Office Properties Income Trust (OPI) 10-Q 31 Oct 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 30, 2017
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, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		99,145,921
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Real estate properties:
Land	$ 269,332	$ 267,855
Buildings and improvements	1,660,379	1,620,905
Total real estate properties, gross	1,929,711	1,888,760
Accumulated depreciation	(331,069)	(296,804)
Total real estate properties, net	1,598,642	1,591,956
Equity investment in Select Income REIT	475,265	487,708
Assets of discontinued operations	0	12,541
Acquired real estate leases, net	99,953	124,848
Deposit escrow for FPO acquisition	651,696	0
Cash and cash equivalents	551,707	29,941
Restricted cash	509	530
Rents receivable, net	47,461	48,458
Deferred leasing costs, net	22,250	21,079
Other assets, net	89,484	68,005
Total assets	3,536,967	2,385,066
LIABILITIES AND SHAREHOLDERS’ EQUITY
Unsecured revolving credit facility	565,000	160,000
Unsecured term loans, net	547,682	547,171
Senior unsecured notes, net	943,543	646,844
Mortgage notes payable, net	26,561	27,837
Liabilities of discontinued operations	0	45
Accounts payable and other liabilities	63,525	54,019
Due to related persons	4,297	3,520
Assumed real estate lease obligations, net	8,832	10,626
Total liabilities	2,159,440	1,450,062
Commitments and contingencies
Shareholders’ equity:
Common shares of beneficial interest, $.01 par value: 150,000,000 and 100,000,000 shares authorized, 99,145,921 and 71,177,906 shares issued and outstanding, respectively	991	712
Additional paid in capital	1,968,249	1,473,533
Cumulative net income	126,410	96,329
Cumulative other comprehensive income	46,980	26,957
Cumulative common distributions	(765,103)	(662,527)
Total shareholders’ equity	1,377,527	935,004
Total liabilities and shareholders’ equity	$ 3,536,967	$ 2,385,066

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
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	100,000,000
Common shares of beneficial interest, shares issued (in shares)	99,145,921	71,177,906
Common shares of beneficial interest, shares outstanding (in shares)	99,145,921	71,177,906

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Rental income	$ 70,179	$ 64,478	$ 209,362	$ 192,150
Expenses:
Real estate taxes	8,862	7,591	24,980	22,810
Utility expenses	5,408	5,483	14,186	13,330
Other operating expenses	14,867	13,854	44,046	40,031
Depreciation and amortization	20,781	18,404	61,949	54,713
Loss on impairment of real estate	230	0	230	0
Acquisition related costs	0	147	0	363
General and administrative	3,266	3,816	12,314	11,350
Total expenses	53,414	49,295	157,705	142,597
Operating income	16,765	15,183	51,657	49,553
Dividend income	304	304	911	667
Interest income	1,715	47	1,843	63
Interest expense (including net amortization of debt premiums and discounts and debt issuance costs of $990, $805, $2,605 and $2,024, respectively)	(16,055)	(12,608)	(43,599)	(32,286)
(Loss) gain on early extinguishment of debt	(1,715)	0	(1,715)	104
Gain on issuance of shares by Select Income REIT	51	72	72	88
Income (loss) from continuing operations before income taxes and equity in earnings of investees	1,065	2,998	9,169	18,189
Income tax expense	(22)	(13)	(65)	(63)
Equity in earnings of investees	9,484	8,668	20,804	28,002
Income from continuing operations	10,527	11,653	29,908	46,128
Income (loss) from discontinued operations	462	(154)	173	(429)
Income before gain on sale of property	10,989	11,499	30,081	45,699
Gain on sale of property	0	79	0	79
Net income	10,989	11,578	30,081	45,778
Other comprehensive income:
Unrealized gain on investment in available for sale securities	3,279	8,463	14,389	28,571
Equity in unrealized gain of investees	1,351	3,273	5,634	10,423
Other comprehensive income	4,630	11,736	20,023	38,994
Comprehensive income	$ 15,619	$ 23,314	$ 50,104	$ 84,772
Weighted average common shares outstanding (basic) (in shares)	96,883	71,054	79,778	71,041
Weighted average common shares outstanding (diluted) (in shares)	96,958	71,084	79,852	71,064
Per common share amounts (basic and diluted):
Income from continuing operations (in dollars per share)	$ 0.11	$ 0.16	$ 0.37	$ 0.65
Income (loss) from discontinued operations (in dollars per share)	0	0	0	(0.01)
Net income (in dollars per share)	$ 0.11	$ 0.16	$ 0.38	$ 0.64

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Net amortization of debt premiums and discounts and deferred financing fees	$ 990	$ 805	$ 2,605	$ 2,024

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 30,081	$ 45,778
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	35,460	31,611
Net amortization of debt premiums and discounts and debt issuance costs	2,605	2,024
Gain on sale of property	0	(79)
Loss (gain) on early extinguishment of debt	1,715	(104)
Straight line rental income	(3,115)	(1,789)
Amortization of acquired real estate leases	25,592	21,948
Amortization of deferred leasing costs	2,790	2,343
Other non-cash expenses, net	352	500
Loss on impairment of real estate	230	0
Increase in carrying value of property included in discontinued operations	(619)	0
Equity in earnings of investees	(20,804)	(28,002)
Gain on issuance of shares by Select Income REIT	(72)	(88)
Distributions of earnings from Select Income REIT	18,062	25,676
Change in assets and liabilities:
Restricted cash	21	508
Deferred leasing costs	(2,846)	(7,998)
Rents receivable	3,839	(126)
Other assets	(7,045)	(1,466)
Accounts payable and accrued expenses	6,703	(150)
Due to related persons	777	1,088
Net cash provided by operating activities	93,726	91,674
CASH FLOWS FROM INVESTING ACTIVITIES:
Real estate acquisitions and deposits	(666,202)	(83,705)
Real estate improvements	(29,377)	(23,357)
Distributions in excess of earnings from Select Income REIT	20,063	11,951
Proceeds from sale of properties, net	13,198	263
Net cash used in investing activities	(662,318)	(94,848)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of mortgage notes payable	(1,150)	(107,562)
Proceeds from issuance of senior notes, after discounts	297,954	300,235
Proceeds from issuance of common shares, net	493,936	0
Borrowings on unsecured revolving credit facility	610,000	254,000
Repayments on unsecured revolving credit facility	(205,000)	(346,000)
Payment of debt issuance costs	(2,551)	(464)
Repurchase of common shares	(255)	(312)
Distributions to common shareholders	(102,576)	(91,759)
Net cash provided by financing activities	1,090,358	8,138
Increase in cash and cash equivalents	521,766	4,964
Cash and cash equivalents at beginning of period	29,941	8,785
Cash and cash equivalents at end of period	551,707	13,749
Supplemental cash flow information:
Interest paid	42,019	32,599
Income taxes paid	100	94
Non-cash investing activities:
Sale of property	0	3,600
Mortgage note receivable related to sale of property	$ 0	$ (3,600)

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2017
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 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, 2016 , or our Annual Report. In the opinion of our management, all adjustments, which include only normal recurring adjustments considered necessary for a fair presentation, 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, impairment of real estate and equity method investments and the valuation of intangible assets.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements On January 1, 2017, we adopted the Financial Accounting Standards Board, or FASB, Accounting Standards Update, or ASU, No. 2017-01, Clarifying the Definition of a Business , which provides additional guidance on evaluating whether a transaction should be accounted for as an acquisition (or disposal) of assets or of a business. This update defines three requirements for a set of assets and activities (collectively referred to as a “set”) to be considered a business: inputs, processes and outputs. As a result of the implementation of this update, certain property acquisitions, which under previous guidance were accounted for as business combinations, are now accounted for as acquisitions of assets. In an acquisition of assets, certain acquisition costs are capitalized as opposed to expensed under the previous guidance. On January 1, 2017, we adopted FASB ASU No. 2016-09, Compensation - Stock Compensation , which identifies areas for simplification involving several aspects of accounting for share based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, an option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the condensed statement of cash flows. The adoption of ASU No. 2016-09 did not have a material impact in our condensed consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, 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. In August 2015, the FASB provided for a one-year deferral of the effective date for ASU No. 2014-09, which is now effective for us beginning January 1, 2018. A substantial portion of our revenue consists of rental income from leasing arrangements, which is specifically excluded from ASU No. 2014-09. We are continuing to evaluate ASU No. 2014-09 (and related clarifying guidance issued by the FASB); however, we do not expect its adoption to have a significant impact on the amount or timing of our revenue recognition in our consolidated financial statements with the exception of profit recognition on real estate sales. We currently have recorded a deferred gain on sale of real estate of $712 that under current guidance would be recognized upon repayment of a promissory note we received in connection with the sale but will be recognized in its entirety upon adoption of ASU No. 2014-09. We currently expect to adopt the standard using the modified retrospective approach. In January 2016, the FASB issued 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. This update is effective for interim and annual periods beginning after December 15, 2017, with early adoption permitted subject to certain conditions. Currently, changes in fair value of these investments are recorded through other comprehensive income. ASU No. 2016-01 states that these changes will be recorded through earnings. We are continuing to evaluate this guidance, but we expect the implementation of this guidance will affect how changes in the fair value of available for sale securities we hold are presented in our condensed consolidated financial statements. 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. In August 2016, the FASB issued 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 statement of cash flows. ASU No. 2016-15 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We do not expect this guidance to have a material impact in our condensed consolidated financial statements and related disclosures. In November 2016, the FASB issued ASU No. 2016-18, Restricted Cash , which clarifies how companies should present restricted cash and restricted cash equivalents. Companies will show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. The new standard requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheets. ASU No. 2016-18 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Upon the adoption of ASU No. 2016-18, we will reconcile both cash and cash equivalents and restricted cash and restricted cash equivalents, whereas under the current guidance we explain the changes during the period for cash and cash equivalents only. In May 2017, the FASB issued ASU No. 2017-09, Scope of Modification Accounting , which clarifies which changes to the terms or conditions of a share based payment award are subject to the guidance on modification accounting under ASC 718. Entities would apply the modification accounting guidance unless the value, vesting requirements and classification of a share based payment award are the same immediately before and after a change to the terms or conditions of the award. ASU No. 2017-09 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We are continuing to evaluate ASU No. 2017-09; however, we do not expect its adoption to have a material impact in our condensed consolidated financial statements.

Weighted Average Common Shares

Weighted Average Common Shares	9 Months Ended
	Sep. 30, 2017
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, 2017 2016 2017 2016 Weighted average common shares for basic earnings per share 96,883 71,054 79,778 71,041 Effect of dilutive securities: unvested share awards 75 30 74 23 Weighted average common shares for diluted earnings per share 96,958 71,084 79,852 71,064

Real Estate Properties

Real Estate Properties	9 Months Ended
	Sep. 30, 2017
Real Estate [Abstract]
Real Estate Properties	Real Estate Properties As of September 30, 2017 , we owned 74 properties ( 96 buildings), with an undepreciated carrying value of $1,929,711 . We generally lease space at our properties on a gross lease or modified gross lease basis pursuant to fixed term contracts expiring between 2017 and 2034. 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, 2017 , we entered into 14 leases for 436,102 rentable square feet, for a weighted (by rentable square feet) average lease term of 8.4 years and we made commitments for $7,902 of leasing related costs. During the nine months ended September 30, 2017 , we entered into 42 leases for 1,084,633 rentable square feet, for a weighted (by rentable square feet) average lease term of 8.8 years and we made commitments for $12,609 of leasing related costs. As of September 30, 2017 , we have estimated unspent leasing related obligations of $26,631 , and we have committed to redevelop and expand an existing property prior to commencement of the lease with an estimated remaining cost to complete as of September 30, 2017 of $3,302 . During the nine months ended September 30, 2017 , we capitalized $328 of interest expense related to the redevelopment and expansion of that existing property. 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 consideration of impairment upon the events or changes in circumstances described above, we regularly evaluate the remaining lives of our long lived assets. If we change our estimate of the remaining lives, we allocate the carrying value of the affected assets over their revised remaining lives. Acquisition Activities During the nine months ended September 30, 2017 , we acquired an office property ( one building) located in Manassas, VA with 69,374 rentable square feet. This property was 100% leased to Prince William County on the date of acquisition. This transaction was accounted for as an acquisition of assets. The purchase price was $12,657 , including capitalized acquisition costs of $37 . Our allocation of the purchase price of this acquisition based on the estimated fair values of the acquired assets and assumed liabilities is presented in the table below. Number of Buildings Other Acquisition Properties/ Square Purchase and Assumed Date Location Type Buildings Feet Price Land Improvements Assets Jan-17 Manassas, VA Office 1/1 69,374 $ 12,657 $ 1,562 $ 8,253 $ 2,842 In September 2017, we acquired transferable development rights that will allow us to expand a property we own in Washington, D.C. for a purchase price of $2,030 , excluding acquisition costs. FPO Acquisition On October 2, 2017, we acquired First Potomac Realty Trust, or FPO, a Maryland REIT, pursuant to merger transactions, or collectively, the FPO Transaction, as a result of which, we acquired 39 office properties ( 74 buildings) with 6,454,382 rentable square feet, including two properties owned by joint ventures in which we acquired FPO's 50% and 51% interests. The estimated aggregate transaction value of the FPO Transaction was $1,374,624 , including $651,696 in cash consideration paid to FPO shareholders, the repayment of $483,000 of FPO debt, the assumption of $167,549 of FPO mortgage debt and an additional $82,000 of mortgage debt that encumber two joint venture properties that are 50% and 51% owned by FPO and the payment of certain transaction fees and expenses, net of FPO cash on hand. We currently expect to complete our purchase price allocation for the FPO Transaction in the fourth quarter of 2017 upon completion of third party appraisals and our analysis of acquired in place leases and building valuations. We financed the cash payments for the FPO Transaction with borrowings under our revolving credit facility and with cash on hand, including net proceeds from our public offerings of common shares and senior unsecured notes, as described further in Notes 7 and 9. The following table presents our pro forma results of operations for each of the nine months ended September 30, 2017 and 2016 as if the FPO Transaction and related financing activities had occurred on January 1, 2016. The historical FPO results of operations included in this pro forma financial information have been adjusted to remove the results of operations of properties and joint venture interests FPO sold since January 1, 2016. The effect of these adjustments was to decrease pro forma rental income $804 and $8,330 for the nine months ended September 30, 2017 and 2016 , respectively, and to decrease (increase) net income (loss) $47,019 and ($2,458) for the nine months ended September 30, 2017 and 2016 , respectively. This pro forma financial information is not necessarily indicative of what our actual results of operations would have been for the periods presented, nor does it represent the results of operations for any future period. Differences could result from numerous factors, including changes to our preliminary purchase price allocation for the FPO Transaction, future changes in our portfolio of investments, changes in interest rates, changes in our capital structure, changes in net property level operating expenses, changes in property level revenues, including rents expected to be received on our existing leases or leases we may enter into during and after 2017, and other reasons. Nine Months Ended September 30, 2017 2016 Rental income $ 328,255 $ 311,167 Net income (loss) (4,733 ) 19,411 Net income (loss) per share $ (0.05 ) $ 0.20 Disposition Activities – Continuing Operations On October 5, 2017, we sold one vacant office property ( one building) located in Albuquerque, NM with 29,045 rentable square feet and a net book value of $1,885 as of September 30, 2017 for $2,000 , excluding closing costs. During the three months ended September 30, 2017 , we recorded a $230 loss on impairment of real estate to reduce the carrying value of this property to its estimated fair value. Disposition Activities – Discontinued Operations 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. During the three months ended September 30, 2017 , we recorded an adjustment of $619 to increase the carrying value of this property to its estimated fair value less costs to sell. Summarized balance sheet and income statement information for this property is as follows: Balance Sheets September 30, December 31, 2017 2016 Real estate properties, net $ — $ 12,260 Other assets — 281 Assets of discontinued operations $ — $ 12,541 Other liabilities $ — $ 45 Liabilities of discontinued operations $ — $ 45 Statements of Operations Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Rental income $ 4 $ 6 $ 17 $ 62 Real estate taxes (40 ) (27 ) (88 ) (73 ) Utility expenses (17 ) (34 ) (97 ) (113 ) Other operating expenses (87 ) (70 ) (202 ) (219 ) General and administrative (17 ) (29 ) (76 ) (86 ) Increase in carrying value of property 619 — 619 — Income (loss) from discontinued operations $ 462 $ (154 ) $ 173 $ (429 )

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2017
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 $711 and $1,205 for the three months ended September 30, 2017 and 2016 , respectively, and $3,115 and $1,789 for the nine months ended September 30, 2017 and 2016 , respectively. Rents receivable include $24,801 and $21,686 of straight line rent receivables, net of allowance for doubtful accounts of $132 and $155 , at September 30, 2017 and December 31, 2016 , respectively.

Concentration

Concentration	9 Months Ended
	Sep. 30, 2017
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 four other government tenants combined were responsible for 87.5% and 92.4% of our annualized rental income as of September 30, 2017 and 2016 , respectively. The U.S. Government is our largest tenant by annualized rental income and was responsible for 59.8% and 63.9% of our annualized rental income as of September 30, 2017 and 2016 , respectively. Geographic Concentration At September 30, 2017 , our 74 properties ( 96 buildings) were located in 31 states and the District of Columbia. Properties located in Virginia, California, the District of Columbia, Georgia, Maryland, New York and Massachusetts were responsible for 14.8% , 14.8% , 9.5% , 8.6% , 7.0% , 6.9% and 4.9% of our annualized rental income as of September 30, 2017 , respectively.

Indebtedness

Indebtedness	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Indebtedness	Indebtedness Our principal debt obligations at September 30, 2017 were: (1) $565,000 of outstanding borrowings under our $750,000 unsecured revolving credit facility; (2) an aggregate outstanding principal amount of $550,000 of unsecured term loans; (3) an aggregate outstanding principal amount of $960,000 of public issuances of senior unsecured notes; and (4) $26,358 aggregate 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 with a syndicate of institutional lenders that includes a number of features common to all of these credit arrangements. This 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 the rate of LIBOR plus a premium, which was 125 basis points per annum at September 30, 2017 , 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, 2017 . Both the interest rate premium and the facility fee are subject to adjustment based upon changes to our credit ratings. As of September 30, 2017 , the annual interest rate payable on borrowings under our revolving credit facility was 2.4% and the weighted average annual interest rate for borrowings under our revolving credit facility was 2.4% and 1.7% for the three months ended September 30, 2017 and 2016 , respectively, and 2.2% and 1.7% for the nine months ended September 30, 2017 and 2016 , respectively. As of September 30, 2017 and October 30, 2017 , we had $565,000 and $545,000 outstanding under our revolving credit facility, respectively. 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 the rate of LIBOR plus a premium, which was 140 basis points per annum at September 30, 2017 , 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, 2017 , the annual interest rate for the amount outstanding under our $300,000 term loan was 2.6% . The weighted average annual interest rate under our $300,000 term loan was 2.6% and 1.9% for the three months ended September 30, 2017 and 2016 , respectively, and 2.4% and 1.9% for the nine months ended September 30, 2017 and 2016 , 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 the rate of LIBOR plus a premium, which was 180 basis points per annum as of September 30, 2017 , 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, 2017 , the annual interest rate for the amount outstanding under our $250,000 term loan was 3.0% . The weighted average annual interest rate under our $250,000 term loan was 3.0% and 2.3% , respectively, for the three months ended September 30, 2017 and 2016 and 2.8% and 2.3% for the nine months ended September 30, 2017 and 2016 , respectively. Our credit agreement and senior 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 The RMR Group LLC, or RMR LLC, ceasing to act as our business and property manager. Our credit agreement and our senior 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 notes indentures and their supplements at September 30, 2017 . On July 20, 2017, we issued $300,000 of 4.000% senior unsecured notes due 2022 in an underwritten public offering. The net proceeds from this offering of $295,403 , after payment of the underwriters' discount and other offering expenses, were used to finance, in part, the FPO Transaction. Concurrently with our entering into the FPO merger agreement, we entered a commitment letter with a group of institutional lenders for a 364 -day senior unsecured bridge loan facility in an initial aggregate principal amount of up to $750,000 . On July 20, 2017, we and the lenders terminated this commitment letter and bridge loan facility as a result of our issuance of the senior unsecured notes described above and the proceeds from the sale of our common shares in July 2017 (see Note 9 for more information regarding this sale), and we recognized a loss on extinguishment of debt of $1,715 . At September 30, 2017 , three of our properties ( three buildings) with an aggregate net book value of $50,031 were encumbered by three mortgages with an aggregate principal balance of $26,358 . These mortgage notes are non-recourse, subject to certain limited exceptions and do not contain any material financial covenants. As described in Note 4, in connection with the FPO Transaction we assumed five mortgage notes with an aggregate principal balance of $167,549 . These mortgage notes are secured by five properties ( five buildings). In connection with the FPO Transaction we also assumed two mortgage notes with an aggregate principal balance of $82,000 , which are secured by two properties owned by joint ventures in which we acquired FPO's 50% and 51% interests.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	9 Months Ended
	Sep. 30, 2017
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, 2017 , 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 Estimated Active Markets for Significant Other Unobservable Fair Identical Assets Observable Inputs Inputs Description Value (Level 1) (Level 2) (Level 3) Recurring Fair Value Measurements Assets: Investment in RMR Inc. (1) $ 62,351 $ 62,351 $ — $ — Non-Recurring Fair Value Measurements Assets: One property (2) $ 1,885 $ — $ 1,885 $ — (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, 2017 . The net unrealized gain of $35,463 for these shares as of September 30, 2017 is included in cumulative other comprehensive income in our condensed consolidated balance sheets. (2) We estimated the fair value of this property at September 30, 2017 based upon the selling price agreed to with a third party (Level 2 inputs as defined in the fair value hierarchy under GAAP). See Note 4 for further details. In addition to the assets described in the table above, our financial instruments include cash and cash equivalents, restricted cash, rents receivable, mortgage notes receivable, accounts payable, our 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, 2017 and December 31, 2016 , 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, 2017 As of December 31, 2016 Carrying Amount (1) Fair Value Carrying Amount (1) Fair Value Senior unsecured notes, 3.75% interest rate, due in 2019 $ 347,810 $ 357,625 $ 346,952 $ 354,078 Senior unsecured notes, 4.000% interest rate, due in 2022 295,587 302,655 — — Senior unsecured notes, 5.875% interest rate, due in 2046 300,146 325,500 299,892 292,268 Mortgage note payable, 5.88% interest rate, due in 2021 (2) 13,677 14,388 13,841 14,492 Mortgage note payable, 7.00% interest rate, due in 2019 (2) 8,490 8,739 8,778 9,188 Mortgage note payable, 8.15% interest rate, due in 2021 (2) 4,394 4,665 5,218 5,575 $ 970,104 $ 1,013,572 $ 674,681 $ 675,601 (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. 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 The Nasdaq Stock Market LLC, or Nasdaq, (Level 1 inputs as defined in the fair value hierarchy under GAAP) as of the measurement date. We estimated the fair values of our mortgage notes payable 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, 2017
Equity [Abstract]
Shareholders' Equity	Shareholders’ Equity Distributions On February 23, 2017 , we paid a regular quarterly distribution to common shareholders of record on January 23, 2017 of $0.43 per share, or $30,606 . On May 22, 2017 , we paid a regular quarterly distribution to common shareholders of record on April 21, 2017 of $0.43 per share, or $30,606 . On August 21, 2017 , we paid a regular quarterly distribution to common shareholders of record on July 24, 2017 of $0.43 per share, or $41,364 . On October 12, 2017 , we declared a regular quarterly distribution payable to common shareholders of record on October 23, 2017 of $0.43 per share, or $42,633 . We expect to pay this distribution on or about November 20, 2017 using cash on hand and borrowings under our revolving credit facility. Sale of Shares On July 5, 2017, we sold 25,000,000 of our common shares at a price of $18.50 per share in an underwritten public offering. On August 3, 2017, we sold 2,907,029 of our common shares at a price of $18.50 per share pursuant to an overallotment option granted to the underwriters for the July offering. The aggregate net proceeds from these sales were $493,936 , after payment of the underwriters' discount and other offering expenses. Share Grants and Purchases On May 17, 2017 , we granted 3,000 of our common shares, valued at $21.75 per share, the closing price of our common shares on the Nasdaq on that day, to each of our six Trustees as part of their annual compensation. On May 17, 2017 , we withheld 450 of our common shares awarded to one of our Trustees to fund that Trustee's resulting minimum required tax withholding obligation. The aggregate value of the withheld shares was $10 , which is reflected as a decrease to shareholders' equity in our condensed consolidated balance sheets. On June 30, 2017, we purchased 278 of our common shares valued at $18.31 per share, the closing price of our common shares on the Nasdaq on that day, from a former employee of RMR LLC in satisfaction of tax withholding and payment obligations in connection with vesting of awards of our common shares. On September 14, 2017, we granted an aggregate of 57,350 of our common shares to our officers and certain other employees of RMR LLC, valued at $18.61 per share, the closing price of our common shares on the Nasdaq on that day. On September 19, 2017, we purchased an aggregate of 13,636 of our common shares valued at $18.30 per share, the closing price of our common shares on the 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. Cumulative Other Comprehensive Income Cumulative other comprehensive income represents the unrealized gain on the RMR Inc. shares we own and our share of the comprehensive income of our equity method investees, Select Income REIT, or SIR, and Affiliates Insurance Company, or AIC. 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, 2017 : Three Months Ended September 30, 2017 Unrealized Gain Equity in on Investment Unrealized Gain in Available for of Sale Securities Investees Total Balance at June 30, 2017 $ 32,184 $ 10,166 $ 42,350 Other comprehensive income before reclassifications 3,279 1,355 4,634 Amounts reclassified from cumulative other comprehensive loss to net income (1) — (4 ) (4 ) Net current period other comprehensive income 3,279 1,351 4,630 Balance at September 30, 2017 $ 35,463 $ 11,517 $ 46,980 Nine Months Ended September 30, 2017 Unrealized Gain Equity in on Investment Unrealized Gain in Available for of Sale Securities Investees Total December 31, 2016 $ 21,074 $ 5,883 $ 26,957 Other comprehensive income before reclassifications 14,389 5,626 20,015 Amounts reclassified from cumulative other comprehensive income to net income (1) — 8 8 Net current period other comprehensive income 14,389 5,634 20,023 Balance at September 30, 2017 $ 35,463 $ 11,517 $ 46,980 (1) Amounts reclassified from cumulative other comprehensive income (loss) are included in equity in earnings of investees in our condensed consolidated statements of comprehensive income.

Business and Property Managemen

Business and Property Management Agreements with RMR LLC	9 Months Ended
	Sep. 30, 2017
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 $1,891 and $2,572 for the three months ended September 30, 2017 and 2016 , respectively, and $8,241 and $7,614 for the nine months ended September 30, 2017 and 2016 , respectively. As of September 30, 2017 , no annual incentive fees were estimated, based on our common share total return, as defined, as of September 30, 2017 , to be payable to RMR LLC for 2017. The business management fee for the three months ended September 30, 2017 includes the reversal of $893 of estimated incentive fees accrued as of June 30, 2017. The actual amount of annual incentive fees payable to RMR LLC for 2017, if any, will be based on our common share total return, as defined, for the three year period ending December 31, 2017, and will be payable in 2018. The net business management fees we recognized 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 $2,338 and $2,249 for the three months ended September 30, 2017 and 2016 , respectively, and $7,371 and $6,636 for the nine months ended September 30, 2017 and 2016 , 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 of 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 $3,436 and $3,221 for property management related expenses for the three months ended September 30, 2017 and 2016 , respectively, and $10,482 and $9,132 for the nine months ended September 30, 2017 and 2016 , 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 amount recognized as expense for internal audit costs was $67 and $34 for the three months ended September 30, 2017 and 2016 , respectively, and $202 and $168 for the nine months ended September 30, 2017 and 2016 , respectively. We include these amounts in general and administrative expenses in our condensed consolidated statements of comprehensive income.

Related Person Transactions

Related Person Transactions	9 Months Ended
	Sep. 30, 2017
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 provides management services and which have trustees, directors and officers who are also our Trustees or officers. Our Manager, RMR LLC. See Note 10 for further information regarding our management agreements with RMR LLC. We have historically granted share awards to certain RMR LLC employees under our equity compensation plans. In September 2017 and 2016, we granted annual share awards of 57,350 and 53,400 of our common shares, respectively, to our officers and to other employees of RMR LLC. In September 2017 and 2016, we purchased 13,636 and 13,209 of our common shares, respectively, at the closing price of our common shares on the Nasdaq on the date of purchase from our officers and other employees of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares. 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 subsidiary of RMR Inc. and RMR Inc. is the managing member of RMR LLC. The controlling shareholder of RMR Inc., ABP Trust, is owned by our Managing Trustees. As of September 30, 2017 , 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, 2017 , we owned 24,918,421 of SIR's common shares, or approximately 27.8% of its outstanding common shares. Our Managing Trustees also serve as managing trustees of SIR, our President and Chief Operating Officer and one of our Independent Trustees also serves as the president and chief operating officer and an independent trustee of SIR, respectively. RMR LLC provides management services to SIR and us. See Note 12 for further information regarding our investment in SIR. AIC . We, SIR, ABP Trust and four other companies to which RMR LLC provides management services currently own AIC, an Indiana insurance company, 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 $757 in connection with this insurance program for the policy year ending June 30, 2018, 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, 2017 and December 31, 2016, our investment in AIC had a carrying value of $8,064 and $7,235 , respectively. These amounts are included in other assets in our condensed consolidated balance sheets. We recognized income related to our investment in AIC, which amounts are 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 which are owned and held for sale by AIC. For further information about these and other such relationships and certain other related person transactions, please refer to our Annual Report.

Equity Investment in Select Inc

Equity Investment in Select Income REIT	9 Months Ended
	Sep. 30, 2017
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, 2017 , we owned 24,918,421 , or approximately 27.8% , of the then outstanding SIR common shares. SIR is a REIT which owns properties that are primarily leased to single tenants. We account for our investment in SIR under the equity method. Under the equity method, we record our proportionate share of SIR’s net income as equity in earnings of an investee in our condensed consolidated statements of comprehensive income. We recorded $9,453 and $8,655 of equity in the earnings of SIR for the three months ended September 30, 2017 and 2016 , respectively, and $20,271 and $27,895 of equity in the earnings of SIR for the nine months ended September 30, 2017 and 2016 , respectively. Our other comprehensive income includes our proportionate share of SIR’s unrealized gains of $1,236 and $3,192 for the three months ended September 30, 2017 and 2016 , respectively, and $5,339 and $10,248 for the nine months ended September 30, 2017 and 2016 , respectively. The adjusted GAAP cost basis of our investments 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, 2017 , our remaining basis difference was $87,976 and, as required under GAAP, we are 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. This accretion increased our equity in the earnings of SIR by $736 and $740 for the three months ended September 30, 2017 and 2016 , respectively, and $2,209 and $2,219 for the nine months ended September 30, 2017 and 2016 , respectively. As of September 30, 2017 , our investment in SIR had a carrying value of $475,265 and a market value, based on the closing price of SIR common shares on the Nasdaq on September 30, 2017 , of $583,589 . We periodically evaluate our equity investment in SIR for possible indicators of other than temporary impairment whenever events or changes in circumstances indicate the carrying amount of the investment might not be recoverable. These indicators may include the length of time the market value of our investment is below our cost basis, the financial condition of SIR, our intent and ability to be a long term holder of the investment and other considerations. If the decline in fair value is judged to be other than temporary, we may record an impairment charge to adjust the basis of the investment to its fair value. We received cash distributions from SIR totaling $12,708 during each of the three months ended September 30, 2017 and 2016 and $38,125 and $37,627 during the nine months ended September 30, 2017 and 2016 , respectively. The following are summarized financial data of SIR as reported in SIR’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2017 , 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, 2017 2016 Real estate properties, net $ 3,922,568 $ 3,899,792 Acquired real estate leases, net 493,780 506,298 Properties held for sale 5,829 — Cash and cash equivalents 18,155 22,127 Rents receivable, net 122,292 124,089 Other assets, net 114,771 87,376 Total assets $ 4,677,395 $ 4,639,682 Unsecured revolving credit facility $ 102,000 $ 327,000 Unsecured term loan, net 348,746 348,373 Senior unsecured notes, net 1,776,087 1,430,300 Mortgage notes payable, net 227,772 245,643 Assumed real estate lease obligations, net 70,989 77,622 Other liabilities 129,502 136,782 Shareholders' equity 2,022,299 2,073,962 Total liabilities and shareholders' equity $ 4,677,395 $ 4,639,682 Condensed Consolidated Statements of Income Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Rental income $ 98,635 $ 96,037 $ 293,020 $ 290,512 Tenant reimbursements and other income 19,379 18,999 57,158 56,660 Total revenues 118,014 115,036 350,178 347,172 Real estate taxes 11,489 10,755 33,168 31,565 Other operating expenses 14,649 14,394 41,039 39,987 Depreciation and amortization 34,713 33,366 102,770 100,240 Acquisition related costs — 13 — 71 General and administrative 1,589 7,553 24,658 21,903 Write-off of straight line rents receivable, net — — 12,517 — Loss on asset impairment — — 4,047 — Loss on impairment of real estate assets — — 229 — Total expenses 62,440 66,081 218,428 193,766 Operating income 55,574 48,955 131,750 153,406 Dividend income 397 397 1,190 872 Interest expense (24,383 ) (20,690 ) (68,278 ) (61,883 ) Income before income tax expense and equity in earnings of an investee 31,588 28,662 64,662 92,395 Income tax expense (177 ) (107 ) (364 ) (370 ) Equity in earnings of an investee 31 13 533 107 Net income 31,442 28,568 64,831 92,132 Net income allocated to noncontrolling interest — — — (33 ) Net income attributed to SIR $ 31,442 $ 28,568 $ 64,831 $ 92,099 Weighted average common shares outstanding (basic) 89,355 89,308 89,341 89,295 Weighted average common shares outstanding (diluted) $ 89,379 $ 89,334 $ 89,364 $ 89,318 Net income attributed to SIR per common share (basic and diluted) $ 0.35 $ 0.32 $ 0.73 $ 1.03

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information We operate in two separate reportable business segments: direct ownership of real estate properties and our equity method investment in SIR. Three Months Ended September 30, 2017 Investment Investment in Real Estate in SIR Corporate Consolidated Rental income $ 70,179 $ — $ — $ 70,179 Expenses: Real estate taxes 8,862 — — 8,862 Utility expenses 5,408 — — 5,408 Other operating expenses 14,867 — — 14,867 Depreciation and amortization 20,781 — — 20,781 Loss on impairment of real estate 230 — — 230 General and administrative — — 3,266 3,266 Total expenses 50,148 — 3,266 53,414 Operating income (loss) 20,031 — (3,266 ) 16,765 Dividend income — — 304 304 Interest income 54 — 1,661 1,715 Interest expense (401 ) — (15,654 ) (16,055 ) Loss on early extinguishment of debt — (1,715 ) (1,715 ) Gain on issuance of shares by Select Income REIT — 51 — 51 Income (loss) from continuing operations before income taxes and equity in earnings of investees 19,684 51 (18,670 ) 1,065 Income tax expense — — (22 ) (22 ) Equity in earnings of investees — 9,453 31 9,484 Income (loss) from continuing operations 19,684 9,504 (18,661 ) 10,527 Income from discontinued operations 462 — — 462 Net income (loss) $ 20,146 $ 9,504 $ (18,661 ) $ 10,989 Nine Months Ended September 30, 2017 Investment Investment in Real Estate in SIR Corporate Consolidated Rental income $ 209,362 $ — $ — $ 209,362 Expenses: Real estate taxes 24,980 — — 24,980 Utility expenses 14,186 — — 14,186 Other operating expenses 44,046 — — 44,046 Depreciation and amortization 61,949 — — 61,949 Loss on impairment of real estate 230 — — 230 General and administrative — — 12,314 12,314 Total expenses 145,391 — 12,314 157,705 Operating income (loss) 63,971 — (12,314 ) 51,657 Dividend income — — 911 911 Interest income 148 — 1,695 1,843 Interest expense (1,238 ) — (42,361 ) (43,599 ) Loss on early extinguishment of debt (1,715 ) — — (1,715 ) Gain on issuance of shares by Select Income REIT — 72 — 72 Income (loss) from continuing operations before income taxes and equity in earnings of investees 61,166 72 (52,069 ) 9,169 Income tax expense — — (65 ) (65 ) Equity in earnings of investees — 20,271 533 20,804 Income (loss) from continuing operations 61,166 20,343 (51,601 ) 29,908 Income from discontinued operations 173 — — 173 Net income (loss) $ 61,339 $ 20,343 $ (51,601 ) $ 30,081 As of September 30, 2017 Investment Investment in Real Estate in SIR Corporate Consolidated Total Assets $ 1,780,753 $ 475,265 $ 1,280,949 $ 3,536,967 Three Months Ended September 30, 2016 Investment Investment in Real Estate in SIR Corporate Consolidated Rental income $ 64,478 $ — $ — $ 64,478 Expenses: Real estate taxes 7,591 — — 7,591 Utility expenses 5,483 — — 5,483 Other operating expenses 13,854 — — 13,854 Depreciation and amortization 18,404 — — 18,404 Acquisition related costs 147 — — 147 General and administrative — — 3,816 3,816 Total expenses 45,479 — 3,816 49,295 Operating income (loss) 18,999 — (3,816 ) 15,183 Dividend income — — 304 304 Interest income — — 47 47 Interest expense (429 ) — (12,179 ) (12,608 ) Gain on issuance of shares by Select Income REIT — 72 — 72 Income (loss) from continuing operations before income taxes and equity in earnings of investees 18,570 72 (15,644 ) 2,998 Income tax expense — — (13 ) (13 ) Equity in earnings of investees — 8,655 13 8,668 Income (loss) from continuing operations 18,570 8,727 (15,644 ) 11,653 Loss from discontinued operations (154 ) — — (154 ) Income (loss) before gain on sale of property 18,416 8,727 (15,644 ) 11,499 Gain on sale of property 79 — — 79 Net income (loss) $ 18,495 $ 8,727 $ (15,644 ) $ 11,578 Nine Months Ended September 30, 2016 Investment Investment in Real Estate in SIR Corporate Consolidated Rental income $ 192,150 $ — $ — $ 192,150 Expenses: Real estate taxes 22,810 — — 22,810 Utility expenses 13,330 — — 13,330 Other operating expenses 40,031 — — 40,031 Depreciation and amortization 54,713 — — 54,713 Acquisition related costs 363 — — 363 General and administrative — — 11,350 11,350 Total expenses 131,247 — 11,350 142,597 Operating income (loss) 60,903 — (11,350 ) 49,553 Dividend income — — 667 667 Interest income — — 63 63 Interest expense (1,953 ) — (30,333 ) (32,286 ) Gain on early extinguishment of debt 104 — — 104 Gain on issuance of shares by Select Income REIT — 88 — 88 Income (loss) from continuing operations before income taxes and equity in earnings of investees 59,054 88 (40,953 ) 18,189 Income tax expense — — (63 ) (63 ) Equity in earnings of investees — 27,895 107 28,002 Income (loss) from continuing operations 59,054 27,983 (40,909 ) 46,128 Loss from discontinued operations (429 ) — — (429 ) Income (loss) before gain on sale of property 58,625 27,983 (40,909 ) 45,699 Gain on sale of property 79 — — 79 Net income (loss) $ 58,704 $ 27,983 $ (40,909 ) $ 45,778 As of December 31, 2016 Investment Investment in Real Estate in SIR Corporate Consolidated Total Assets $ 1,807,560 $ 487,708 $ 89,798 $ 2,385,066

Recent Accounting Pronounceme20

Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements On January 1, 2017, we adopted the Financial Accounting Standards Board, or FASB, Accounting Standards Update, or ASU, No. 2017-01, Clarifying the Definition of a Business , which provides additional guidance on evaluating whether a transaction should be accounted for as an acquisition (or disposal) of assets or of a business. This update defines three requirements for a set of assets and activities (collectively referred to as a “set”) to be considered a business: inputs, processes and outputs. As a result of the implementation of this update, certain property acquisitions, which under previous guidance were accounted for as business combinations, are now accounted for as acquisitions of assets. In an acquisition of assets, certain acquisition costs are capitalized as opposed to expensed under the previous guidance. On January 1, 2017, we adopted FASB ASU No. 2016-09, Compensation - Stock Compensation , which identifies areas for simplification involving several aspects of accounting for share based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, an option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the condensed statement of cash flows. The adoption of ASU No. 2016-09 did not have a material impact in our condensed consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, 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. In August 2015, the FASB provided for a one-year deferral of the effective date for ASU No. 2014-09, which is now effective for us beginning January 1, 2018. A substantial portion of our revenue consists of rental income from leasing arrangements, which is specifically excluded from ASU No. 2014-09. We are continuing to evaluate ASU No. 2014-09 (and related clarifying guidance issued by the FASB); however, we do not expect its adoption to have a significant impact on the amount or timing of our revenue recognition in our consolidated financial statements with the exception of profit recognition on real estate sales. We currently have recorded a deferred gain on sale of real estate of $712 that under current guidance would be recognized upon repayment of a promissory note we received in connection with the sale but will be recognized in its entirety upon adoption of ASU No. 2014-09. We currently expect to adopt the standard using the modified retrospective approach. In January 2016, the FASB issued 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. This update is effective for interim and annual periods beginning after December 15, 2017, with early adoption permitted subject to certain conditions. Currently, changes in fair value of these investments are recorded through other comprehensive income. ASU No. 2016-01 states that these changes will be recorded through earnings. We are continuing to evaluate this guidance, but we expect the implementation of this guidance will affect how changes in the fair value of available for sale securities we hold are presented in our condensed consolidated financial statements. 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. In August 2016, the FASB issued 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 statement of cash flows. ASU No. 2016-15 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We do not expect this guidance to have a material impact in our condensed consolidated financial statements and related disclosures. In November 2016, the FASB issued ASU No. 2016-18, Restricted Cash , which clarifies how companies should present restricted cash and restricted cash equivalents. Companies will show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. The new standard requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheets. ASU No. 2016-18 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Upon the adoption of ASU No. 2016-18, we will reconcile both cash and cash equivalents and restricted cash and restricted cash equivalents, whereas under the current guidance we explain the changes during the period for cash and cash equivalents only. In May 2017, the FASB issued ASU No. 2017-09, Scope of Modification Accounting , which clarifies which changes to the terms or conditions of a share based payment award are subject to the guidance on modification accounting under ASC 718. Entities would apply the modification accounting guidance unless the value, vesting requirements and classification of a share based payment award are the same immediately before and after a change to the terms or conditions of the award. ASU No. 2017-09 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We are continuing to evaluate ASU No. 2017-09; however, we do not expect its adoption to have a material impact in our condensed consolidated financial statements.

Weighted Average Common Shares

Weighted Average Common Shares (Tables)	9 Months Ended
	Sep. 30, 2017
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, 2017 2016 2017 2016 Weighted average common shares for basic earnings per share 96,883 71,054 79,778 71,041 Effect of dilutive securities: unvested share awards 75 30 74 23 Weighted average common shares for diluted earnings per share 96,958 71,084 79,852 71,064

Real Estate Properties (Tables)

Real Estate Properties (Tables)	9 Months Ended
	Sep. 30, 2017
Real Estate [Abstract]
Schedule of purchase prices of acquisitions allocated based on the estimated fair values of the acquired assets and assumed liabilities	Our allocation of the purchase price of this acquisition based on the estimated fair values of the acquired assets and assumed liabilities is presented in the table below. Number of Buildings Other Acquisition Properties/ Square Purchase and Assumed Date Location Type Buildings Feet Price Land Improvements Assets Jan-17 Manassas, VA Office 1/1 69,374 $ 12,657 $ 1,562 $ 8,253 $ 2,842
Pro forma information	The following table presents our pro forma results of operations for each of the nine months ended September 30, 2017 and 2016 as if the FPO Transaction and related financing activities had occurred on January 1, 2016. The historical FPO results of operations included in this pro forma financial information have been adjusted to remove the results of operations of properties and joint venture interests FPO sold since January 1, 2016. The effect of these adjustments was to decrease pro forma rental income $804 and $8,330 for the nine months ended September 30, 2017 and 2016 , respectively, and to decrease (increase) net income (loss) $47,019 and ($2,458) for the nine months ended September 30, 2017 and 2016 , respectively. This pro forma financial information is not necessarily indicative of what our actual results of operations would have been for the periods presented, nor does it represent the results of operations for any future period. Differences could result from numerous factors, including changes to our preliminary purchase price allocation for the FPO Transaction, future changes in our portfolio of investments, changes in interest rates, changes in our capital structure, changes in net property level operating expenses, changes in property level revenues, including rents expected to be received on our existing leases or leases we may enter into during and after 2017, and other reasons. Nine Months Ended September 30, 2017 2016 Rental income $ 328,255 $ 311,167 Net income (loss) (4,733 ) 19,411 Net income (loss) per share $ (0.05 ) $ 0.20
Summarized balance sheet and income statement information for properties classified as discontinued operations	Summarized balance sheet and income statement information for this property is as follows: Balance Sheets September 30, December 31, 2017 2016 Real estate properties, net $ — $ 12,260 Other assets — 281 Assets of discontinued operations $ — $ 12,541 Other liabilities $ — $ 45 Liabilities of discontinued operations $ — $ 45 Statements of Operations Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Rental income $ 4 $ 6 $ 17 $ 62 Real estate taxes (40 ) (27 ) (88 ) (73 ) Utility expenses (17 ) (34 ) (97 ) (113 ) Other operating expenses (87 ) (70 ) (202 ) (219 ) General and administrative (17 ) (29 ) (76 ) (86 ) Increase in carrying value of property 619 — 619 — Income (loss) from discontinued operations $ 462 $ (154 ) $ 173 $ (429 )

Fair Value of Assets and Liab23

Fair Value of Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2017
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, 2017 , 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 Estimated Active Markets for Significant Other Unobservable Fair Identical Assets Observable Inputs Inputs Description Value (Level 1) (Level 2) (Level 3) Recurring Fair Value Measurements Assets: Investment in RMR Inc. (1) $ 62,351 $ 62,351 $ — $ — Non-Recurring Fair Value Measurements Assets: One property (2) $ 1,885 $ — $ 1,885 $ — (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, 2017 . The net unrealized gain of $35,463 for these shares as of September 30, 2017 is included in cumulative other comprehensive income in our condensed consolidated balance sheets. (2) We estimated the fair value of this property at September 30, 2017 based upon the selling price agreed to with a third party (Level 2 inputs as defined in the fair value hierarchy under GAAP). See Note 4 for further details.
Schedule of fair value and carrying value of financial instruments	At September 30, 2017 and December 31, 2016 , 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, 2017 As of December 31, 2016 Carrying Amount (1) Fair Value Carrying Amount (1) Fair Value Senior unsecured notes, 3.75% interest rate, due in 2019 $ 347,810 $ 357,625 $ 346,952 $ 354,078 Senior unsecured notes, 4.000% interest rate, due in 2022 295,587 302,655 — — Senior unsecured notes, 5.875% interest rate, due in 2046 300,146 325,500 299,892 292,268 Mortgage note payable, 5.88% interest rate, due in 2021 (2) 13,677 14,388 13,841 14,492 Mortgage note payable, 7.00% interest rate, due in 2019 (2) 8,490 8,739 8,778 9,188 Mortgage note payable, 8.15% interest rate, due in 2021 (2) 4,394 4,665 5,218 5,575 $ 970,104 $ 1,013,572 $ 674,681 $ 675,601 (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.

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2017
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, 2017 : Three Months Ended September 30, 2017 Unrealized Gain Equity in on Investment Unrealized Gain in Available for of Sale Securities Investees Total Balance at June 30, 2017 $ 32,184 $ 10,166 $ 42,350 Other comprehensive income before reclassifications 3,279 1,355 4,634 Amounts reclassified from cumulative other comprehensive loss to net income (1) — (4 ) (4 ) Net current period other comprehensive income 3,279 1,351 4,630 Balance at September 30, 2017 $ 35,463 $ 11,517 $ 46,980 Nine Months Ended September 30, 2017 Unrealized Gain Equity in on Investment Unrealized Gain in Available for of Sale Securities Investees Total December 31, 2016 $ 21,074 $ 5,883 $ 26,957 Other comprehensive income before reclassifications 14,389 5,626 20,015 Amounts reclassified from cumulative other comprehensive income to net income (1) — 8 8 Net current period other comprehensive income 14,389 5,634 20,023 Balance at September 30, 2017 $ 35,463 $ 11,517 $ 46,980 (1) Amounts reclassified from cumulative other comprehensive income (loss) are included in equity in earnings of investees in our condensed consolidated statements of comprehensive income.

Equity Investment in Select I25

Equity Investment in Select Income REIT (Tables) - SIR	9 Months Ended
	Sep. 30, 2017
Schedule Of Summarized Balance Sheet Information Of Equity Method Investee	Condensed Consolidated Balance Sheets September 30, December 31, 2017 2016 Real estate properties, net $ 3,922,568 $ 3,899,792 Acquired real estate leases, net 493,780 506,298 Properties held for sale 5,829 — Cash and cash equivalents 18,155 22,127 Rents receivable, net 122,292 124,089 Other assets, net 114,771 87,376 Total assets $ 4,677,395 $ 4,639,682 Unsecured revolving credit facility $ 102,000 $ 327,000 Unsecured term loan, net 348,746 348,373 Senior unsecured notes, net 1,776,087 1,430,300 Mortgage notes payable, net 227,772 245,643 Assumed real estate lease obligations, net 70,989 77,622 Other liabilities 129,502 136,782 Shareholders' equity 2,022,299 2,073,962 Total liabilities and shareholders' equity $ 4,677,395 $ 4,639,682
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, 2017 2016 2017 2016 Rental income $ 98,635 $ 96,037 $ 293,020 $ 290,512 Tenant reimbursements and other income 19,379 18,999 57,158 56,660 Total revenues 118,014 115,036 350,178 347,172 Real estate taxes 11,489 10,755 33,168 31,565 Other operating expenses 14,649 14,394 41,039 39,987 Depreciation and amortization 34,713 33,366 102,770 100,240 Acquisition related costs — 13 — 71 General and administrative 1,589 7,553 24,658 21,903 Write-off of straight line rents receivable, net — — 12,517 — Loss on asset impairment — — 4,047 — Loss on impairment of real estate assets — — 229 — Total expenses 62,440 66,081 218,428 193,766 Operating income 55,574 48,955 131,750 153,406 Dividend income 397 397 1,190 872 Interest expense (24,383 ) (20,690 ) (68,278 ) (61,883 ) Income before income tax expense and equity in earnings of an investee 31,588 28,662 64,662 92,395 Income tax expense (177 ) (107 ) (364 ) (370 ) Equity in earnings of an investee 31 13 533 107 Net income 31,442 28,568 64,831 92,132 Net income allocated to noncontrolling interest — — — (33 ) Net income attributed to SIR $ 31,442 $ 28,568 $ 64,831 $ 92,099 Weighted average common shares outstanding (basic) 89,355 89,308 89,341 89,295 Weighted average common shares outstanding (diluted) $ 89,379 $ 89,334 $ 89,364 $ 89,318 Net income attributed to SIR per common share (basic and diluted) $ 0.35 $ 0.32 $ 0.73 $ 1.03

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Schedule of Segment Information	Three Months Ended September 30, 2017 Investment Investment in Real Estate in SIR Corporate Consolidated Rental income $ 70,179 $ — $ — $ 70,179 Expenses: Real estate taxes 8,862 — — 8,862 Utility expenses 5,408 — — 5,408 Other operating expenses 14,867 — — 14,867 Depreciation and amortization 20,781 — — 20,781 Loss on impairment of real estate 230 — — 230 General and administrative — — 3,266 3,266 Total expenses 50,148 — 3,266 53,414 Operating income (loss) 20,031 — (3,266 ) 16,765 Dividend income — — 304 304 Interest income 54 — 1,661 1,715 Interest expense (401 ) — (15,654 ) (16,055 ) Loss on early extinguishment of debt — (1,715 ) (1,715 ) Gain on issuance of shares by Select Income REIT — 51 — 51 Income (loss) from continuing operations before income taxes and equity in earnings of investees 19,684 51 (18,670 ) 1,065 Income tax expense — — (22 ) (22 ) Equity in earnings of investees — 9,453 31 9,484 Income (loss) from continuing operations 19,684 9,504 (18,661 ) 10,527 Income from discontinued operations 462 — — 462 Net income (loss) $ 20,146 $ 9,504 $ (18,661 ) $ 10,989 Nine Months Ended September 30, 2017 Investment Investment in Real Estate in SIR Corporate Consolidated Rental income $ 209,362 $ — $ — $ 209,362 Expenses: Real estate taxes 24,980 — — 24,980 Utility expenses 14,186 — — 14,186 Other operating expenses 44,046 — — 44,046 Depreciation and amortization 61,949 — — 61,949 Loss on impairment of real estate 230 — — 230 General and administrative — — 12,314 12,314 Total expenses 145,391 — 12,314 157,705 Operating income (loss) 63,971 — (12,314 ) 51,657 Dividend income — — 911 911 Interest income 148 — 1,695 1,843 Interest expense (1,238 ) — (42,361 ) (43,599 ) Loss on early extinguishment of debt (1,715 ) — — (1,715 ) Gain on issuance of shares by Select Income REIT — 72 — 72 Income (loss) from continuing operations before income taxes and equity in earnings of investees 61,166 72 (52,069 ) 9,169 Income tax expense — — (65 ) (65 ) Equity in earnings of investees — 20,271 533 20,804 Income (loss) from continuing operations 61,166 20,343 (51,601 ) 29,908 Income from discontinued operations 173 — — 173 Net income (loss) $ 61,339 $ 20,343 $ (51,601 ) $ 30,081 As of September 30, 2017 Investment Investment in Real Estate in SIR Corporate Consolidated Total Assets $ 1,780,753 $ 475,265 $ 1,280,949 $ 3,536,967 Three Months Ended September 30, 2016 Investment Investment in Real Estate in SIR Corporate Consolidated Rental income $ 64,478 $ — $ — $ 64,478 Expenses: Real estate taxes 7,591 — — 7,591 Utility expenses 5,483 — — 5,483 Other operating expenses 13,854 — — 13,854 Depreciation and amortization 18,404 — — 18,404 Acquisition related costs 147 — — 147 General and administrative — — 3,816 3,816 Total expenses 45,479 — 3,816 49,295 Operating income (loss) 18,999 — (3,816 ) 15,183 Dividend income — — 304 304 Interest income — — 47 47 Interest expense (429 ) — (12,179 ) (12,608 ) Gain on issuance of shares by Select Income REIT — 72 — 72 Income (loss) from continuing operations before income taxes and equity in earnings of investees 18,570 72 (15,644 ) 2,998 Income tax expense — — (13 ) (13 ) Equity in earnings of investees — 8,655 13 8,668 Income (loss) from continuing operations 18,570 8,727 (15,644 ) 11,653 Loss from discontinued operations (154 ) — — (154 ) Income (loss) before gain on sale of property 18,416 8,727 (15,644 ) 11,499 Gain on sale of property 79 — — 79 Net income (loss) $ 18,495 $ 8,727 $ (15,644 ) $ 11,578 Nine Months Ended September 30, 2016 Investment Investment in Real Estate in SIR Corporate Consolidated Rental income $ 192,150 $ — $ — $ 192,150 Expenses: Real estate taxes 22,810 — — 22,810 Utility expenses 13,330 — — 13,330 Other operating expenses 40,031 — — 40,031 Depreciation and amortization 54,713 — — 54,713 Acquisition related costs 363 — — 363 General and administrative — — 11,350 11,350 Total expenses 131,247 — 11,350 142,597 Operating income (loss) 60,903 — (11,350 ) 49,553 Dividend income — — 667 667 Interest income — — 63 63 Interest expense (1,953 ) — (30,333 ) (32,286 ) Gain on early extinguishment of debt 104 — — 104 Gain on issuance of shares by Select Income REIT — 88 — 88 Income (loss) from continuing operations before income taxes and equity in earnings of investees 59,054 88 (40,953 ) 18,189 Income tax expense — — (63 ) (63 ) Equity in earnings of investees — 27,895 107 28,002 Income (loss) from continuing operations 59,054 27,983 (40,909 ) 46,128 Loss from discontinued operations (429 ) — — (429 ) Income (loss) before gain on sale of property 58,625 27,983 (40,909 ) 45,699 Gain on sale of property 79 — — 79 Net income (loss) $ 58,704 $ 27,983 $ (40,909 ) $ 45,778 As of December 31, 2016 Investment Investment in Real Estate in SIR Corporate Consolidated Total Assets $ 1,807,560 $ 487,708 $ 89,798 $ 2,385,066

Recent Accounting Pronounceme27

Recent Accounting Pronouncements (Details) $ in Thousands	Sep. 30, 2017USD ($)
Accounting Policies [Abstract]
Deferred gain on sale of real estate	$ 712

Weighted Average Common Share28

Weighted Average Common Shares (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share, Basic and Diluted [Abstract]
Weighted average common shares for basic earnings per share (in shares)	96,883	71,054	79,778	71,041
Effect of dilutive securities: unvested share awards (in shares)	75	30	74	23
Weighted average common shares for diluted earnings per share (in shares)	96,958	71,084	79,852	71,064

Real Estate Properties - Narrat

Real Estate Properties - Narrative (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017USD ($)ft²leasepropertybuilding	Sep. 30, 2017USD ($)ft²leasepropertybuilding	Dec. 31, 2016USD ($)
Real Estate Properties [Line Items]
Number of properties | property	74	74
Number of buildings | building	96	96
Carrying value of real estate properties	$ 1,929,711	$ 1,929,711	$ 1,888,760
Number of leases entered | lease	14	42
Rentable square feet (in feet) | ft²	436,102	1,084,633
Weighted average lease term	8 years 4 months 24 days	8 years 9 months 18 days
Expenditures committed on leases	$ 7,902	$ 12,609
Committed but unspent tenant related obligations estimated	$ 26,631	26,631
Square foot expansion cost		3,302
Interest costs capitalized		$ 328
Continuing operations
Real Estate Properties [Line Items]
Number of properties | property	74	74
Number of buildings | building	96	96
Carrying value of real estate properties	$ 1,929,711	$ 1,929,711

Real Estate Properties - Acquis

Real Estate Properties - Acquisition Activities (Details) $ in Thousands	Oct. 02, 2017USD ($)ft²propertyjoint_venturebuilding	Sep. 30, 2017USD ($)ft²property	Jan. 31, 2017USD ($)ft²propertybuilding	Sep. 30, 2017USD ($)ft²propertybuilding	Sep. 30, 2016USD ($)
Real Estate Properties [Line Items]
Purchase price				$ 666,202	$ 83,705
Manassas, VA
Real Estate Properties [Line Items]
Number of properties | property		1	1	1
Number of buildings acquired | building			1	1
Rentable square feet of properties (in square feet) | ft²		69,374	69,374	69,374
Percentage of property leased				100.00%
Purchase price			$ 12,657	$ 12,657
Capitalized acquisition costs		$ 37		$ 37
Land			1,562
Buildings and Improvement			8,253
Other assumed assets			$ 2,842
Transferable Development Rights | Washington D.C.
Real Estate Properties [Line Items]
Consideration transferred		$ 2,030
Subsequent Event | First Potomac Realty Trust
Real Estate Properties [Line Items]
Number of properties | property	39
Number of buildings acquired | building	74
Rentable square feet of properties (in square feet) | ft²	6,454,382
Consideration transferred	$ 1,374,624
Number of joint ventures | joint_venture	2
Cash consideration paid	$ 651,696
Expected repayment of debt	$ 483,000
Subsequent Event | First Potomac Realty Trust
Real Estate Properties [Line Items]
Number of joint ventures | joint_venture	2
Subsequent Event | Joint Venture Property 1 | First Potomac Realty Trust
Real Estate Properties [Line Items]
Ownership percentage	50.00%
Subsequent Event | Joint Venture Property 2 | First Potomac Realty Trust
Real Estate Properties [Line Items]
Ownership percentage	51.00%
FPO Mortgage | Mortgage | Subsequent Event | First Potomac Realty Trust
Real Estate Properties [Line Items]
Mortgage debt assumed	$ 167,549
Joint Venture Mortgage | Mortgage | Subsequent Event | First Potomac Realty Trust
Real Estate Properties [Line Items]
Mortgage debt assumed	$ 82,000

Real Estate Properties - Pro Fo

Real Estate Properties - Pro Forma (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Rental income	$ 328,255	$ 311,167
Net (loss) income	$ (4,733)	$ 19,411
Net (loss) income per share (in dollars per share)	$ (0.05)	$ 0.20
Acquisition-related costs
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Decrease in rental income	$ 804	$ 8,330
Decrease (Increase) in net income	$ 47,019	$ (2,458)

Real Estate Properties - Dispos

Real Estate Properties - Disposition Activities (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2017USD ($)ft²propertybuilding	Sep. 30, 2017USD ($)propertybuilding	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)propertybuilding	Sep. 30, 2016USD ($)	Oct. 05, 2017USD ($)ft²propertybuilding	Dec. 31, 2016USD ($)
Real Estate Properties [Line Items]
Number of properties | property		74		74
Number of buildings | building		96		96
Net book value		$ 1,598,642		$ 1,598,642			$ 1,591,956
Loss on impairment of real estate		230	$ 0	230	$ 0
Discontinued Operations, Held-for-sale | One building | Albuquerque, NM | Office Building
Real Estate Properties [Line Items]
Aggregate sale price of properties sold, excluding closing costs				$ 2,000
Loss on impairment of real estate		230
Discontinued operations | One building | Falls Church, VA | Office Building
Real Estate Properties [Line Items]
Number of properties | property	1
Number of buildings | building	1
Rentable square feet of properties (in square feet) | ft²	164,746
Net book value	$ 12,901
Aggregate sale price of properties sold, excluding closing costs	$ 13,523
Increase in carrying value of property included in discontinued operations		$ (619)
Subsequent Event | Discontinued Operations, Held-for-sale | One building | Albuquerque, NM | Office Building
Real Estate Properties [Line Items]
Number of properties | property						1
Number of buildings | building						1
Rentable square feet of properties (in square feet) | ft²						29,045
Net book value						$ 1,885

Real Estate Properties - Balanc

Real Estate Properties - Balance Sheet Information for Disposal of Property (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets of discontinued operations	$ 0	$ 12,541
Liabilities of discontinued operations	0	45
Discontinued Operations, Held-for-sale | Discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate properties, net	0	12,260
Other assets	0	281
Assets of discontinued operations	0	12,541
Other liabilities	0	45
Liabilities of discontinued operations	$ 0	$ 45

Real Estate Properties - Income

Real Estate Properties - Income Statement Information for Disposal of Property (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations	$ 462	$ (154)	$ 173	$ (429)
Discontinued Operations, Held-for-sale | Discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rental income	4	6	17	62
Real estate taxes	(40)	(27)	(88)	(73)
Utility expenses	(17)	(34)	(97)	(113)
Other operating expenses	(87)	(70)	(202)	(219)
General and administrative	(17)	(29)	(76)	(86)
Increase in carrying value of property	619	0	619	0
Income (loss) from discontinued operations	$ 462	$ (154)	$ 173	$ (429)

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Revenue Recognition [Abstract]
Increase in rental income to record revenue on straight line basis	$ 711	$ 1,205	$ 3,115	$ 1,789
Straight line rent receivables	24,801		24,801		$ 21,686
Allowance for doubtful accounts	$ 132		$ 132		$ 155

Concentration (Details)

Concentration (Details)	9 Months Ended
	Sep. 30, 2017propertygovernment_tenantstate_governmentstatebuilding	Sep. 30, 2016
Concentration
Number of state governments | state_government	13
Number of other governments | government_tenant	4
Number of properties | property	74
Number of buildings | building	96
Number of states in which acquired properties located | state	31
Annualized rental income, excluding properties classified as discontinued operations | Virginia
Concentration
Annualized Rental income percent	14.80%
Annualized rental income, excluding properties classified as discontinued operations | California
Concentration
Annualized Rental income percent	14.80%
Annualized rental income, excluding properties classified as discontinued operations | District of Columbia
Concentration
Annualized Rental income percent	9.50%
Annualized rental income, excluding properties classified as discontinued operations | Georgia
Concentration
Annualized Rental income percent	8.60%
Annualized rental income, excluding properties classified as discontinued operations | Maryland
Concentration
Annualized Rental income percent	7.00%
Annualized rental income, excluding properties classified as discontinued operations | New York
Concentration
Annualized Rental income percent	6.90%
Annualized rental income, excluding properties classified as discontinued operations | Massachusetts
Concentration
Annualized Rental income percent	4.90%
Annualized rental income, excluding properties classified as discontinued operations | Tenant concentration | U.S. Government, state governments and Other Three Government
Concentration
Concentration risk percentage	87.50%	92.40%
Annualized rental income, excluding properties classified as discontinued operations | Tenant concentration | U.S. Government
Concentration
Concentration risk percentage	59.80%	63.90%

Indebtedness - Debt Obligations

Indebtedness - Debt Obligations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Oct. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Borrowings outstanding	$ 565,000		$ 565,000			$ 160,000
Maximum borrowing capacity on revolving credit facility	2,500,000		2,500,000
Aggregate principal amount on secured properties	26,358		26,358
Unsecured term loan, due in 2020
Debt Instrument [Line Items]
Face amount	$ 300,000		$ 300,000
Interest rate (as a percent)	2.60%		2.60%
The weighted average annual interest rate (as a percent)	2.60%	1.90%	2.40%	1.90%
Unsecured term loan, due in 2022
Debt Instrument [Line Items]
Face amount	$ 250,000		$ 250,000
Interest rate (as a percent)	3.00%		3.00%
The weighted average annual interest rate (as a percent)	3.00%	2.30%	2.80%	2.30%
Unsecured revolving credit facility
Debt Instrument [Line Items]
Borrowings outstanding	$ 565,000		$ 565,000
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)	2.40%		2.40%
The weighted average annual interest rate (as a percent)	2.40%	1.70%	2.20%	1.70%
Unsecured revolving credit facility | Subsequent Event
Debt Instrument [Line Items]
Borrowings outstanding					$ 545,000
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	Oct. 02, 2017mortgage_notepropertyloanjoint_venturebuilding	Jul. 20, 2017USD ($)	Sep. 30, 2017USD ($)propertybuilding	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)propertyloanbuilding	Sep. 30, 2016USD ($)
Debt Instrument [Line Items]
Loss on extinguishment of debt			$ 1,715	$ 0	$ 1,715	$ (104)
Number of properties secured by mortgage notes | property			3		3
Number of buildings secured by mortgage notes | building			3		3
Aggregate net book value of secured properties			$ 50,031		$ 50,031
Number of assumed secured mortgage loans | loan					3
Aggregate principal amount on secured properties			$ 26,358		$ 26,358
Senior unsecured notes, 4.000% interest rate, due in 2022
Debt Instrument [Line Items]
Interest rate (as a percent)			4.00%		4.00%
Senior unsecured notes | Senior unsecured notes, 4.000% interest rate, due in 2022
Debt Instrument [Line Items]
Face amount		$ 300,000
Interest rate (as a percent)		4.00%
Proceeds from issuance of debt		$ 295,403
Commitment Letter
Debt Instrument [Line Items]
Loss on extinguishment of debt		1,715
Commitment Letter | Bridge Loan Facility
Debt Instrument [Line Items]
Face amount		$ 750,000
Term of debt instrument		364 days
First Potomac Realty Trust | Subsequent Event
Debt Instrument [Line Items]
Number of properties secured by mortgage notes | property	5
Number of buildings secured by mortgage notes | building	5
Number of assumed secured mortgage loans | loan	5
Number mortgage notes securing joint ventures | mortgage_note	2
Number of joint ventures | joint_venture	2
First Potomac Realty Trust | Subsequent Event
Debt Instrument [Line Items]
Number of joint ventures | joint_venture	2
First Potomac Realty Trust | Joint Venture Property 1 | Subsequent Event
Debt Instrument [Line Items]
Ownership percentage	50.00%
First Potomac Realty Trust | Joint Venture Property 2 | Subsequent Event
Debt Instrument [Line Items]
Ownership percentage	51.00%

Fair Value of Assets and Liab39

Fair Value of Assets and Liabilities - Recurring and Nonrecurring Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
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 investment in available for sale securities	3,279	$ 8,463	14,389	$ 28,571
Recurring
Fair Value of Assets and Liabilities
Investment in RMR Inc.	62,351		62,351
Recurring | Level 1 inputs
Fair Value of Assets and Liabilities
Investment in RMR Inc.	62,351		62,351
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
Nonrecurring | Discontinued Operations, Held-for-sale
Fair Value of Assets and Liabilities
One property	1,885		1,885
Nonrecurring | Level 1 inputs | Discontinued Operations, Held-for-sale
Fair Value of Assets and Liabilities
One property	0		0
Nonrecurring | Level 2 inputs | Discontinued Operations, Held-for-sale
Fair Value of Assets and Liabilities
One property	1,885		1,885
Nonrecurring | Level 3 inputs | Discontinued Operations, Held-for-sale
Fair Value of Assets and Liabilities
One property	$ 0		0
Other Comprehensive Income (Loss)
Fair Value of Assets and Liabilities
Unrealized gain on investment in available for sale securities			$ 35,463

Fair Value of Assets and Liab40

Fair Value of Assets and Liabilities - Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value of Financial Instruments
Senior Notes	$ 943,543	$ 646,844
Mortgage notes payable, net	$ 26,561	27,837
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, 4.000% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)	4.00%
Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Interest rate (as a percent)	5.875%
Mortgage note payable, 5.88% interest rate, due in 2021
Fair Value of Financial Instruments
Interest rate (as a percent)	5.88%
Mortgage note payable, 7.00% interest rate, due in 2019
Fair Value of Financial Instruments
Interest rate (as a percent)	7.00%
Mortgage note payable, 8.15% interest rate, due in 2021
Fair Value of Financial Instruments
Interest rate (as a percent)	8.15%
Carrying Amount
Fair Value of Financial Instruments
Mortgage notes payable, net	$ 970,104	674,681
Carrying Amount | Senior unsecured notes, 3.75% interest rate, due in 2019
Fair Value of Financial Instruments
Senior Notes	347,810	346,952
Carrying Amount | Senior unsecured notes, 4.000% interest rate, due in 2022
Fair Value of Financial Instruments
Senior Notes	295,587	0
Carrying Amount | Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Senior Notes	300,146	299,892
Carrying Amount | Mortgage note payable, 5.88% interest rate, due in 2021
Fair Value of Financial Instruments
Mortgage notes payable, net	13,677	13,841
Carrying Amount | Mortgage note payable, 7.00% interest rate, due in 2019
Fair Value of Financial Instruments
Mortgage notes payable, net	8,490	8,778
Carrying Amount | Mortgage note payable, 8.15% interest rate, due in 2021
Fair Value of Financial Instruments
Mortgage notes payable, net	4,394	5,218
Fair Value
Fair Value of Financial Instruments
Mortgage notes payable, net	1,013,572	675,601
Fair Value | Senior unsecured notes, 3.75% interest rate, due in 2019
Fair Value of Financial Instruments
Senior Notes	357,625	354,078
Fair Value | Senior unsecured notes, 4.000% interest rate, due in 2022
Fair Value of Financial Instruments
Senior Notes	302,655	0
Fair Value | Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Senior Notes	325,500	292,268
Fair Value | Mortgage note payable, 5.88% interest rate, due in 2021
Fair Value of Financial Instruments
Mortgage notes payable, net	14,388	14,492
Fair Value | Mortgage note payable, 7.00% interest rate, due in 2019
Fair Value of Financial Instruments
Mortgage notes payable, net	8,739	9,188
Fair Value | Mortgage note payable, 8.15% interest rate, due in 2021
Fair Value of Financial Instruments
Mortgage notes payable, net	$ 4,665	$ 5,575

Shareholders' Equity - Addition

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

Oct. 12, 2017USD ($)$ / shares

Sep. 19, 2017$ / sharesshares

Sep. 14, 2017$ / sharesshares

Aug. 21, 2017USD ($)$ / shares

Aug. 03, 2017USD ($)$ / sharesshares

Jul. 05, 2017$ / sharesshares

Jun. 30, 2017$ / sharesshares

May 22, 2017USD ($)$ / shares

May 17, 2017USD ($)trustee$ / sharesshares

Feb. 23, 2017USD ($)$ / shares

Sep. 30, 2017shares

Sep. 30, 2016shares

Distributions

Cash distribution to common shareholders (in dollars per share)

$ 0.43

$ 0.43

$ 0.43

Distribution paid to common shareholders | $

$ 41,364

$ 30,606

$ 30,606

Proceeds from offering | $

$ 493,936

Number of trustees | trustee

6

Shares withheld for tax withholding (in shares) | shares

450

Value of shares withheld for tax withholding | $

$ 10

Subsequent Event

Distributions

Distribution paid to common shareholders | $

$ 42,633

Distribution payable to common shareholders (in dollars per share)

$ 0.43

Common shares | Trustees

Distributions

Common shares granted (in shares) | shares

3,000

Value of shares granted (in dollars per share)

$ 21.75

Common shares | Officers and certain employees

Distributions

Common shares granted (in shares) | shares

57,350

Value of shares granted (in dollars per share)

$ 18.61

Underwritten Public Offering

Distributions

Number of shares sold in offering (in shares) | shares

25,000,000

Price per share in offering (in dollars per share)

$ 18.50

Over-Allotment Option

Distributions

Number of shares sold in offering (in shares) | shares

2,907,029

Price per share in offering (in dollars per share)

$ 18.50

Former Employee of RMR LLC

Distributions

Stock repurchased to satisfy tax withholding obligation (in shares) | shares

13,636

278

13,636

13,209

Stock repurchased to satisfy tax withholding obligation (in dollars per share)

$ 18.30

$ 18.31

Shareholders' Equity - AOCI Rol

Shareholders' Equity - AOCI Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			$ 935,004
Other comprehensive income	$ 4,630	$ 11,736	20,023	$ 38,994
Ending balance	1,377,527		1,377,527
Unrealized Gain on Investment in Available for Sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	32,184		21,074
Other comprehensive income before reclassifications	3,279		14,389
Amounts reclassified from cumulative other comprehensive income to net income	0		0
Other comprehensive income	3,279		14,389
Ending balance	35,463		35,463
Equity in Unrealized Gain of an Investee
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	10,166		5,883
Other comprehensive income before reclassifications	1,355		5,626
Amounts reclassified from cumulative other comprehensive income to net income	(4)		8
Other comprehensive income	1,351		5,634
Ending balance	11,517		11,517
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	42,350		26,957
Other comprehensive income before reclassifications	4,634		20,015
Amounts reclassified from cumulative other comprehensive income to net income	(4)		8
Other comprehensive income	4,630		20,023
Ending balance	$ 46,980		$ 46,980

Business and Property Managem43

Business and Property Management Agreements with RMR LLC (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)employeeagreement	Sep. 30, 2016USD ($)
RMR LLC
Related Party Transaction [Line Items]
Number of employees | employee			0
Number of agreements | agreement			2
Related party expense	$ 1,891	$ 2,572	$ 8,241	$ 7,614
Reimbursement expense	3,436	3,221	10,482	9,132
Internal audit costs	67	34	202	168
Net Property Management and Construction Supervision Fees | RMR LLC
Related Party Transaction [Line Items]
Related party transaction amount	2,338	$ 2,249	$ 7,371	$ 6,636
RMR LLC | Affiliated Entity
Related Party Transaction [Line Items]
Reversal of expense with related party	$ 893
RMR LLC | Business Management Agreement, Incentive Fees | Affiliated Entity
Related Party Transaction [Line Items]
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) - USD ($) $ in Thousands	Sep. 19, 2017	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Dec. 31, 2016
SIR
Related Party Transaction [Line Items]
Shares holding (in shares)					24,918,421
Percentage of outstanding shares owned			27.80%		27.80%
RMR Inc | Class A common shares
Related Party Transaction [Line Items]
Shares holding (in shares)					1,214,225
Former Employee of RMR LLC
Related Party Transaction [Line Items]
Stock repurchased to satisfy tax withholding obligation (in shares)	13,636	278	13,636	13,209
AIC
Related Party Transaction [Line Items]
Carrying value of equity method investments			$ 8,064		$ 8,064	$ 7,235
Officers and Other Employees | Common shares
Related Party Transaction [Line Items]
Common shares granted (in shares)			57,350	53,400
Property Insurance Premium Expense | AIC
Related Party Transaction [Line Items]
Property insurance premiums paid					$ 757

Equity Investment in Select I45

Equity Investment in Select Income REIT - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Equity in earnings of investees	$ 9,484	$ 8,668	$ 20,804	$ 28,002
Investment at carrying value	$ 475,265		475,265		$ 487,708
Cash distributions from SIR			$ 18,062	25,676
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 investees	$ 9,453	8,655	$ 20,271	27,895
Equity in unrealized gain (loss) of investees	1,236	3,192	5,339	10,248
The amount of investment in exceed the underlying equity of the investee	87,976		87,976
Accretion in equity of earnings	736	740	2,209	2,219
Investment at carrying value	475,265		475,265
Equity Investments, market value	583,589		583,589
Cash distributions from SIR	$ 12,708	$ 12,708	$ 38,125	$ 37,627

Equity Investment in Select I46

Equity Investment in Select Income REIT - Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Real estate properties, net	$ 1,598,642	$ 1,591,956
Acquired real estate leases, net	99,953	124,848
Cash and cash equivalents	551,707	29,941	$ 13,749	$ 8,785
Rents receivable, net	47,461	48,458
Other assets, net	89,484	68,005
Total assets	3,536,967	2,385,066
Unsecured revolving credit facility	565,000	160,000
Unsecured term loan, net	547,682	547,171
Senior unsecured notes, net	943,543	646,844
Mortgage notes payable, net	26,561	27,837
Assumed real estate lease obligations, net	8,832	10,626
Other liabilities	63,525	54,019
Shareholders' equity	1,377,527	935,004
Total liabilities and shareholders’ equity	3,536,967	2,385,066
SIR | SIR
Schedule of Equity Method Investments [Line Items]
Real estate properties, net	3,922,568	3,899,792
Acquired real estate leases, net	493,780	506,298
Properties held for sale	5,829	0
Cash and cash equivalents	18,155	22,127
Rents receivable, net	122,292	124,089
Other assets, net	114,771	87,376
Total assets	4,677,395	4,639,682
Unsecured revolving credit facility	102,000	327,000
Unsecured term loan, net	348,746	348,373
Senior unsecured notes, net	1,776,087	1,430,300
Mortgage notes payable, net	227,772	245,643
Assumed real estate lease obligations, net	70,989	77,622
Other liabilities	129,502	136,782
Shareholders' equity	2,022,299	2,073,962
Total liabilities and shareholders’ equity	$ 4,677,395	$ 4,639,682

Equity Investment in Select I47

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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Equity Method Investments [Line Items]
Total revenues	$ 70,179	$ 64,478	$ 209,362	$ 192,150
Real estate taxes	8,862	7,591	24,980	22,810
Other operating expenses	14,867	13,854	44,046	40,031
Depreciation and amortization	20,781	18,404	61,949	54,713
Acquisition related costs	0	147	0	363
General and administrative	3,266	3,816	12,314	11,350
Loss on impairment of real estate assets	230	0	230	0
Total expenses	53,414	49,295	157,705	142,597
Operating income	16,765	15,183	51,657	49,553
Dividend income	304	304	911	667
Interest expense	(16,055)	(12,608)	(43,599)	(32,286)
Income (loss) from continuing operations before income taxes and equity in earnings of investees	1,065	2,998	9,169	18,189
Income tax expense	(22)	(13)	(65)	(63)
Equity in earnings of an investee	$ 9,484	$ 8,668	$ 20,804	$ 28,002
Weighted average common shares outstanding (basic) (in shares)	96,883	71,054	79,778	71,041
Weighted average common shares outstanding (diluted) (in shares)	96,958	71,084	79,852	71,064
Net income attributed to SIR per common share (basic and diluted) (in dollars per share)	$ 0.11	$ 0.16	$ 0.38	$ 0.64
SIR
Schedule of Equity Method Investments [Line Items]
Equity in earnings of an investee	$ 9,453	$ 8,655	$ 20,271	$ 27,895
SIR | SIR
Schedule of Equity Method Investments [Line Items]
Rental income	98,635	96,037	293,020	290,512
Tenant reimbursements and other income	19,379	18,999	57,158	56,660
Total revenues	118,014	115,036	350,178	347,172
Real estate taxes	11,489	10,755	33,168	31,565
Other operating expenses	14,649	14,394	41,039	39,987
Depreciation and amortization	34,713	33,366	102,770	100,240
Acquisition related costs	0	13	0	71
General and administrative	1,589	7,553	24,658	21,903
Write-off of straight line rents receivable, net	0	0	12,517	0
Loss on asset impairment	0	0	4,047	0
Loss on impairment of real estate assets	0	0	229	0
Total expenses	62,440	66,081	218,428	193,766
Operating income	55,574	48,955	131,750	153,406
Dividend income	397	397	1,190	872
Interest expense	(24,383)	(20,690)	(68,278)	(61,883)
Income (loss) from continuing operations before income taxes and equity in earnings of investees	31,588	28,662	64,662	92,395
Income tax expense	(177)	(107)	(364)	(370)
Equity in earnings of an investee	31	13	533	107
Net income	31,442	28,568	64,831	92,132
Net income allocated to noncontrolling interest	0	0	0	(33)
Net income attributed to SIR	$ 31,442	$ 28,568	$ 64,831	$ 92,099
Weighted average common shares outstanding (basic) (in shares)	89,355	89,308	89,341	89,295
Weighted average common shares outstanding (diluted) (in shares)	89,379	89,334	89,364	89,318
Net income attributed to SIR per common share (basic and diluted) (in dollars per share)	$ 0.35	$ 0.32	$ 0.73	$ 1.03

Segment Information (Details)

Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)segment	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Number of segments | segment			2
Rental income	$ 70,179	$ 64,478	$ 209,362	$ 192,150
Expenses:
Real estate taxes	8,862	7,591	24,980	22,810
Utility expenses	5,408	5,483	14,186	13,330
Other operating expenses	14,867	13,854	44,046	40,031
Depreciation and amortization	20,781	18,404	61,949	54,713
Loss on impairment of real estate	230	0	230	0
Acquisition related costs	0	147	0	363
General and administrative	3,266	3,816	12,314	11,350
Total expenses	53,414	49,295	157,705	142,597
Operating income	16,765	15,183	51,657	49,553
Dividend income	304	304	911	667
Interest income	1,715	47	1,843	63
Interest expense	(16,055)	(12,608)	(43,599)	(32,286)
(Loss) gain on early extinguishment of debt	(1,715)	0	(1,715)	104
Gain on issuance of shares by Select Income REIT	51	72	72	88
Income (loss) from continuing operations before income taxes and equity in earnings of investees	1,065	2,998	9,169	18,189
Income tax expense	(22)	(13)	(65)	(63)
Equity in earnings of investees	9,484	8,668	20,804	28,002
Income from continuing operations	10,527	11,653	29,908	46,128
Income (loss) from discontinued operations	462	(154)	173	(429)
Income (loss) before gain on sale of property	10,989	11,499	30,081	45,699
Gain on sale of property	0	79	0	79
Net income	10,989	11,578	30,081	45,778
Total assets	3,536,967		3,536,967		$ 2,385,066
Operating Segments | Investment in Real Estate
Segment Reporting Information [Line Items]
Rental income	70,179	64,478	209,362	192,150
Expenses:
Real estate taxes	8,862	7,591	24,980	22,810
Utility expenses	5,408	5,483	14,186	13,330
Other operating expenses	14,867	13,854	44,046	40,031
Depreciation and amortization	20,781	18,404	61,949	54,713
Loss on impairment of real estate	230		230
Acquisition related costs		147		363
Total expenses	50,148	45,479	145,391	131,247
Operating income	20,031	18,999	63,971	60,903
Interest income	54		148	0
Interest expense	(401)	(429)	(1,238)	(1,953)
(Loss) gain on early extinguishment of debt			(1,715)	104
Income (loss) from continuing operations before income taxes and equity in earnings of investees	19,684	18,570	61,166	59,054
Income from continuing operations	19,684	18,570	61,166	59,054
Income (loss) from discontinued operations	462	(154)	173	(429)
Income (loss) before gain on sale of property		18,416		58,625
Gain on sale of property		79		79
Net income	20,146	18,495	61,339	58,704
Total assets	1,780,753		1,780,753		1,807,560
Operating Segments | Investment in SIR
Expenses:
Gain on issuance of shares by Select Income REIT	51	72	72	88
Income (loss) from continuing operations before income taxes and equity in earnings of investees	51	72	72	88
Equity in earnings of investees	9,453	8,655	20,271	27,895
Income from continuing operations	9,504	8,727	20,343	27,983
Income (loss) before gain on sale of property		8,727		27,983
Net income	9,504	8,727	20,343	27,983
Total assets	475,265		475,265		487,708
Corporate, Non-Segment
Expenses:
Acquisition related costs				0
General and administrative	3,266	3,816	12,314	11,350
Total expenses	3,266	3,816	12,314	11,350
Operating income	(3,266)	(3,816)	(12,314)	(11,350)
Dividend income	304	304	911	667
Interest income	1,661	47	1,695	63
Interest expense	(15,654)	(12,179)	(42,361)	(30,333)
(Loss) gain on early extinguishment of debt	(1,715)
Income (loss) from continuing operations before income taxes and equity in earnings of investees	(18,670)	(15,644)	(52,069)	(40,953)
Income tax expense	(22)	(13)	(65)	(63)
Equity in earnings of investees	31	13	533	107
Income from continuing operations	(18,661)	(15,644)	(51,601)	(40,909)
Income (loss) before gain on sale of property		(15,644)		(40,909)
Net income	(18,661)	$ (15,644)	(51,601)	$ (40,909)
Total assets	$ 1,280,949		$ 1,280,949		$ 89,798