Office Properties Income Trust (OPI) 10-Q 1 Nov 19 2019 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	1-34364
Entity Registrant Name	Office Properties Income Trust
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	26-4273474
Entity Address, Address Line One	Two Newton Place
Entity Address, Address Line Two	255 Washington Street
Entity Address, Address Line Three	Suite 300
Entity Address, City or Town	Newton
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02458-1634
City Area Code	617
Local Phone Number	219-1440
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		48,202,778
Entity Central Index Key	0001456772
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Common Shares of Beneficial Interest
Entity Information [Line Items]
Title of 12(b) Security	Common Shares of Beneficial Interest
Trading Symbol	OPI
Security Exchange Name	NASDAQ
5.875% Senior Notes due 2046
Entity Information [Line Items]
Title of 12(b) Security	5.875% Senior Notes due 2046
Trading Symbol	OPINI
Security Exchange Name	NASDAQ

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019		Dec. 31, 2018
Real estate properties:
Land	$ 854,083		$ 924,164
Buildings and improvements	2,702,657		3,020,472
Total real estate properties, gross	3,556,740		3,944,636
Accumulated depreciation	(375,565)		(375,147)
Total real estate properties, net	3,181,175		3,569,489
Assets of properties held for sale	155,395		253,501
Investments in unconsolidated joint ventures	40,502		43,665
Acquired real estate leases, net	808,817		1,056,558
Cash and cash equivalents	29,002		35,349
Restricted cash	4,031	[1]	3,594
Rents receivable, net	70,234		72,051
Deferred leasing costs, net	37,890		25,672
Other assets, net	33,203		178,704
Total assets	4,360,249		5,238,583
LIABILITIES AND SHAREHOLDERS’ EQUITY
Unsecured revolving credit facility	210,000		175,000
Unsecured term loans, net	0		387,152
Senior unsecured notes, net	2,015,099		2,357,497
Mortgage notes payable, net	311,025		335,241
Liabilities of properties held for sale	16,240		4,271
Accounts payable and other liabilities	118,338		145,536
Due to related persons	7,674		34,887
Assumed real estate lease obligations, net	15,260		20,031
Total liabilities	2,693,636		3,459,615
Commitments and contingencies
Shareholders’ equity:
Common shares of beneficial interest, $.01 par value: 200,000,000 shares authorized, 48,203,332 and 48,082,903 shares issued and outstanding, respectively	482		481
Additional paid in capital	2,612,062		2,609,801
Cumulative net income	112,188		146,882
Cumulative other comprehensive income (loss)	(461)		106
Cumulative common distributions	(1,057,658)		(978,302)
Total shareholders’ equity	1,666,613		1,778,968
Total liabilities and shareholders’ equity	$ 4,360,249		$ 5,238,583
[1]	Restricted cash consists of amounts escrowed for future real estate taxes, insurance, leasing costs, capital expenditures and debt service, as required by certain of our mortgage debts.

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
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)	200,000,000	200,000,000
Common shares of beneficial interest, shares issued (in shares)	48,203,332	48,082,903
Common shares of beneficial interest, shares outstanding (in shares)	42,203,332	48,082,903

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Rental income	$ 167,411	$ 106,102	$ 518,220	$ 322,904
Expenses:
Real estate taxes	18,824	12,072	55,363	37,402
Utility expenses	9,518	7,783	26,369	20,490
Other operating expenses	30,376	21,785	90,204	66,221
Depreciation and amortization	74,939	42,569	226,373	129,444
Loss on impairment of real estate	8,521	0	14,105	5,800
Acquisition and transaction related costs	0	3,813	682	3,813
General and administrative	7,990	22,383	25,457	36,438
Total expenses	150,168	110,405	438,553	299,608
Gain on sale of real estate	11,463	0	33,538	17,329
Dividend income	0	304	1,960	912
Gain (loss) on equity securities, net	0	17,425	(44,007)	40,677
Interest income	358	140	847	405
Interest expense (including amortization of debt premiums, discounts and issuance costs of $2,560, $893, $8,264 and $2,749, respectively)	(32,367)	(23,374)	(104,848)	(69,444)
Loss on early extinguishment of debt	(284)	0	(769)	0
Income (loss) from continuing operations before income tax expense and equity in net income (loss) of investees	(3,587)	(9,808)	(33,612)	13,175
Income tax expense	(156)	(9)	(509)	(124)
Equity in net income (loss) of investees	(196)	94	(573)	(1,112)
Income (loss) from continuing operations	(3,939)	(9,723)	(34,694)	11,939
Income from discontinued operations	0	9,274	0	23,872
Net income (loss)	(3,939)	(449)	(34,694)	35,811
Other comprehensive income (loss):
Unrealized gain (loss) on financial instrument	80	0	(287)	0
Equity in unrealized gain (loss) of investees	(46)	126	91	119
Other comprehensive income (loss)	34	126	(196)	119
Comprehensive income (loss)	(3,905)	(323)	(34,890)	35,930
Net income (loss)	(3,939)	(449)	(34,694)	35,811
Preferred units of limited partnership distributions	0	0	0	(371)
Net income (loss) available for common shareholders	$ (3,939)	$ (449)	$ (34,694)	$ 35,440
Weighted average common shares outstanding (basic) (in shares)	48,073	24,768	48,051	24,764
Weighted average common shares outstanding (diluted) (in shares)	48,073	24,768	48,051	24,769
Per common share amounts (basic and diluted):
Income (loss) from continuing operations (in dollars per share)	$ (0.08)	$ (0.39)	$ (0.72)	$ 0.47
Income from discontinued operations (in dollars per share)	0	0.37	0	0.96
Net income (loss) available for common shareholders (in dollars per share)	$ (0.08)	$ (0.02)	$ (0.72)	$ 1.43

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net amortization of debt premiums and discounts and issuance costs	$ 2,560	$ 893	$ 8,264	$ 2,749

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Shares	Additional Paid In Capital	Cumulative Net Income	Cumulative Other Comprehensive Income (Loss)	Cumulative Common Distributions
Balance (in shares) at Dec. 31, 2017		24,786,479
Balance beginning at Dec. 31, 2017	$ 1,330,043	$ 248	$ 1,968,960	$ 108,144	$ 60,427	$ (807,736)
Increase (Decrease) in Shareholders' Equity
Net current period other comprehensive loss	(41)				(41)
Net income available for common shareholders	6,287			6,287
Distributions to common shareholders	(42,632)					(42,632)
Share repurchases (in shares)		(153)
Share repurchases	(11)		(11)
Balance (in shares) at Mar. 31, 2018		24,786,326
Balance ending at Mar. 31, 2018	1,294,358	$ 248	1,968,949	175,424	105	(850,368)
Balance (in shares) at Dec. 31, 2017		24,786,479
Balance beginning at Dec. 31, 2017	1,330,043	$ 248	1,968,960	108,144	60,427	(807,736)
Increase (Decrease) in Shareholders' Equity
Net current period other comprehensive loss	119
Net income available for common shareholders	35,440
Equity in unrealized gain of investees	119
Balance (in shares) at Sep. 30, 2018		24,801,300
Balance ending at Sep. 30, 2018	1,239,361	$ 248	1,969,914	204,577	265	(935,643)
Balance (in shares) at Mar. 31, 2018		24,786,326
Balance beginning at Mar. 31, 2018	1,294,358	$ 248	1,968,949	175,424	105	(850,368)
Increase (Decrease) in Shareholders' Equity
Share grants (in shares)		5,250
Share grants	297		297
Net income available for common shareholders	29,602			29,602
Distributions to common shareholders	(42,634)					(42,634)
Share repurchases (in shares)		(113)
Share repurchases	(7)		(7)
Equity in unrealized gain of investees	34				34
Balance (in shares) at Jun. 30, 2018		24,791,463
Balance ending at Jun. 30, 2018	1,281,650	$ 248	1,969,239	205,026	139	(893,002)
Increase (Decrease) in Shareholders' Equity
Share grants (in shares)		14,675
Share grants	887		887
Net current period other comprehensive loss	126
Net income available for common shareholders	(449)			(449)
Distributions to common shareholders	(42,641)					(42,641)
Share repurchases (in shares)		(4,838)
Share repurchases	(212)		(212)
Equity in unrealized gain of investees	126				126
Balance (in shares) at Sep. 30, 2018		24,801,300
Balance ending at Sep. 30, 2018	1,239,361	$ 248	1,969,914	204,577	265	(935,643)
Balance (in shares) at Dec. 31, 2018		48,082,903
Balance beginning at Dec. 31, 2018	1,778,968	$ 481	2,609,801	146,882	106	(978,302)
Increase (Decrease) in Shareholders' Equity
Share grants (in shares)		9,000
Share grants	865		865
Amounts reclassified from cumulative other comprehensive income to net income	(371)				(371)
Net current period other comprehensive loss	(32)				(32)
Net income available for common shareholders	34,019			34,019
Distributions to common shareholders	(26,445)					(26,445)
Balance (in shares) at Mar. 31, 2019		48,091,903
Balance ending at Mar. 31, 2019	1,787,004	$ 481	2,610,666	180,901	(297)	(1,004,747)
Balance (in shares) at Dec. 31, 2018		48,082,903
Balance beginning at Dec. 31, 2018	1,778,968	$ 481	2,609,801	146,882	106	(978,302)
Increase (Decrease) in Shareholders' Equity
Net current period other comprehensive loss	(196)
Net income available for common shareholders	(34,694)
Equity in unrealized gain of investees	91
Balance (in shares) at Sep. 30, 2019		48,203,332
Balance ending at Sep. 30, 2019	1,666,613	$ 482	2,612,062	112,188	(461)	(1,057,658)
Balance (in shares) at Mar. 31, 2019		48,091,903
Balance beginning at Mar. 31, 2019	1,787,004	$ 481	2,610,666	180,901	(297)	(1,004,747)
Increase (Decrease) in Shareholders' Equity
Share grants (in shares)		24,000
Share grants	971		971
Net current period other comprehensive loss	(198)				(198)
Net income available for common shareholders	(64,774)			(64,774)
Distributions to common shareholders	(26,450)					(26,450)
Share repurchases (in shares)		(2,245)
Share repurchases	(63)		(63)
Share forfeitures (in shares)		(214)
Share forfeitures	(4)		(4)
Balance (in shares) at Jun. 30, 2019		48,113,444
Balance ending at Jun. 30, 2019	1,696,486	$ 481	2,611,570	116,127	(495)	(1,031,197)
Increase (Decrease) in Shareholders' Equity
Share grants (in shares)		103,100
Share grants	889	$ 1	888
Net current period other comprehensive loss	34				34
Net income available for common shareholders	(3,939)			(3,939)
Distributions to common shareholders	(26,461)					(26,461)
Share repurchases (in shares)		(13,212)
Share repurchases	(396)		(396)
Equity in unrealized gain of investees	(46)
Balance (in shares) at Sep. 30, 2019		48,203,332
Balance ending at Sep. 30, 2019	$ 1,666,613	$ 482	$ 2,612,062	$ 112,188	$ (461)	$ (1,057,658)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ (34,694)	$ 35,811
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation	68,095	51,121
Amortization of debt premiums, discounts and issuance costs	8,264	2,749
Amortization of acquired real estate leases	157,108	77,434
Amortization of deferred leasing costs	4,329	3,524
Gain on sale of real estate	(33,538)	(17,329)
Loss on impairment of real estate	14,105	5,800
Loss on early extinguishment of debt	769	0
Straight line rental income	(19,365)	(7,825)
Other non-cash expenses, net	1,907	189
(Gain) loss on equity securities, net	44,007	(40,677)
Equity in losses of investees	573	1,112
Equity in earnings of Select Income REIT included in discontinued operations	0	(23,843)
Net gain on issuance of shares by Select Income REIT included in discontinued operations	0	(29)
Distributions of earnings from Select Income REIT	0	23,843
Change in assets and liabilities:
Rents receivable	17,185	7,535
Deferred leasing costs	(22,759)	(5,937)
Other assets	(32)	(1,393)
Accounts payable and other liabilities	(30,603)	(10,361)
Due to related persons	(27,213)	18,441
Net cash provided by operating activities	148,138	120,165
CASH FLOWS FROM INVESTING ACTIVITIES:
Real estate improvements	(39,010)	(32,625)
Distributions in excess of earnings from Select Income REIT	0	14,281
Distributions in excess of earnings from unconsolidated joint ventures	1,973	3,046
Proceeds from sale of properties, net	572,131	142,189
Proceeds from sale of RMR Inc. common shares, net	104,674	0
Net cash provided by investing activities	639,768	126,891
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of mortgage notes payable	(11,001)	(2,732)
Repayment of unsecured term loans	(388,000)	0
Repayment of senior unsecured notes	(350,000)	0
Borrowings on unsecured revolving credit facility	420,000	95,000
Repayments on unsecured revolving credit facility	(385,000)	(198,000)
Repurchase of common shares	(459)	(232)
Redemption of preferred units of limited partnership	0	(20,221)
Preferred units of limited partnership distributions	0	(646)
Distributions to common shareholders	(79,356)	(127,907)
Net cash used in financing activities	(793,816)	(254,738)
Decrease in cash, cash equivalents and restricted cash	(5,910)	(7,682)
Cash, cash equivalents and restricted cash at beginning of period	38,943	19,680
Cash, cash equivalents and restricted cash at end of period	33,033	11,998
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid	114,226	72,651
Income taxes paid	491	44
SUPPLEMENTAL DISCLOSURE OF CASH, CASH EQUIVALENTS AND RESTRICTED CASH:
Total cash, cash equivalents and restricted cash shown in the condensed consolidated statements of cash flows	$ 38,943	$ 19,680

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements of Office Properties Income Trust and its subsidiaries, or OPI, 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, 2018 , or our 2018 Annual Report. In the opinion of management, all adjustments, consisting of normal recurring accruals considered necessary for a fair statement of results for the interim period have been included. All intercompany transactions and balances with or among our consolidated subsidiaries have been eliminated. Our operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. Reclassifications have been made to the prior years' condensed consolidated financial statements to conform to the current year’s presentation.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2016-02, Leases . In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements . In December 2018, the FASB issued ASU No. 2018-20 Leases (Topic 842), Narrow-Scope Improvements for Lessors . Collectively, these standards set out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). ASU No. 2016-02 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase of the leased asset by the lessee. This classification will determine whether the lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease. ASU No. 2016-02 requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales type leases, direct financing leases and operating leases. These standards were effective as of January 1, 2019. Upon adoption, we applied the package of practical expedients that has allowed us to not reassess (i) whether any expired or existing contracts are or contain leases, (ii) lease classification for any expired or existing leases and (iii) initial direct costs for any expired or existing leases. Furthermore, we applied the optional transition method in ASU No. 2018-11, which has allowed us to initially apply the new leases standard at the adoption date and recognize a cumulative effect adjustment to the opening balance of retained earnings in the adoption period, although we did not have an adjustment. Additionally, our leases met the criteria in ASU No. 2018-11 to not separate non-lease components from the related lease component; therefore, the accounting for these leases remained largely unchanged from the previous standard. The adoption of ASU No. 2016-02 and the related improvements did not have a material impact in our condensed consolidated financial statements. Upon adoption, (i) allowances for bad debts are now recognized as a direct reduction of rental income, and (ii) legal costs associated with the execution of our leases, which were previously capitalized and amortized over the life of their respective leases, are expensed as incurred. Subsequent to January 1, 2019, provisions for credit losses are now included in "rental income" in our condensed consolidated financial statements. Provisions for credit losses prior to January 1, 2019 were previously included in other operating expenses in our condensed consolidated financial statements and prior periods are not reclassified to conform to the current presentation. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments

Weighted Average Common Shares

Weighted Average Common Shares	9 Months Ended
	Sep. 30, 2019
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, 2019 2018 2019 2018 Weighted average common shares for basic earnings per share 48,073 24,768 48,051 24,764 Effect of dilutive securities: unvested share awards — — — 5 Weighted average common shares for diluted earnings per share (1) 48,073 24,768 48,051 24,769 (1) For the three and nine months ended September 30, 2019, 22 and 11 unvested common shares, respectively, were not included in the calculation of diluted earnings per share because to do so would have been antidilutive. For the three months ended September 30, 2018, 8 unvested common shares were not included in the calculation of diluted earnings per share because to do so would have been antidilutive.

Real Estate Properties

Real Estate Properties	9 Months Ended
	Sep. 30, 2019
Real Estate [Abstract]
Real Estate Properties	Real Estate Properties As of September 30, 2019 , our wholly owned properties were comprised of 200 properties with approximately 27,290,000 rentable square feet, with an aggregate undepreciated carrying value of $3,727,607 , including $170,867 classified as held for sale, and we had a noncontrolling ownership interest in three properties totaling approximately 443,867 rentable square feet through two unconsolidated joint ventures in which we own 50% and 51% interests. We generally lease space at our properties on a gross lease, modified gross lease or net lease basis pursuant to fixed term contracts expiring between 2019 and 2039 . Some of our leases 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, 2019 , we entered into 22 leases for 759,162 rentable square feet, for a weighted (by rentable square feet) average lease term of 12.7 years and we made leasing cost commitments of $17,567 . During the nine months ended September 30, 2019 , we entered into 78 leases for 2,155,394 rentable square feet, for a weighted (by rentable square feet) average lease term of 9.1 years and we made leasing cost commitments of $61,748 . As of September 30, 2019 , we have estimated unspent leasing related obligations of $56,494 . We regularly evaluate whether events or changes in circumstances have occurred that could indicate an impairment in the value of our long lived assets. If there is an indication that the carrying value of an asset is not recoverable, we estimate the projected undiscounted cash flows to determine if an impairment loss should be recognized. We determine the amount of any impairment loss by comparing the historical carrying value to estimated fair value. We estimate fair value through an evaluation of recent financial performance and projected discounted cash flows using standard industry valuation techniques. In addition to evaluating for impairment upon the events or changes in circumstances described above, we regularly evaluate the remaining lives of our long lived assets. If we change our estimate of the remaining lives, we allocate the carrying value of the affected assets over their revised remaining lives. Disposition Activities During the nine months ended September 30, 2019 , we sold 47 properties with a combined 4,610,104 rentable square feet for an aggregate sales price of $584,865 , excluding closing costs. The sales of these properties, as presented in the table below, do not represent significant dispositions individually or in the aggregate nor do they represent a strategic shift in our business. As a result, the results of operations of these properties are included in continuing operations through the date of sale in our condensed consolidated statements of comprehensive income (loss). Date of Sale Number of Properties Location Rentable Square Feet Gross Sales Price (1) Feb 2019 (2) 34 Northern Virginia and Maryland 1,635,868 $ 198,500 Mar 2019 (3) 1 Washington, D.C. 129,035 70,000 May 2019 (4) 1 Buffalo, NY 121,711 16,900 May 2019 1 Maynard, MA 287,037 5,000 June 2019 1 Kapolei, HI 416,956 7,100 July 2019 1 San Jose, CA 71,750 14,000 July 2019 (5) 1 Nashua, NH 321,800 25,000 August 2019 1 Arlington, TX 182,630 14,900 August 2019 1 Rochester, NY 94,800 4,765 August 2019 1 Hanover, PA 502,300 5,500 August 2019 1 San Antonio, TX 618,017 198,000 September 2019 1 Topeka, KS 143,934 15,600 September 2019 (6) 1 Falling Waters, WV 40,348 650 September 2019 (7) 1 San Diego, CA 43,918 8,950 47 4,610,104 $ 584,865 (1) Gross sales price includes purchase price adjustments, if any, and excludes closing costs. (2) We recorded a $447 loss on impairment of real estate during 2019 as a result of this sale. (3) We recorded a $22,075 gain on sale of real estate during 2019 as a result of this sale. (4) We recorded a $5,137 loss on impairment of real estate during 2019 as a result of this sale. (5) We recorded a $8,401 gain on sale of real estate during 2019 as a result of this sale. (6) We recorded a $2,179 loss on impairment of real estate during 2019 as a result of this sale. (7) We recorded a $3,062 gain on sale of real estate during 2019 as a result of this sale. As of September 30, 2019 , we had 15 properties with an aggregate undepreciated carrying value of $170,867 classified as held for sale in our condensed consolidated balance sheet. The operating results of these properties are included in continuing operations in our condensed consolidated statements of comprehensive income (loss). As of October 31, 2019, three of the 15 properties held for sale were sold and 10 of the 15 properties held for sale were under contract to be sold as summarized in the table below: Location Number of Properties Square Feet Gross (1) San Jose, CA 1 75,621 $ 13,000 Windsor, CT 1 97,256 7,000 Kansas City, KS (2) 1 170,817 11,700 DC Metro - MD (3) 4 457,279 66,600 Columbia, SC (4) 3 180,703 10,750 Fairfax, VA 1 83,130 23,000 Stafford, VA 2 64,656 14,563 13 1,129,462 $ 146,613 (1) Gross sales price includes purchase price adjustments, if any, and excludes closing costs. (2) We recorded a $ 2,408 loss on impairment of real estate to adjust the carrying value of this property to its estimated fair value less costs to sell. (3) We recorded a $688 loss on impairment of real estate to adjust the carrying value of these four properties to their estimated fair value less costs to sell. (4) We recorded a $3,246 loss on impairment of real estate to adjust the carrying value of these three properties to their estimated fair value less costs to sell. The sale of these properties was completed in October 2019. In addition to the properties discussed above, we are currently marketing for sale six properties comprising approximately 587,000 square feet. We have determined that these properties were not impaired nor did they meet the held for sale criteria as of September 30, 2019 . We cannot be sure we will sell any of our properties that we are marketing for sale, that we sell them for prices in excess of our carrying values or that we will not recognize impairment losses with respect to these properties. In addition, our pending sales are subject to conditions; accordingly, we cannot be sure that we will complete these sales or that these sales will not be delayed or their terms will not change. Acquisition Activities In July 2019, we entered into an agreement to acquire a land parcel near one of our properties located in Boston, MA for $2,900 , excluding acquisition related costs. Pro Forma Financial Information On December 31, 2018, we acquired Select Income REIT, or SIR, in a merger of SIR with and into our wholly owned subsidiary that closed on December 31, 2018, or the Merger, pursuant to an agreement and plan of merger, or the Merger Agreement, that we and SIR entered into on September 14, 2018, as a result of which we acquired 99 properties with approximately 16.5 million rentable square feet. The aggregate transaction value of the Merger was $2,415,053 , excluding closing costs of approximately $27,497 ( $14,508 of which was paid by us and $12,989 of which was paid by SIR) and including the repayment or assumption of $1,719,772 of SIR debt. As a condition of the Merger, on October 9, 2018 , we sold all of the 24,918,421 common shares of SIR we then owned, or the Secondary Sale, in an underwritten public offering at a price to the public of $18.25 per share, raising net proceeds of $435,125 , after deducting underwriting discounts and offering expenses. We used the net proceeds from the Secondary Sale to repay amounts outstanding under our revolving credit facility. In addition, as a condition of the Merger, on December 27, 2018, SIR paid a pro rata distribution to SIR's shareholders of record as of the close of business on December 20, 2018 of all 45,000,000 common shares of beneficial interest of Industrial Logistics Properties Trust, or ILPT, that SIR owned, or the ILPT Distribution. For further information about these transactions, refer to our 2018 Annual Report. The following table presents our pro forma results of operations for the nine months ended September 30, 2018 as if the Merger, the Secondary Sale and the ILPT Distribution had occurred on January 1, 2018. The SIR results of operations included in this pro forma financial information have been adjusted to remove ILPT's results of operations for the nine months ended September 30, 2018 . The effect of the adjustments to remove ILPT's results of operations was to decrease pro forma rental income by $120,456 for the nine months ended September 30, 2018 and to decrease net income by $38,818 for the nine months ended September 30, 2018 from the amounts that would have otherwise been included in the pro forma results. This unaudited pro forma financial information is not necessarily indicative of what our actual results of operations would have been for the period presented or for any future period. Differences could result from numerous factors, including future changes in our portfolio of investments, capital structure, property level operating expenses and revenues, including rents expected to be received pursuant to our existing leases or leases we may enter into, changes in interest rates and other reasons. Actual future results are likely to be different from amounts presented in this unaudited pro forma financial information and such differences could be significant. Nine Months Ended September 30, 2018 Rental income $ 563,213 Net income $ 37,531 Net income per common share $ 0.78 During the nine months ended September 30, 2018 , we did not recognize any revenue or operating income from the assets acquired and liabilities assumed in the Merger. Unconsolidated Joint Ventures We own noncontrolling interests in two joint ventures that own three properties. We account for these investments under the equity method of accounting. As of September 30, 2019 and December 31, 2018 , our investments in unconsolidated joint ventures consisted of the following: OPI Carrying Value of Investment at Joint Venture OPI Ownership September 30, December 31, 2018 Number of Properties Location Square Feet Prosperity Metro Plaza 51% $ 22,857 $ 23,969 2 Fairfax, VA 328,456 1750 H Street, NW 50% 17,645 19,696 1 Washington, D.C. 115,411 Total $ 40,502 $ 43,665 3 443,867 The following table provides a summary of the mortgage debt of our unconsolidated joint ventures: Joint Venture Interest Rate (1) Maturity Date Principal Balance at September 30, 2019 (2) Prosperity Metro Plaza 4.09% 12/1/2029 $ 50,000 1750 H Street, NW 3.69% 8/1/2024 32,000 Weighted Average / Total 3.93% $ 82,000 (1) Includes the effect of mark to market purchase accounting. (2) Reflects the entire balance of the debt secured by the properties and is not adjusted to reflect the interests in the joint venture we do not own. None of the debt is recourse to us. At September 30, 2019 , the aggregate unamortized basis difference of our unconsolidated joint ventures of $8,074 is primarily attributable to the difference between the amount we paid to purchase our interest in these joint ventures, including transaction costs, and the historical carrying value of the net assets of these joint ventures. This difference is being amortized over the remaining useful life of the properties owned by these joint ventures and the resulting amortization expense is included in equity in net losses of investees in our condensed consolidated statements of comprehensive income (loss).

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases Revenue Recognition . We are a lessor of commercial office properties. Our leases provide our tenants with the contractual right to use and economically benefit from all of the physical space specified in the leases; therefore, we have determined to evaluate our leases as lease arrangements. Our leases provide for base rent payments and in addition may include variable payments. Rental income from operating leases, including any payments derived by index or market-based indices, is recognized on a straight line basis over the lease term when we have determined that the collectability of substantially all of the lease payments is probable. Some of our leases have options to extend or terminate the lease exercisable at the option of our tenants, which are considered when determining the lease term. In certain circumstances, some leases provide the tenant with the right to terminate if the legislature or other funding authority does not appropriate the funding necessary for the 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 $6,904 and $1,990 for the three months ended September 30, 2019 and 2018, respectively, and $19,365 and $7,825 for the nine months ended September 30, 2019 and 2018, respectively. Rents receivable, excluding properties classified as held for sale, include $47,148 and $34,006 of straight line rent receivables at September 30, 2019 and December 31, 2018 , respectively. We do not include in our measurement of our lease receivables certain variable payments, including payments determined by changes in the index or market-based indices after the inception of the lease, certain tenant reimbursements and other income until the specific events that trigger the variable payments have occurred. Such payments totaled $23,092 and $69,182 for the three and nine months ended September 30, 2019 , respectively, of which tenant reimbursements totaled $21,914 and $65,577 , respectively. Certain of our leases contain non-lease components, such as property level operating expenses and capital expenditures reimbursed by our tenants as well as other required lease payments. We have determined that all of our leases qualify for the practical expedient to not separate the lease and non-lease components because (i) the lease components are operating leases and (ii) the timing and pattern of recognition of the non-lease components are the same as those of the lease components. We apply Accounting Standards Codification 842, Leases , to the combined component. Income derived by our leases is recorded in rental income in our condensed consolidated statements of comprehensive income (loss). Certain tenants are obligated to pay directly their obligations under their leases for insurance, real estate taxes and certain other expenses. These obligations, which have been assumed by the tenants under the terms of their respective leases, are not reflected in our condensed consolidated financial statements. To the extent any tenant responsible for any such obligations under the applicable lease defaults on such lease or if it is deemed probable that the tenant will fail to pay for such obligations, we would record a liability for such obligations. The following table presents our operating lease maturity analysis as of September 30, 2019 : Year Amount 2019 $ 130,897 2020 498,567 2021 476,585 2022 436,876 2023 390,567 Thereafter 1,396,144 Total $ 3,329,636 Right of Use Asset and Lease Liability . For leases where we are the lessee, we are required to record a right of use asset and lease liability for all leases with a term greater than 12 months. As of September 30, 2019 , we had one lease that met this criterion where we are the lessee which expires on January 31, 2021. The value of the right of use asset and related liability representing our future obligation under the lease arrangement for which we are the lessee were $2,633 and $2,662 , respectively, as of September 30, 2019 . The right of use asset and related lease liability are included within other assets, net and accounts payable and other liabilities, respectively, within our condensed consolidated balance sheets.
Leases	Leases Revenue Recognition . We are a lessor of commercial office properties. Our leases provide our tenants with the contractual right to use and economically benefit from all of the physical space specified in the leases; therefore, we have determined to evaluate our leases as lease arrangements. Our leases provide for base rent payments and in addition may include variable payments. Rental income from operating leases, including any payments derived by index or market-based indices, is recognized on a straight line basis over the lease term when we have determined that the collectability of substantially all of the lease payments is probable. Some of our leases have options to extend or terminate the lease exercisable at the option of our tenants, which are considered when determining the lease term. In certain circumstances, some leases provide the tenant with the right to terminate if the legislature or other funding authority does not appropriate the funding necessary for the 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 $6,904 and $1,990 for the three months ended September 30, 2019 and 2018, respectively, and $19,365 and $7,825 for the nine months ended September 30, 2019 and 2018, respectively. Rents receivable, excluding properties classified as held for sale, include $47,148 and $34,006 of straight line rent receivables at September 30, 2019 and December 31, 2018 , respectively. We do not include in our measurement of our lease receivables certain variable payments, including payments determined by changes in the index or market-based indices after the inception of the lease, certain tenant reimbursements and other income until the specific events that trigger the variable payments have occurred. Such payments totaled $23,092 and $69,182 for the three and nine months ended September 30, 2019 , respectively, of which tenant reimbursements totaled $21,914 and $65,577 , respectively. Certain of our leases contain non-lease components, such as property level operating expenses and capital expenditures reimbursed by our tenants as well as other required lease payments. We have determined that all of our leases qualify for the practical expedient to not separate the lease and non-lease components because (i) the lease components are operating leases and (ii) the timing and pattern of recognition of the non-lease components are the same as those of the lease components. We apply Accounting Standards Codification 842, Leases , to the combined component. Income derived by our leases is recorded in rental income in our condensed consolidated statements of comprehensive income (loss). Certain tenants are obligated to pay directly their obligations under their leases for insurance, real estate taxes and certain other expenses. These obligations, which have been assumed by the tenants under the terms of their respective leases, are not reflected in our condensed consolidated financial statements. To the extent any tenant responsible for any such obligations under the applicable lease defaults on such lease or if it is deemed probable that the tenant will fail to pay for such obligations, we would record a liability for such obligations. The following table presents our operating lease maturity analysis as of September 30, 2019 : Year Amount 2019 $ 130,897 2020 498,567 2021 476,585 2022 436,876 2023 390,567 Thereafter 1,396,144 Total $ 3,329,636 Right of Use Asset and Lease Liability . For leases where we are the lessee, we are required to record a right of use asset and lease liability for all leases with a term greater than 12 months. As of September 30, 2019 , we had one lease that met this criterion where we are the lessee which expires on January 31, 2021. The value of the right of use asset and related liability representing our future obligation under the lease arrangement for which we are the lessee were $2,633 and $2,662 , respectively, as of September 30, 2019 . The right of use asset and related lease liability are included within other assets, net and accounts payable and other liabilities, respectively, within our condensed consolidated balance sheets.

Concentration

Concentration	9 Months Ended
	Sep. 30, 2019
Risks and Uncertainties [Abstract]
Concentration	Concentration Tenant 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. As of September 30, 2019 , the U.S. Government, 13 state governments and three other government tenants combined were responsible for approximately 36.3% of our annualized rental income, and as of September 30, 2018 , the U.S. Government, 13 state governments and three other government tenants combined were responsible for approximately 62.5% of our annualized rental income. The U.S. Government is our largest tenant by annualized rental income and was responsible for approximately 25.8% and 45.6% of our annualized rental income as of September 30, 2019 and 2018 , respectively. Geographic Concentration At September 30, 2019 , our 200 wholly owned properties were located in 36 states and the District of Columbia. Properties located in Virginia , California , the District of Columbia , Texas and Maryland were responsible for 15.8% , 11.6% , 9.8% , 9.7% and 7.4% of our annualized rental income as of September 30, 2019 , respectively. Properties located in the metropolitan Washington, D.C. market area were responsible for approximately 24.6% of our annualized rental income as of September 30, 2019 .

Indebtedness

Indebtedness	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Indebtedness	Indebtedness Our principal debt obligations at September 30, 2019 were: (1) $210,000 of outstanding borrowings under our $750,000 unsecured revolving credit facility; (2) $2,060,000 aggregate outstanding principal amount of senior unsecured notes; and (3) $327,262 aggregate outstanding principal amount of mortgage notes, including one mortgage note with an outstanding principal balance of $13,236 classified in liabilities of properties held for sale in our condensed consolidated balance sheet. Our $750,000 revolving credit facility is governed by a credit agreement, or our credit agreement, with a syndicate of institutional lenders that includes a feature under which the maximum aggregate borrowing availability may be increased to up to $1,950,000 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, 2023 and, subject to our payment of an extension fee and meeting certain other conditions, we have the option to extend the stated maturity date of our revolving credit facility by two additional six month periods. We can borrow, repay and reborrow funds available under our revolving credit facility until maturity and no principal repayment is due until maturity. We are required to pay interest at a rate of LIBOR plus a premium, which was 110 basis points per annum at September 30, 2019 , on the amount outstanding 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, 2019 . Both the interest rate premium and the facility fee are subject to adjustment based upon changes to our credit ratings. As of September 30, 2019 and December 31, 2018, the annual interest rate payable on borrowings under our revolving credit facility was 3.0% and 3.6% , respectively. The weighted average annual interest rate for borrowings under our revolving credit facility was 3.3% and 3.2% for the three months ended September 30, 2019 and 2018 , respectively, and 3.4% and 3.0% for the nine months ended September 30, 2019 and 2018 , respectively. As of September 30, 2019 and October 31, 2019, we had $210,000 and $185,000 , respectively, outstanding under our revolving credit facility, and $540,000 and $565,000 , respectively, available for borrowing under our revolving credit facility. The remaining outstanding balance of our $300,000 term loan, which was scheduled to mature on March 31, 2020, was repaid in full on August 23, 2019, without penalty, using cash on hand, proceeds from the sale of properties and the proceeds from our sale of our 2,801,060 shares of class A common stock of The RMR Group Inc., or RMR Inc., as described in Note 11. The weighted average annual interest rate under this term loan was 3.7% and 3.5% for the period from July 1, 2019 to August 23, 2019 and the three months ended September 30, 2018, respectively, and 3.9% and 3.3% for the period from January 1, 2019 to August 23, 2019 and the nine months ended September 30, 2018, respectively. Our $250,000 term loan, which was scheduled to mature on March 31, 2022 and had a principal balance of $88,000 as of December 31, 2018, was repaid in full on February 11, 2019, without penalty, using proceeds from the sale of a property portfolio. The weighted average annual interest rate under this term loan was 4.3% for the period from January 1, 2019 to February 11, 2019, and 3.9% and 3.7% for the three and nine months ended September 30, 2018 , respectively. As a result of the principal payments of our term loans, we recognized a loss on early extinguishment of debt of $158 and $643 for the three and nine months ended September 30, 2019 , respectively, to write off unamortized debt issuance costs. On July 15, 2019, we redeemed, at par plus accrued interest, all $350,000 of our 3.75% senior unsecured notes that had a maturity date in August 2019 using cash on hand and borrowings under our revolving credit facility. As a result of the redemption of our 3.75% senior unsecured notes, we recognized a loss on early extinguishment of debt of $126 for the three and nine months ended September 30, 2019 to write off unamortized debt issuance costs and discounts. Our credit agreement and senior unsecured notes indentures and their supplements provide for acceleration of payment of all amounts due thereunder upon the occurrence and continuation of certain events of default, such as, in the case of our credit agreement, a change of control of us, which includes The RMR Group LLC, or RMR LLC, ceasing to act as our business and property manager. Our credit agreement and senior unsecured notes indentures and their supplements also contain covenants, including those that restrict our ability to incur debts, require us to maintain certain financial ratios and, in the case of our credit agreement, restrict our ability to make distributions under certain circumstances. We believe we were in compliance with the terms and conditions of the respective covenants under our credit agreement and senior unsecured notes indentures and their supplements at September 30, 2019 . On March 1, 2019, we repaid at maturity, at par plus accrued interest, a mortgage note secured by one property with an outstanding principal balance of $7,890 using cash on hand. At September 30, 2019 , 11 of our consolidated properties with an aggregate net book value of $601,003 were encumbered by mortgage notes with an aggregate principal amount of $327,262 , including one mortgage note with an outstanding principal balance of $13,236 classified in liabilities of properties held for sale in our condensed consolidated balance sheet. Our mortgage notes are non-recourse, subject to certain limited exceptions and do not contain any material financial covenants.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	9 Months Ended
	Sep. 30, 2019
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, 2019 , 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 Description Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Non-Recurring Fair Value Measurements Assets: Assets of properties held for sale (1) $ 89,050 $ — $ 89,050 $ — (1) During the three months ended September 30, 2019, we recorded impairment charges of $6,342 to reduce the carrying value of eight properties that are classified as held for sale in our condensed consolidated balance sheet to their estimated fair value less costs to sell based upon negotiated sales prices with third party buyers (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 our cash and cash equivalents, restricted cash, rents receivable, a mortgage note receivable, accounts payable, a revolving credit facility, senior unsecured notes, mortgage notes payable, amounts due to related persons, other accrued expenses and security deposits. At September 30, 2019 and December 31, 2018, the fair values of our financial instruments approximated their carrying values in our condensed consolidated financial statements, due to their short term nature or floating interest rates, except as follows: As of September 30, 2019 As of December 31, 2018 Financial Instrument Carrying Amount (1) Fair Value Carrying Amount (1) Fair Value Senior unsecured notes, 3.75% interest rate, due in 2019 $ — $ — $ 349,239 $ 348,903 Senior unsecured notes, 3.60% interest rate, due in 2020 399,738 401,348 399,146 399,146 Senior unsecured notes, 4.00% interest rate, due in 2022 297,426 306,341 296,735 295,047 Senior unsecured notes, 4.15% interest rate, due in 2022 297,530 306,747 296,736 296,736 Senior unsecured notes, 4.25% interest rate, due in 2024 339,447 359,704 337,736 337,736 Senior unsecured notes, 4.50% interest rate, due in 2025 380,124 413,982 377,329 377,329 Senior unsecured notes, 5.875% interest rate, due in 2046 300,834 328,352 300,576 274,288 Mortgage notes payable (2) 324,223 335,481 335,241 336,365 Total $ 2,339,322 $ 2,451,955 $ 2,692,738 $ 2,665,550 (1) Includes unamortized debt premiums, discounts and issuance costs totaling $47,940 and $55,524 as of September 30, 2019 and December 31, 2018, respectively. (2) Includes one mortgage note with a carrying value of $13,198 net of unamortized issuance costs totaling $38 and which is classified in liabilities of properties held for sale in our condensed consolidated balance sheet as of September 30, 2019. We estimated the fair value of our senior unsecured notes (except for our senior unsecured notes due in 2046) using an average of the bid and ask price of the notes as of the measurement date (Level 2 inputs as defined in the fair value hierarchy under GAAP). We estimated the fair value of our senior unsecured notes due 2046 based on the closing price on The Nasdaq Stock Market LLC, or Nasdaq, as of the measurement date (Level 1 inputs as defined in the fair value hierarchy under GAAP). We estimated the fair values of our mortgage notes payable by using discounted cash flow analyses and currently prevailing market rates as of the measurement date (Level 3 inputs as defined in the fair value hierarchy under GAAP). Because Level 3 inputs are unobservable, our estimated fair value may differ materially from the actual fair value.

Shareholders' Equity

Shareholders' Equity	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Shareholders' Equity	Shareholders’ Equity Share Awards On February 27, 2019, in connection with the election of three of our Trustees we granted each Trustee 3,000 of our common shares, valued at $29.95 per share, the closing price of our common shares on Nasdaq on that day. On May 29, 2019, in accordance with our Trustee compensation arrangements, we granted 3,000 of our common shares, valued at $23.97 per share, the closing price of our common shares on Nasdaq on that day, to each of our eight Trustees as part of their annual compensation. On September 18, 2019, we granted an aggregate of 103,100 of our common shares, valued at $29.87 per share, the closing price of our common shares on Nasdaq on that day, to our officers and certain other employees of RMR LLC under our equity compensation plan. Share Purchases On April 5, 2019, we purchased 1,795 of our common shares valued at $28.96 per share, the closing price of our common shares on Nasdaq on that day, from a former officer of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares. On May 29, 2019, we purchased 450 of our common shares valued at $23.97 per share, the closing price of our common shares on Nasdaq on that day, from one of our Trustees in satisfaction of tax withholding and payment obligations in connection with an award of our common shares. On July 3, 2019, we purchased 1,779 of our common shares valued at $27.73 per share, the closing price of our common shares on Nasdaq on that day, from a former officer in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares. On September 25, 2019, we purchased an aggregate of 11,433 of our common shares, valued at $30.41 per share, the closing price of our common shares on Nasdaq on that day, from our officers and certain other employees of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares. Distributions On February 21, 2019 , we paid a regular quarterly distribution to common shareholders of record on January 28, 2019 of $0.55 per share, or $26,445 . On May 16, 2019 , we paid a regular quarterly distribution to common shareholders of record on April 29, 2019 of $0.55 per share, or $26,450 . On August 15, 2019, we paid a regular quarterly distribution to common shareholders of record on July 29, 2019 of $0.55 per share, or $26,461 . On October 17, 2019 , we declared a regular quarterly distribution to common shareholders of record on October 28, 2019 of $0.55 per share, or approximately $26,500 . We expect to pay this distribution on or about November 14, 2019 . Cumulative Other Comprehensive Income (Loss)

Business and Property Managemen

Business and Property Management Agreements with RMR LLC	9 Months Ended
	Sep. 30, 2019
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. Prior to completion of the Merger, SIR had similar business and property management agreements with RMR LLC, which agreements were terminated in connection with the Merger. See Notes 4 and 11 for further information regarding our relationship, agreements and transactions with SIR and RMR LLC. Pursuant to our business management agreement with RMR LLC, we recognized net business management fees of $5,159 and $20,575 for the three months ended September 30, 2019 and 2018 , respectively, and $16,203 and $30,059 for the nine months ended September 30, 2019 and 2018 , respectively. Based on our common share total return, as defined in our business management agreement, as of September 30, 2019 , no estimated 2019 incentive fees are included in the net business management fees we recognized for the three and nine months ended September 30, 2019 , respectively. The actual amount of annual incentive fees for 2019, if any, will be based on our common share total return, as defined in our business management agreement, for the three year period ending December 31, 2019, and will be payable in 2020. The net business management fees recognized for the three and nine months ended September 30, 2018 included $16,236 and $16,973 , respectively, of estimated business management incentive fees. We include business management fees in general and administrative expenses in our condensed consolidated statements of comprehensive income (loss). Pursuant to our property management agreement with RMR LLC, we recognized aggregate net property management and construction supervision fees of $5,622 and $3,415 for the three months ended September 30, 2019 and 2018 , respectively, and $16,605 and $10,201 for the nine months ended September 30, 2019 and 2018 , respectively. These amounts are included in other operating expenses or have been capitalized, as appropriate, in our condensed consolidated financial statements. In January 2019, we paid RMR LLC $2,185 for SIR’s 2018 business management, property management and construction supervision fees that it had accrued, but not paid, as of December 31, 2018. We also paid RMR LLC a business management incentive fee of $25,817 , which represented the incentive fee incurred, but not paid, by SIR for the year ended December 31, 2018. We had assumed the obligation to pay these amounts as a result of the Merger. We are generally responsible for all our operating expenses, including certain expenses incurred or arranged by RMR LLC on our behalf. We are generally not responsible for payment of RMR LLC’s employment, office or administrative expenses incurred to provide management services to us, except for the employment and related expenses of RMR LLC’s employees assigned to work exclusively or partly at our properties, our share of the wages, benefits and other related costs of RMR LLC's centralized accounting personnel, our share of RMR LLC’s costs for providing our internal audit function, or as otherwise agreed. Our property level operating expenses are generally incorporated into the rents charged to our tenants, including certain payroll and related costs incurred by RMR LLC. We reimbursed RMR LLC $6,850 and $5,150 for these expenses and costs for the three months ended September 30, 2019 and 2018 , respectively, and $20,007 and $15,294 for these expenses and costs for the nine months ended September 30, 2019 and 2018 , respectively. We included these amounts in other operating expenses and general and administrative expenses, as applicable, in our condensed consolidated statements of comprehensive income (loss).

Related Person Transactions

Related Person Transactions	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Related Person Transactions	Related Person Transactions We have relationships and historical and continuing transactions with SIR (prior to the Merger), RMR LLC, RMR Inc., AIC and others related to them, including other companies to which RMR LLC or its subsidiaries provide management services and some of which have trustees, directors or officers who are also our Trustees or officers. Our Manager, RMR LLC. We have two agreements with RMR LLC to provide management services to us. See Note 10 for further information regarding our management agreements with RMR LLC. See Note 9 for further information relating to our awards of common shares to our officers and certain other employees of RMR LLC in September 2019 and our repurchases of common shares from our current and former officers, and certain other current and former employees of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares to them. We include amounts recognized as expense for awards of our common shares to our officers and to other RMR LLC employees in general and administrative expenses in our condensed consolidated statements of comprehensive income (loss). Leases with RMR LLC. We lease office space to RMR LLC in certain of our properties for RMR LLC's property management offices. Pursuant to our lease agreements with RMR LLC, we recognized rental income from RMR LLC for leased office space of $288 and $263 for the three months ended September 30, 2019 and 2018 , respectively, and $854 and $763 for the nine months ended September 30, 2019 and 2018 , respectively. RMR Inc. RMR LLC is a majority owned subsidiary of RMR Inc. and RMR Inc. is the managing member of RMR LLC. Adam D. Portnoy, the Chair of our Board of Trustees and one of our Managing Trustees, is the sole trustee, an officer and the controlling shareholder of ABP Trust, which is the controlling shareholder of RMR Inc., a managing director, president and chief executive officer of RMR Inc. and an officer and employee of RMR LLC. David M. Blackman, our other Managing Trustee and our President and Chief Executive Officer, also serves as an officer and employee of RMR LLC, and each of our other officers is an officer and employee of RMR LLC. On July 1, 2019, we sold all of the 2,801,060 shares of class A common stock of RMR Inc. that we owned in an underwritten public offering at a price to the public of $40.00 per share pursuant to an underwriting agreement among us, RMR Inc., certain other real estate investment trusts, or REITs, managed by RMR LLC that also sold their class A common stock of RMR Inc. in the offering, and the underwriters named therein. We received net proceeds of $104,674 from this sale, after deducting underwriting discounts and commissions and other offering expenses. SIR . As described further in Note 4, we completed the Merger effective December 31, 2018. Our Managing Trustees and three of our Independent Trustees previously served as managing trustees and independent trustees, respectively, of SIR, our President and Chief Executive Officer also served as SIR’s president and chief executive officer, and each of SIR’s officers was also an officer and employee of RMR LLC. RMR LLC provides management services to us and provided management services to SIR until it ceased to exist. See Notes 4 and 12 for further information regarding the Merger and our former equity method investment in SIR. AIC . We, ABP Trust and five other companies to which RMR LLC provides management services currently own AIC in equal amounts. We and the other AIC shareholders historically participated in a combined property insurance program arranged and insured or reinsured in part by AIC. The policies under that program expired on June 30, 2019, and we and the other AIC shareholders elected not to renew the AIC property insurance program; we have instead purchased standalone property insurance coverage with unrelated third party insurance providers. As of September 30, 2019 and December 31, 2018, our investment in AIC had a carrying value of $9,459 and $8,751 , respectively. These amounts are included in other assets in our condensed consolidated balance sheets. We recognized income of $83 and $831 for the three months ended September 30, 2019 and 2018, respectively, and $617 and $882 for the nine months ended September 30, 2019 and 2018 , respectively, which are presented as equity in net income (loss) of investees in our condensed consolidated statements of comprehensive income (loss). Our other comprehensive income (loss) includes our proportionate part of unrealized gains (losses) on fixed income securities, which are owned by AIC, related to our investment in AIC. AIC is in the process of dissolving. In connection with its dissolution, we expect to receive a capital distribution in the fourth quarter of 2019. For further information about these and other such relationships and certain other related person transactions, refer to our 2018 Annual Report.

Discontinued Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2019
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Discontinued Operations We previously accounted for our investment in SIR under the equity method and had previously reported our investment in SIR as a reportable segment. As a result of the Secondary Sale and the elimination of a reportable segment, our former equity method investment in SIR is classified as discontinued operations in our condensed consolidated financial statements. See Note 4 for further information regarding the Secondary Sale. For the three and nine months ended September 30, 2018 , we recorded $9,253 and $23,843 , respectively, of equity in earnings of SIR which is included in income from discontinued operations in our condensed consolidated statement of comprehensive income (loss). The following table presents a summarized income statement of SIR as reported in SIR’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2018 , or the SIR Quarterly Report. References in our condensed consolidated financial statements to the SIR Quarterly Report are included as references to the source of the data only, and the information in the SIR Quarterly Report is not incorporated by reference into our condensed consolidated financial statements. Three Months Ended Nine Months Ended September 30, 2018 September 30, 2018 Rental income $ 101,833 $ 298,003 Tenant reimbursements and other income 20,048 60,514 Total revenues 121,881 358,517 Real estate taxes 12,518 36,748 Other operating expenses 14,814 43,714 Depreciation and amortization 35,371 105,326 Acquisition and transaction related costs 3,796 3,796 General and administrative 15,331 47,353 Write-off of straight line rent receivable, net — 10,626 Loss on impairment of real estate assets 9,706 9,706 Total expenses 91,536 257,269 Gain on sale of real estate 4,075 4,075 Dividend income 397 1,190 Unrealized gain on equity securities 22,771 53,159 Interest income 133 753 Interest expense (23,287 ) (69,446 ) Loss on early extinguishment of debt — (1,192 ) Income before income tax expense and equity in earnings of an investee 34,434 89,787 Income tax expense (185 ) (446 ) Equity in earnings of an investee 831 882 Net income 35,080 90,223 Net income allocated to noncontrolling interest (5,597 ) (15,841 ) Net income attributed to SIR $ 29,483 $ 74,382 Weighted average common shares outstanding (basic) 89,410 89,395 Weighted average common shares outstanding (diluted) 89,437 89,411 Net income attributed to SIR per common share (basic and diluted) $ 0.33 $ 0.83

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Recent Accounting Pronouncements	In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2016-02, Leases . In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements . In December 2018, the FASB issued ASU No. 2018-20 Leases (Topic 842), Narrow-Scope Improvements for Lessors . Collectively, these standards set out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). ASU No. 2016-02 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase of the leased asset by the lessee. This classification will determine whether the lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease. ASU No. 2016-02 requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales type leases, direct financing leases and operating leases. These standards were effective as of January 1, 2019. Upon adoption, we applied the package of practical expedients that has allowed us to not reassess (i) whether any expired or existing contracts are or contain leases, (ii) lease classification for any expired or existing leases and (iii) initial direct costs for any expired or existing leases. Furthermore, we applied the optional transition method in ASU No. 2018-11, which has allowed us to initially apply the new leases standard at the adoption date and recognize a cumulative effect adjustment to the opening balance of retained earnings in the adoption period, although we did not have an adjustment. Additionally, our leases met the criteria in ASU No. 2018-11 to not separate non-lease components from the related lease component; therefore, the accounting for these leases remained largely unchanged from the previous standard. The adoption of ASU No. 2016-02 and the related improvements did not have a material impact in our condensed consolidated financial statements. Upon adoption, (i) allowances for bad debts are now recognized as a direct reduction of rental income, and (ii) legal costs associated with the execution of our leases, which were previously capitalized and amortized over the life of their respective leases, are expensed as incurred. Subsequent to January 1, 2019, provisions for credit losses are now included in "rental income" in our condensed consolidated financial statements. Provisions for credit losses prior to January 1, 2019 were previously included in other operating expenses in our condensed consolidated financial statements and prior periods are not reclassified to conform to the current presentation. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments

Weighted Average Common Shares

Weighted Average Common Shares (Tables)	9 Months Ended
	Sep. 30, 2019
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, 2019 2018 2019 2018 Weighted average common shares for basic earnings per share 48,073 24,768 48,051 24,764 Effect of dilutive securities: unvested share awards — — — 5 Weighted average common shares for diluted earnings per share (1) 48,073 24,768 48,051 24,769 (1) For the three and nine months ended September 30, 2019, 22 and 11 unvested common shares, respectively, were not included in the calculation of diluted earnings per share because to do so would have been antidilutive. For the three months ended September 30, 2018, 8 unvested common shares were not included in the calculation of diluted earnings per share because to do so would have been antidilutive.

Real Estate Properties (Tables)

Real Estate Properties (Tables)	9 Months Ended
	Sep. 30, 2019
Real Estate [Abstract]
Schedule of disposed assets	The sales of these properties, as presented in the table below, do not represent significant dispositions individually or in the aggregate nor do they represent a strategic shift in our business. As a result, the results of operations of these properties are included in continuing operations through the date of sale in our condensed consolidated statements of comprehensive income (loss). Date of Sale Number of Properties Location Rentable Square Feet Gross Sales Price (1) Feb 2019 (2) 34 Northern Virginia and Maryland 1,635,868 $ 198,500 Mar 2019 (3) 1 Washington, D.C. 129,035 70,000 May 2019 (4) 1 Buffalo, NY 121,711 16,900 May 2019 1 Maynard, MA 287,037 5,000 June 2019 1 Kapolei, HI 416,956 7,100 July 2019 1 San Jose, CA 71,750 14,000 July 2019 (5) 1 Nashua, NH 321,800 25,000 August 2019 1 Arlington, TX 182,630 14,900 August 2019 1 Rochester, NY 94,800 4,765 August 2019 1 Hanover, PA 502,300 5,500 August 2019 1 San Antonio, TX 618,017 198,000 September 2019 1 Topeka, KS 143,934 15,600 September 2019 (6) 1 Falling Waters, WV 40,348 650 September 2019 (7) 1 San Diego, CA 43,918 8,950 47 4,610,104 $ 584,865 (1) Gross sales price includes purchase price adjustments, if any, and excludes closing costs. (2) We recorded a $447 loss on impairment of real estate during 2019 as a result of this sale. (3) We recorded a $22,075 gain on sale of real estate during 2019 as a result of this sale. (4) We recorded a $5,137 loss on impairment of real estate during 2019 as a result of this sale. (5) We recorded a $8,401 gain on sale of real estate during 2019 as a result of this sale. (6) We recorded a $2,179 loss on impairment of real estate during 2019 as a result of this sale. (7) We recorded a $3,062 gain on sale of real estate during 2019 as a result of this sale. The following table presents a summarized income statement of SIR as reported in SIR’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2018 , or the SIR Quarterly Report. References in our condensed consolidated financial statements to the SIR Quarterly Report are included as references to the source of the data only, and the information in the SIR Quarterly Report is not incorporated by reference into our condensed consolidated financial statements. Three Months Ended Nine Months Ended September 30, 2018 September 30, 2018 Rental income $ 101,833 $ 298,003 Tenant reimbursements and other income 20,048 60,514 Total revenues 121,881 358,517 Real estate taxes 12,518 36,748 Other operating expenses 14,814 43,714 Depreciation and amortization 35,371 105,326 Acquisition and transaction related costs 3,796 3,796 General and administrative 15,331 47,353 Write-off of straight line rent receivable, net — 10,626 Loss on impairment of real estate assets 9,706 9,706 Total expenses 91,536 257,269 Gain on sale of real estate 4,075 4,075 Dividend income 397 1,190 Unrealized gain on equity securities 22,771 53,159 Interest income 133 753 Interest expense (23,287 ) (69,446 ) Loss on early extinguishment of debt — (1,192 ) Income before income tax expense and equity in earnings of an investee 34,434 89,787 Income tax expense (185 ) (446 ) Equity in earnings of an investee 831 882 Net income 35,080 90,223 Net income allocated to noncontrolling interest (5,597 ) (15,841 ) Net income attributed to SIR $ 29,483 $ 74,382 Weighted average common shares outstanding (basic) 89,410 89,395 Weighted average common shares outstanding (diluted) 89,437 89,411 Net income attributed to SIR per common share (basic and diluted) $ 0.33 $ 0.83
Disclosure of Assets held-for-sale	As of October 31, 2019, three of the 15 properties held for sale were sold and 10 of the 15 properties held for sale were under contract to be sold as summarized in the table below: Location Number of Properties Square Feet Gross (1) San Jose, CA 1 75,621 $ 13,000 Windsor, CT 1 97,256 7,000 Kansas City, KS (2) 1 170,817 11,700 DC Metro - MD (3) 4 457,279 66,600 Columbia, SC (4) 3 180,703 10,750 Fairfax, VA 1 83,130 23,000 Stafford, VA 2 64,656 14,563 13 1,129,462 $ 146,613 (1) Gross sales price includes purchase price adjustments, if any, and excludes closing costs. (2) We recorded a $ 2,408 loss on impairment of real estate to adjust the carrying value of this property to its estimated fair value less costs to sell. (3) We recorded a $688 loss on impairment of real estate to adjust the carrying value of these four properties to their estimated fair value less costs to sell. (4) We recorded a $3,246 loss on impairment of real estate to adjust the carrying value of these three properties to their estimated fair value less costs to sell. The sale of these properties was completed in October 2019.
Schedule of Pro Forma Information	The following table presents our pro forma results of operations for the nine months ended September 30, 2018 as if the Merger, the Secondary Sale and the ILPT Distribution had occurred on January 1, 2018. The SIR results of operations included in this pro forma financial information have been adjusted to remove ILPT's results of operations for the nine months ended September 30, 2018 . The effect of the adjustments to remove ILPT's results of operations was to decrease pro forma rental income by $120,456 for the nine months ended September 30, 2018 and to decrease net income by $38,818 for the nine months ended September 30, 2018 from the amounts that would have otherwise been included in the pro forma results. This unaudited pro forma financial information is not necessarily indicative of what our actual results of operations would have been for the period presented or for any future period. Differences could result from numerous factors, including future changes in our portfolio of investments, capital structure, property level operating expenses and revenues, including rents expected to be received pursuant to our existing leases or leases we may enter into, changes in interest rates and other reasons. Actual future results are likely to be different from amounts presented in this unaudited pro forma financial information and such differences could be significant. Nine Months Ended September 30, 2018 Rental income $ 563,213 Net income $ 37,531 Net income per common share $ 0.78
Schedule of Joint Ventures	As of September 30, 2019 and December 31, 2018 , our investments in unconsolidated joint ventures consisted of the following: OPI Carrying Value of Investment at Joint Venture OPI Ownership September 30, December 31, 2018 Number of Properties Location Square Feet Prosperity Metro Plaza 51% $ 22,857 $ 23,969 2 Fairfax, VA 328,456 1750 H Street, NW 50% 17,645 19,696 1 Washington, D.C. 115,411 Total $ 40,502 $ 43,665 3 443,867 The following table provides a summary of the mortgage debt of our unconsolidated joint ventures: Joint Venture Interest Rate (1) Maturity Date Principal Balance at September 30, 2019 (2) Prosperity Metro Plaza 4.09% 12/1/2029 $ 50,000 1750 H Street, NW 3.69% 8/1/2024 32,000 Weighted Average / Total 3.93% $ 82,000 (1) Includes the effect of mark to market purchase accounting. (2) Reflects the entire balance of the debt secured by the properties and is not adjusted to reflect the interests in the joint venture we do not own. None of the debt is recourse to us.

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Lessee, Operating Lease, Liability, Maturity	The following table presents our operating lease maturity analysis as of September 30, 2019 : Year Amount 2019 $ 130,897 2020 498,567 2021 476,585 2022 436,876 2023 390,567 Thereafter 1,396,144 Total $ 3,329,636

Fair Value of Assets and Liab_2

Fair Value of Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2019
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, 2019 , 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 Description Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Non-Recurring Fair Value Measurements Assets: Assets of properties held for sale (1) $ 89,050 $ — $ 89,050 $ — (1) During the three months ended September 30, 2019, we recorded impairment charges of $6,342 to reduce the carrying value of eight properties that are classified as held for sale in our condensed consolidated balance sheet to their estimated fair value less costs to sell based upon negotiated sales prices with third party buyers (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, 2019 and December 31, 2018, the fair values of our financial instruments approximated their carrying values in our condensed consolidated financial statements, due to their short term nature or floating interest rates, except as follows: As of September 30, 2019 As of December 31, 2018 Financial Instrument Carrying Amount (1) Fair Value Carrying Amount (1) Fair Value Senior unsecured notes, 3.75% interest rate, due in 2019 $ — $ — $ 349,239 $ 348,903 Senior unsecured notes, 3.60% interest rate, due in 2020 399,738 401,348 399,146 399,146 Senior unsecured notes, 4.00% interest rate, due in 2022 297,426 306,341 296,735 295,047 Senior unsecured notes, 4.15% interest rate, due in 2022 297,530 306,747 296,736 296,736 Senior unsecured notes, 4.25% interest rate, due in 2024 339,447 359,704 337,736 337,736 Senior unsecured notes, 4.50% interest rate, due in 2025 380,124 413,982 377,329 377,329 Senior unsecured notes, 5.875% interest rate, due in 2046 300,834 328,352 300,576 274,288 Mortgage notes payable (2) 324,223 335,481 335,241 336,365 Total $ 2,339,322 $ 2,451,955 $ 2,692,738 $ 2,665,550 (1) Includes unamortized debt premiums, discounts and issuance costs totaling $47,940 and $55,524 as of September 30, 2019 and December 31, 2018, respectively. (2) Includes one mortgage note with a carrying value of $13,198 net of unamortized issuance costs totaling $38 and which is classified in liabilities of properties held for sale in our condensed consolidated balance sheet as of September 30, 2019.

Discontinued Operations (Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2019
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Discontinued Operations	The sales of these properties, as presented in the table below, do not represent significant dispositions individually or in the aggregate nor do they represent a strategic shift in our business. As a result, the results of operations of these properties are included in continuing operations through the date of sale in our condensed consolidated statements of comprehensive income (loss). Date of Sale Number of Properties Location Rentable Square Feet Gross Sales Price (1) Feb 2019 (2) 34 Northern Virginia and Maryland 1,635,868 $ 198,500 Mar 2019 (3) 1 Washington, D.C. 129,035 70,000 May 2019 (4) 1 Buffalo, NY 121,711 16,900 May 2019 1 Maynard, MA 287,037 5,000 June 2019 1 Kapolei, HI 416,956 7,100 July 2019 1 San Jose, CA 71,750 14,000 July 2019 (5) 1 Nashua, NH 321,800 25,000 August 2019 1 Arlington, TX 182,630 14,900 August 2019 1 Rochester, NY 94,800 4,765 August 2019 1 Hanover, PA 502,300 5,500 August 2019 1 San Antonio, TX 618,017 198,000 September 2019 1 Topeka, KS 143,934 15,600 September 2019 (6) 1 Falling Waters, WV 40,348 650 September 2019 (7) 1 San Diego, CA 43,918 8,950 47 4,610,104 $ 584,865 (1) Gross sales price includes purchase price adjustments, if any, and excludes closing costs. (2) We recorded a $447 loss on impairment of real estate during 2019 as a result of this sale. (3) We recorded a $22,075 gain on sale of real estate during 2019 as a result of this sale. (4) We recorded a $5,137 loss on impairment of real estate during 2019 as a result of this sale. (5) We recorded a $8,401 gain on sale of real estate during 2019 as a result of this sale. (6) We recorded a $2,179 loss on impairment of real estate during 2019 as a result of this sale. (7) We recorded a $3,062 gain on sale of real estate during 2019 as a result of this sale. The following table presents a summarized income statement of SIR as reported in SIR’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2018 , or the SIR Quarterly Report. References in our condensed consolidated financial statements to the SIR Quarterly Report are included as references to the source of the data only, and the information in the SIR Quarterly Report is not incorporated by reference into our condensed consolidated financial statements. Three Months Ended Nine Months Ended September 30, 2018 September 30, 2018 Rental income $ 101,833 $ 298,003 Tenant reimbursements and other income 20,048 60,514 Total revenues 121,881 358,517 Real estate taxes 12,518 36,748 Other operating expenses 14,814 43,714 Depreciation and amortization 35,371 105,326 Acquisition and transaction related costs 3,796 3,796 General and administrative 15,331 47,353 Write-off of straight line rent receivable, net — 10,626 Loss on impairment of real estate assets 9,706 9,706 Total expenses 91,536 257,269 Gain on sale of real estate 4,075 4,075 Dividend income 397 1,190 Unrealized gain on equity securities 22,771 53,159 Interest income 133 753 Interest expense (23,287 ) (69,446 ) Loss on early extinguishment of debt — (1,192 ) Income before income tax expense and equity in earnings of an investee 34,434 89,787 Income tax expense (185 ) (446 ) Equity in earnings of an investee 831 882 Net income 35,080 90,223 Net income allocated to noncontrolling interest (5,597 ) (15,841 ) Net income attributed to SIR $ 29,483 $ 74,382 Weighted average common shares outstanding (basic) 89,410 89,395 Weighted average common shares outstanding (diluted) 89,437 89,411 Net income attributed to SIR per common share (basic and diluted) $ 0.33 $ 0.83

Weighted Average Common Share_2

Weighted Average Common Shares (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share, Basic and Diluted [Abstract]
Weighted average common shares for basic earnings per share (in shares)	48,073	24,768	48,051	24,764
Effect of dilutive securities: unvested share awards (in shares)	0	0	0	5
Weighted average common shares for diluted earnings per share (in shares)	48,073	24,768	48,051	24,769
Unvested common shares (in shares)	22	8	11

Real Estate Properties - Additi

Real Estate Properties - Additional Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)ft²leaseproperty	Sep. 30, 2019USD ($)ft²leasepropertyjoint_venture	Dec. 31, 2018USD ($)
Real Estate Properties [Line Items]
Real estate properties at aggregate cost	$ 3,556,740	$ 3,556,740	$ 3,944,636
Number of joint ventures | joint_venture		2
Number of leases entered | lease	22	78
Rentable square feet (in sqft) | ft²	759,162	2,155,394
Weighted average lease term	12 years 8 months 12 days	9 years 1 month 6 days
Expenditures committed on leases	$ 17,567	$ 61,748
Committed but unspent tenant related obligations estimated	$ 56,494	$ 56,494
Continuing operations
Real Estate Properties [Line Items]
Number of properties | property	200	200
Rentable area of properties (in square feet) | ft²	27,290,000	27,290,000
Real estate properties at aggregate cost	$ 3,727,607	$ 3,727,607
Unconsolidated Joint Ventures
Real Estate Properties [Line Items]
Number of properties | property	3	3
Rentable area of properties (in square feet) | ft²	443,867	443,867
Number of buildings, noncontrolling interest | property		3
Joint Venture 1
Real Estate Properties [Line Items]
Ownership percentage	50.00%	50.00%
Joint Venture 2
Real Estate Properties [Line Items]
Ownership percentage	51.00%	51.00%

Real Estate Properties - Dispos

Real Estate Properties - Disposition Activities (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)ft²property	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)ft²property	Sep. 30, 2018USD ($)
Real Estate Properties [Line Items]
Loss on impairment of real estate	$ 8,521	$ 0	$ 14,105	$ 5,800
Gain (loss) on sale of real estate	$ 11,463	$ 0	$ 33,538	$ 17,329
Disposed of by Sale
Real Estate Properties [Line Items]
Number of Properties | property	47		47
Rentable area of properties (in square feet) | ft²	4,610,104		4,610,104
Aggregate sale price of properties sold, excluding closing costs			$ 584,865
Disposed of by Sale | Northern Virginia and Maryland
Real Estate Properties [Line Items]
Number of Properties | property	34		34
Rentable area of properties (in square feet) | ft²	1,635,868		1,635,868
Aggregate sale price of properties sold, excluding closing costs			$ 198,500
Loss on impairment of real estate			$ 447
Disposed of by Sale | Washington, D.C.
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	129,035		129,035
Aggregate sale price of properties sold, excluding closing costs			$ 70,000
Gain (loss) on sale of real estate			$ 22,075
Disposed of by Sale | Buffalo, NY
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	121,711		121,711
Aggregate sale price of properties sold, excluding closing costs			$ 16,900
Loss on impairment of real estate			$ 5,137
Disposed of by Sale | Maynard, MA
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	287,037		287,037
Aggregate sale price of properties sold, excluding closing costs			$ 5,000
Disposed of by Sale | Kapolei, HI
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	416,956		416,956
Aggregate sale price of properties sold, excluding closing costs			$ 7,100
Disposed of by Sale | San Jose, CA
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	71,750		71,750
Aggregate sale price of properties sold, excluding closing costs			$ 14,000
Disposed of by Sale | Nashua, NH
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	321,800		321,800
Aggregate sale price of properties sold, excluding closing costs			$ 25,000
Gain (loss) on sale of real estate			$ 8,401
Disposed of by Sale | Arlington, TX
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	182,630		182,630
Aggregate sale price of properties sold, excluding closing costs			$ 14,900
Disposed of by Sale | Rochester, NY
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	94,800		94,800
Aggregate sale price of properties sold, excluding closing costs			$ 4,765
Disposed of by Sale | Hanover, PA
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	502,300		502,300
Aggregate sale price of properties sold, excluding closing costs			$ 5,500
Disposed of by Sale | San Antonio, TX
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	618,017		618,017
Aggregate sale price of properties sold, excluding closing costs			$ 198,000
Disposed of by Sale | Topeka, KS
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	143,934		143,934
Aggregate sale price of properties sold, excluding closing costs			$ 15,600
Disposed of by Sale | Falling Waters, WV
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	40,348		40,348
Aggregate sale price of properties sold, excluding closing costs			$ 650
Loss on impairment of real estate			$ 2,179
Disposed of by Sale | San Diego, CA
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Rentable area of properties (in square feet) | ft²	43,918		43,918
Aggregate sale price of properties sold, excluding closing costs			$ 8,950
Gain (loss) on sale of real estate			$ 3,062

Real Estate Properties - Assets

Real Estate Properties - Assets Held-for-Sale (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)ft²property	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)ft²property	Sep. 30, 2018USD ($)	Oct. 31, 2019property
Real Estate Properties [Line Items]
Loss on impairment of real estate assets | $	$ 8,521	$ 0	$ 14,105	$ 5,800
Kansas City, KS
Real Estate Properties [Line Items]
Loss on impairment of real estate assets | $			2,408
DC Metro, MD
Real Estate Properties [Line Items]
Loss on impairment of real estate assets | $			688
Columbia, SC
Real Estate Properties [Line Items]
Loss on impairment of real estate assets | $			$ 3,246
Marketing For Sale
Real Estate Properties [Line Items]
Number of Properties | property	6		6
Square Footage (in square feet) | ft²	587,000		587,000
Held-for-sale or Disposed of by Sale
Real Estate Properties [Line Items]
Number of Properties | property	13		13
Square Footage (in square feet) | ft²	1,129,462		1,129,462
Gross Sale Price | $			$ 146,613
Held-for-sale or Disposed of by Sale | San Jose, CA
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Square Footage (in square feet) | ft²	75,621		75,621
Gross Sale Price | $			$ 13,000
Held-for-sale or Disposed of by Sale | Windsor, CT
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Square Footage (in square feet) | ft²	97,256		97,256
Gross Sale Price | $			$ 7,000
Held-for-sale or Disposed of by Sale | Kansas City, KS
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Square Footage (in square feet) | ft²	170,817		170,817
Gross Sale Price | $			$ 11,700
Held-for-sale or Disposed of by Sale | DC Metro, MD
Real Estate Properties [Line Items]
Number of Properties | property	4		4
Square Footage (in square feet) | ft²	457,279		457,279
Gross Sale Price | $			$ 66,600
Held-for-sale or Disposed of by Sale | Columbia, SC
Real Estate Properties [Line Items]
Number of Properties | property	3		3
Square Footage (in square feet) | ft²	180,703		180,703
Gross Sale Price | $			$ 10,750
Held-for-sale or Disposed of by Sale | Fairfax, VA
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Square Footage (in square feet) | ft²	83,130		83,130
Gross Sale Price | $			$ 23,000
Held-for-sale or Disposed of by Sale | Stafford, VA
Real Estate Properties [Line Items]
Number of Properties | property	2		2
Square Footage (in square feet) | ft²	64,656		64,656
Gross Sale Price | $			$ 14,563
Held-for-sale
Real Estate Properties [Line Items]
Number of Properties | property	15		15
Real estate held for sale | $	$ 170,867		$ 170,867
Loss on impairment of real estate assets | $	$ 6,342
Held-for-sale | DC Metro, MD
Real Estate Properties [Line Items]
Number of Properties | property	4		4
Held-for-sale | Columbia, SC
Real Estate Properties [Line Items]
Number of Properties | property	3		3
Disposed of by Sale
Real Estate Properties [Line Items]
Number of Properties | property	47		47
Square Footage (in square feet) | ft²	4,610,104		4,610,104
Gross Sale Price | $			$ 584,865
Disposed of by Sale | San Jose, CA
Real Estate Properties [Line Items]
Number of Properties | property	1		1
Square Footage (in square feet) | ft²	71,750		71,750
Gross Sale Price | $			$ 14,000
Subsequent Event | Disposed of by Sale
Real Estate Properties [Line Items]
Number of Properties | property					3
Subsequent Event | Under Contract to Sell
Real Estate Properties [Line Items]
Number of Properties | property					10

Real Estate Properties - Acquis

Real Estate Properties - Acquisition Activities and Pro Forma Financial Information (Details) $ / shares in Units, $ in Thousands, ft² in Millions	Jul. 01, 2019USD ($)$ / shares	Dec. 31, 2018USD ($)ft²property	Dec. 27, 2018shares	Oct. 09, 2018USD ($)$ / sharesshares	Jul. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)
Business Acquisition [Line Items]
Consideration transferred					$ 2,900
Proceeds from sale of RMR Inc. common shares, net						$ 104,674	$ 0
ILPT | SIR
Business Acquisition [Line Items]
Shares holding (in shares) | shares			45,000,000
Underwritten public offering
Business Acquisition [Line Items]
Price per share (in dollars per share) | $ / shares	$ 40
Proceeds from sale of RMR Inc. common shares, net	$ 104,674
Underwritten public offering | Common shares
Business Acquisition [Line Items]
Shares sold (in shares) | shares				24,918,421
Price per share (in dollars per share) | $ / shares				$ 18.25
Proceeds from sale of RMR Inc. common shares, net				$ 435,125
SIR
Business Acquisition [Line Items]
Consideration transferred		$ 2,415,053
Number of properties acquired | property		99
Rentable area of properties (in square feet) | ft²		16.5
Closing costs		$ 27,497
Payments for closing costs		14,508
Debt assumed		1,719,772
SIR | SIR
Business Acquisition [Line Items]
Payments for closing costs		$ 12,989

Real Estate Properties - Schedu

Real Estate Properties - Schedule of Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Decrease in revenues	$ (167,411)	$ (106,102)	$ (518,220)	$ (322,904)
Rental income				563,213
Net income				$ 37,531
Net income per common share (in dollars per share)				$ 0.78
Acquisition-related costs
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Decrease in revenues				$ 120,456
Decrease in net income				$ 38,818

Real Estate Properties - Sche_2

Real Estate Properties - Schedule of Joint Ventures (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)ft²propertyjoint_venture	Dec. 31, 2018USD ($)
Real Estate [Line Items]
Number of joint ventures | joint_venture	2
Unconsolidated Joint Ventures
Real Estate [Line Items]
Number of Properties | property	3
Investment at carrying value	$ 40,502	$ 43,665
Square Feet (in square feet) | ft²	443,867
Unamortized basis difference	$ 8,074
Unconsolidated Joint Ventures | Prosperity Metro Plaza
Real Estate [Line Items]
Number of Properties | property	2
Ownership percentage	51.00%
Investment at carrying value	$ 22,857	23,969
Square Feet (in square feet) | ft²	328,456
Unconsolidated Joint Ventures | 1750 H Street, NW
Real Estate [Line Items]
Number of Properties | property	1
Ownership percentage	50.00%
Investment at carrying value	$ 17,645	$ 19,696
Square Feet (in square feet) | ft²	115,411
Mortgages | Unconsolidated Joint Ventures
Real Estate [Line Items]
Interest rate (as a percent)	3.93%
Debt Instrument, Face Amount	$ 82,000
Mortgages | Unconsolidated Joint Ventures | Prosperity Metro Plaza
Real Estate [Line Items]
Interest rate (as a percent)	4.09%
Debt Instrument, Face Amount	$ 50,000
Mortgages | Unconsolidated Joint Ventures | 1750 H Street, NW
Real Estate [Line Items]
Interest rate (as a percent)	3.69%
Debt Instrument, Face Amount	$ 32,000

Leases - Lease Receivables (Det

Leases - Lease Receivables (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Leases [Abstract]
Straight line rent adjustments	$ 6,904	$ 1,990	$ 19,365	$ 7,825
Straight line rent receivables	47,148		47,148		$ 34,006
Variable lease, income	23,092		69,182
Tenant reimbursements and other income	$ 21,914		$ 65,577

Leases - Maturity of Lease Liab

Leases - Maturity of Lease Liabilities (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
2019	$ 130,897
2020	498,567
2021	476,585
2022	436,876
2023	390,567
Thereafter	1,396,144
Total	$ 3,329,636

Leases - Right of Use Asset and

Leases - Right of Use Asset and Lease Liability (Details) $ in Thousands	Sep. 30, 2019USD ($)lease
Leases [Abstract]
Number of leases | lease	1
Operating lease, right-of-use asset	$ 2,633
Operating lease liability	$ 2,662

Concentration (Details)

Concentration (Details)	9 Months Ended
	Sep. 30, 2019governmentpropertygovernment_tenantstate_governmentstate	Sep. 30, 2018government_tenantstate_government
Concentration
Number of US government | government	1
Number of state governments | state_government	13	13
Number of other governments | government_tenant	3	3
Annualized rental income, excluding properties classified as discontinued operations | Tenant concentration | U.S. Government, state governments and Other Four Government
Concentration
Concentration risk percentage	36.30%	62.50%
Annualized rental income, excluding properties classified as discontinued operations | Tenant concentration | U.S. Government
Concentration
Concentration risk percentage	25.80%	45.60%
Annualized rental income, excluding properties classified as discontinued operations | Geographic Concentration Risk | Virginia
Concentration
Concentration risk percentage	15.80%
Annualized rental income, excluding properties classified as discontinued operations | Geographic Concentration Risk | California
Concentration
Concentration risk percentage	11.60%
Annualized rental income, excluding properties classified as discontinued operations | Geographic Concentration Risk | Washington, D.C.
Concentration
Concentration risk percentage	9.80%
Annualized rental income, excluding properties classified as discontinued operations | Geographic Concentration Risk | Texas
Concentration
Concentration risk percentage	9.70%
Annualized rental income, excluding properties classified as discontinued operations | Geographic Concentration Risk | Maryland
Concentration
Concentration risk percentage	7.40%
Annualized rental income, excluding properties classified as discontinued operations | Geographic Concentration Risk | Metropolitan Washington D.C.
Concentration
Concentration risk percentage	24.60%
Continuing operations
Concentration
Number of wholly owned properties | property	200
Number of states in which acquired properties located | state	36

Indebtedness - Debt Obligations

Indebtedness - Debt Obligations (Details) $ in Thousands	Jul. 15, 2019USD ($)	Mar. 01, 2019USD ($)	Feb. 11, 2019	Aug. 23, 2019	Sep. 30, 2019USD ($)extension_optionbuilding	Sep. 30, 2018USD ($)	Aug. 23, 2019	Sep. 30, 2019USD ($)extension_optionbuildingshares	Sep. 30, 2018USD ($)	Oct. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Borrowings outstanding					$ 210,000			$ 210,000			$ 175,000
Aggregate principal amount on secured properties					327,262			327,262
Loss on early extinguishment of debt					$ 284	$ 0		769	$ 0
Redemption of debt								$ 350,000	$ 0
Number of buildings secured by mortgage notes | building					11			11
Aggregate net book value of secured properties					$ 601,003			$ 601,003
Unsecured term loan, due in 2020
Debt Instrument [Line Items]
Maximum borrowing capacity on revolving credit facility					300,000			300,000
The weighted average annual interest rate (as a percent)				3.70%		3.50%	3.90%		3.30%
Unsecured revolving credit facility
Debt Instrument [Line Items]
Borrowings outstanding					210,000			210,000
Maximum borrowing capacity on revolving credit facility					750,000			750,000
Aggregate principal amount on secured properties					$ 1,950,000			$ 1,950,000
Number of extension options | extension_option					2			2
Interest rate (as a percent)					3.00%			3.00%			3.60%
The weighted average annual interest rate (as a percent)					3.30%	3.20%		3.40%	3.00%
Extension option duration								6 months
Facility fee (as a percent)								0.25%
Remaining borrowing capacity					$ 540,000			$ 540,000
Senior unsecured notes
Debt Instrument [Line Items]
Borrowings outstanding					2,060,000			2,060,000
Interest rate (as a percent)	3.75%
Loss on early extinguishment of debt					126			$ 126
Redemption of debt	$ 350,000
LIBOR | Unsecured term loan, due in 2020
Debt Instrument [Line Items]
Interest rate premium (as a percent)								1.40%
LIBOR | Unsecured revolving credit facility
Debt Instrument [Line Items]
Interest rate premium (as a percent)								1.10%
Mortgages
Debt Instrument [Line Items]
Outstanding principal amount					327,262			$ 327,262
Amount of debt repaid		$ 7,890
Unsecured debt | Term loan due in 2022
Debt Instrument [Line Items]
Maximum borrowing capacity on revolving credit facility					250,000			250,000
The weighted average annual interest rate (as a percent)			4.30%			3.90%			3.70%
Long term debt											$ 88,000
Loss on early extinguishment of debt					158			643
Liabilities of Properties Held-for-sale | Mortgages
Debt Instrument [Line Items]
Outstanding principal amount					$ 13,236			$ 13,236
Subsequent Event | Unsecured revolving credit facility
Debt Instrument [Line Items]
Borrowings outstanding										$ 185,000
Remaining borrowing capacity										$ 565,000
Class A common shares | Underwritten public offering
Debt Instrument [Line Items]
Shares sold (in shares) | shares								2,801,060

Fair Value of Assets and Liab_3

Fair Value of Assets and Liabilities - Recurring and Nonrecurring Assets (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)property	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)
Fair Value of Assets and Liabilities
Loss on impairment of real estate assets	$ 8,521	$ 0	$ 14,105	$ 5,800
Nonrecurring
Fair Value of Assets and Liabilities
Other liability	89,050		89,050
Nonrecurring | Level 1 inputs
Fair Value of Assets and Liabilities
Other liability	0		0
Nonrecurring | Level 2 inputs
Fair Value of Assets and Liabilities
Other liability	89,050		89,050
Nonrecurring | Level 3 inputs
Fair Value of Assets and Liabilities
Other liability	0		$ 0
Held-for-sale
Fair Value of Assets and Liabilities
Loss on impairment of real estate assets	$ 6,342
Number of impaired properties | property	8

Fair Value of Assets and Liab_4

Fair Value of Assets and Liabilities - Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value of Financial Instruments
Senior notes	$ 2,015,099	$ 2,357,497
Mortgage notes payable, net	311,025	335,241
Unamortized debt premiums, discounts and issuance costs	$ 47,940	55,524
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, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Interest rate (as a percent)	3.60%
Senior unsecured notes, 4.00% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)	4.00%
Senior unsecured notes, 4.15% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)	4.15%
Senior unsecured notes, 4.25% interest rate, due in 2024
Fair Value of Financial Instruments
Interest rate (as a percent)	4.25%
Senior unsecured notes, 4.50% interest rate, due in 2025
Fair Value of Financial Instruments
Interest rate (as a percent)	4.50%
Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Interest rate (as a percent)	5.875%
Carrying Amount
Fair Value of Financial Instruments
Mortgage notes payable, net	$ 324,223	335,241
Fair value of financial instruments	2,339,322	2,692,738
Carrying Amount | Senior unsecured notes, 3.75% interest rate, due in 2019
Fair Value of Financial Instruments
Senior notes	0	349,239
Carrying Amount | Senior unsecured notes, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Senior notes	399,738	399,146
Carrying Amount | Senior unsecured notes, 4.00% interest rate, due in 2022
Fair Value of Financial Instruments
Senior notes	297,426	296,735
Carrying Amount | Senior unsecured notes, 4.15% interest rate, due in 2022
Fair Value of Financial Instruments
Senior notes	297,530	296,736
Carrying Amount | Senior unsecured notes, 4.25% interest rate, due in 2024
Fair Value of Financial Instruments
Senior notes	339,447	337,736
Carrying Amount | Senior unsecured notes, 4.50% interest rate, due in 2025
Fair Value of Financial Instruments
Senior notes	380,124	377,329
Carrying Amount | Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Senior notes	300,834	300,576
Fair Value
Fair Value of Financial Instruments
Mortgage notes payable, net	335,481	336,365
Fair value of financial instruments	2,451,955	2,665,550
Fair Value | Senior unsecured notes, 3.75% interest rate, due in 2019
Fair Value of Financial Instruments
Senior notes	0	348,903
Fair Value | Senior unsecured notes, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Senior notes	401,348	399,146
Fair Value | Senior unsecured notes, 4.00% interest rate, due in 2022
Fair Value of Financial Instruments
Senior notes	306,341	295,047
Fair Value | Senior unsecured notes, 4.15% interest rate, due in 2022
Fair Value of Financial Instruments
Senior notes	306,747	296,736
Fair Value | Senior unsecured notes, 4.25% interest rate, due in 2024
Fair Value of Financial Instruments
Senior notes	359,704	337,736
Fair Value | Senior unsecured notes, 4.50% interest rate, due in 2025
Fair Value of Financial Instruments
Senior notes	413,982	377,329
Fair Value | Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Senior notes	328,352	$ 274,288
Mortgages
Fair Value of Financial Instruments
Long-term Debt	327,262
Held-for-sale | Mortgages
Fair Value of Financial Instruments
Long-term Debt	13,198
Unamortized Debt Issuance Expense	$ 38

Shareholders' Equity (Details)

Shareholders' Equity (Details) $ / shares in Units, $ in Thousands	Oct. 17, 2019USD ($)$ / shares	Sep. 25, 2019$ / sharesshares	Sep. 18, 2019$ / sharesshares	Aug. 15, 2019USD ($)$ / shares	Jul. 03, 2019$ / sharesshares	May 29, 2019trustee$ / sharesshares	May 16, 2019USD ($)$ / shares	Apr. 05, 2019$ / sharesshares	Feb. 27, 2019trustee$ / sharesshares	Feb. 21, 2019USD ($)$ / shares	Sep. 30, 2019shares	Jun. 30, 2019shares	Sep. 30, 2018shares	Jun. 30, 2018shares	Mar. 31, 2018shares	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)
Share Awards
Cash distribution to common shareholders (in dollars per share)				$ 0.55			$ 0.55			$ 0.55
Distributions to common shareholders | $							$ 26,450			$ 26,445						$ 79,356	$ 127,907
Dividends declared | $				$ 26,461
Subsequent Event
Share Awards
Dividends declared (in dollars per share)	$ 0.55
Dividends declared | $	$ 26,500
Officers and Other Employees of RMR LLC
Share Awards
Share repurchase price (in dollars per share)		$ 30.41
Stock Repurchased During Period, Shares | shares		11,433
Former Employee of RMR LLC
Share Awards
Share repurchase price (in dollars per share)					$ 27.73	$ 23.97		$ 28.96
Stock Repurchased During Period, Shares | shares					1,779	450		1,795
Common shares
Share Awards
Stock Repurchased During Period, Shares | shares											13,212	2,245	4,838	113	153
Common shares | Trustees
Share Awards
Number of trustees | trustee						8			3
Shares granted (in shares) | shares						3,000			3,000
Shares granted (in dollars per share)						$ 23.97			$ 29.95
Common shares | Officers and Other Employees of RMR LLC
Share Awards
Shares granted (in shares) | shares			103,100
Shares granted (in dollars per share)			$ 29.87

Business and Property Managem_2

Business and Property Management Agreements with RMR LLC (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)agreementemployee	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
RMR LLC
Related Party Transaction [Line Items]
Number of employees | employee				0
Number of agreements | agreement				2
Related party expense		$ 5,159	$ 20,575	$ 16,203	$ 30,059
Incentive fee (reversal)			16,236		16,973
Reimbursement expense		6,850	5,150	20,007	15,294
RMR LLC | Net Property Management and Construction Supervision Fees
Related Party Transaction [Line Items]
Related party transaction amount		$ 5,622	$ 3,415	$ 16,605	$ 10,201
RMR LLC | SIR | Net Property Management and Construction Supervision Fees
Related Party Transaction [Line Items]
Payment for incentive fees	$ 2,185					$ 25,817
Affiliated entity | RMR LLC
Related Party Transaction [Line Items]
Period of common share total return, incentive fees payable		3 years

Related Person Transactions (De

Related Person Transactions (Details) $ / shares in Units, $ in Thousands	Jul. 01, 2019USD ($)$ / shares	Sep. 30, 2019USD ($)company	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)companyagreementshares	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Related Party Transaction [Line Items]
Proceeds from sale of RMR Inc. common shares, net				$ 104,674	$ 0
Equity in net income (loss) of investees		$ (196)	$ 94	$ (573)	(1,112)
RMR LLC
Related Party Transaction [Line Items]
Number of agreements | agreement				2
Revenue from related party		$ 288	263	$ 854	763
AIC
Related Party Transaction [Line Items]
Number of entities to whom services are provided | company		5		5
Carrying value of equity method investments		$ 9,459		$ 9,459		$ 8,751
Equity in net income (loss) of investees		$ 83	$ 831	$ 617	$ 882
Underwritten public offering
Related Party Transaction [Line Items]
Price per share (in dollars per share) | $ / shares	$ 40
Proceeds from sale of RMR Inc. common shares, net	$ 104,674
Underwritten public offering | Class A common shares
Related Party Transaction [Line Items]
Shares holding (in shares) | shares				2,801,060

Discontinued Operations - Addit

Discontinued Operations - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Equity in earnings of Select Income REIT included in discontinued operations	$ 9,253	$ 0	$ 23,843

Discontinued Operations - Summa

Discontinued Operations - Summarized Income (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gains (Losses) on Sales of Investment Real Estate		$ 4,075		$ 4,075
Total revenues	$ 167,411	106,102	$ 518,220	322,904
Real estate taxes	18,824	12,072	55,363	37,402
Other operating expenses	30,376	21,785	90,204	66,221
Depreciation and amortization	74,939	42,569	226,373	129,444
Business Combination, Acquisition Related Costs	0	3,813	682	3,813
General and administrative	7,990	22,383	25,457	36,438
Loss on impairment of real estate assets	8,521	0	14,105	5,800
Total expenses	150,168	110,405	438,553	299,608
Dividend income	0	304	1,960	912
Unrealized gain on equity securities	0	17,425	(44,007)	40,677
Interest income	358	140	847	405
Interest expense	(32,367)	(23,374)	(104,848)	(69,444)
Loss on early extinguishment of debt	(284)	0	(769)	0
Income before income tax expense and equity in earnings of an investee	(3,587)	(9,808)	(33,612)	13,175
Income tax expense	(156)	(9)	(509)	(124)
Equity in earnings of an investee	(196)	94	(573)	(1,112)
Net income attributed to SIR	$ (3,939)	$ (449)	$ (34,694)	$ 35,811
Weighted average common shares outstanding (basic) (in shares)	48,073	24,768	48,051	24,764
Weighted average common shares outstanding (diluted) (in shares)	48,073	24,768	48,051	24,769
Net income attributed to SIR per common share (basic and diluted) (in dollars per share)	$ (0.08)	$ (0.02)	$ (0.72)	$ 1.43
SIR | SIR
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rental income		$ 101,833		$ 298,003
Tenant reimbursements and other income		20,048		60,514
Total revenues		121,881		358,517
Real estate taxes		12,518		36,748
Other operating expenses		14,814		43,714
Depreciation and amortization		35,371		105,326
Business Combination, Acquisition Related Costs		3,796		3,796
General and administrative		15,331		47,353
Write-off of straight line rent receivable, net		0		10,626
Loss on impairment of real estate assets		9,706		9,706
Total expenses		91,536		257,269
Dividend income		397		1,190
Unrealized gain on equity securities		22,771		53,159
Interest income		133		753
Interest expense		(23,287)		(69,446)
Loss on early extinguishment of debt		0		(1,192)
Income before income tax expense and equity in earnings of an investee		34,434		89,787
Income tax expense		(185)		(446)
Equity in earnings of an investee		831		882
Net income		35,080		90,223
Net income allocated to noncontrolling interest		(5,597)		(15,841)
Net income attributed to SIR		$ 29,483		$ 74,382
Weighted average common shares outstanding (basic) (in shares)		89,410		89,395
Weighted average common shares outstanding (diluted) (in shares)		89,437		89,411
Net income attributed to SIR per common share (basic and diluted) (in dollars per share)		$ 0.33		$ 0.83

Uncategorized Items - opi093019

Label	Element	Value
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	$ 1,330,755,000
Common Stock [Member]
Shares, Outstanding	us-gaap_SharesOutstanding	24,786,479
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	$ 248,000
Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	169,137,000
AOCI Attributable to Parent [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	146,000
Additional Paid-in Capital [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	1,968,960,000
Cumulative Common Distributions [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	(807,736,000)
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	60,281,000
Accounting Standards Update 2016-01 [Member] | AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(60,281,000)
Accounting Standards Update 2014-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	712,000
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 712,000