR Inc. See Note 8 for further information regarding our investment in RMR Inc. SIR . As of September 30, 2018 , we owned 24,918,421 SIR common shares, or approximately 27.8% of its outstanding common shares. As described further in Note 1, on September 14, 2018, we and SIR entered into the Merger Agreement, and on October 9, 2018, we completed the Secondary Sale. Adam D. Portnoy, one of our Managing Trustees, also serves as a managing trustee of SIR, and our President and Chief Executive Officer also serves as a managing trustee and the president and chief executive officer of SIR. RMR LLC provides management services to SIR and us. See Note 1 for further information regarding the Merger Agreement and the Secondary Sale and Notes 12 and 13 for further information regarding our investment in SIR. AIC . We, ABP Trust, SIR and four other companies to which RMR LLC provides management services currently own AIC in equal amounts. We and the other AIC shareholders participate in a combined property insurance program arranged and reinsured in part by AIC. We paid aggregate annual premiums, including taxes and fees, of approximately $1,211 in connection with the renewal of this insurance program for the policy year ending June 30, 2019, which amount may be adjusted from time to time as we acquire and dispose of properties that are included in this insurance program. As of September 30, 2018 and December 31, 2017, our investment in AIC had a carrying value of $9,276 and $8,304 , respectively. These amounts are included in other assets in our condensed consolidated balance sheets. We recognized income related to our investment in AIC, which is presented as equity in earnings of investees in our condensed consolidated statements of comprehensive income. Our other comprehensive income includes our proportionate part of unrealized gains on securities that are owned by AIC related to our investment in AIC. For further information about these and other such relationships and certain other related person transactions, refer to our Annual Report.

Equity Investment in Select Inc

Equity Investment in Select Income REIT	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Investment in Select Income REIT	Equity Investment in Select Income REIT As described in Note 11, as of September 30, 2018 , we owned 24,918,421 , or approximately 27.8% , of the then outstanding SIR common shares. SIR is a REIT that primarily owns single tenant, net leased properties. As described in Note 1, we completed the Secondary Sale on October 9, 2018. We expect to record a loss on the Secondary Sale of approximately $19,372 in the fourth quarter of 2018. We accounted for our investment in SIR under the equity method. As a result of the Secondary Sale, our equity method investment in SIR has been reclassified to discontinued operations in our condensed consolidated financial statements as of September 30, 2018 . 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 included in discontinued operations in our condensed consolidated statements of comprehensive income. We recorded $9,253 and $9,453 of equity in the earnings of SIR for the three months ended September 30, 2018 and 2017 , respectively, and $23,843 and $20,271 of equity in the earnings of SIR for the nine months ended September 30, 2018 and 2017 , respectively. Our other comprehensive income includes our proportionate share of SIR’s unrealized gains (losses) of ($47) and $1,236 for the three months ended September 30, 2018 and 2017 , respectively, and $28 and $5,339 for the nine months ended September 30, 2018 and 2017 , 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. As of September 30, 2018 and December 31, 2017, our basis difference was $120,492 and $87,137 , respectively, and as required under GAAP, we were accreting this basis difference to earnings over the estimated remaining useful lives of certain real estate assets and intangible assets and liabilities owned by SIR. The increase in the basis difference primarily related to SIR's capital finance activities and changes in its net equity during the nine months ended September 30, 2018 . This accretion increased our equity in the earnings of SIR by $1,044 and $736 for the three months ended September 30, 2018 and 2017 , respectively, and $3,131 and $2,209 for the nine months ended September 30, 2018 and 2017 , respectively. As of September 30, 2018 , our investment in SIR had a carrying value of $453,275 and a market value, based on the closing price of SIR common shares on Nasdaq on September 30, 2018 , of $546,710 . We received aggregate cash distributions from SIR of $12,708 during both the three months ended September 30, 2018 and 2017 , and $38,124 and $38,125 during the nine months ended September 30, 2018 and 2017 , respectively. During the three months ended September 30, 2018 and 2017 , SIR issued a net amount of 45,774 and 44,724 common shares, respectively. During the nine months ended September 30, 2018 and 2017 , SIR issued a net amount of 63,157 and 59,502 common shares, respectively. We recognized a gain on issuance of shares by SIR of $21 and $51 for the three months ended September 30, 2018 and 2017 , respectively, and a gain on issuance of shares by SIR of $29 and $72 for the nine months ended September 30, 2018 and 2017 , 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 presents summarized financial data of SIR as reported in SIR’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2018 , or the SIR Quarterly Report. References in our condensed consolidated financial statements to the SIR Quarterly Report are included as references to the source of the data only, and the information in the SIR Quarterly Report is not incorporated by reference into our condensed consolidated financial statements. Condensed Consolidated Balance Sheets September 30, December 31, 2018 2017 Real estate properties, net $ 3,926,606 $ 3,905,616 Acquired real estate leases, net 433,947 477,577 Properties held for sale 15,289 5,829 Cash and cash equivalents 25,982 658,719 Rents receivable, net 131,642 127,672 Other assets, net 188,033 127,617 Total assets $ 4,721,499 $ 5,303,030 Unsecured revolving credit facility $ 108,000 $ — Industrial Logistics Properties Trust revolving credit facility 380,000 750,000 Unsecured term loan, net — 348,870 Senior unsecured notes, net 1,430,688 1,777,425 Mortgage notes payable, net 210,624 210,785 Assumed real estate lease obligations, net 62,176 68,783 Other liabilities 150,371 155,348 Total shareholders' equity attributable to SIR 2,061,556 1,991,819 Noncontrolling interest in consolidated subsidiary 318,084 — Total liabilities and shareholders' equity $ 4,721,499 $ 5,303,030 Condensed Consolidated Statements of Income Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Rental income $ 101,833 $ 98,635 $ 298,003 $ 293,020 Tenant reimbursements and other income 20,048 19,379 60,514 57,158 Total revenues 121,881 118,014 358,517 350,178 Real estate taxes 12,518 11,489 36,748 33,168 Other operating expenses 14,814 14,649 43,714 41,039 Depreciation and amortization 35,371 34,713 105,326 102,770 Acquisition and transaction related costs 3,796 — 3,796 — General and administrative 15,331 1,608 47,353 24,697 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 — 9,706 229 Total expenses 91,536 62,459 257,269 218,467 Operating income 30,345 55,555 101,248 131,711 Dividend income 397 397 1,190 1,190 Unrealized gain on equity securities 22,771 — 53,159 — Interest income 133 19 753 39 Interest expense (23,287 ) (24,383 ) (69,446 ) (68,278 ) Loss on early extinguishment of debt — — (1,192 ) — Income before income tax expense, equity in earnings of an investee and gain on of real estate 30,359 31,588 85,712 64,662 Income tax expense (185 ) (177 ) (446 ) (364 ) Equity in earnings of an investee 831 31 882 533 Net income before gain on sale of real estate 31,005 31,442 86,148 64,831 Gain on sale of real estate 4,075 — 4,075 — Net income 35,080 31,442 90,223 64,831 Net income allocated to noncontrolling interest (5,597 ) — (15,841 ) — Net income attributed to SIR $ 29,483 $ 31,442 $ 74,382 $ 64,831 Weighted average common shares outstanding (basic) 89,410 89,355 89,395 89,341 Weighted average common shares outstanding (diluted) 89,437 89,379 89,411 89,364 Net income attributed to SIR per common share (basic and diluted) $ 0.33 $ 0.35 $ 0.83 $ 0.73

Discontinued Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Discontinued Operations Our equity method investment in SIR has been reclassified to discontinued operations in our condensed consolidated financial statements as of September 30, 2018 . See Notes 1 and 12 for further information regarding our equity method investment in SIR and the Secondary Sale. In August 2017, we sold one vacant office property ( one 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 condensed consolidated financial statements. Below are the components of our income from discontinued operations: Three Months Ended Nine Months Ended 2018 2017 2018 2017 Equity in earnings of Select Income REIT $ 9,253 $ 9,453 $ 23,843 $ 20,271 Net gain on issuance of shares by Select Income REIT 21 51 29 72 Income from property classified as discontinued operations — 462 — 173 Income from discontinued operations $ 9,274 $ 9,966 $ 23,872 $ 20,516

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements On January 1, 2018, we adopted the Financial Accounting Standards Board, or FASB, Accounting Standards Update, or 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 condensed 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 available for sale 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 $2,209 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 nine months ended September 30, 2017 . 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 2016-18 resulted in an increase of $21 of net cash provided by operating activities for the nine months ended September 30, 2017 . This update also requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheets. As a result, amounts included in restricted cash on our condensed consolidated balance sheets are included with cash and cash equivalents on the condensed consolidated statements of cash flows. Restricted cash, which 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, totaled $2,354 and $509 as of September 30, 2018 and 2017, respectively. The adoption of this update did not change our balance sheet presentation. In February 2016, the FASB issued ASU No. 2016-02, Leases , which sets 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. A lessee is also required to record a right of use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases today. 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. ASU No. 2016-02 is effective for reporting periods beginning after December 15, 2018, with early adoption permitted. We are currently assessing the potential impact the adoption of ASU No. 2016-02 will have in our condensed 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 condensed consolidated financial statements. We currently expect to adopt the standard using the modified retrospective approach. In June 2018, the FASB issued 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. ASU No. 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We are currently assessing the potential impact the adoption of ASU No. 2018-07 will have in our condensed consolidated financial statements.

Weighted Average Common Shares

Weighted Average Common Shares (Tables)	9 Months Ended
	Sep. 30, 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 Three Months For the Nine Months Ended September 30, Ended September 30, 2018 2017 2018 2017 Weighted average common shares for basic earnings per share 99,071 96,883 99,055 79,778 Effect of dilutive securities: unvested share awards — 75 20 74 Weighted average common shares for diluted earnings per share (1) 99,071 96,958 99,075 79,852

Real Estate Properties (Tables)

Real Estate Properties (Tables)	9 Months Ended
	Sep. 30, 2018
Real Estate [Abstract]
Disclosure of Assets held-for-sale	As of September 30, 2018 , we had 20 properties ( 50 buildings) with an aggregate undepreciated carrying value of $355,858 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 condensed consolidated balance sheet at September 30, 2018 . Date of Agreement (1) Number of Properties Number of Buildings Location Square Footage Gross Sale Price (2) August 2018 1 1 Washington D.C. 129,035 $ 70,000 September 2018 8 34 Northern Virginia and Maryland 1,635,868 201,500 October 2018 11 15 Southern Virginia 1,641,109 167,000 20 50 3,406,012 $ 438,500 (1) 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. (2) Gross sale price excludes closing costs.
Schedule of Pro Forma Information	The following table presents our pro forma results of operations for the nine months ended September 30, 2017 as if the FPO Transaction and related financing activities had occurred on January 1, 2017. The historical FPO results of operations included in this pro forma financial information have been adjusted to eliminate the results of operations of FPO properties and joint venture interests that were sold from January 1, 2017 to October 2, 2017, the closing date of the FPO Transaction. The effect of these adjustments was a decrease in pro forma rental income of $804 and a decrease in net income of $47,019 for the nine months ended September 30, 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 pursuant to our existing leases or leases we may enter during the remainder of 2018 and thereafter, 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. Nine Months Ended September 30, 2017 Rental income $ 328,255 Net loss $ (4,733 ) Net loss per share $ (0.05 )
Schedule of Joint Ventures	As of September 30, 2018 , our investment in unconsolidated joint ventures consisted of the following: Joint Venture GOV Ownership GOV Carrying Value of Investment at September 30, 2018 Property Type Number of Buildings Location Square Feet Prosperity Metro Plaza 51% $ 24,821 Office 2 Fairfax, VA 328,456 1750 H Street, NW 50% 20,340 Office 1 Washington, DC 115,411 Total $ 45,161 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 September 30, 2018 (2) 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. (2) Reflects the entire balance of the debt secured by the properties and is not adjusted to reflect the interests in the joint venture we do not own. None of the debt is recourse to us.

Fair Value of Assets and Liab_2

Fair Value of Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of assets measured on a recurring and 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 September 30, 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 Significant Active Markets for Significant Other Unobservable Identical Assets Observable Inputs Inputs Description Total (Level 1) (Level 2) (Level 3) Recurring Fair Value Measurements Assets: Investment in RMR Inc. (1) $ 112,680 $ 112,680 $ — $ — (1) Our 1,214,225 shares of class A common stock of The RMR Group Inc., or RMR Inc., which are included in other assets in our condensed consolidated balance sheets, are reported at fair value which is based on quoted market prices (Level 1 inputs as defined in the fair value hierarchy under GAAP). Our historical cost basis for these shares is $26,888 as of September 30, 2018 . During the three and nine months ended September 30, 2018 , we recorded an unrealized gain of $17,425 and $40,677 , respectively, to adjust our investment in RMR Inc. to its fair value.
Schedule of fair value and carrying value of financial instruments	At September 30, 2018 and December 31, 2017 , the fair values of our financial instruments approximated their carrying values in our condensed consolidated financial statements due to their short term nature or variable interest rates, except as follows: As of September 30, 2018 As of December 31, 2017 Carrying Amount (1) Fair Value Carrying Amount (1) Fair Value Senior unsecured notes, 3.75% interest rate, due in 2019 $ 348,953 $ 351,468 $ 348,096 $ 354,993 Senior unsecured notes, 5.875% interest rate, due in 2046 300,490 309,380 300,232 320,416 Senior unsecured notes, 4.000% interest rate, due in 2022 296,505 296,609 295,812 302,655 Mortgage note payable, 4.050% interest rate, due in 2030 (2) 64,441 62,363 64,293 65,198 Mortgage note payable, 5.720% interest rate, due in 2020 (2) 35,067 34,877 36,085 36,332 Mortgage note payable, 4.220% interest rate, due in 2022 (2) 27,408 27,422 27,906 28,432 Mortgage note payable, 4.800% interest rate, due in 2023 (2) 25,145 25,220 25,501 25,904 Mortgage note payable, 5.877% interest rate, due in 2021 (2) 13,445 13,978 13,620 14,565 Mortgage note payable, 7.000% interest rate, due in 2019 (2) 8,087 8,129 8,391 8,555 Mortgage note payable, 8.150% interest rate, due in 2021 (2) 3,235 3,360 4,111 4,340 Mortgage note payable, 4.260% interest rate, due in 2020 (2) (3) 3,047 3,028 3,193 3,216 $ 1,125,823 $ 1,135,834 $ 1,127,240 $ 1,164,606 (1) Carrying amount includes certain unamortized debt issuance costs and unamortized premiums and discounts. (2) We assumed these mortgages 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 date of acquisition and we are amortizing the fair value premiums, if any, to interest expense over the respective terms of the mortgages to reduce interest expense to the estimated market interest rates as of the date of acquisition. (3) Secured by one property (one building) that is held for sale at September 30, 2018.

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
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 by component for the three and nine months ended September 30, 2018 : Three Months Ended September 30, 2018 Unrealized Gain Equity in on Investment Unrealized in Equity Gain Securities of Investees Total Balance at June 30, 2018 $ — $ 139 $ 139 Other comprehensive income before reclassifications — 143 143 Amounts reclassified from cumulative other comprehensive income to net income (1) — (17 ) (17 ) Net current period other comprehensive income — 126 126 Balance at September 30, 2018 $ — $ 265 $ 265 Nine Months Ended September 30, 2018 Unrealized Gain Equity in on Investment Unrealized in Equity Gain (Loss) Securities of Investees Total 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 ) Other comprehensive income before reclassifications — 155 155 Amounts reclassified from cumulative other comprehensive income to net income (1) — (36 ) (36 ) Net current period other comprehensive income — 119 119 Balance at September 30, 2018 $ — $ 265 $ 265 (1) Amounts reclassified from cumulative other comprehensive income to net income (loss) are included in equity in net earnings of investees in our condensed consolidated statements of comprehensive income.

Equity Investment in Select I_2

Equity Investment in Select Income REIT (Tables) - SIR	9 Months Ended
	Sep. 30, 2018
Schedule Of Summarized Balance Sheet Information Of Equity Method Investee	Condensed Consolidated Balance Sheets September 30, December 31, 2018 2017 Real estate properties, net $ 3,926,606 $ 3,905,616 Acquired real estate leases, net 433,947 477,577 Properties held for sale 15,289 5,829 Cash and cash equivalents 25,982 658,719 Rents receivable, net 131,642 127,672 Other assets, net 188,033 127,617 Total assets $ 4,721,499 $ 5,303,030 Unsecured revolving credit facility $ 108,000 $ — Industrial Logistics Properties Trust revolving credit facility 380,000 750,000 Unsecured term loan, net — 348,870 Senior unsecured notes, net 1,430,688 1,777,425 Mortgage notes payable, net 210,624 210,785 Assumed real estate lease obligations, net 62,176 68,783 Other liabilities 150,371 155,348 Total shareholders' equity attributable to SIR 2,061,556 1,991,819 Noncontrolling interest in consolidated subsidiary 318,084 — Total liabilities and shareholders' equity $ 4,721,499 $ 5,303,030
Schedule Of Summarized Income Statement Information Of Equity Method Investee	Condensed Consolidated Statements of Income Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Rental income $ 101,833 $ 98,635 $ 298,003 $ 293,020 Tenant reimbursements and other income 20,048 19,379 60,514 57,158 Total revenues 121,881 118,014 358,517 350,178 Real estate taxes 12,518 11,489 36,748 33,168 Other operating expenses 14,814 14,649 43,714 41,039 Depreciation and amortization 35,371 34,713 105,326 102,770 Acquisition and transaction related costs 3,796 — 3,796 — General and administrative 15,331 1,608 47,353 24,697 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 — 9,706 229 Total expenses 91,536 62,459 257,269 218,467 Operating income 30,345 55,555 101,248 131,711 Dividend income 397 397 1,190 1,190 Unrealized gain on equity securities 22,771 — 53,159 — Interest income 133 19 753 39 Interest expense (23,287 ) (24,383 ) (69,446 ) (68,278 ) Loss on early extinguishment of debt — — (1,192 ) — Income before income tax expense, equity in earnings of an investee and gain on of real estate 30,359 31,588 85,712 64,662 Income tax expense (185 ) (177 ) (446 ) (364 ) Equity in earnings of an investee 831 31 882 533 Net income before gain on sale of real estate 31,005 31,442 86,148 64,831 Gain on sale of real estate 4,075 — 4,075 — Net income 35,080 31,442 90,223 64,831 Net income allocated to noncontrolling interest (5,597 ) — (15,841 ) — Net income attributed to SIR $ 29,483 $ 31,442 $ 74,382 $ 64,831 Weighted average common shares outstanding (basic) 89,410 89,355 89,395 89,341 Weighted average common shares outstanding (diluted) 89,437 89,379 89,411 89,364 Net income attributed to SIR per common share (basic and diluted) $ 0.33 $ 0.35 $ 0.83 $ 0.73

Discontinued Operations (Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Schedule of discontinued operations	Below are the components of our income from discontinued operations: Three Months Ended Nine Months Ended 2018 2017 2018 2017 Equity in earnings of Select Income REIT $ 9,253 $ 9,453 $ 23,843 $ 20,271 Net gain on issuance of shares by Select Income REIT 21 51 29 72 Income from property classified as discontinued operations — 462 — 173 Income from discontinued operations $ 9,274 $ 9,966 $ 23,872 $ 20,516

Basis of Presentation - Merger

Basis of Presentation - Merger with SIR (Details) $ / shares in Units, $ in Thousands	Oct. 09, 2018USD ($)$ / sharesshares	Sep. 14, 2018USD ($)ft²property$ / sharesshares	Sep. 13, 2018shares	Sep. 30, 2018segmentshares
Business Acquisition [Line Items]
Number of segments | segment				1
Reverse stock split ratio		0.25
SIR
Business Acquisition [Line Items]
Right to receive (shares) | shares		1.04
Number of properties acquired | property		99
Rentable area of properties (in square feet) | ft²		16,538,462
Share price (in dollars per share) | $ / shares		$ 11.29
Purchase price | $		$ 2,738,488
Merger closing costs | $		40,000
Debt repaid on behalf of the acquiree | $		$ 1,720,000
Agreement covenant 1, minimum percentage		20.00%
Agreement covenant 2, minimum percentage		75.00%
SIR
Business Acquisition [Line Items]
Shares holding (in shares) | shares			24,918,421	24,918,421
Subsequent Event | Underwritten Public Offering | Common shares
Business Acquisition [Line Items]
Number of shares sold (in shares) | shares	24,918,421
Sale price (in dollars per share) | $ / shares	$ 18.25
Proceeds from sale of transaction | $	$ 434,700
SIR | Industrial Logistics Properties Trust
Business Acquisition [Line Items]
Shares holding (in shares) | shares			45,000,000

Recent Accounting Pronounceme_3

Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred gain on sale of real estate					$ 712
Unrealized gain on investment in equity securities	$ 0	$ 3,279	$ 0	$ 14,389
Equity in earnings of an investee	94	31	(1,112)	533
Increase in cash provided by operating activities			120,165	95,914
Restricted cash	$ 2,354	$ 509	$ 2,354	509	3,111
ASU 2016-01 | Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unrealized gain on investment in equity securities					45,116
ASU 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accretion in equity of earnings				2,209
ASU 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in cash provided by operating activities				$ 21
SIR and AIC | ASU 2016-01 | Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity in earnings of an investee					$ 15,165

Weighted Average Common Share_2

Weighted Average Common Shares - Weighted Average Shars (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share, Basic and Diluted [Abstract]
Weighted average common shares for basic earnings per share (in shares)	99,071	96,883	99,055	79,778
Effect of dilutive securities: unvested share awards (in shares)	0	75	20	74
Weighted average common shares for diluted earnings per share (in shares)	99,071	96,958	99,075	79,852
Antidilutive shares (in shares)	0

Real Estate Properties - Additi

Real Estate Properties - Additional Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)ft²leasepropertybuilding	Sep. 30, 2018USD ($)ft²leasepropertyjoint_venturebuilding
Real Estate Properties [Line Items]
Number of Properties | property	105	105
Number of buildings | building	164	164
Number of joint ventures | joint_venture		2
Number of properties, noncontrolling interest | property		2
Number of buildings, noncontrolling interest | building		3
Number of leases entered | lease	24	94
Rentable square feet (in sqft) | ft²	182,220	858,998
Weighted average lease term	8 years 1 month	6 years 5 months
Expenditures committed on leases | $	$ 6,479	$ 21,287
Committed but unspent tenant related obligations estimated | $	$ 34,048	$ 34,048
Continuing operations
Real Estate Properties [Line Items]
Number of Properties | property	105	105
Number of buildings | building	164	164
Carry value of properties | $	$ 2,854,937	$ 2,854,937

Real Estate Properties - Dispos

Real Estate Properties - Disposition Activities (Details) $ in Thousands	1 Months Ended		3 Months Ended				9 Months Ended
	May 31, 2018USD ($)ft²propertybuilding	Mar. 31, 2018USD ($)ft²propertybuilding	Sep. 30, 2018USD ($)propertybuilding	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)ft²propertybuilding	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)propertybuilding	Sep. 30, 2017USD ($)	Oct. 31, 2018property	Feb. 28, 2018ft²propertybuilding	Dec. 31, 2017USD ($)
Real Estate Properties [Line Items]
Number of properties | property			105				105
Number of buildings | building			164				164
Loss on impairment of real estate			$ 0			$ 230	$ 5,800	$ 230
Gain (loss) on sale of real estate			0			$ 0	17,329	$ 0
Net book value			$ 2,135,589				$ 2,135,589				$ 2,633,873
Office Building | Disposal Group, Disposed of by Sale | Minneapolis, NM | One building
Real Estate Properties [Line Items]
Number of properties | property		1			1
Number of buildings | building		1			1
Rentable area of properties (in square feet) | ft²		193,594			193,594
Aggregate sale price of properties sold, excluding closing costs		$ 20,000
Loss on impairment of real estate					$ 640
Office Building | Disposal Group, Disposed of by Sale | Safford, AZ | One building
Real Estate Properties [Line Items]
Number of properties | property										1
Number of buildings | building										1
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
Fair value adjustment				$ 322
Office Building | Disposal Group, Disposed of by Sale | New York, NY | One building
Real Estate Properties [Line Items]
Number of properties | property	1
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 (loss) on sale of real estate				17,329
Office Building | Disposal Group, Disposed of by Sale | Sacramento, CA | One building
Real Estate Properties [Line Items]
Number of properties | property	1
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				$ 6	$ 3,023
FPO Transaction | Disposal Group, Disposed of by Sale
Real Estate Properties [Line Items]
Number of properties | property			3				3
Number of buildings | building			3				3
Net book value			$ 24,566				$ 24,566
Subsequent Event | Office Building | Disposal Group, Disposed of by Sale | Washington D.C. | One building
Real Estate Properties [Line Items]
Number of properties | property									1

Real Estate Properties - Assets

Real Estate Properties - Assets Held-for-Sale (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)ft²propertybuilding	Dec. 31, 2017USD ($)
Real Estate Properties [Line Items]
Assets of properties held for sale	$ 408,626	$ 0
Number of Properties | property	105
Number of Buildings | building	164
Held-for-sale
Real Estate Properties [Line Items]
Assets of properties held for sale	$ 355,858
Number of Properties | property	20
Number of Buildings | building	50
Square Footage (in square feet) | ft²	3,406,012
Gross Sale Price	$ 438,500
Held-for-sale | Washington D.C.
Real Estate Properties [Line Items]
Number of Properties | property	1
Number of Buildings | building	1
Square Footage (in square feet) | ft²	129,035
Gross Sale Price	$ 70,000
Held-for-sale | Northern Virginia and Maryland
Real Estate Properties [Line Items]
Number of Properties | property	8
Number of Buildings | building	34
Square Footage (in square feet) | ft²	1,635,868
Gross Sale Price	$ 201,500
Held-for-sale | Southern Virginia
Real Estate Properties [Line Items]
Number of Properties | property	11
Number of Buildings | building	15
Square Footage (in square feet) | ft²	1,641,109
Gross Sale Price	$ 167,000

Real Estate Properties - FPO Tr

Real Estate Properties - FPO Transaction (Details) $ in Thousands	Oct. 02, 2017USD ($)ft²propertyjoint_venturebuilding	Sep. 30, 2018propertyjoint_venturebuilding
Business Acquisition [Line Items]
Number of joint ventures | joint_venture		2
Number of Properties | property		105
Number of buildings | building		164
First Potomac Realty Trust
Business Acquisition [Line Items]
Number of properties acquired | property	35
Number of buildings acquired | building	72
Rentable area of properties (in square feet) | ft²	6,028,072
Purchase price | $	$ 1,370,888
First Potomac Realty Trust
Business Acquisition [Line Items]
Number of joint ventures | joint_venture	2
Number of Properties | property	2
Number of buildings | building	3
First Potomac Realty Trust | First Potomac Realty Trust
Business Acquisition [Line Items]
Rentable area of properties (in square feet) | ft²	443,867
Joint Venture Property 1 | First Potomac Realty Trust
Business Acquisition [Line Items]
Percentage of ownership interest	50.00%
Joint Venture Property 2 | First Potomac Realty Trust
Business Acquisition [Line Items]
Percentage of ownership interest	51.00%

Real Estate Properties - Pro Fo

Real Estate Properties - Pro Forma (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)$ / shares
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Rental income	$ 328,255
Net loss	$ (4,733)
Net loss per share (in dollars per share) | $ / shares	$ (0.05)
Acquisition-related costs
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Decrease in revenues	$ 804
Decrease in net income	$ 47,019

Real Estate Properties - Schedu

Real Estate Properties - Schedule of Joint Ventures (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)ft²propertyjoint_venturebuilding
Real Estate [Line Items]
Number of joint ventures | joint_venture	2
Number of Properties | property	105
Number of buildings | building	164
Unconsolidated Joint Ventures
Real Estate [Line Items]
Investment at carrying value	$ 45,161
Number of buildings | building	3
Square Feet (in square feet) | ft²	443,867
Interest rate (as a percent)	3.9339%
Principal Balance	$ 82,000
Unamortized basis difference	$ 8,565
Unconsolidated Joint Ventures | Prosperity Metro Plaza
Real Estate [Line Items]
GOV Ownership	51.00%
Investment at carrying value	$ 24,821
Number of 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]
GOV Ownership	50.00%
Investment at carrying value	$ 20,340
Number of buildings | building	1
Square Feet (in square feet) | ft²	115,411
Interest rate (as a percent)	3.69%
Principal Balance	$ 32,000

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Revenue Recognition [Abstract]
Increase in rental income to record revenue on straight line basis	$ 1,990	$ 711	$ 7,825	$ 3,115
Straight line rent receivables	33,978		33,978		$ 27,267
Straight line rent receivable, properties held for sale	1,819		1,819
Allowance for doubtful accounts	1,755		1,755		$ 1,503
Allowance for doubtful accounts, properties held for sale	$ 976		$ 976

Concentration (Details)

Concentration (Details)	9 Months Ended
	Sep. 30, 2018propertygovernment_tenantstate_governmentstatebuilding	Sep. 30, 2017
Concentration
Number of state governments | state_government	13
Number of other governments | government_tenant	3
Number of properties | property	105
Number of buildings | building	164
Number of states in which acquired properties located | state	30
Annualized rental income, excluding properties classified as discontinued operations | Virginia
Concentration
Annualized Rental income percent	23.70%
Annualized rental income, excluding properties classified as discontinued operations | District of Columbia
Concentration
Annualized Rental income percent	18.10%
Annualized rental income, excluding properties classified as discontinued operations | Maryland
Concentration
Annualized Rental income percent	15.30%
Annualized rental income, excluding properties classified as discontinued operations | California
Concentration
Annualized Rental income percent	9.40%
Annualized rental income, excluding properties classified as discontinued operations | Georgia
Concentration
Annualized Rental income percent	6.10%
Annualized rental income, excluding properties classified as discontinued operations | Washington, DC Market Area
Concentration
Concentration risk percentage	44.10%
Annualized rental income, excluding properties classified as discontinued operations | Tenant concentration | U.S. Government, state governments and Other Four Government
Concentration
Concentration risk percentage	62.50%	87.50%
Annualized rental income, excluding properties classified as discontinued operations | Tenant concentration | U.S. Government
Concentration
Concentration risk percentage	45.60%	59.80%

Indebtedness - Debt Obligations

Indebtedness - Debt Obligations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Oct. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Borrowings outstanding	$ 467,000		$ 467,000			$ 570,000
Maximum borrowing capacity on revolving credit facility	2,500,000		2,500,000
Aggregate principal amount on secured properties	180,416		180,416
Unsecured term loan, due in 2020
Debt Instrument [Line Items]
Face amount	$ 300,000		$ 300,000
Interest rate (as a percent)	3.60%		3.60%
The weighted average annual interest rate (as a percent)	3.50%	2.60%	3.30%	2.40%
Unsecured term loan, due in 2022
Debt Instrument [Line Items]
Face amount	$ 250,000		$ 250,000
Interest rate (as a percent)	4.00%		4.00%
The weighted average annual interest rate (as a percent)	3.90%	3.00%	3.70%	2.80%
Unsecured revolving credit facility
Debt Instrument [Line Items]
Borrowings outstanding	$ 467,000		$ 467,000
Maximum borrowing capacity on revolving credit facility	$ 750,000		$ 750,000
Option to extend the maturity date subject to certain conditions and the payment of a fee			1 year
Facility fee (as a percent)			0.25%
Interest rate (as a percent)	3.40%		3.40%
The weighted average annual interest rate (as a percent)	3.20%	2.40%	3.00%	2.20%
Unsecured revolving credit facility | Subsequent Event
Debt Instrument [Line Items]
Borrowings outstanding					$ 32,000
Term loans
Debt Instrument [Line Items]
Face amount	$ 550,000		$ 550,000
Senior unsecured notes
Debt Instrument [Line Items]
Face amount	$ 960,000		$ 960,000
LIBOR | Unsecured term loan, due in 2020
Debt Instrument [Line Items]
Interest rate premium (as a percent)			1.40%
LIBOR | Unsecured term loan, due in 2022
Debt Instrument [Line Items]
Interest rate premium (as a percent)			1.80%
LIBOR | Unsecured revolving credit facility
Debt Instrument [Line Items]
Interest rate premium (as a percent)			1.25%

Indebtedness - Additional Infor

Indebtedness - Additional Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)propertyloanbuilding
Debt Disclosure [Abstract]
Number of properties secured by mortgage notes | property	8
Number of buildings secured by mortgage notes | building	8
Aggregate net book value of secured properties	$ 417,842
Number of assumed secured mortgage loans | loan	8
Aggregate principal amount on secured properties	$ 180,416

Fair Value of Assets and Liab_3

Fair Value of Assets and Liabilities - Recurring and Nonrecurring Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value of Assets and Liabilities
Common shares owned in RMR Inc. (in shares)	1,214,225		1,214,225
Historical cost	$ 26,888		$ 26,888
Unrealized gain on equity securities	17,425	$ 0	40,677	$ 0
Recurring
Fair Value of Assets and Liabilities
Investment in RMR Inc.	112,680		112,680
Recurring | Level 1 inputs
Fair Value of Assets and Liabilities
Investment in RMR Inc.	112,680		112,680
Recurring | Level 2 inputs
Fair Value of Assets and Liabilities
Investment in RMR Inc.	0		0
Recurring | Level 3 inputs
Fair Value of Assets and Liabilities
Investment in RMR Inc.	$ 0		$ 0

Fair Value of Assets and Liab_4

Fair Value of Assets and Liabilities - Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value of Financial Instruments
Senior Notes	$ 945,948	$ 944,140
Mortgage notes payable, net	$ 176,828	183,100
Senior unsecured notes, 3.75% interest rate, due in 2019
Fair Value of Financial Instruments
Interest rate (as a percent)	3.75%
Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Interest rate (as a percent)	5.875%
Senior unsecured notes, 4.000% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)	4.00%
Mortgage note payable, 4.050% interest rate, due in 2030
Fair Value of Financial Instruments
Interest rate (as a percent)	4.05%
Mortgage note payable, 5.720% interest rate, due in 2020
Fair Value of Financial Instruments
Interest rate (as a percent)	5.72%
Mortgage note payable, 4.220% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)	4.22%
Mortgage note payable, 4.800% interest rate, due in 2023
Fair Value of Financial Instruments
Interest rate (as a percent)	4.80%
Mortgage note payable, 5.877% interest rate, due in 2021
Fair Value of Financial Instruments
Interest rate (as a percent)	5.877%
Mortgage note payable, 7.000% interest rate, due in 2019
Fair Value of Financial Instruments
Interest rate (as a percent)	7.00%
Mortgage note payable, 8.150% interest rate, due in 2021
Fair Value of Financial Instruments
Interest rate (as a percent)	8.15%
Mortgage note payable, 4.260% interest rate, due in 2020
Fair Value of Financial Instruments
Interest rate (as a percent)	4.26%
Carrying Amount
Fair Value of Financial Instruments
Fair value of financial instruments	$ 1,125,823	1,127,240
Carrying Amount | Senior unsecured notes, 3.75% interest rate, due in 2019
Fair Value of Financial Instruments
Senior Notes	348,953	348,096
Carrying Amount | Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Senior Notes	300,490	300,232
Carrying Amount | Senior unsecured notes, 4.000% interest rate, due in 2022
Fair Value of Financial Instruments
Senior Notes	296,505	295,812
Carrying Amount | Mortgage note payable, 4.050% interest rate, due in 2030
Fair Value of Financial Instruments
Mortgage notes payable, net	64,441	64,293
Carrying Amount | Mortgage note payable, 5.720% interest rate, due in 2020
Fair Value of Financial Instruments
Mortgage notes payable, net	35,067	36,085
Carrying Amount | Mortgage note payable, 4.220% interest rate, due in 2022
Fair Value of Financial Instruments
Mortgage notes payable, net	27,408	27,906
Carrying Amount | Mortgage note payable, 4.800% interest rate, due in 2023
Fair Value of Financial Instruments
Mortgage notes payable, net	25,145	25,501
Carrying Amount | Mortgage note payable, 5.877% interest rate, due in 2021
Fair Value of Financial Instruments
Mortgage notes payable, net	13,445	13,620
Carrying Amount | Mortgage note payable, 7.000% interest rate, due in 2019
Fair Value of Financial Instruments
Mortgage notes payable, net	8,087	8,391
Carrying Amount | Mortgage note payable, 8.150% interest rate, due in 2021
Fair Value of Financial Instruments
Mortgage notes payable, net	3,235	4,111
Carrying Amount | Mortgage note payable, 4.260% interest rate, due in 2020
Fair Value of Financial Instruments
Mortgage notes payable, net	3,047	3,193
Fair Value
Fair Value of Financial Instruments
Fair value of financial instruments	1,135,834	1,164,606
Fair Value | Senior unsecured notes, 3.75% interest rate, due in 2019
Fair Value of Financial Instruments
Senior Notes	351,468	354,993
Fair Value | Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Senior Notes	309,380	320,416
Fair Value | Senior unsecured notes, 4.000% interest rate, due in 2022
Fair Value of Financial Instruments
Senior Notes	296,609	302,655
Fair Value | Mortgage note payable, 4.050% interest rate, due in 2030
Fair Value of Financial Instruments
Mortgage notes payable, net	62,363	65,198
Fair Value | Mortgage note payable, 5.720% interest rate, due in 2020
Fair Value of Financial Instruments
Mortgage notes payable, net	34,877	36,332
Fair Value | Mortgage note payable, 4.220% interest rate, due in 2022
Fair Value of Financial Instruments
Mortgage notes payable, net	27,422	28,432
Fair Value | Mortgage note payable, 4.800% interest rate, due in 2023
Fair Value of Financial Instruments
Mortgage notes payable, net	25,220	25,904
Fair Value | Mortgage note payable, 5.877% interest rate, due in 2021
Fair Value of Financial Instruments
Mortgage notes payable, net	13,978	14,565
Fair Value | Mortgage note payable, 7.000% interest rate, due in 2019
Fair Value of Financial Instruments
Mortgage notes payable, net	8,129	8,555
Fair Value | Mortgage note payable, 8.150% interest rate, due in 2021
Fair Value of Financial Instruments
Mortgage notes payable, net	3,360	4,340
Fair Value | Mortgage note payable, 4.260% interest rate, due in 2020
Fair Value of Financial Instruments
Mortgage notes payable, net	$ 3,028	$ 3,216

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Details) $ / shares in Units, $ in Thousands

Oct. 18, 2018USD ($)$ / shares

Sep. 24, 2018$ / sharesshares

Sep. 13, 2018$ / sharesshares

Aug. 20, 2018USD ($)$ / shares

May 24, 2018trustee$ / sharesshares

May 21, 2018USD ($)$ / shares

Apr. 03, 2018$ / sharesshares

Feb. 26, 2018USD ($)$ / shares

Jan. 01, 2018$ / sharesshares

Sep. 30, 2018shares

Sep. 30, 2017shares

Sep. 30, 2018

May 01, 2018USD ($)$ / sharesshares

Share Awards

Cash distribution to common shareholders (in dollars per share)

$ 0.43

Distribution paid to common shareholders | $

$ 42,641

$ 42,634

$ 42,632

Distribution payable to common shareholders (in dollars per share)

$ 0.43

Dividends declared (in dollars per share)

$ 0.43

Subsequent Event

Share Awards

Dividends declared (in dollars per share)

$ 0.43

Dividends declared | $

$ 42,658

Officers and Other Employees

Share Awards

Shares paid for tax withholding (in shares) | shares

18,875

13,636

Former Employee of RMR LLC

Share Awards

Shares paid for tax withholding (in shares) | shares

617

Stock repurchased (in dollars per share)

$ 18.54

Trustees

Share Awards

Number of trustees | trustee

1

Shares paid for tax withholding (in shares) | shares

450

Stock repurchased (in dollars per share)

$ 14.10

Officers and Other Employees

Share Awards

Shares paid for tax withholding (in shares) | shares

18,875

Stock repurchased (in dollars per share)

$ 11.35

Share Award Plan | Common shares | Trustees

Share Awards

Shares granted (in shares) | shares

3,000

3,000

Shares granted (in dollars per share)

$ 14.10

$ 13.59

Number of trustees | trustee

6

Share Award Plan | Common shares | Officers and Other Employees

Share Awards

Shares granted (in shares) | shares

58,700

Shares granted (in dollars per share)

$ 16.95

Series A Cumulative Preferred Units

Share Awards

Temporary equity (in shares) | shares

1,813,504

Redemption percentage

5.50%

Redemption price (in dollars per share)

$ 11.15

Redemption amount | $

$ 20,310

Shareholders' Equity - AOCI Rol

Shareholders' Equity - AOCI Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			$ 1,330,043
Other comprehensive income	$ 126	$ 4,630	119	$ 20,023
Ending balance	1,239,361		1,239,361
Unrealized Gain on Investment in Equity Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	0		45,116
Amounts reclassified from cumulative other comprehensive income to cumulative net income			(45,116)
Other comprehensive income before reclassifications	0		0
Amounts reclassified from cumulative other comprehensive loss to net income	0		0
Other comprehensive income	0		0
Ending balance	0		0
Equity in Unrealized Gain (Loss) of an Investee
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	139		15,311
Amounts reclassified from cumulative other comprehensive income to cumulative net income			(15,165)
Other comprehensive income before reclassifications	143		155
Amounts reclassified from cumulative other comprehensive loss to net income	(17)		(36)
Other comprehensive income	126		119
Ending balance	265		265
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	139		60,427
Amounts reclassified from cumulative other comprehensive income to cumulative net income			(60,281)
Other comprehensive income before reclassifications	143		155
Amounts reclassified from cumulative other comprehensive loss to net income	(17)		(36)
Other comprehensive income	126		119
Ending balance	$ 265		$ 265

Business and Property Managem_2

Business and Property Management Agreements with RMR LLC (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)employeeagreement	Sep. 30, 2017USD ($)
RMR LLC
Related Party Transaction [Line Items]
Number of employees | employee			0
Number of agreements | agreement			2
Related party expense	$ 20,575	$ 1,891	$ 30,059	$ 8,241
Reimbursement expense	5,100	3,436	15,121	10,482
Internal audit costs	50	67	173	202
Net Property Management and Construction Supervision Fees | RMR LLC
Related Party Transaction [Line Items]
Related party transaction amount	3,415	2,338	10,201	$ 7,371
RMR LLC | Affiliated Entity
Related Party Transaction [Line Items]
Reversal of expense with related party	$ 16,236	$ (893)	$ 16,973
Period of common share total return, incentive fees payable	3 years

Related Person Transactions - R

Related Person Transactions - REITs, for which RMR LLC provides Management Services (Details) $ in Thousands	Sep. 13, 2018shares	Sep. 30, 2018USD ($)companyshares	Sep. 30, 2017shares	Sep. 30, 2018USD ($)company	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)agreementcompanyshares	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
SIR
Related Party Transaction [Line Items]
Shares holding (in shares) | shares	24,918,421					24,918,421
Percentage of outstanding shares owned		27.80%		27.80%		27.80%
RMR Inc | Class A common shares
Related Party Transaction [Line Items]
Shares holding (in shares) | shares						1,214,225
RMR LLC
Related Party Transaction [Line Items]
Number of agreements | agreement						2
Revenue from related party | $				$ 263	$ 90	$ 763	$ 272
Property insurance premiums paid | $				$ 20,575	$ 1,891	$ 30,059	$ 8,241
AIC
Related Party Transaction [Line Items]
Number of entities to whom services are provided | company		4		4		4
Carrying value of equity method investments | $		$ 9,276		$ 9,276		$ 9,276		$ 8,304
Property Insurance Premium Expense
Related Party Transaction [Line Items]
Property insurance premiums paid | $						$ 1,211
Officers and Other Employees
Related Party Transaction [Line Items]
Shares paid for tax withholding (in shares) | shares		18,875	13,636
Common shares | Officers and Other Employees
Related Party Transaction [Line Items]
Common shares issued (in shares) | shares		58,700	57,350

Equity Investment in Select I_3

Equity Investment in Select Income REIT - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Equity in earnings of an investee		$ 94	$ 31	$ (1,112)	$ 533
Cash distributions from SIR				23,843	20,271
Net gain on issuance of shares by Select Income REIT				$ 29	72
SIR
Schedule of Equity Method Investments [Line Items]
Equity investments, common shares owned (in shares)		24,918,421		24,918,421
Percentage of outstanding shares owned		27.80%		27.80%
Equity in earnings of an investee		$ 9,253	9,453	$ 23,843	20,271
Equity in unrealized gain (loss) of investees		(47)	1,236	28	5,339
The amount of investment in exceed the underlying equity of the investee		120,492		120,492		$ 87,137
Accretion in equity of earnings		1,044	736	3,131	2,209
Investment at carrying value		453,275		453,275
Equity Investments, market value		546,710		546,710
Cash distributions from SIR		12,708	12,708	38,124	38,125
SIR | SIR
Schedule of Equity Method Investments [Line Items]
Equity in earnings of an investee		$ 831	$ 31	$ 882	$ 533
Common shares issued (in shares)		45,774	44,724	63,157	59,502
Net gain on issuance of shares by Select Income REIT		$ 21	$ 51	$ 29	$ 72
Forecast | Secondary Sale
Schedule of Equity Method Investments [Line Items]
Loss on Secondary Sale	$ 19,372

Equity Investment in Select I_4

Equity Investment in Select Income REIT - Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Real estate properties, net	$ 2,135,589	$ 2,633,873
Acquired real estate leases, net	215,938	351,872
Properties held for sale	408,626	0
Cash and cash equivalents	9,644	16,569	$ 551,707
Rents receivable, net	55,297	61,429
Other assets, net	136,360	96,033
Total assets	3,484,425	3,703,565
Unsecured revolving credit facility	467,000	570,000
Unsecured term loan, net	548,363	547,852
Senior unsecured notes, net	945,948	944,140
Mortgage notes payable, net	176,828	183,100
Assumed real estate lease obligations, net	8,759	13,635
Other liabilities	64,868	89,440
Total shareholders' equity attributable to SIR	1,239,361	1,330,043
Total liabilities and shareholders’ equity	3,484,425	3,703,565
SIR | SIR
Schedule of Equity Method Investments [Line Items]
Real estate properties, net	3,926,606	3,905,616
Acquired real estate leases, net	433,947	477,577
Properties held for sale	15,289	5,829
Cash and cash equivalents	25,982	658,719
Rents receivable, net	131,642	127,672
Other assets, net	188,033	127,617
Total assets	4,721,499	5,303,030
Unsecured revolving credit facility	108,000	0
Industrial Logistics Properties Trust revolving credit facility	380,000	750,000
Unsecured term loan, net	0	348,870
Senior unsecured notes, net	1,430,688	1,777,425
Mortgage notes payable, net	210,624	210,785
Assumed real estate lease obligations, net	62,176	68,783
Other liabilities	150,371	155,348
Total shareholders' equity attributable to SIR	2,061,556	1,991,819
Noncontrolling interest in consolidated subsidiary	318,084	0
Total liabilities and shareholders’ equity	$ 4,721,499	$ 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
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Rental income	$ 106,102	$ 70,179	$ 322,904	$ 209,362
Real estate taxes	12,072	8,862	37,402	24,980
Other operating expenses	21,785	14,867	66,221	44,046
Depreciation and amortization	42,569	20,781	129,444	61,949
Acquisition and transaction related costs	3,813	0	3,813	0
General and administrative	22,383	3,266	36,438	12,314
Loss on impairment of real estate assets	0	230	5,800	230
Total expenses	110,405	53,414	299,608	157,705
Operating income	(4,303)	16,765	23,296	51,657
Dividend income	304	304	912	911
Unrealized gain on equity securities	17,425	0	40,677	0
Interest income	140	1,715	405	1,843
Interest expense	(23,374)	(16,055)	(69,444)	(43,599)
Loss on early extinguishment of debt	0	(1,715)	0	(1,715)
Income (loss) from continuing operations before income taxes, equity in net earnings (losses) of investees and gain on sale of real estate	(9,808)	1,014	(4,154)	9,097
Income tax expense	(9)	(22)	(124)	(65)
Equity in earnings of an investee	94	31	(1,112)	533
Net income before gain on sale of real estate	(449)	10,989	18,482	30,081
Gain on sale of real estate	0	0	17,329	0
Net income attributed to SIR	$ (449)	$ 10,989	$ 35,811	$ 30,081
Weighted average common shares outstanding (basic) (in shares)	99,071	96,883	99,055	79,778
Weighted average common shares outstanding (diluted) (in shares)	99,071	96,958	99,075	79,852
Net income attributed to SIR per common share (basic and diluted) (in dollars per share)	$ 0	$ 0.11	$ 0.36	$ 0.38
SIR
Schedule of Equity Method Investments [Line Items]
Equity in earnings of an investee	$ 9,253	$ 9,453	$ 23,843	$ 20,271
SIR | SIR
Schedule of Equity Method Investments [Line Items]
Rental income	101,833	98,635	298,003	293,020
Tenant reimbursements and other income	20,048	19,379	60,514	57,158
Total revenues	121,881	118,014	358,517	350,178
Real estate taxes	12,518	11,489	36,748	33,168
Other operating expenses	14,814	14,649	43,714	41,039
Depreciation and amortization	35,371	34,713	105,326	102,770
Acquisition and transaction related costs	3,796	0	3,796	0
General and administrative	15,331	1,608	47,353	24,697
Write-off of straight line rents, net	0	0	10,626	12,517
Loss on asset impairment	0	0	0	4,047
Loss on impairment of real estate assets	9,706	0	9,706	229
Total expenses	91,536	62,459	257,269	218,467
Operating income	30,345	55,555	101,248	131,711
Dividend income	397	397	1,190	1,190
Unrealized gain on equity securities	22,771	0	53,159	0
Interest income	133	19	753	39
Interest expense	(23,287)	(24,383)	(69,446)	(68,278)
Loss on early extinguishment of debt	0	0	(1,192)	0
Income (loss) from continuing operations before income taxes, equity in net earnings (losses) of investees and gain on sale of real estate	30,359	31,588	85,712	64,662
Income tax expense	(185)	(177)	(446)	(364)
Equity in earnings of an investee	831	31	882	533
Net income before gain on sale of real estate	31,005	31,442	86,148	64,831
Gain on sale of real estate	4,075	0	4,075	0
Net income	35,080	31,442	90,223	64,831
Net income allocated to noncontrolling interest	(5,597)	0	(15,841)	0
Net income attributed to SIR	$ 29,483	$ 31,442	$ 74,382	$ 64,831
Weighted average common shares outstanding (basic) (in shares)	89,410	89,355	89,395	89,341
Weighted average common shares outstanding (diluted) (in shares)	89,437	89,379	89,411	89,364
Net income attributed to SIR per common share (basic and diluted) (in dollars per share)	$ 0.33	$ 0.35	$ 0.83	$ 0.73

Discontinued Operations - Addit

Discontinued Operations - Additional Information (Details) $ in Thousands	1 Months Ended
	Aug. 31, 2017USD ($)ft²propertybuilding	Sep. 30, 2018USD ($)propertybuilding	Dec. 31, 2017USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties | property		105
Number of buildings | building		164
Net book value		$ 2,135,589	$ 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
Number of buildings | building	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

Discontinued Operations - Sched

Discontinued Operations - Schedule of Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity in earnings of Select Income REIT	$ 94	$ 31	$ (1,112)	$ 533
Net gain on issuance of shares by Select Income REIT			29	72
Income from discontinued operations	9,274	9,966	23,872	20,516
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	9,253	9,453	23,843	20,271
Net gain on issuance of shares by Select Income REIT	21	51	29	72
Income from property classified as discontinued operations	0	462	0	173
Income from discontinued operations	$ 9,274	$ 9,966	$ 23,872	$ 20,516