JBG SMITH Properties (JBGS) 10-K 26 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 20, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	JBG SMITH PROPERTIES
Entity Central Index Key	1,689,796
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		122,593,995
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 4,143,697,293
Shares Issued, Price Per Share			$ 36.47

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Real estate, at cost:
Land and improvements	$ 1,371,874	$ 1,368,294
Buildings and improvements	3,722,930	3,670,268
Construction in progress, including land	697,930	978,942
Real estate, at cost	5,792,734	6,017,504
Less accumulated depreciation	(1,051,875)	(1,011,330)
Real estate, net	4,740,859	5,006,174
Cash and cash equivalents	260,553	316,676
Restricted cash	138,979	21,881
Tenant and other receivables, net	46,568	46,734
Deferred rent receivable, net	143,473	146,315
Investments in and advances to unconsolidated real estate ventures	322,878	261,811
Other assets, net	264,994	263,923
Assets Held-for-sale, Not Part of Disposal Group	78,981	8,293
TOTAL ASSETS	5,997,285	6,071,807
Liabilities:
Mortgages payable, net	1,838,381	2,025,692
Revolving credit facility	0	115,751
Unsecured term loans, net	297,129	46,537
Accounts payable and accrued expenses	130,960	138,607
Other liabilities, net	181,606	161,277
Liabilities related to assets held for sale	3,717	0
Total liabilities	2,451,793	2,487,864
Commitments and Contingencies
Redeemable noncontrolling interests	558,140	609,129
Shareholders' equity:
Preferred shares, $0.01 par value - 200,000 shares authorized, none issued	0	0
Common shares, $0.01 par value - 500,000 shares authorized; 120,917 and 117,955 shares issued and outstanding as of September 30, 2018 and December 31, 2017	1,210	1,180
Additional paid-in capital	3,155,256	3,063,625
Accumulated deficit	(176,018)	(95,809)
Accumulated other comprehensive income	6,700	1,612
Shareholders' equity / Former parent equity	2,987,148	2,970,608
Noncontrolling interests in consolidated subsidiaries	204	4,206
Total equity	2,987,352	2,974,814
TOTAL LIABILITIES, REDEEMABLE NONCONTROLLING INTERESTS AND EQUITY	$ 5,997,285	$ 6,071,807

Consolidated and Combined Balan

Consolidated and Combined Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred shares, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred shares, shares authorized	200,000,000	200,000,000
Preferred shares, shares issued	0	0
Preferred shares, shares outstanding	0	0
Common shares, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares, shares authorized	500,000,000	500,000,000
Common shares, shares issued	120,937,000	117,955,000
Common shares, shares outstanding	120,937,000	117,955,000
Commitments and Contingencies

Consolidated and Combined State

Consolidated and Combined Statements of Operations - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
REVENUE
Property rentals	$ 499,835,000	$ 436,625,000	$ 401,595,000
Reimbursements from Tenants	39,290,000	37,985,000	37,661,000
Third-party real estate services, including reimbursements	98,699,000	63,236,000	33,882,000
Other income	6,358,000	5,167,000	5,381,000
Total revenue	644,182,000	543,013,000	478,519,000
EXPENSES
Depreciation and amortization	211,436,000	161,659,000	133,343,000
Property operating	148,081,000	118,836,000	100,304,000
Real estate taxes	71,054,000	66,434,000	57,784,000
General and administrative:
Corporate and other	33,728,000	39,350,000	48,753,000
Third-party real estate services	89,826,000	51,919,000	19,066,000
Share-based compensation related to Formation Transaction	36,030,000	29,251,000	0
Transaction and other costs	27,706,000	127,739,000	6,476,000
Total Expenses	617,861,000	595,188,000	365,726,000
Income (loss) from unconsolidated real estate ventures, net	39,409,000	(4,143,000)	(947,000)
Interest and other income (loss), net	15,168,000	1,788,000	2,992,000
Interest expense	(74,447,000)	(58,141,000)	(51,781,000)
Gains (Losses) on Sales of Investment Real Estate	52,183,000	0	0
Loss on extinguishment of debt	(5,153,000)	(701,000)	0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Bargain Purchase, Reduction Of Gain	(7,606,000)	24,376,000	0
Total Other Income (Expense)	19,554,000	(36,821,000)	(49,736,000)
INCOME (LOSS) BEFORE INCOME TAX BENEFIT	45,875,000	(88,996,000)	63,057,000
Income tax benefit	738,000	9,912,000	(1,083,000)
NET INCOME (LOSS)	46,613,000	(79,084,000)	61,974,000
Net (income) loss attributable to redeemable noncontrolling interests	(6,710,000)	7,328,000	0
Net loss attributable to noncontrolling interests	21,000	3,000	0
NET INCOME (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 39,924,000	$ (71,753,000)	$ 61,974,000
EARNINGS (LOSS) PER COMMON SHARE:
Earnings Per Share, Basic	$ 0.31	$ (0.70)	$ 0.62
Earnings Per Share, Diluted	$ 0.31	$ (0.70)	$ 0.62
WEIGHTED AVERAGE NUMBER OF COMMON SHARES OUTSTANDING - basic and diluted (in shares)	119,176	105,359	100,571
Weighted Average Number of Shares Outstanding, Diluted	119,176	105,359	100,571

Consolidated and Combined Sta_2

Consolidated and Combined Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
NET INCOME (LOSS)	$ 46,613	$ (79,084)	$ 61,974
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Change in fair value of derivative financial instruments	5,382	1,438	0
Reclassification of net loss on derivative financial instruments from accumulated other comprehensive income into interest expense	1,090	399	0
Other comprehensive income	(6,472)	(1,837)	0
COMPREHENSIVE INCOME (LOSS)	53,085	(77,247)	61,974
Net (income) loss attributable to redeemable noncontrolling interests	6,710	(7,328)	0
Other comprehensive income attributable to redeemable noncontrolling interests	(1,384)	(225)	0
Net loss attributable to noncontrolling interests	21	3	0
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO JBG SMITH PROPERTIES	$ 45,012	$ (70,141)	$ 61,974

Consolidated and Combined Sta_3

Consolidated and Combined Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Shares	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income	Former Parent Equity	Noncontrolling Interests in Consolidated Subsidiaries
Common Stock, Dividends, Per Share, Declared	$ 0
Balance at beginning of period at Dec. 31, 2015	$ 2,059,491					$ 2,058,976	$ 515
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to common shareholders	61,974						0
Net income (loss)	61,974					61,974
Deferred compensation shares and options, net	4,502					4,502
Issuance of common shares in connection with the Combination	0
Other comprehensive income	0
Balance at end of period at Dec. 31, 2016	2,121,984					2,121,689	295
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders Equity Note, Spinoff Transaction, Distributions To Former Parent	$ (3,983)					(3,763)	(220)
Common Stock, Dividends, Per Share, Declared	$ 0.45
Net loss attributable to common shareholders	$ (71,756)			$ (42,729)			(3)
Dividends	(53,080)			(53,080)
Net income (loss)	(79,084)					(29,024)
Deferred compensation shares and options, net	1,526					1,526
Contributions from former parent, net	333,020					333,020	0
Stock Repurchased During Period, Value	(96,632)					(96,632)
Stock Issued During Period, Shares, New Issues		94,736
Stock Issued During Period, Value, New Issues	0	$ (947)	$ (2,329,632)			(2,330,579)
Stock Issued During Period, Shares, Acquisitions		23,219
Issuance of common shares in connection with the Combination	864,918	$ 233	864,685
Noncontrolling Interest, Increase from Business Combination	3,586						3,586
Distributions to noncontrolling interests	(171)						(171)
Noncontrolling Interest, Contributions	499						499
Redeemable noncontrolling interest redemption value adjustment and other comprehensive income allocation	(130,917)		(130,692)		$ (225)
Other comprehensive income	$ 1,837				1,837
Balance at end of period (in shares) at Dec. 31, 2017	117,955	117,955
Balance at end of period at Dec. 31, 2017	$ 2,974,814	$ 1,180	3,063,625	(95,809)	1,612	0	4,206
Common Stock, Dividends, Per Share, Declared	$ 1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to common shareholders	$ 39,903			39,924			(21)
Common Shares Issued During Period in Connection with Redemption of OP Units	2,962
Dividends	$ (120,133)			(120,133)
Net income (loss)	46,613					0
Stock Issued During Period, Value, New Issues	$ (109,122)	(30)	(109,092)
Stock Issued During Period, Shares, Employee Stock Purchase Plans	20
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 741	$ 0	741
Issuance of common shares in connection with the Combination	0
Distributions to noncontrolling interests	(347)						(347)
Noncontrolling Interest, Contributions	250						250
Redeemable noncontrolling interest redemption value adjustment and other comprehensive income allocation	(17,556)		(16,172)		(1,384)
Other comprehensive income	6,472				6,472
Stockholders' Equity, Other	$ (364)		(364)
Balance at end of period (in shares) at Dec. 31, 2018	120,937	120,937
Balance at end of period at Dec. 31, 2018	$ 2,987,352	$ 1,210	3,155,256	$ (176,018)	$ 6,700	$ 0	204
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling interests in consolidated subsidiaries	$ (5,550)		$ (1,666)				$ (3,884)

Consolidated and Combined Sta_4

Consolidated and Combined Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES:
Net income (loss)	$ 46,613,000	$ (79,084,000)	$ 61,974,000
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Share-based compensation expense	52,675,000	33,693,000	4,502,000
Depreciation and amortization, including amortization of debt issuance costs	215,659,000	164,580,000	135,072,000
Deferred rent	(14,056,000)	(10,388,000)	(15,551,000)
(Income) loss from unconsolidated real estate ventures, net	(39,409,000)	4,143,000	947,000
Amortization of above- and below-market lease intangibles, net	(220,000)	(862,000)	(1,353,000)
Amortization of lease incentives	3,406,000	4,023,000	3,592,000
Return on capital from unconsolidated real estate ventures	7,827,000	2,563,000	1,520,000
Reduction of gain (gain) on bargain purchase	7,606,000	(24,376,000)	0
Non-Cash Gain (Loss) on Extinguishment of Debt	(4,536,000)
Loss on extinguishment of debt	5,153,000	701,000	0
Gain on sale of real estate	(52,183,000)	0	0
Unrealized gain on interest rate swaps and caps	(926,000)	(1,348,000)	0
Bad debt expense	3,298,000	3,807,000	750,600
Other non-cash items	1,388,000	3,955,000	6,236,000
Deferred Income Taxes and Tax Credits	(718,000)	(10,408,000)	0
Changes in operating assets and liabilities:
Tenant and other receivables	(5,582,000)	(2,098,000)	(3,693,000)
Other assets, net	(16,600,000)	(23,481,000)	(16,614,000)
Accounts payable and accrued expenses	(5,984,000)	16,160,000	7,667,000
Other liabilities, net	(19,137,000)	(7,397,000)	(25,509,000)
Net cash provided by operating activities	188,193,000	74,183,000	159,541,000
INVESTING ACTIVITIES:
Development costs, construction in progress and real estate additions	(385,943,000)	(210,593,000)	(237,814,000)
Payments to Acquire Real Estate	(23,246,000)	0	0
Cash and restricted cash received in connection with the Combination, net		97,416,000
Proceeds from Sale of Real Estate	413,077,000	0	0
Acquisition of interests in unconsolidated real estate ventures, net of cash acquired	(386,000)	(8,834,000)	0
Distributions of capital from unconsolidated real estate ventures	14,408,000	6,929,000	0
Distribution of capital from sale of interest in an unconsolidated real estate venture	80,279,000	0	0
Investments in and advances to unconsolidated real estate ventures	(31,197,000)	(16,321,000)	(23,027,000)
Proceeds from Collection of Notes Receivable	0	50,934,000	0
Other investments	(665,000)	(2,207,000)	(1,966,000)
Proceeds from repayment of receivable from former parent	0	75,000,000	4,000,000
Net cash provided by investing activities	66,327,000	(7,676,000)	(258,807,000)
FINANCING ACTIVITIES:
Contributions from former parent, net	0	160,203,000
Payments of Distributions to Affiliates			(3,763,000)
Acquisition of interest in consolidated real estate venture	(5,550,000)	0	0
Repayment of borrowings from former parent	0	(115,630,000)	0
Proceeds from borrowings from former parent	0	4,000,000	79,500,000
Capital lease payments	(114,000)	(17,827,000)	0
Borrowings under mortgages payable	118,141,000	366,239,000	0
Borrowings under revolving credit facility	35,000,000	115,751,000	0
Borrowings under unsecured term loans	250,000,000	50,000,000	0
Repayments of mortgages payable	(312,894,000)	(272,905,000)	(24,364,000)
Repayments of revolving credit facility	(150,751,000)	0	0
Debt issuance costs	(3,114,000)	(19,287,000)	(70,000)
Proceeds from common stock issued pursuant to Employee Share Purchase Plan	597,000	0	0
Dividends paid to common shareholders	(107,372,000)	(26,540,000)	0
Distributions to redeemable noncontrolling interests	(17,398,000)	(4,556,000)	0
Contributions from noncontrolling interests	250,000	357,000	0
Distributions to noncontrolling interests	(340,000)	(18,000)	(220,000)
Net cash (used in) provided by financing activities	(193,545,000)	239,787,000	51,083,000
Net increase in cash and cash equivalents and restricted cash	60,975,000	306,294,000	(48,183,000)
Cash and cash equivalents and restricted cash as of the beginning of the period	338,557,000	32,263,000	80,446,000
Cash and cash equivalents and restricted cash as of the end of the period	399,532,000	338,557,000	32,263,000
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH AS OF END OF THE PERIOD:
Cash and cash equivalents and restricted cash	338,557,000	32,263,000	80,446,000
SUPPLEMENTAL DISCLOSURE OF CASH FLOW AND NON-CASH INFORMATION:
Transfer Mortgage Payable	0	115,630,000	115,022,000
Cash paid for interest (net of capitalized interest of $14,863 and $2,285 in 2018 and 2017)	64,605,000	52,388,000	45,373,000
Accrued capital expenditures included in accounts payable and accrued expenses	53,073,000	12,445,000	8,851,000
Write-off of fully depreciated assets	52,272,000	55,998,000	100,076,000
Cash receipts from (payments for) income taxes	(1,965,000)	(3,396,000)	(1,165,000)
Noncash Contribution From Redeemable Noncontrolling Interests	0	5,420,000	0
Temporary Equity, Redemptions of OP Units	(109,208,000)	0	0
Issuance of common limited partnership units at the Separation	0	96,632,000	0
Issuance of common shares at the Separation	0	2,330,579,000	0
Issuance of common shares in connection with the Combination	0	864,918,000	0
Issuance of common limited partnership units in connection with the Combination	0	359,967,000	0
Contribution from former parent in connection with the Separation	$ 0	$ 172,817,000	$ 0

Consolidated and Combined Sta_5

Consolidated and Combined Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Capitalized interest	$ 20,804	$ 12,727	$ 4,076

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Organization JBG SMITH Properties ("JBG SMITH") was organized by Vornado Realty Trust ("Vornado" or "former parent") as a Maryland real estate investment trust ("REIT") on October 27, 2016 for the purpose of receiving, via the spin-off on July 17, 2017 (the "Separation"), substantially all of the assets and liabilities of Vornado’s Washington, D.C. segment, which operated as Vornado / Charles E. Smith, (the "Vornado Included Assets"). On July 18, 2017, JBG SMITH acquired the management business and certain assets and liabilities (the "JBG Assets") of The JBG Companies ("JBG") (the "Combination"). The Separation and the Combination are collectively referred to as the "Formation Transaction." Unless the context otherwise requires, all references to "we," "us," and "our," refer to the Vornado Included Assets (our predecessor and accounting acquirer) for periods prior to the Separation and to JBG SMITH for periods after the Separation. References to "our share" refers to our ownership percentage of consolidated and unconsolidated assets in real estate ventures. Substantially all of our assets are held by, and our operations are conducted through, JBG SMITH Properties LP ("JBG SMITH LP"), our operating partnership. Prior to the Separation from Vornado, JBG SMITH was a wholly owned subsidiary of Vornado and had no material assets or operations. On July 17, 2017, Vornado distributed 100% of the then outstanding common shares of JBG SMITH on a pro rata basis to the holders of its common shares. Prior to such distribution by Vornado, Vornado Realty L.P. ("VRLP"), Vornado's operating partnership, distributed common limited partnership units ("OP Units") in JBG SMITH LP on a pro rata basis to the holders of VRLP's common limited partnership units, consisting of Vornado and the other common limited partners of VRLP. Following such distribution by VRLP and prior to such distribution by Vornado, Vornado contributed to JBG SMITH all of the OP Units it received in exchange for common shares of JBG SMITH. Each Vornado common shareholder received one JBG SMITH common share for every two Vornado common shares held as of the close of business on July 7, 2017 (the "Record Date"). Vornado and each of the other limited partners of VRLP received one JBG SMITH LP OP Unit for every two common limited partnership units in VRLP held as of the close of business on the Record Date. In connection with the Separation, JBG SMITH issued 94.7 million common shares and JBG SMITH LP issued 5.8 million OP Units to parties other than JBG SMITH. In connection with the Combination, JBG SMITH issued 23.2 million common shares and JBG SMITH LP issued 13.9 million OP Units to parties other than JBG SMITH. As of the completion of the Formation Transaction there were 118.0 million JBG SMITH common shares outstanding and 19.8 million JBG SMITH LP OP Units outstanding that were owned by parties other than JBG SMITH. As of December 31, 2018 , we, as its sole general partner, controlled JBG SMITH LP and owned 87.8% of its OP Units. Our operations are presented as if the transfer of the Vornado Included Assets had been consummated prior to all historical periods presented in the accompanying consolidated and combined financial statements at the carrying amounts of such assets and liabilities reflected in Vornado’s books and records. The assets and liabilities of the JBG Assets and subsequent results of operations and cash flows are reflected in our consolidated and combined financial statements beginning on the date of the Combination. We own and operate a portfolio of high-quality commercial and multifamily assets, many of which are amenitized with ancillary retail. Our portfolio reflects our longstanding strategy of owning and operating assets within Metro-served submarkets in the Washington, D.C. metropolitan area that have high barriers to entry and key urban amenities, including being within walking distance of a Metro station. As of December 31, 2018 , our Operating Portfolio consists of 62 operating assets comprising 46 commercial assets totaling approximately 12.9 million square feet ( 11.3 million square feet at our share) and 16 multifamily assets totaling 6,315 units ( 4,531 units at our share). Additionally, we have (i) nine assets under construction comprising five commercial assets totaling approximately 1.2 million square feet ( 927,000 square feet at our share) and four multifamily assets totaling 1,476 units ( 1,298 units at our share); and (ii) 41 future development assets totaling approximately 23.1 million square feet ( 19.6 million square feet at our share) of estimated potential development density. Our revenues are derived primarily from leases with commercial and multifamily tenants, including fixed rents and reimbursements from tenants for certain expenses such as real estate taxes, property operating expenses, and repairs and maintenance. In addition, our third-party asset management and real estate services business provides fee-based real estate services to third parties and the legacy funds (the "JBG Legacy Funds") formerly organized by JBG. As of December 31, 2018 , five of our assets in the aggregate generated approximately 27% of our share of annualized rent. Only the U.S. federal government accounted for 10% or more of our rental revenue, which consists of property rentals and tenant reimbursements, as follows: Year Ended December 31, (Dollars in thousands) 2018 2017 2016 Rental revenue from the U.S. federal government $ 94,822 $ 92,192 $ 103,864 Percentage of commercial segment rental revenue 22.0 % 24.0 % 29.1 % Percentage of total rental revenue 17.6 % 19.4 % 23.6 % Basis of Presentation The accompanying consolidated and combined financial statements and notes are prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"). All intercompany transactions and balances have been eliminated. The accompanying consolidated and combined financial statements include the accounts of JBG SMITH and our wholly owned subsidiaries and those other entities, including JBG SMITH LP, in which we have a controlling financial interest, including where we have been determined to be the primary beneficiary of a variable interest entity ("VIE"). See Note 7 for additional information on our VIEs. The portions of the equity and net income of consolidated subsidiaries that are not attributable to JBG SMITH are presented separately as amounts attributable to noncontrolling interests in our consolidated and combined financial statements. References to the financial statements refer to our consolidated and combined financial statements as of December 31, 2018 and 2017 , and for each of the three years in the period ended December 31, 2018 . References to the balance sheets refer to our consolidated balance sheets as of December 31, 2018 and 2017 . References to the statements of operations refer to our consolidated and combined statements of operations for each of the three years in the period ended December 31, 2018 . References to the statements of cash flows refer to our consolidated and combined statements of cash flows for each of the three years in the period ended December 31, 2018 . Formation Transaction JBG SMITH and the Vornado Included Assets were under common control of Vornado for all periods prior to the Separation. The transfer of the Vornado Included Assets from Vornado to JBG SMITH was completed prior to the Separation, at net book values (historical carrying amounts) carved out from Vornado’s books and records. For purposes of the formation of JBG SMITH, the Vornado Included Assets were designated as the predecessor and the accounting acquirer of the JBG Assets. Consequently, the financial statements of JBG SMITH, as set forth herein, represent a continuation of the financial information of the Vornado Included Assets as the predecessor and accounting acquirer such that the historical financial information included herein as of any date or for any periods on or prior to the completion of the Combination represents the pre-Combination financial information of the Vornado Included Assets. The financial statements reflect the common shares as of the date of the Separation as outstanding for all periods prior to July 17, 2017. The acquisition of the JBG Assets completed subsequently by JBG SMITH was accounted for as a business combination using the acquisition method whereby identifiable assets acquired and liabilities assumed are recorded at acquisition-date fair values and income and cash flows from the operations were consolidated into the financial statements of JBG SMITH commencing July 18, 2017. Consequently, the financial statements for the periods before and after the Formation Transaction are not directly comparable. The accompanying financial statements as of December 31, 2018 and 2017 and for the year ended December 31, 2018 include our consolidated accounts. The results of operations for the year ended December 31, 2017 reflect the aggregate operations and changes in cash flows and equity on a combined basis for all periods prior to July 17, 2017 and on a consolidated basis for all periods subsequent to July 17, 2017. The results of operations for the year ended December 31, 2016 include the Vornado Included Assets. Therefore, our results of operations, cash flows and financial condition set forth in this report are not necessarily indicative of our future results of operations, cash flows or financial condition as an independent, publicly traded company. The historical financial results for the Vornado Included Assets reflect charges for certain corporate costs allocated by the former parent, which were based on either actual costs incurred or a proportion of costs estimated to be applicable, to the Vornado Included Assets based on an analysis of key metrics, including total revenues. Such costs do not necessarily reflect what the actual costs would have been if JBG SMITH had been operating as a separate standalone public company. See Note 20 for additional information. Reclassification: To conform to the current year presentation, $7.8 million of expenses incurred in the operation and management of our properties that were previously included in "General and administrative expenses: corporate and other" for the year ended December 31, 2017 have been reclassified to "Property operating expenses". This reclassification relates to the portion of the year ended December 31, 2017 subsequent to the Formation Transaction on July 18, 2017, as general and administrative expenses incurred prior to the Formation Transaction reflect costs allocated by the former parent.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Use of Estimates The preparation of the financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. The most significant of these estimates include: (i) the underlying cash flows used to establish the fair values recorded in connection with the Combination and used in assessing impairment and (ii) the determination of useful lives for tangible and intangible assets. Actual results could differ from these estimates. Business Combinations We account for business combinations, including the acquisition of real estate, using the acquisition method pursuant to which we recognize and measure the identifiable assets acquired, liabilities assumed, and any noncontrolling interests in the acquiree at their acquisition date fair values. Accordingly, we estimate the fair values of acquired tangible assets (consisting of real estate, cash and cash equivalents, tenant and other receivables, investments in unconsolidated real estate ventures and other assets, as applicable), identified intangible assets and liabilities (consisting of the value of in-place leases, above- and below-market leases, options to enter into ground leases and management contracts, as applicable), assumed debt and other liabilities, and noncontrolling interests, as applicable, based on our evaluation of information and estimates available at that date. Based on these estimates, we allocate the purchase price to the identified assets acquired and liabilities assumed. Any excess of the purchase price over the estimated fair value of the net assets acquired is recorded as goodwill. Any excess of the fair value of assets acquired over the purchase price is recorded as a gain on bargain purchase. If, up to one year from the acquisition date, information regarding the fair value of the net assets acquired and liabilities assumed is received and estimates are refined, appropriate adjustments are made on a prospective basis to the purchase price allocation, which may include adjustments to identified assets, assumed liabilities, and goodwill or the gain on bargain purchase, as applicable. The results of operations of acquisitions are prospectively included in our financial statements beginning with the date of the acquisition. Transaction costs related to business combinations are expensed as incurred and included in "Transaction and other costs" in our statements of operations. The fair values of buildings are determined using the "as-if vacant" approach whereby we use discounted income or cash flow models with inputs and assumptions that we believe are consistent with current market conditions for similar assets. The most significant assumptions in determining the allocation of the purchase price to buildings are the exit capitalization rate, discount rate, estimated market rents and hypothetical expected lease-up periods. We assess fair value of land based on market comparisons and development projects using an income approach of cost plus a margin. The fair values of identified intangible assets are determined based on the following: • The value allocable to the above- or below-market component of an acquired in-place lease is determined based upon the present value (using a discount rate which reflects the risks associated with the acquired leases) of the difference between (i) the contractual amounts to be received pursuant to the lease over its remaining term and (ii) management’s estimate of the amounts that would be received using market rates over the remaining term of the lease. Amounts allocated to above- market leases are recorded as "Identified intangible assets" in "Other assets, net" in the balance sheets, and amounts allocated to below-market leases are recorded as "Lease intangible liabilities" in "Other liabilities, net" in the balance sheets. These intangibles are amortized to "Property rentals" in our statements of operations over the remaining terms of the respective leases. • Factors considered in determining the value allocable to in-place leases during hypothetical lease-up periods related to space that is leased at the time of acquisition include (i) lost rent and operating cost recoveries during the hypothetical lease-up period and (ii) theoretical leasing commissions required to execute similar leases. These intangible assets are recorded as "Identified intangible assets" in "Other assets, net" in the balance sheets and are amortized to "Depreciation and amortization expenses" in our statements of operations over the remaining term of the existing lease. • The fair value of the in-place property management, leasing, asset management, and development and construction management contracts is based on revenue and expense projections over the estimated life of each contract discounted using a market discount rate. These management contract intangibles are amortized to "Depreciation and amortization expenses" in our statements of operations over the weighted average life of the management contracts. The fair value of investments in unconsolidated real estate ventures and related noncontrolling interests is based on the estimated fair values of the identified assets acquired and liabilities assumed of each venture, including future expected cash flows from promote interests. The fair value of the mortgages payable assumed is determined using current market interest rates for comparable debt financings. The fair values of the interest rate swaps and caps are based on the estimated amounts we would receive or pay to terminate the contract at the acquisition date and are determined using interest rate pricing models and observable inputs. The carrying value of cash, restricted cash, working capital balances, leasehold improvements and equipment, and other assets acquired and liabilities assumed approximates fair value. Real Estate Real estate is carried at cost, net of accumulated depreciation and amortization. Maintenance and repairs are expensed as incurred and are included in "Property operating expenses" in our statements of operations. As real estate is undergoing redevelopment activities, all property operating expenses directly associated with and attributable to the redevelopment, including interest expense, are capitalized to the extent that we believe such costs are recoverable through the value of the property. The capitalization period ends when redevelopment activities are substantially complete. General and administrative costs are expensed as incurred. Depreciation requires an estimate of the useful life of each property and improvement as well as an allocation of the costs associated with a property to its various components. Depreciation is recognized on a straight‑line basis over estimated useful lives, which range from three to 40 years . Tenant improvements are amortized on a straight‑line basis over the lives of the related leases, which approximate the useful lives of the tenant improvements. When assets are sold or retired, their costs and related accumulated depreciation are removed from the accounts with the resulting gains or losses reflected in net income or loss for the period in “Depreciation and amortization expense.” Construction in progress, including land, is carried at cost, and no depreciation is recorded. Real estate undergoing significant renovations and improvements is considered to be under development. All direct and indirect costs related to development activities are capitalized into "Construction in progress, including land" on our balance sheets, except for certain demolition costs, which are expensed as incurred. Direct development costs incurred include: pre-development expenditures directly related to a specific project, development and construction costs, interest, insurance and real estate taxes. Indirect development costs include: employee salaries and benefits, travel and other related costs that are directly associated with the development. Our method of calculating capitalized interest expense is based upon applying our weighted average borrowing rate to the actual accumulated expenditures if the property does not have property specific debt. If the property is encumbered by specific debt, we will capitalize both the interest incurred applicable to that debt and additional interest expense using our weighted average borrowing rate for any accumulated expenditures in excess of the principal balance of the debt encumbering the property. The capitalization of such expenses ceases when the real estate is ready for its intended use, but no later than one-year from substantial completion of major construction activity. If we determine that a construction project is no longer viable, all capitalized pre-development project costs are immediately expensed. Our assets and related intangible assets are individually reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. An impairment exists when the carrying amount of an asset exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. Estimates of future cash flows are based on our current plans, intended holding periods and available market information at the time the analyses are prepared. An impairment loss is recognized if the carrying amount of the asset is not recoverable and is measured based on the excess of the property’s carrying amount over its estimated fair value. If our estimates of future cash flows, anticipated holding periods, or fair values change, based on market conditions or otherwise, our evaluation of impairment charges may be different and such differences could be material to our financial statements. Estimates of future cash flows are subjective and are based, in part, on assumptions regarding future occupancy, rental rates and capital requirements that could differ materially from actual results. Cash and Cash Equivalents Cash and cash equivalents consist of highly liquid investments with a purchase date life to maturity of three months or less and are carried at cost, which approximates fair value, due to their short‑term maturities. Restricted Cash Restricted cash consists primarily of proceeds from property dispositions held in escrow, security deposits held on behalf of our tenants and cash escrowed under loan agreements for debt service, real estate taxes, property insurance and capital improvements. Allowance for Doubtful Accounts We periodically evaluate the collectability of amounts due from tenants, including the receivable arising from deferred rent receivable, and maintain an allowance for doubtful accounts for the estimated losses resulting from the inability of tenants to make required payments under lease agreements. We exercise judgment in establishing these allowances and consider payment history and current credit status in developing these estimates. Investments in and Advances to Real Estate Ventures We analyze our real estate ventures to determine whether the entities should be consolidated. If it is determined that these investments do not require consolidation because the entities are not VIEs in accordance with the Consolidation Topic of the Financial Accounting Standards Board ("FASB"), Accounting Standards Codification ("ASC"), we are not considered the primary beneficiary of the entities determined to be VIEs, we do not have voting control, and/or the limited partners (or non-managing members) have substantive participatory rights, then the selection of the accounting method used to account for our investments in unconsolidated real estate ventures is generally determined by our voting interests and the degree of influence we have over the entity. Management uses its judgment when determining if we are the primary beneficiary of, or have a controlling financial interest in, an entity in which we have a variable interest. Factors considered in determining whether we have the power to direct the activities that most significantly impact the entity’s economic performance include risk and reward sharing, experience and financial condition of the other partners, voting rights, involvement in day-to-day capital and operating decisions and the extent of our involvement in the entity. We use the equity method of accounting for investments in unconsolidated real estate ventures when we own 20% or more of the voting interests and have significant influence but do not have a controlling financial interest, or if we own less than 20% of the voting interests but have determined that we have significant influence. Under the equity method, we record our investments in and advances to these entities in our balance sheets, and our proportionate share of earnings or losses earned by the real estate venture is recognized in "Income (loss) from unconsolidated real estate ventures, net" in the accompanying statements of operations. We earn revenues from the management services we provide to unconsolidated entities. These fees are determined in accordance with the terms specific to each arrangement and may include property and asset management fees or transactional fees for leasing, acquisition, development and construction, financing, and legal services provided. We account for this revenue gross of our ownership interest in each respective real estate venture and recognize such revenue in "Third-party real estate services, including reimbursements" in our statements of operations. Our proportionate share of related expenses is recognized in "Income (loss) from unconsolidated real estate ventures, net" in our statements of operations. We may also earn incremental promote distributions if certain financial return benchmarks are achieved upon ultimate disposition of the underlying properties. Management fees are recognized when earned, and promote fees are recognized when certain earnings events have occurred, and the amount is determinable and collectible. Any promote fees are reflected in "Income (loss) from unconsolidated real estate ventures, net" in our statements of operations. With regard to distributions from unconsolidated real estate ventures, we use the information that is available to us to determine the nature of the underlying activity that generated the distributions. Using the nature of distribution approach, cash flows generated from the operations of an unconsolidated real estate venture are classified as a return on investment (cash inflow from operating activities) and cash flows that from property sales, debt refinancing or sales of our investments are classified as a return of investment (cash inflow from investing activities). On a periodic basis, we evaluate our investments in unconsolidated entities for impairment. We assess whether there are any indicators, including underlying property operating performance and general market conditions, that the value of our investments in unconsolidated real estate ventures may be impaired. An investment in a real estate venture is considered impaired if we determine that its fair value is less than the net carrying value of the investment in that real estate venture on an other-than-temporary basis. Cash flow projections for the investments consider property level factors such as expected future operating income, trends and prospects, as well as the effects of demand, competition and other factors. We consider various qualitative factors to determine if a decrease in the value of our investment is other-than-temporary. These factors include age of the venture, our intent and ability to retain our investment in the entity, financial condition and long-term prospects of the entity and relationships with our partners and banks. If we believe that the decline in the fair value of the investment is temporary, no impairment charge is recorded. If our analysis indicates that there is an other-than temporary impairment related to the investment in a particular real estate venture, the carrying value of the venture will be adjusted to an amount that reflects the estimated fair value of the investment. Intangibles Intangible assets consist of in-place leases, below-market ground rent obligations, above-market real estate leases and options to enter into ground leases that were recorded in connection with the acquisition of properties. Intangible assets also include management and leasing contracts acquired in the Combination. Intangible liabilities consist of above-market ground rent obligations and below-market real estate leases that are also recorded in connection with the acquisition of properties. Both intangible assets and liabilities are amortized and accreted using the straight-line method over their applicable remaining useful life. When a lease or contract is terminated early, any remaining unamortized or unaccreted balances are charged to earnings. The useful lives of intangible assets are evaluated each reporting period with any changes in estimated useful lives being accounted for over the revised remaining useful life. Assets Held for Sale Assets, primarily consisting of real estate, are classified as held for sale when all the necessary criteria are met. The criteria include (i) management, having the authority to approve action, commits to a plan to sell the property in its present condition, (ii) the sale of the property is at a price reasonable in relation to its current fair value and (iii) the sale is probable and expected to be completed within one year. Real estate held for sale is carried at the lower of carrying amounts or estimated fair value less disposal costs. Depreciation and amortization is not recognized on real estate classified as held for sale. Deferred Costs Deferred financing costs consist of loan issuance costs directly related to financing transactions that are deferred and amortized over the term of the related loan as a component of interest expense. Unamortized deferred financing costs related to our mortgages payable and unsecured term loan are presented as a direct deduction from the carrying amounts of the related debt instruments, while such costs related to our revolving credit facility are included in other assets. Direct salaries, third-party fees and other costs incurred by us to originate a lease are capitalized in "Other assets, net" in the balance sheets and are amortized against the respective leases using the straight-line method over the term of the related leases. Noncontrolling Interests We identify our noncontrolling interests separately within the equity section on the balance sheets. Amounts of consolidated net income (loss) attributable to redeemable noncontrolling interests and to the noncontrolling interests in consolidated subsidiaries are presented separately in the statements of operations. Redeemable Noncontrolling Interests - Redeemable noncontrolling interests consists of OP Units issued in conjunction with the Formation Transaction and our venture partner's interest in 965 Florida Avenue. The OP Units became redeemable for our common shares or cash beginning August 1, 2018, subject to certain limitations. Redeemable noncontrolling interests are generally redeemable at the option of the holder and are presented in the mezzanine section between total liabilities and shareholders' equity on the balance sheets. The carrying amount of redeemable noncontrolling interests is adjusted to its redemption value at the end of each reporting period, but no less than its initial carrying value, with such adjustments recognized in "Additional paid-in capital". See Note 12 for additional information. Noncontrolling Interests - Noncontrolling interests represents the portion of equity that we do not own in entities we consolidate, including interests in consolidated real estate ventures. Derivative Financial Instruments and Hedge Accounting Derivative financial instruments are used at times to manage exposure to variable interest rate risk. Derivative financial instruments are recognized as either assets or liabilities and are measured at fair value. The accounting for changes in the fair value of a derivative depends on the intended use of the derivative and the resulting designation . Derivative Financial Instruments Designated as Cash Flow Hedges - Certain derivative financial instruments, consisting of interest rate swap and cap agreements, are designated as cash flow hedges, and are carried at their estimated fair value on a recurring basis. We assess the effectiveness of our cash flow hedges both at inception and on an ongoing basis. If the hedges are deemed to be effective, the fair value is recorded in accumulated other comprehensive income and is subsequently reclassified into "Interest expense" in the period that the hedged forecasted transactions affect earnings. Our cash flow hedges become less than perfectly effective if the critical terms of the hedging instrument and the forecasted transactions do not perfectly match such as notional amounts, settlement dates, reset dates, calculation period and interest rates. In addition, we evaluate the default risk of the counterparty by monitoring the creditworthiness of the counterparty. Derivative instruments and hedging activities require management to make judgments on the nature of its derivatives and their effectiveness as hedges. These judgments determine if the changes in fair value of the derivative instruments are reported in the statements of operations or as a component of comprehensive income and as a component of shareholders’ equity on the balance sheets. Derivative Financial Instruments Not Designated as Hedges - Certain derivative financial instruments, consisting of interest rate swap and cap agreements, are considered economic hedges, but not designated as accounting hedges, and are carried at their estimated fair value on a recurring basis. Realized and unrealized gains are recorded in "Interest expense" in the statements of operations in the period in which the change occurs. Fair Value of Assets and Liabilities ASC 820, Fair Value Measurement and Disclosures, defines fair value and establishes a framework for measuring fair value. The objective of fair value is to determine the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (the exit price). ASC 820 establishes a fair value hierarchy that prioritizes observable and unobservable inputs used to measure fair value into three levels: Level 1 — quoted prices (unadjusted) in active markets that are accessible at the measurement date for assets or liabilities; Level 2 — observable prices that are based on inputs not quoted in active markets, but corroborated by market data; and Level 3 — unobservable inputs that are used when little or no market data is available. The fair value hierarchy gives the highest priority to Level 1 inputs and the lowest priority to Level 3 inputs. In determining fair value, we utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as consider counterparty credit risk in our assessment of fair value. Revenue Recognition Property rentals income includes base rents that each tenant pays in accordance with the terms of its respective lease and is reported on a straight-line basis over the non-cancellable term of the lease, which includes the effects of periodic step-ups in rent and rent abatements under the leases. We commence rental revenue recognition when the tenant takes possession of the leased space or controls the physical use of the leased space and the leased space is substantially ready for its intended use. In circumstances where we provide a tenant improvement allowance for improvements that are owned by the tenant, we recognize the allowance as a reduction of property rentals revenue on a straight-line basis over the term of the lease. Differences between rental income recognized and amounts due under the respective lease agreements are recorded as an increase or decrease to "Deferred rent receivable, net" on our balance sheets. Property rentals also includes the amortization/accretion of acquired above-and below-market leases. Tenant reimbursements provide for the recovery of all or a portion of the operating expenses and real estate taxes of the respective assets. Tenant reimbursements are accrued in the same periods as the related expenses are incurred. Third-party real estate services revenue, including reimbursements, is determined in accordance with the terms specific to each arrangement and may include property and asset management fees or transactional fees for leasing, acquisition, development and construction, financing, and legal services provided. These fees are determined in accordance with the terms specific to each arrangement and are recognized as the related services are performed. Development and construction fees earned from providing services to our unconsolidated real estate ventures are recorded on a percentage of completion basis. Third-Party Real Estate Services Expenses Third-party real estate services expenses include the costs associated with the management services provided to our unconsolidated real estate ventures and other third parties. We allocate personnel and other overhead costs using the estimates of the time spent performing services for our third-party real estate services and other allocation methodologies. Transaction and Other Costs Transaction and other costs consist primarily of fees and expenses incurred in connection with the Formation Transaction, including amounts incurred for transition services provided by our former parent, integration costs and severance costs, as well as pursuit costs related to other completed, potential and pursued transactions. Transaction and other costs are expensed as incurred. Income Taxes We have elected to be taxed as a REIT under sections 856-860 of the Internal Revenue Code of 1986, as amended (the "Code"). Under those sections, a REIT which distributes at least 90% of its REIT taxable income as dividends to its shareholders each year and which meets certain other conditions will not be taxed on that portion of its taxable income which is distributed to its shareholders. Prior to the Separation, Vornado operated as a REIT and distributed 100% of its REIT taxable income to its shareholders; accordingly, no provision for federal income taxes has been made in the accompanying financial statements for the periods prior to the Separation. We currently adhere and intend to continue to adhere to these requirements and to maintain our REIT status in future periods. As a REIT, we can reduce our taxable income by distributing all or a portion of such taxable income to shareholders. Future distributions will be declared and paid at the discretion of the Board of Trustees and will depend upon cash generated by operating activities, our financial condition, capital requirements, annual dividend requirements under the REIT provisions of the Code and such other factors as our Board of Trustees deems relevant. We also participate in the activities conducted by our subsidiary entities that have elected to be treated as taxable REIT subsidiaries ("TRS") under the Code. As such, we are subject to federal, state, and local taxes on the income from these activities. Income taxes attributable to our TRSs are accounted for under the asset and liability method. Under the asset and liability method, deferred income taxes arise from temporary differences between the tax basis of assets and liabilities and their reported amounts in the financial statements, which will result in taxable or deductible amounts in the future. We provide for a valuation allowance for deferred income tax assets if we believe all or some portion of the deferred tax asset may not be realized. Any increase or decrease in the valuation allowance that results from a change in circumstances that causes a change in the estimated ability to realize the related deferred tax asset is included in deferred tax benefit (expense). ASC 740-10, Income Taxes, provides guidance for how uncertain tax positions should be recognized, measured, presented and disclosed in the financial statements. ASC 740-10 requires the evaluation of tax positions taken in the course of preparing our tax returns to determine whether the tax positions are "more-likely-than-not" of being sustained by the applicable tax authority. Tax benefits of positions not deemed to meet the more-likely-than-not threshold are recorded as a tax expense in the current year. Earnings (Loss) Per Common Share Basic earnings (loss) per common share is computed by dividing net income (loss) attributable to common shareholders by the weighted average common shares outstanding during the period. Unvested and vested share-based payment awards that entitle holders to receive non-forfeitable dividends, which include OP Units and long-term incentive partnership units ("LTIP Units"), are considered participating securities. Consequently, we are required to apply the two-class method of computing basic and diluted earnings that would otherwise have been available to common shareholders. Under the two-class method, earnings for the period are allocated between common shareholders and participating securities based on their respective rights to receive dividends. During periods of net loss, losses are allocated only to the extent the participating securities are required to absorb their share of such losses. Diluted earnings per common share reflects the potential dilution of the assumed exchange of various unit and share-based payment awards into common shares to the extent they are dilutive. Share-Based Compensation The fair value of OP Units, formation awards ("Formation Awards"), LTIP Units, LTIP Units with time-based vesting requirements ("Time-Based LTIP Units"), performance-based LTIP Units ("Performance-Based LTIP Units") and Employee Share Purchase Plan ("ESPP") common shares granted to our trustees, management and employees is determined, depending on the type of award, using the Monte Carlo or Black-Scholes methods, which is intended to estimate the fair value of the awards at the grant date using dividend yields, expected volatilities that are primarily based on available implied data and peer group companies' historical data and post-vesting restriction periods. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. The shortcut method is used for determining the expected life used in the valuation method. Compensation expense is based on the fair value of our common shares at the date of the grant and is recognized ratably over the vesting period using a graded vesting attribution model. We account for forfeitures as they occur. Distributions paid on unvested OP Units, LTIP Units, Time-Based LTIP Units and Performance-Based LTIP Units are charged to "Net income attributable to noncontrolling interests" in the statements of operations. Recent Accounting Pronouncements The following table provides a brief description of recent significant accounting pronouncements by the Financial Accounting Standards Board ("FASB") that have been or will be required to be adopted by us: Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standards adopted ASU 2014-09, Revenue from Contracts with Customers (Topic 606), as clarified and amended by ASU 2016-08, ASU 2016-10 and ASU 2016-12 This standard establishes a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most of the existing revenue recognition guidance. It requires an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services and also requires certain additional disclosures. January 2018 We utilized the modified retrospective method of adoption. The standard excludes from its scope the areas of accounting that most significantly affect our revenue recognition, including accounting for leases and financial instruments. Our evaluation determined there were no required changes to our recognition of re

The Combination The Combination

The Combination The Combination (Notes)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	The Combination In the Combination on July 18, 2017, we acquired the JBG Assets in exchange for approximately 37.2 million common shares and OP Units. The Combination has been accounted for at fair value under the acquisition method of accounting. The following allocation of the purchase price is based on the fair value of the assets acquired and liabilities assumed (in thousands): Fair value of purchase consideration: Common shares and OP Units $ 1,224,885 Cash 20,573 Total consideration paid $ 1,245,458 Fair value of assets acquired and liabilities assumed: Land and improvements $ 338,072 Building and improvements 609,156 Construction in progress, including land 699,800 Leasehold improvements and equipment 7,890 Real estate 1,654,918 Cash 104,529 Restricted cash 13,460 Investments in and advances to unconsolidated real estate ventures 241,142 Identified intangible assets 138,371 Notes receivable (1) 50,934 Identified intangible liabilities (8,687 ) Mortgages payable assumed (2) (768,523 ) Capital lease obligations assumed (3) (33,543 ) Lease assumption liabilities (4) (48,127 ) Deferred tax liability (5) (18,610 ) Other liabilities acquired, net (60,048 ) Noncontrolling interests in consolidated subsidiaries (3,588 ) Net assets acquired 1,262,228 Gain on bargain purchase (6) 16,770 Total consideration paid $ 1,245,458 ____________________ (1) During the year ended December 31, 2017 , we received proceeds of $50.9 million from the repayment of the notes receivable acquired in the Combination. (2) Subject to various interest rate swap and cap agreements assumed in the Combination that are considered economic hedges, but not designated as accounting hedges. (3) In the Combination, two ground leases were assumed that were determined to be capital leases. On July 25, 2017, we purchased a land parcel located in Reston, Virginia associated with one of the ground leases for $19.5 million . (4) Includes a $14.0 million payment to a tenant, which was paid in 2018, and a $34.1 million lease liability we assumed in relocating a tenant to one of our office buildings. The $34.1 million assumed lease liability is based on the contractual payments we assumed under the tenant’s previous lease, which are partially offset by estimated sub-tenant income we anticipate receiving as we actively pursue a sub-tenant. (5) Related to the management and leasing contracts acquired in the Combination. (6) The Combination resulted in a gain on bargain purchase of $24.4 million for the year ended December 31, 2017 because the fair value of the identifiable net assets acquired exceeded the purchase consideration. As a result of finalizing our fair value estimates used in the purchase price allocation related to the Combination, during the year ended December 31, 2018 , we adjusted the fair value of certain assets acquired and liabilities assumed consisting of a decrease of $468,000 to investments in and advances to unconsolidated real estate ventures, an increase of $4.7 million to lease assumption liabilities and an increase of $2.4 million to other liabilities acquired, resulting in a reduction of the gain on bargain purchase of $7.6 million for the year ended December 31, 2018 . The purchase consideration was based on the fair value of the common shares and OP Units issued in the Combination. We have concluded that all acquired assets and liabilities were recognized and that the valuation procedures and resulting estimates of fair values were appropriate. The fair value of the common shares and OP Units purchase consideration was determined as follows (i n thousands, except exchange ratio and price per share/unit): Outstanding common shares and common limited partnership units prior to the Combination 100,571 Exchange ratio (1) 2.71 Common shares and OP Units issued in consideration 37,164 Price per share/unit (2) $ 37.10 Fair value of common shares and OP Units issued in consideration $ 1,378,780 Fair value adjustment to OP Units due to transfer restrictions (43,304 ) Portion of consideration attributable to performance of future services (3) (110,591 ) Fair value of common shares and OP Units purchase consideration $ 1,224,885 ____________________ (1) Represents the implied exchange ratio of one common share and OP Unit of JBG SMITH for 2.71 common shares and common limited partnership units prior to the Combination. (2) Represents the volume weighted average share price on July 18, 2017. (3) OP Unit consideration paid to certain of the owners of the JBG Assets which have a fair value of $110.6 million is subject to post-combination employment with vesting over periods of either 12 or 60 months and amortization is recognized as compensation expense over the period of employment in "General and administrative expense: Share-based compensation related to Formation Transaction and special equity awards" in the statements of operations. The JBG Assets acquired on July 18, 2017 comprise: (i) 30 operating assets comprising 21 commercial assets totaling approximately 4.1 million square feet ( 2.4 million square feet at our share) and nine multifamily assets with 2,883 units ( 1,099 units at our share); (ii) 11 commercial and multifamily assets under construction totaling over 2.5 million square feet ( 2.2 million square feet at our share); (iii) two near-term development commercial and multifamily assets totaling approximately 401,000 square feet ( 242,000 square feet at our share); (iv) 26 future development assets totaling approximately 11.7 million square feet ( 8.5 million square feet at our share) of estimated potential development density; and (v) JBG/Operating Partners, L.P., a real estate services company providing investment, development, asset management, property management, leasing, construction management and other services. Before the Combination, JBG/Operating Partners, L.P. was owned by 20 unrelated individuals, 19 of whom became our employees and three of whom serve on our Board of Trustees. The fair values of tangible and identified intangible assets and liabilities, which have definite lives, are as follows: Total Fair Value Weighted Average Amortization Period Useful Life (1) (In thousands) (In years) Tangible assets: Building and improvements $ 543,584 3 - 40 years Tenant improvements 65,572 Shorter of useful life or remaining life of the respective lease Total building and improvements $ 609,156 Leasehold improvements $ 4,422 Shorter of useful life or remaining life of the respective lease Equipment 3,468 5 years Total leasehold improvements and equipment $ 7,890 Identified intangible assets: In-place leases $ 60,317 6.4 Remaining life of the respective lease Above-market real estate leases 11,732 6.3 Remaining life of the respective lease Below-market ground leases 332 88.5 Remaining life of the respective lease Option to enter into ground lease 17,090 N/A Remaining life of contract Management and leasing contracts (2) 48,900 7.5 Estimated remaining life of contracts, ranging between 3 - 9 years Total identified intangible assets $ 138,371 Identified intangible liabilities: Below-market real estate leases $ 8,687 10.3 Remaining life of the respective lease ____________________ (1) In determining these useful lives, we considered the length of time the asset had been in existence, the maintenance history, as well as anticipated future maintenance, and any contractual stipulations that might limit the useful life. (2) Includes in-place property management, leasing, asset management and development management contracts. Costs related to the Formation Transaction (such as advisory, severance, legal, accounting, valuation and other professional fees) are included in "Transaction and other costs" in our statements of operations. Transaction and other costs of $27.7 million for the year ended December 31, 2018 comprised fees and expenses incurred in connection with the Formation Transaction (including transition services provided by our former parent, integration costs and severance costs) of $15.9 million , costs related to other completed, potential and pursued transactions of $9.0 million and costs related to the successful pursuit of an Amazon.com, Inc. ("Amazon") headquarters at our properties in National Landing (“Amazon HQ2”) of $2.8 million . Transaction and other costs of $127.7 million for the year ended December 31, 2017 consist primarily of fees and expenses incurred in connection with the Formation Transaction, including severance and transaction bonus expense of $40.8 million , investment banking fees of $33.6 million , legal fees of $13.9 million and accounting fees of $10.8 million . The following pro forma information for the year ended December 31, 2017 is presented as if the Formation Transaction had occurred on January 1, 2016. This pro forma information is based upon historical financial statements, adjusted for certain factually supported items directly related to the Formation Transaction. This pro forma information does not purport to represent what the actual results of our operations would have been, nor does it purport to predict the results of operations of future periods. The pro forma information was adjusted to exclude transaction and other costs of $127.7 million and the gain on bargain purchase of $24.4 million and their related income tax benefits for the year ended December 31, 2017 . Year Ended December 31, 2017 (In thousands) Unaudited pro forma information: Total revenue $ 637,672 Net loss attributable to common shareholders (19,343 ) The total revenue and net loss of the JBG Assets for the year ended December 31, 2017 included in our statements of operations from the acquisition date was $71.3 million and $23.1 million .

Acquisitions, Disposals and Ass

Acquisitions, Disposals and Assets Held for Sale (Notes)	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	Acquisitions, Dispositions and Assets Held for Sale Acquisitions In December 2018, we purchased a 4.25-acre land parcel, Potomac Yard Land Bay H located in Alexandria, Virginia, for $23.0 million through a reverse Section 1031 of the Code like-kind exchange agreement with a third party intermediary. See Note 7 for further discussion. In conjunction with the acquisition, we recorded a liability of $15.1 million , based on the fair value estimate to remediate pre-existing environmental matters, which was capitalized as part of the cost of the land. In December 2018, we acquired the remaining 3.1% interest in West Half, a real estate venture, for $5.0 million , which increased our interest to 100.0% . Prior to the acquisition, West Half was a consolidated VIE. Dispositions The following is a summary of disposition activity for the year ended December 31, 2018 : Date Disposed Assets Segment Location Total Square Feet Gross Sales Price Cash Proceeds from Sale (1) Gain on Sale of Real Estate (In thousands) February 13, 2018 Summit - MWAA Commercial Reston, Virginia — $ 2,154 $ 2,154 $ 455 April 3, 2018 Summit I and II / Summit Land (2) Commercial Reston, Virginia 284,118 95,000 35,240 6,189 May 1, 2018 Bowen Building (3) Commercial Washington, D.C. 231,402 140,000 136,488 27,207 September 21, 2018 Executive Tower (4) Commercial Washington, D.C. 129,831 121,445 113,267 12,378 October 23, 2018 1233 20th Street (5) Commercial Washington, D.C. 149,684 65,000 21,229 4,354 October 25, 2018 Falkland Chase - North (out-of-service portion) Multifamily Silver Spring, Maryland 13,284 3,819 3,819 1,600 Total 808,319 $ 427,418 $ 312,197 $ 52,183 ______________ (1) Net of related mortgage loan payments. (2) Total square feet included 700,000 square feet of estimated potential development density. In connection with the sale, we repaid the related $59.0 million mortgage loan. (3) In connection with the sale, we repaid $115.0 million of the then outstanding balance on our revolving credit facility. (4) Proceeds from the sale were held in escrow and classified as "Restricted cash" on our balance sheet as of December 31, 2018 . (5) In connection with the sale, we repaid the related $41.9 million mortgage loan. In August 2018, JP Morgan, our partner in the real estate venture that owned the Investment Building, a 401,000 square foot office building located in Washington, D.C., acquired our 5.0% interest in the venture. In December 2018, our unconsolidated real estate venture with Canadian Pension Plan Investment Board ("CPPIB") sold The Warner, a 583,000 square foot office building located in Washington, D.C. See Note 6 for additional information. Assets Held for Sale As of December 31, 2018 and 2017 , we had certain real estate properties that were classified as held for sale. The amounts included in "Assets held for sale" in our balance sheets primarily represent real estate investment balances. The following is a summary of assets held for sale: Assets Segment Location Total Square Feet Assets Held for Sale Liabilities Related to Assets Held for Sale (In thousands) December 31, 2018 Commerce Executive (1) Commercial Reston, Virginia 388,562 $ 78,981 $ 3,717 December 31, 2017 Summit - MWAA (2) Commercial Reston, Virginia — $ 1,699 $ — Potomac Yard Land Bay G (3) Other Alexandria, Virginia — 6,594 — $ 8,293 $ — _______________ (1) In July 2018, the buyer’s deposit related to the contract to sell Commerce Executive became non-refundable. In February 2019 , we sold Commerce Executive for $115.0 million . The sale also included approximately 894,000 square feet of estimated potential development density. The sale was part of a reverse 1031 like-kind exchange. See Note 7 for additional information. (2) As previously disclosed, in February 2018, Summit - MWAA was sold for $2.2 million . (3) During the second quarter of 2018, the buyer forfeited their deposit and the property was removed from assets held for sale.

Tenant and Other Receivables, N

Tenant and Other Receivables, Net (Notes)	12 Months Ended
	Dec. 31, 2018
Tenant and Other Receivables, Net [Abstract]
Tenant and Other Receivables Disclosure, Net	Tenant and Other Receivables, Net The following is a summary of tenant and other receivables: December 31, 2018 2017 (In thousands) Tenants $ 31,362 $ 30,672 Third-party real estate services 12,443 8,954 Other 9,463 12,992 Allowance for doubtful accounts (6,700 ) (5,884 ) Total tenant and other receivables, net $ 46,568 $ 46,734 We incurred bad debt expense of approximately $3.3 million , $3.8 million and $750,600 during each of the three years in the period ended December 31, 2018 , which is included in "Property operating expenses" in the statements of operations.

Investments in and Advances to

Investments in and Advances to Unconsolidated Real Estate Ventures	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investments in and Advances to Unconsolidated Real Estate Ventures	Investments in and Advances to Unconsolidated Real Estate Ventures The following is a summary of the composition of our investments in and advances to unconsolidated real estate ventures: Ownership Interest (1) December 31, Real Estate Venture Partners 2018 2017 (In thousands) CPPIB 55.0% - 68.5% $ 97,521 $ 36,317 Landmark 1.8% - 49.0% 84,320 95,368 CBREI Venture 5.0% - 64.0% 73,776 79,062 Berkshire Group 50.0% 43,937 27,761 Brandywine 30.0% 13,777 13,741 CIM Group ("CIM") and Pacific Life Insurance Company ("PacLife") 16.7% 9,339 — JP Morgan —% — 9,296 Other 128 246 Total investments in unconsolidated real estate ventures 322,798 261,791 Advances to unconsolidated real estate ventures 80 20 Total investments in and advances to unconsolidated real estate ventures $ 322,878 $ 261,811 _______________ (1) Ownership interests as of December 31, 2018 . We have multiple investments with certain venture partners with varying ownership interests. In January 2018, we invested $10.1 million for a 16.67% interest in a real estate venture with CIM and PacLife, which purchased the 1,152-key Wardman Park hotel, located adjacent to the Woodley Park Metro Station in northwest Washington, D.C. Prior to the acquisition by this venture, the JBG Legacy Funds owned a 47.64% interest in the Wardman Park hotel. The JBG Legacy Funds did not receive any proceeds from the sale, as the net proceeds were used to satisfy the prior mortgage debt. A third-party asset manager oversees the hotel operations on behalf of the venture and our involvement will increase only to the extent the land development opportunity becomes the primary business plan for the asset. In February 2018, we entered into a real estate venture with CPPIB to develop and own 1900 N Street, an under construction commercial asset in Washington, D.C. We contributed 1900 N Street, valued at $95.9 million , to the real estate venture, and CPPIB has committed to contribute approximately $101.3 million to the venture for a 45.0% interest, which will reduce our ownership interest from 100.0% at the real estate venture's formation to 55.0% as contributions are funded. In June 2018, the real estate venture with CPPIB that owns 1101 17th Street, a 216,000 square foot office building located in Washington, D.C., in which we have a 55.0% ownership interest, refinanced a mortgage loan payable that was collateralized by the property. The terms of the new mortgage loan eliminated the principal guaranty provisions that had been included in the prior loan. At the time of refinancing, distributions and our share of the cumulative earnings of the venture exceeded our investment in the venture by $5.4 million , which resulted in a negative investment balance. After the elimination of the principal guaranty provisions in the prior mortgage loan, we no longer guarantee the obligations of the venture or are obligated to provide further financial support to the venture. Accordingly, we recognized the $5.4 million negative investment balance as income within "Income from unconsolidated real estate ventures, net" in our statements of operations for the year ended December 31, 2018 , which results in a zero investment balance in the real estate venture that owns 1101 17th Street in our balance sheet as of December 31, 2018 . We have also suspended the equity method accounting for this real estate venture. We will recognize as income any future distributions from the venture until our share of unrecorded earnings and contributions exceed the cumulative excess distributions previously recognized in income. During the year ended December 31, 2018 , we recognized income of $8.3 million related to distributions from the real estate venture that owns 1101 17th Street, which is included in "Income from unconsolidated real estate ventures, net" in our statement of operations. In August 2018, JP Morgan, our partner in the real estate venture that owned the Investment Building, a 401,000 square foot office building located in Washington, D.C., acquired our 5.0% interest in the venture for $24.6 million , resulting in a gain of $15.5 million , which is included in "Income from unconsolidated real estate ventures, net" in our statement of operations for the year ended December 31, 2018 . In December 2018, our unconsolidated real estate venture with CPPIB sold The Warner, a 583,000 square foot office building located in Washington, D.C., for $376.5 million . In connection with the sale, the unconsolidated real estate venture recognized a gain on sale of $32.5 million , of which our proportionate share was $20.6 million , which is included in "Income from unconsolidated real estate ventures, net" in our statement of operations for the year ended December 31, 2018 . Additionally, in connection with the sale, our unconsolidated real estate venture repaid the related mortgage payable of $270.5 million . The following is a summary of the debt of our unconsolidated real estate ventures: Weighted Average Effective (1) December 31, 2018 2017 (In thousands) Variable rate (2) 5.53% $ 461,704 $ 534,500 Fixed rate (3) 4.02% 665,662 657,701 Unconsolidated real estate ventures - mortgages payable 1,127,366 1,192,201 Unamortized deferred financing costs (1,998 ) (2,000 ) Unconsolidated real estate ventures - mortgages payable, net (4) $ 1,125,368 $ 1,190,201 ______________ (1) Weighted average effective interest rate as of December 31, 2018 . (2) Includes variable rate mortgages payable with interest rate cap agreements. (3) Includes variable rate mortgages payable with interest rates fixed by interest rate swap agreements. (4) See Note 19 for additional information on guarantees of the debt of certain of our unconsolidated real estate ventures. The following is a summary of the financial information for our unconsolidated real estate ventures: December 31, 2018 2017 Combined balance sheet information: (In thousands) Real estate, net $ 2,050,985 $ 2,106,670 Other assets, net 169,264 264,731 Total assets $ 2,220,249 $ 2,371,401 Borrowings, net $ 1,125,368 $ 1,190,201 Other liabilities, net 94,845 76,416 Total liabilities 1,220,213 1,266,617 Total equity 1,000,036 1,104,784 Total liabilities and equity $ 2,220,249 $ 2,371,401 Year Ended December 31, 2018 2017 2016 Combined income statement information: (In thousands) Total revenue $ 300,032 $ 135,256 $ 68,118 Operating income (1) 56,262 14,741 19,283 Net income (loss) (1,155 ) (7,593 ) 5,234 _____________ (1) Includes gain on sale of The Warner of $32.5 million recognized by our unconsolidated real estate venture with CPPIB during the year ended December 31, 2018 .

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	Variable Interest Entities We hold various interests in entities deemed to be VIEs, which we evaluate at acquisition, formation, after a change in the ownership agreement or a change in the real estate venture's economics to determine if the VIEs should be consolidated in our financial statements or should no longer be considered a VIE. Certain criteria we assess in determining whether the VIEs should be consolidated relate to our at-risk equity, our control over significant business activities, our voting rights, the noncontrolling interest kick-out rights and whether we are the primary beneficiary of the VIE. Unconsolidated VIEs As of December 31, 2018 and 2017 , we have interests in entities deemed to be VIEs that are in the development stage and do not hold sufficient equity at risk or conduct substantially all their operations on behalf of an investor with disproportionately few voting rights. Although we are engaged to act as the managing partner in charge of day-to-day operations of these investees, we are not the primary beneficiary of these VIEs as we do not hold unilateral power over activities that, when taken together, most significantly impact the respective VIE’s performance. We account for our investment in these entities under the equity method. As of December 31, 2018 and 2017 , the net carrying amounts of our investment in these entities were $232.8 million and $163.5 million , which are included in "Investments in and advances to unconsolidated real estate ventures" in our balance sheets. Our equity in the income of unconsolidated VIEs is included in "Income from unconsolidated real estate ventures, net" in our statements of operations. Our maximum exposure to loss in these entities is limited to our investments, construction commitments and debt guarantees. See Note 19 for additional information. Consolidated VIEs JBG SMITH LP is our most significant consolidated VIE. We hold the majority membership interest in the operating partnership, act as the general partner and exercise full responsibility, discretion and control over its day-to-day management. The noncontrolling interests of the operating partnership do not have substantive liquidation rights, substantive kick-out rights without cause, or substantive participating rights that could be exercised by a simple majority of noncontrolling interest members (including by such a member unilaterally). Because the noncontrolling interest holders do not have these rights, the operating partnership is a VIE. As general partner, we have the power to direct the core activities of the operating partnership that most significantly affect its performance, and through our majority interest in the operating partnership have both the right to receive benefits from and the obligation to absorb losses of the operating partnership. Accordingly, we are the primary beneficiary of the operating partnership and consolidate the operating partnership in our financial statements. As we conduct our business and hold our assets and liabilities through the operating partnership, the total assets and liabilities of the operating partnership comprise substantially all of our consolidated assets and liabilities. In conjunction with the acquisition of Potomac Yard Land Bay H located in Alexandria, Virginia in December 2018, we entered into a reverse Code Section 1031 like-kind exchange agreement with a third party intermediary, which, for a maximum of 180 days, allowed us to defer for tax purposes, gains on the sale of other properties identified and sold within this period. Until the earlier of the termination of the exchange agreement or 180 days after the acquisition date, the third party intermediary was the legal owner of the entity that owned this property. The agreement that governed the operations of this entity provided us with the power to direct the activities that most significantly impacted the entity's economic performance. This entity is deemed a VIE as of December 31, 2018 primarily because it may not have sufficient equity at risk to finance its activities without additional subordinated financial support from other parties. We determined that we are the primary beneficiary of the VIE as a result of having the power to direct the activities that most significantly impact its economic performance and the obligation to absorb losses, as well as the right to receive benefits, that could be potentially significant to the VIE. Accordingly, we consolidated the property and its operations as of the acquisition date. Legal ownership of this entity was transferred to us by the qualified intermediary after of the sale of Commerce Executive in February 2019 . We also consolidate certain other VIEs in which we control the most significant business activities. These entities are VIEs because they are in the development stage and do not hold sufficient equity at risk. We are the primary beneficiaries of these VIEs because the noncontrolling interest holders do not have substantive kick-out or participating rights and we control all of the significant business activities. As of December 31, 2018 , we consolidated two VIEs with total assets and liabilities, excluding the operating partnership, of $94.8 million and $43.4 million . As of December 31, 2017 , we consolidated two VIEs with total assets and liabilities, excluding the operating partnership, of $111.0 million and $8.8 million . In December 2018, we acquired the remaining interest in West Half. Prior to the acquisition, West Half was a consolidated VIE. See Note 4 for additional information.

Other Assets, Net

Other Assets, Net	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Assets, Net	Other Assets, Net The following is a summary of other assets, net: December 31, 2018 2017 (In thousands) Deferred leasing costs $ 202,066 $ 171,153 Accumulated amortization (72,465 ) (67,180 ) Deferred leasing costs, net 129,601 103,973 Identified intangible assets, net 89,859 126,467 Prepaid expenses 6,482 9,038 Deferred financing costs on credit facility, net 4,806 6,654 Deposits 3,633 6,317 Derivative agreements, at fair value 10,383 2,141 Other 20,230 9,333 Total other assets, net $ 264,994 $ 263,923 The following is a summary of the composition of identified intangible assets, net: December 31, 2018 2017 Identified intangible assets: (in thousands) In-place leases $ 38,216 $ 72,086 Above-market real estate leases 9,414 12,066 Below-market ground leases 2,215 2,547 Option to enter into ground lease 17,090 17,090 Management and leasing contracts 48,900 48,900 Other 166 206 Total identified intangibles assets 116,001 152,895 Accumulated amortization: In-place leases 11,602 20,015 Above-market real estate leases 2,405 1,600 Below-market ground leases 1,448 1,365 Option to enter into ground lease 251 78 Management and leasing contracts 10,297 3,209 Other 139 161 Total accumulated amortization 26,142 26,428 Identified intangible assets, net $ 89,859 $ 126,467 The following is a summary of amortization expense included in the statements of operations related to identified intangible assets: Year Ended December 31, 2018 2017 2016 In-place lease amortization (1) $ 11,807 $ 10,216 $ 485 Above-market real estate lease amortization (2) 2,390 1,428 78 Below-market ground lease amortization (3) 85 87 85 Option to enter into ground lease amortization (3) 173 — — Management and leasing contract amortization (1) 7,088 3,209 — Other amortization (1) 18 14 92 Total identified intangible asset amortization $ 21,561 $ 14,954 $ 740 ___________________________________________ (1) Amounts are included in "Depreciation and amortization expenses" in our statements of operations. (2) Amounts are included in "Property rentals revenue" in our statements of operations. (3) Amounts are included in "Property operating expenses" in our statements of operations. As of December 31, 2018 , the estimated amortization of identified intangible assets is as follows for the next five years and thereafter: Year ending December 31, Amount (in thousands) 2019 $ 16,184 2020 13,720 2021 10,591 2022 9,506 2023 8,924 Thereafter 30,934 Total $ 89,859

Debt

Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Debt	Debt Mortgages Payable The following is a summary of mortgages payable: Weighted Average (1) December 31, 2018 2017 (In thousands) Variable rate (2) 4.30% $ 308,918 $ 498,253 Fixed rate (3) 4.09% 1,535,734 1,537,706 Mortgages payable 1,844,652 2,035,959 Unamortized deferred financing costs and premium/ discount, net (6,271 ) (10,267 ) Mortgages payable, net $ 1,838,381 $ 2,025,692 __________________________ (1) Weighted average effective interest rate as of December 31, 2018 . (2) Includes variable rate mortgages payable with interest rate cap agreements. (3) Includes variable rate mortgages payable with interest rates fixed by interest rate swap agreements. As of December 31, 2018 , the net carrying value of real estate collateralizing our mortgages payable, excluding assets held for sale, totaled $2.3 billion . Our mortgage loans contain covenants that limit our ability to incur additional indebtedness on these properties and in certain circumstances, require lender approval of tenant leases and/or yield maintenance upon repayment prior to maturity. Certain of our mortgage loans are recourse to us. As of December 31, 2018 , we were not in default under any mortgage loan. During the year ended December 31, 2018 , aggregate borrowings totaled $118.1 million , of which $47.5 million relates to the principal balance on a new mortgage loan collateralized by 1730 M Street and the remainder related to construction draws under mortgages payable. We repaid mortgages payable with an aggregate principal balance of $298.1 million and recognized losses on the extinguishment of debt in conjunction with these repayments of $5.2 million for the year ended December 31, 2018 . In the Combination, we assumed mortgages payable with an aggregate principal balance of $768.5 million . In addition, we entered into mortgages payable with an aggregate principal balance of $79.3 million during the year ended December 31, 2017 with an ability to draw an additional $143.7 million for construction. During the year ended December 31, 2017 , we repaid mortgages payable with an aggregate principal balance of $250.0 million , which includes mortgages payable totaling $64.8 million assumed in the Combination. We recognized losses on the extinguishment of debt in conjunction with these repayments of $701,000 for the year ended December 31, 2017 . As of December 31, 2018 and 2017 , we had various interest rate swap and cap agreements with an aggregate notional value of $1.3 billion and $1.4 billion on certain of our mortgages payable, which mature on various dates concurrent with the maturity of the related mortgages payable. During the year ended December 31, 2018 , we entered into various interest rate swap and cap agreements on certain of our mortgages payable with an aggregate notional value of $381.3 million . See Note 17 for additional information. Credit Facility In July 2017, we entered into a $1.4 billion credit facility, consisting of a $1.0 billion revolving credit facility maturing in July 2021 , with two six -month extension options, a delayed draw $200.0 million unsecured term loan ("Tranche A-1 Term Loan") maturing in January 2023 , and a delayed draw $200.0 million unsecured term loan ("Tranche A-2 Term Loan") maturing in July 2024 . The interest rate for the credit facility varies based on a ratio of our total outstanding indebtedness to a valuation of certain real property and assets and ranges (a) in the case of the revolving credit facility, from LIBOR plus 1.10% to LIBOR plus 1.50% , (b) in the case of the Tranche A-1 Term Loan, from LIBOR plus 1.20% to LIBOR plus 1.70% and (c) in the case of the Tranche A-2 Term Loan, from LIBOR plus 1.55% to LIBOR plus 2.35% . There are various LIBOR options in the credit facility, and we elected the one-month LIBOR option as of December 31, 2018 . As of December 31, 2018 , we were not in default under our credit facility. In July 2017, in connection with the Combination, we drew $115.8 million on the revolving credit facility and $50.0 million under the Tranche A-1 Term Loan. In connection with the execution of the credit facility, we incurred $11.2 million in debt issuance costs during the year ended December 31, 2017 . In October 2017, we entered into an interest rate swap with a notional value of $50.0 million effectively to convert the variable interest rate applicable to our Tranche A-1 Term Loan to a fixed interest rate. In January 2018, we drew $50.0 million under the Tranche A-1 Term Loan in accordance with the delayed draw provisions of the credit facility, bringing the outstanding borrowings under the term loan facility to $100.0 million . Concurrent with the draw, we entered into an interest rate swap agreement effectively to convert the variable interest rate to a fixed interest rate. As of December 31, 2018 and 2017 , we had interest rate swaps with an aggregate notional value of $100.0 million and $50.0 million effectively to convert the variable interest rate applicable to our Tranche A-1 Term Loan to a fixed interest rate, providing weighted average base interest rates under the facility agreement of 2.12% and 1.97% per annum. The interest rate swaps mature in January 2023, concurrent with the maturity of our Tranche A-1 Term Loan. In July 2018, we drew $200.0 million under the Tranche A-2 Term Loan, in accordance with the delayed draw provisions of the credit facility. The following is a summary of amounts outstanding under the credit facility: December 31, Interest Rate (1) 2018 2017 (In thousands) Revolving credit facility (2) (3) (4) (5) 3.60% $ — $ 115,751 Tranche A-1 Term Loan 3.32% $ 100,000 $ 50,000 Tranche A-2 Term Loan 4.05% 200,000 — Unsecured term loans 300,000 50,000 Unamortized deferred financing costs, net (2,871 ) (3,463 ) Unsecured term loans, net $ 297,129 $ 46,537 __________________________ (1) Interest rate as of December 31, 2018 . (2) As of December 31, 2018 and 2017 , letters of credit with an aggregate face amount of $5.7 million were provided under our revolving credit facility. (3) As of December 31, 2018 and 2017 , net deferred financing costs related to our revolving credit facility totaling $4.8 million and $6.7 million were included in "Other assets, net." (4) In May 2018, in connection with the sale of the Bowen Building, we repaid $115.0 million of the then outstanding balance on our revolving credit facility. See Note 4 for additional information. (5) The interest rate for the revolving credit facility excludes a 0.15% facility fee. Principal Maturities Principal maturities of debt outstanding as of December 31, 2018 , including mortgages payable and the term loans, are as follows:

Other Liabilities, Net

Other Liabilities, Net	12 Months Ended
	Dec. 31, 2018
Other Liabilities Disclosure [Abstract]
Other Liabilities, Net	Other Liabilities, Net The following is a summary of other liabilities, net: December 31, 2018 2017 (In thousands) Lease intangible liabilities $ 40,179 $ 44,917 Accumulated amortization (26,081 ) (26,950 ) Lease intangible liabilities, net 14,098 17,967 Prepaid rent 21,998 15,751 Lease assumption liabilities and accrued tenant incentives 32,422 50,866 Capital lease obligation 15,704 15,819 Security deposits 17,696 13,618 Environmental liabilities (1) 17,898 2,900 Ground lease deferred rent payable 3,510 3,730 Net deferred tax liability 6,878 8,202 Dividends payable 45,193 31,097 Other 6,209 1,327 Total other liabilities, net $ 181,606 $ 161,277 __________________________ (1) Includes a $15.1 million liability to remediate pre-existing environmental matters related to Potomac Yard Land Bay H, which was acquired in December 2018. Amortization expense included in "Property rentals" in the statements of operations related to lease intangible liabilities for each of the three years in the period ended December 31, 2018 was $2.6 million , $2.3 million and $1.4 million . As of December 31, 2018 , the estimated amortization of lease intangible liabilities is as follows for the next five years and thereafter: Year ending December 31, Amount (in thousands) 2019 $ 2,232 2020 2,019 2021 1,753 2022 1,734 2023 1,726 Thereafter 4,634 Total $ 14,098

Income Taxes (Notes)

Income Taxes (Notes)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes For the years ended December 31, 2018 and 2017 , we have elected to be taxed as a REIT, and our former parent also elected to be taxed as a REIT for the year ended December 31, 2016 . Accordingly, we incurred no federal income tax expense for any of the three years in the period ended December 31, 2018 related to our REIT subsidiaries. The only federal income taxes included in the accompanying financial statements relate to activities of our TRSs. Due to the passage of federal tax reform legislation, which was signed into law on December 22, 2017 and which we refer as the 2017 Tax Act, our TRSs were required to decrease the net deferred tax liability, which resulted in a net tax benefit of $3.9 million during the year ended December 31, 2017 . The recorded tax charges in 2017 for the impact of the 2017 Tax Act were made using the current available information and technical guidance on the interpretations of the 2017 Tax Act. As permitted by Securities and Exchange Commission Staff Accounting Bulletin 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act, we recorded estimates and have subsequently finalized our accounting analysis based on the guidance, interpretations and data available as of December 31, 2018 . We did not have any changes to our 2017 estimate related to the 2017 Tax Act and therefore, it had no impact to our 2018 financial statements. Our financial statements include the operations of our TRSs, which are subject to federal, state and local income taxes on their taxable income. As a REIT, we may also be subject to federal excise taxes if we engage in certain types of transactions. Continued qualification as a REIT depends on our ability to satisfy the REIT distribution tests, stock ownership requirements and various other qualification tests. As of December 31, 2018 , our TRSs have an estimated federal and state net operating loss of $6.8 million , which will expire in 2037 and 2038 . The net basis of our assets and liabilities for tax reporting purposes is approximately $114.0 million lower than the amounts reported in our balance sheet as of December 31, 2018 . The following is a summary of our income tax benefit (expense): Year Ended December 31, 2018 2017 2016 (in thousands) Current tax benefit (expense) $ 20 $ (496 ) $ (1,083 ) Deferred tax benefit (expense) 718 10,408 — Income tax benefit (expense) $ 738 $ 9,912 $ (1,083 ) As of December 31, 2018 and 2017 , we have a net deferred tax liability of $6.9 million and $8.2 million primarily related to the management and leasing contracts assumed in the Combination, partially offset by deferred tax assets associated with tax versus book differences, related general and administrative expenses and the net operating loss for 2018 and 2017 . We are subject to federal, state and local income tax examinations by taxing authorities for 2015 through 2018. December 31, 2018 2017 (in thousands) Deferred tax assets: Accrued bonus $ — $ 1,675 Net operating loss 2,326 1,710 Deferred revenue 998 71 Bad debt expense 583 111 Other 198 623 Total deferred tax assets 4,105 4,190 Valuation allowance (469 ) — Total deferred tax assets, net of valuation allowance 3,636 4,190 Deferred tax liabilities: Management and leasing contracts (9,905 ) (11,840 ) Other (609 ) (552 ) Total deferred tax liabilities (10,514 ) (12,392 ) Net deferred tax liability $ (6,878 ) $ (8,202 ) During 2018, we established a valuation allowance attributable to a portion of the federal loss carry forward as we do not consider it more likely than not that a deferred tax asset will be realized. During the year ended December 31, 2018 , our Board of Trustees declared cash dividends totaling $1.00 (regular dividends of $0.90 per common share and a special dividend of $0.10 per common share) of which $0.42 was taxable as ordinary income for federal income tax purposes in 2018 , $0.355 were capital gain distributions and the remaining $0.225 will be determined in 2019. During the year ended December 31, 2017 , our Board of Trustees declared cash dividends of $0.45 per common share of which $0.385 was taxable as ordinary income for federal income tax purposes in 2017 and $0.065 were capital gains distributions. No dividends were declared or paid in 2016.

Redeemable Noncontrolling Inter

Redeemable Noncontrolling Interests	12 Months Ended
	Dec. 31, 2018
Noncontrolling Interest [Abstract]
Redeemable Noncontrolling Interests	Redeemable Noncontrolling Interests JBG SMITH LP In July 2017, JBG SMITH LP issued 19.8 million OP Units to persons other than JBG SMITH that became redeemable for cash or, at our election, our common shares beginning on August 1, 2018, subject to certain limitations. During the year ended December 31, 2018 , unitholders redeemed 3.0 million OP units, which we elected to redeem for an equivalent number of our common shares. As of December 31, 2018 , outstanding OP Units totaled 16.8 million , representing a 12.2% interest in JBG SMITH LP. On our balance sheets, our redeemable noncontrolling interests are presented at the higher of their redemption value at the end of each reporting period or their carrying value, with such adjustments recognized in "Additional paid-in capital." Redemption value is equivalent to the market value of one of our common shares at the end of the period multiplied by the number of vested OP units outstanding. In 2019, unitholders redeemed 1.7 million OP units, which we elected to redeem for an equivalent number of our common shares. Consolidated Real Estate Venture In November 2017, we became a partner in a real estate venture that owns an under construction multifamily asset located at 965 Florida Avenue in Washington, D.C. Pursuant to the terms of the 965 Florida Avenue real estate venture agreement, we will fund all capital contributions until our ownership interest reaches a maximum of 97.0% . Our partner can redeem its interest for cash two years after delivery, but no later than seven years subsequent to delivery. As of December 31, 2018 , we held an 88.1% ownership interest in the real estate venture. Below is a summary of the activity of redeemable noncontrolling interests: Year Ended December 31, 2018 2017 JBG SMITH LP Consolidated Real Estate Venture Total JBG SMITH LP Consolidated Real Estate Venture Total (In thousands) Balance as of beginning of period $ 603,717 $ 5,412 $ 609,129 $ — $ — $ — Fair value of OP Unit redemptions (109,208 ) — (109,208 ) — — — OP Units issued at the Separation — — — 96,632 — 96,632 OP Units issued in connection with the Combination (1) — — — 359,967 — 359,967 Net income (loss) attributable to redeemable noncontrolling interests 6,641 69 6,710 (7,320 ) (8 ) (7,328 ) Other comprehensive income 1,384 — 1,384 225 — 225 Contributions (distributions) (18,737 ) 500 (18,237 ) (9,113 ) 5,420 (3,693 ) Share-based compensation expense 52,190 — 52,190 32,634 — 32,634 Adjustment to redemption value 16,172 — 16,172 130,692 — 130,692 Balance as of end of period $ 552,159 $ 5,981 $ 558,140 $ 603,717 $ 5,412 $ 609,129 _______________________________________ (1) Excludes certain OP Units issued as part of the Combination which had an estimated fair value of $110.6 million , the vesting of which is subject to post-combination employment. See Note 13 for additional information.

Share-Based Payments and Employ

Share-Based Payments and Employee Benefits	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Payments and Employee Benefits	Share-Based Payments and Employee Benefits OP UNITS The acquisition of JBG/Operating Partners, L.P. in the Combination, resulted in the issuance of 3.3 million OP Units to its former owners with an estimated grant-date fair value of $110.6 million . The OP Units were subject to post-combination vesting over periods of either 12 or 60 months based on continued employment. The significant assumptions used to value the OP Units included expected volatility ( 18.0% to 27.0% ), risk-free interest rates ( 1.3% to 1.5% ) and post-vesting restriction periods ( 1 year to 3 years ). Compensation expense for these OP Units is recognized over the graded vesting period. See Note 3 for additional information. The following table presents information regarding the OP Units activity: Unvested Shares Weighted Average Grant-Date Fair Value Unvested at December 31, 2017 3,086,962 33.49 Vested (86,975 ) 37.10 Unvested at December 31, 2018 2,999,987 33.39 The total-grant date fair value of the OP Units that vested during the years ended December 31, 2018 and 2017 was $3.2 million and $7.2 million . JBG SMITH 2017 Omnibus Share Plan On June 23, 2017, our Board of Trustees adopted the JBG SMITH 2017 Omnibus Share Plan (the "Plan"), effective as of July 17, 2017, and authorized the reservation of approximately 10.3 million of our common shares pursuant to the Plan. On July 10, 2017, our then sole-shareholder approved the Plan. As of December 31, 2018 , there were 4.8 million common shares available for issuance under the Plan. Formation Awards Pursuant to the Plan, on July 18, 2017, we granted approximately 2.7 million Formation Awards based on an aggregate notional value of approximately $100.0 million divided by the volume-weighted average price on July 18, 2017 of $37.10 per common share. In 2018, we granted 93,784 Formation Awards based on an aggregate notional value of approximately $3.2 million divided by the volume-weighted average price on the date of issuance of $34.40 per common share. The Formation Awards are structured in the form of profits interests in JBG SMITH LP that provide for a share of appreciation determined by the increase in the value of a common share at the time of conversion over the volume-weighted average price of a common share at the time the formation unit was granted. The Formation Awards, subject to certain conditions, generally vest 25% on each of the third and fourth anniversaries and 50% on the fifth anniversary, of the date granted, subject to continued employment with JBG SMITH through each vesting date. The value of vested Formation Awards is realized through conversion of the award into a number of LTIP Units, and subsequent conversion into a number of OP Units determined based on the difference between the volume-weighted average price of a common share at the time the Formation Award was granted and the value of a common share on the conversion date. The conversion ratio between Formation Awards and OP Units, which starts at zero, is the quotient of (i) the excess of the value of a common share on the conversion date above the per share value at the time the Formation Award was granted over (ii) the value of a common share as of the date of conversion. Like options, Formation Awards have a finite 10 -year term over which their value is allowed to increase and during which they may be converted into LTIP Units (and in turn, OP Units). Holders of Formation Awards will not receive distributions or allocations of net income or net loss prior to vesting and conversion to LTIP Units. The aggregate grant-date fair value of the Formation Awards granted during the years ended December 31, 2018 and 2017 was $725,000 and $23.7 million estimated using Monte Carlo simulations. Compensation expense for these awards is being recognized over a five -year period. The significant assumptions used to value the awards included: Year Ended December 31, 2018 2017 Expected volatility 27.0% to 29.0% 26.0 % Dividend yield 2.5% to 2.7% 2.3 % Risk-free interest rate 2.8% to 3.0% 2.3 % Expected life 7 years 7 years The following table presents information regarding the Formation Awards activity: Unvested Shares Weighted Average Grant-Date Fair Value Unvested at December 31, 2017 2,673,814 $ 8.84 Granted 93,784 7.73 Vested (39,970 ) 8.32 Forfeited (72,234 ) 8.84 Unvested at December 31, 2018 2,655,394 8.81 The total-grant date fair value of the Formation Awards that vested during the year ended December 31, 2018 was $333,000 . LTIP, Time-Based LTIP and Special Time-Based LTIP Units On July 18, 2017, we granted a total of 47,166 fully vested LTIP Units to the seven independent trustees in the notional amount of $250,000 each. The LTIP Units may not be sold while such non-employee trustee is serving on the Board. On the same date, we also granted 59,927 LTIP units to a key employee of which 50% vested immediately and the remaining 50% vests ratably from the 31 st to the 60 th month following the grant date. In May 2018, as part of their annual compensation, we granted a total of 25,770 fully vested LTIP Units to non-employee trustees with an aggregate grant-date fair value of approximately $794,000 . During the years ended December 31, 2018 and 2017 , we granted 367,519 and 302,518 Time-Based LTIP Units to management and other employees with a weighted average grant-date fair value of $31.48 and $33.71 per unit that vest over four years, 25.0% per year, subject to continued employment. Compensation expense for these units is being recognized over a four -year period. Additionally, during the year ended December 31, 2018 , related to our successful pursuit of Amazon HQ2, we granted 356,591 Special Time-Based LTIP Units to management and other employees with a weighted average grant-date fair value of $36.84 per unit. Vesting of the Special Time-Based LTIP Units is conditioned on Amazon entering into definitive lease or asset purchase documentation with JBG SMITH prior to the fourth anniversary of the grant date; if such condition is satisfied, then the Special Time-Based LTIP Units vest 50% on each of the fourth and fifth anniversaries of the grant date, subject to continued employment. Compensation expense for these units is being recognized over a five -year period. The aggregate grant-date fair value of the LTIP, Time-Based LTIP and Special Time-Based LTIP Units granted (collectively "Granted LTIPs") during the years ended December 31, 2018 and 2017 was $25.5 million and $13.7 million . Net income and net loss is allocated to each of the Granted LTIPs. Holders of the Granted LTIPs have the right to convert all or a portion of vested units into OP Units, which are then subsequently exchangeable for our common shares. Granted LTIPs do not have redemption rights, but any OP Units into which units are converted are entitled to redemption rights. Granted LTIPs, generally, vote with the OP Units and do not have any separate voting rights except in connection with actions that would materially and adversely affect the rights of the Granted LTIPs. The significant assumptions used to value these awards included: Year Ended December 31, 2018 2017 Expected volatility 20.0% to 22.0% 17.0% to 19.0% Risk-free interest rate 1.9% to 2.6% 1.3% to 1.5% Post-grant restriction periods 2 to 3 years 2 to 3 years The following table presents information regarding Granted LTIP activity: Unvested Shares Weighted Average Grant-Date Fair Value Unvested at December 31, 2017 332,207 $ 33.68 Granted 749,880 34.01 Vested (110,723 ) 32.91 Forfeited (8,702 ) 32.51 Unvested at December 31, 2018 962,662 34.03 The total-grant date fair value of the Granted LTIPs that vested during the years ended December 31, 2018 and 2017 was $3.6 million and $2.5 million . Performance-Based LTIP and Special Performance-Based LTIP Units During the years ended December 31, 2018 and 2017 , we granted 567,106 and 605,072 Performance-Based LTIP Units to management and other employees under the Plan. Also, during the year ended December 31, 2018, related to our successful pursuit of Amazon HQ2, we granted 511,555 Special Performance-Based LTIP Units to management and other employees. Performance-Based LTIP Units, including the Special Performance-Based LTIP Units, are performance-based equity compensation pursuant to which participants have the opportunity to earn LTIP Units based on the relative performance of the total shareholder return ("TSR") of our common shares compared to the companies in the FTSE NAREIT Equity Office Index, over the defined performance period beginning on the grant date, inclusive of dividends and stock price appreciation. Our Performance-Based LTIP and Special Performance-Based LTIP Units have a three -year performance period. Fifty percent of any Performance-Based LTIP Units that are earned vest at the end of the three -year performance period and the remaining 50% on the fourth anniversary of the date of grant, subject to continued employment. Vesting of the Special Performance-Based LTIP Units is conditioned on Amazon entering into definitive lease or asset purchase documentation with JBG SMITH prior to the fourth anniversary of the grant date; if such condition is satisfied, then fifty percent of any Special Performance-Based LTIP Units that are earned at the end of the three -year performance period vest on the fourth anniversary of the date of grant and the remaining 50% on the fifth anniversary of the date of grant, subject to continued employment. The grant-date fair value of the Performance-Based LTIP and Special Performance-Based LTIP Units granted during the years ended December 31, 2018 and 2017 was $21.1 million and $9.7 million valued using Monte Carlo simulations. Compensation expense for the Performance-Based LTIP Units is being recognized over a four -year period, while Compensation expense for the Special Performance Based LTIP Units is being recognized over a five -year period. The significant assumptions used to value both the Performance-Based LTIP and Special Performance-Based LTIP Units included: Year Ended December 31, 2018 2017 Expected volatility 19.9% to 26.0% 18.0 % Dividend yield 2.5% to 2.7% 2.3 % Risk-free interest rate 2.3% to 3.0% 1.5 % The following table presents information regarding the Performance-Based LTIP and Special Performance-Based LTIP Units activity: Unvested Shares Weighted Average Grant-Date Fair Value Unvested at December 31, 2017 604,522 $ 15.95 Granted 1,078,661 19.52 Forfeited (25,605 ) 16.29 Unvested at December 31, 2017 1,657,578 18.27 JBG SMITH 2017 Employee Share Purchase Plan The JBG SMITH 2017 ESPP authorizes the issuance of up to 2.1 million common shares. The ESPP provides eligible employees an option to purchase, through payroll deductions, our common shares at a discount of 15.0% of the closing price of a common shares on relevant determination dates, provided that the fair market value of common shares, determined as of the first day of the relevant offering period, purchased by any eligible employee may not exceed $25,000 in any calendar year. The maximum aggregate number of common shares reserved for issuance under the ESPP will automatically increase on January 1 of each year, unless the Compensation Committee of the Board of Trustees determines to limit any such increase, by the lesser of (i) 0.10% of the total number of outstanding common shares on December 31 of the preceding calendar year or (ii) 206,600 common shares. Pursuant to the ESPP, employees purchased 20,178 common shares for $597,000 during the year ended December 31, 2018 . Compensation expense for the year ended December 31, 2018 was $144,000 valued using the Black-Scholes model. The significant assumptions used to value the ESPP common shares included expected volatility ( 21.0% ), dividend yield ( 2.5% ), risk-free interest rate ( 2.0% ) and expected life ( six months ). As of December 31, 2018 , there were 2.0 million common shares authorized and available for issuance under the ESPP. Share-Based Compensation Expense Share-based compensation expense is summarized as follows: Year Ended December 31, 2018 2017 2016 (In thousands) Time-Based LTIP Units $ 10,095 $ 2,211 — Performance-Based LTIP Units 5,271 1,172 — LTIP Units 794 — — Other equity awards (1) 3,826 1,526 4,502 Share-based compensation expense - other 19,986 4,909 4,502 Formation Awards 5,606 5,169 $ — OP Units (2) 29,455 21,467 — LTIP Units (2) 277 2,615 — Special Performance-Based LTIP Units 323 — — Special Time-Based LTIP Units 369 — — Share-based compensation related to Formation Transaction and special equity awards (3) 36,030 29,251 — Total share-based compensation expense 56,016 34,160 4,502 Less amount capitalized (3,341 ) (467 ) — Share-based compensation expense $ 52,675 $ 33,693 $ 4,502 ______________________________________________ (1) For the year ended December 31, 2018 , primarily includes compensation expense for certain executives who have elected to receive all or a portion of any cash bonus that may be paid in 2019, related to 2018 service, in the form of fully vested LTIP Units. For the years ended December 31, 2017 and 2016, represents share-based compensation expense related to equity awards prior to the Formation Transaction. (2) Represents share-based compensation expense for LTIP Units and OP Units subject to post-Combination employment obligations. (3) Included in "General and administrative expense: Share-based compensation related to Formation Transaction and special equity awards" in the accompanying statements of operations. As of December 31, 2018 , we had $119.0 million of total unrecognized compensation expense related to unvested share-based payment arrangements (unvested OP Units, Formation Awards, Time-Based LTIP Units, Special Time-Based LTIP Units, Performance-Based LTIP Units and Special Performance-Based LTIP Units). This expense is expected to be recognized over a weighted average period of 2.8 years. Employee Benefits We have a 401(k) defined contribution plan (the "401(k) Plan") covering substantially all of our officers and employees which permits participants to defer compensation up to the maximum amount permitted by law. We provide a discretionary matching contribution. Employees’ contributions vest immediately and our matching contributions vest over five years. Our contributions for each of the three years in the period ended December 31, 2018 were $1.8 million , $3.6 million and $2.4 million .

Interest Expense Interest Expen

Interest Expense Interest Expense	12 Months Ended
	Dec. 31, 2018
Interest Expense [Abstract]
Interest Income and Interest Expense Disclosure [Text Block]	Interest Expense The following is a summary of interest expense included in the statements of operations: Year Ended December 31, 2018 2017 2016 (In thousands) Interest expense $ 91,651 $ 69,178 $ 54,379 Amortization of deferred financing costs 4,661 3,011 1,478 Net loss (gain) on derivative financial instruments Net unrealized (926 ) (1,348 ) — Net realized (135 ) 27 — Capitalized interest (20,804 ) (12,727 ) (4,076 ) Interest expense $ 74,447 $ 58,141 $ 51,781

Earnings (Loss) Per Common Shar

Earnings (Loss) Per Common Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings (Loss) Per Common Share	Earnings (Loss) Per Common Share The following summarizes the calculation of basic and diluted earnings per common share and provides a reconciliation of the amounts of net income (loss) available to common shareholders used in calculating basic and diluted earnings per common share: Year Ended December 31, 2018 2017 2016 (In thousands, except per share amounts) Net income (loss) $ 46,613 $ (79,084 ) $ 61,974 Net (income) loss attributable to redeemable noncontrolling (6,710 ) 7,328 — Net loss attributable to noncontrolling interests 21 3 — Net income (loss) attributable to common shareholders 39,924 (71,753 ) 61,974 Distributions to participating securities (2,599 ) (1,655 ) — Net income (loss) available to common shareholders — basic and diluted $ 37,325 $ (73,408 ) $ 61,974 Weighted average number of common shares outstanding — basic and diluted (1) 119,176 105,359 100,571 Earnings (loss) per common share: Basic $ 0.31 $ (0.70 ) $ 0.62 Diluted $ 0.31 $ (0.70 ) 0.62 ______________ (1) Reflects the weighted average common shares attributable to the Vornado Included Assets as of the date of the Separation for all periods prior to July 17, 2017, The effect of the redemption of OP Units that were outstanding as of December 31, 2018 and 2017 is excluded in the computation of basic and diluted earnings per common share, as the assumed exchange of such units for common shares on a one-for-one basis was antidilutive (the assumed redemption of these units would have no impact on the determination of diluted earnings per share). Since vested and outstanding OP Units, which are held by noncontrolling interests, are attributed gains and losses at an identical proportion to the common shareholders, the gains and losses attributable and their equivalent weighted average OP Unit impact are excluded from net income (loss) available to common shareholders and from the weighted average number of common shares outstanding in calculating basic and diluted earnings per common share. Performance-Based LTIP Units, Special Performance-Based LTIP Units and Formation Awards, which totaled 3.9 million and 3.3 million for the years ended December 31, 2018 and 2017 , were excluded from the calculation of diluted earnings per common share as they were antidilutive, but potentially could be dilutive in the future.

Minimum Rental Income (Notes)

Minimum Rental Income (Notes)	12 Months Ended
	Dec. 31, 2018
Minimum Rental Income [Abstract]
Lessor, Operating Leases [Text Block]	Future Minimum Rental Income We lease space to tenants under operating leases that expire at various dates through the year 2036. The leases provide for the payment of fixed base rents payable monthly in advance as well as reimbursements of real estate taxes, insurance and maintenance costs. Retail leases may also provide for the payment by the lessee of additional rents based on a percentage of their sales. As of December 31, 2018 , future base rental revenue under these non-cancelable operating leases excluding extension options is as follows: Year ending December 31, Amount (In thousands) 2019 $ 377,427 2020 321,205 2021 287,463 2022 256,352 2023 215,203 Thereafter 1,188,767 In December 2018, we leased (as landlord) the unimproved land at 1700 M Street for a 99 -year term, with no extension options. 1700 M Street is a 34,000 square foot development site located in Washington, D.C.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis To manage or hedge our exposure to interest rate risk, we follow established risk management policies and procedures, including the use of a variety of derivative financial instruments. We do not enter into derivative financial instruments for speculative purposes. As of December 31, 2018 and 2017 , we had various derivative financial instruments consisting of interest rate swap and cap agreements that are measured at fair value on a recurring basis. The net unrealized gain on our derivative financial instruments designated as cash flow hedges was $8.3 million and $1.8 million as of December 31, 2018 and 2017 and was recorded in "Accumulated other comprehensive income" in the balance sheet, of which a portion was reclassified to "Redeemable noncontrolling interests" as of December 31, 2018 . Within the next 12 months, we expect to reclassify $3.5 million as a decrease to interest expense. The net unrealized gain on our derivative financial instruments not designated as cash flow hedges was $926,000 and $1.3 million for the years ended December 31, 2018 and 2017 and is recorded in "Interest expense" in our statements of operations. The fair values of the derivative financial instruments are based on the estimated amounts we would receive or pay to terminate the contracts at the reporting date and are determined using interest rate pricing models and observable inputs. The derivative financial instruments are classified within Level 2 of the valuation hierarchy. The following are assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements Total Level 1 Level 2 Level 3 December 31, 2018 (In thousands) Derivative financial instruments designated as cash flow hedges: Classified as assets in "Other assets, net" $ 7,913 $ — $ 7,913 $ — Classified as liabilities in "Other liabilities, net" 1,723 — 1,723 — Derivative financial instruments not designated as cash flow hedges: Classified as assets in "Other assets, net" 2,470 — 2,470 — December 31, 2017 Derivative financial instruments designated as cash flow hedges: Classified as assets in "Other assets, net" $ 1,506 $ — $ 1,506 $ — Classified as liabilities in "Other liabilities, net" 2,640 — 2,640 — Derivative financial instruments not designated as cash flow hedges: Classified as assets in "Other assets, net" 635 — 635 — Classified as liabilities in "Other liabilities, net" 22 — 22 — The fair values of our derivative financial instruments were determined using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of the derivative financial instrument. This analysis reflected the contractual terms of the derivative, including the period to maturity, and used observable market-based inputs, including interest rate market data and implied volatilities in such interest rates. While it was determined that the majority of the inputs used to value the derivatives fall within Level 2 of the fair value hierarchy under authoritative accounting guidance, the credit valuation adjustments associated with the derivatives also utilized Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default. However, as of December 31, 2018 , the significance of the impact of the credit valuation adjustments on the overall valuation of the derivative financial instruments was assessed and it was determined that these adjustments were not significant to the overall valuation of the derivative financial instruments. As a result, it was determined that the derivative financial instruments in their entirety should be classified in Level 2 of the fair value hierarchy. The net unrealized gain included in "Other comprehensive income'' was primarily attributable to the net change in unrealized gains or losses related to the interest rate swaps that were outstanding as of December 31, 2018 , none of which were reported in the statements of operations because they were documented and qualified as hedging instruments. Financial Assets and Liabilities Not Measured at Fair Value As of December 31, 2018 and 2017 , all financial instruments and liabilities were reflected in our balance sheets at amounts which, in our estimation, reasonably approximated their fair values, except for the following: December 31, 2018 December 31, 2017 Carrying Amount (1) Fair Value Carrying Amount (1) Fair Value (In thousands) Financial liabilities: Mortgages payable $ 1,844,652 $ 1,870,078 $ 2,035,959 $ 2,060,899 Revolving credit facility — — 115,751 115,768 Unsecured term loans 300,000 300,727 50,000 50,029 ______________________________________ ( 1) The carrying amount consists of principal only. The fair value of the mortgages payable, revolving credit facility and unsecured term loans was determined using Level 2 inputs of the fair value hierarchy.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information We review operating and financial data for each property on an individual basis; therefore, each of our individual properties is a separate operating segment. As of December 31, 2018 , we redefined our reportable segments to be aligned with our new method of internal reporting and the way our Chief Executive Officer, who is also our Chief Operating Decision Maker ("CODM"), makes key operating decisions, evaluates financial results, allocates resources and manages our business. Accordingly, we aggregate our operating segments into three reportable segments (commercial, multifamily, and third-party asset management and real estate services) based on the economic characteristics and nature of our assets and services. To conform to the current period presentation, we have reclassified the prior period segment financial data for certain properties that had been classified as part of other to the commercial and multifamily segments and the elimination of intersegment activity has been included as part of other. The commercial segment was previously referred to as the office segment. The CODM measures and evaluates the performance of our operating segments, with the exception of the third-party asset management and real estate services business, based on the net operating income ("NOI") of properties within each segment. NOI includes property rental revenues and tenant reimbursements and deducts property operating expenses and real estate taxes. With respect to the third-party asset management and real estate services business, the CODM reviews revenues streams generated by this segment ("Third-party real estate services, including reimbursements"), as well as the expenses attributable to the segment ("General and administrative: third-party real estate services"), which are disclosed separately in the statements of operations. Management company assets primarily consist of management and leasing contracts with a net book value of $38.6 million and $45.7 million and are classified in "Other assets, net" in the balance sheets as of December 31, 2018 and 2017 . Consistent with internal reporting presented to our CODM and our definition of NOI, the third-party asset management and real estate services operating results are excluded from the NOI data below. The following table reflects the reconciliation of net income (loss) attributable to common shareholders to consolidated NOI: Year Ended December 31, 2018 2017 2016 (In thousands) Net income (loss) attributable to common shareholders $ 39,924 $ (71,753 ) $ 61,974 Add: Depreciation and amortization expense 211,436 161,659 133,343 General and administrative expense: Corporate and other 33,728 39,350 48,753 Third-party real estate services 89,826 51,919 19,066 Share-based compensation related to Formation Transaction and 36,030 29,251 — Transaction and other costs 27,706 127,739 6,476 Interest expense 74,447 58,141 51,781 Loss on extinguishment of debt 5,153 701 — Reduction of gain (gain) on bargain purchase 7,606 (24,376 ) — Income tax expense (benefit) (738 ) (9,912 ) 1,083 Net (income) loss attributable to redeemable noncontrolling interests 6,710 (7,328 ) — Less: Third-party real estate services, including reimbursements 98,699 63,236 33,882 Other income 6,358 5,167 5,381 Income (loss) from unconsolidated real estate ventures, net 39,409 (4,143 ) (947 ) Interest and other income, net 15,168 1,788 2,992 Gain on sale of real estate 52,183 — — Net loss attributable to noncontrolling interests 21 3 — Consolidated NOI $ 319,990 $ 289,340 $ 281,168 Below is a summary of NOI by segment. Items classified in other include future development assets, corporate entities and the elimination of intersegment activity. Year Ended December 31, 2018 Commercial Multifamily Other Total (In thousands) Rental revenue: Property rentals $ 395,089 $ 102,617 $ 2,129 $ 499,835 Tenant reimbursements 34,953 6,740 (2,403 ) 39,290 Total rental revenue 430,042 109,357 (274 ) 539,125 Rental expense: — Property operating 118,288 31,502 (1,709 ) 148,081 Real estate taxes 53,324 14,280 3,450 71,054 Total rental expense 171,612 45,782 1,741 219,135 Consolidated NOI $ 258,430 $ 63,575 $ (2,015 ) $ 319,990 Year Ended December 31, 2017 Commercial Multifamily Other Total (In thousands) Rental revenue: Property rentals $ 351,517 $ 86,439 $ (1,331 ) $ 436,625 Tenant reimbursements 32,380 5,130 475 37,985 Total rental revenue 383,897 91,569 (856 ) 474,610 Rental expense: Property operating 97,701 24,623 (3,488 ) 118,836 Real estate taxes 50,546 11,030 4,858 66,434 Total rental expense 148,247 35,653 1,370 185,270 Consolidated NOI $ 235,650 $ 55,916 $ (2,226 ) $ 289,340 Year Ended December 31, 2016 Commercial Multifamily Other Total (In thousands) Rental revenue: Property rentals $ 323,133 $ 63,401 $ 15,061 $ 401,595 Tenant reimbursements 33,361 3,454 846 37,661 Total rental revenue 356,494 66,855 15,907 439,256 Rental expense: — Property operating 91,148 17,238 (8,082 ) 100,304 Real estate taxes 46,115 6,993 4,676 57,784 Total rental expense 137,263 24,231 (3,406 ) 158,088 Consolidated NOI $ 219,231 $ 42,624 $ 19,313 $ 281,168 The following is a summary of certain balance sheet data by segment: Commercial Multifamily Other Total December 31, 2018 (In thousands) Real estate, at cost $ 3,634,472 $ 1,656,974 $ 501,288 $ 5,792,734 Investments in and advances to unconsolidated real estate ventures 177,173 109,232 36,473 322,878 Total assets (1) 3,707,255 1,528,177 761,853 5,997,285 December 31, 2017 Real estate, at cost $ 4,023,544 $ 1,480,812 $ 513,148 $ 6,017,504 Investments in and advances to unconsolidated real estate ventures 134,138 98,835 28,838 261,811 Total assets (1) 3,612,947 1,403,452 1,055,408 6,071,807 __________________________ (1) Includes assets held for sale. See Note 4 for additional information.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Insurance We maintain general liability insurance with limits of $200.0 million per occurrence and in the aggregate, and property and rental value insurance coverage with limits of $2.0 billion per occurrence, with sub-limits for certain perils such as floods and earthquakes on each of our properties. We also maintain coverage, through our wholly owned captive insurance subsidiary, for both terrorist acts and for nuclear, biological, chemical or radiological terrorism events with limits of $2.0 billion per occurrence. These policies are partially reinsured by third-party insurance providers. We will continue to monitor the state of the insurance market and the scope and costs of coverage for acts of terrorism. We cannot anticipate what coverage will be available on commercially reasonable terms in the future. We are responsible for deductibles and losses in excess of the insurance coverage, which could be material. Our debt, consisting of mortgage loans secured by our properties, revolving credit facility and unsecured term loans contain customary covenants requiring adequate insurance coverage. Although we believe that we currently have adequate insurance coverage, we may not be able to obtain an equivalent amount of coverage at reasonable costs in the future. If lenders insist on greater coverage than we are able to obtain, it could adversely affect the ability to finance or refinance our properties. Construction Commitments As of December 31, 2018 , we have construction in progress that will require an additional $519.4 million to complete ( $440.9 million related to our consolidated entities and $78.5 million related to our unconsolidated real estate ventures at our share), based on our current plans and estimates, which we anticipate will be primarily expended over the next two to three years. These capital expenditures are generally due as the work is performed, and we expect to finance them with debt proceeds, proceeds from asset recapitalizations and sales, and available cash. Environmental Matters Each of our properties has been subjected to varying degrees of environmental assessment at various times. The environmental assessments did not reveal any material environmental contamination that we believe would have a material adverse effect on our overall business, financial condition or results of operations, or that have not been anticipated and remediated during site redevelopment as required by law. Nevertheless, there can be no assurance that the identification of new areas of contamination, changes in the extent or known scope of contamination, the discovery of additional sites or changes in cleanup requirements would not result in significant cost to us. As noted in Note 10, environmental liabilities total $17.9 million as of December 31, 2018 and primarily relate to a liability to remediate pre-existing environmental matters at Potomac Yard Land Bay H, which was acquired in December 2018. Other There are various legal actions against us in the ordinary course of business. In our opinion, the outcome of such matters will not have a material adverse effect on our financial condition, results of operations or cash flows. From time to time, we (or ventures in which we have an ownership interest) have agreed, and may in the future agree with respect to unconsolidated real estate ventures, to (1) guarantee portions of the principal, interest and other amounts in connection with their borrowings, (2) provide customary environmental indemnifications and nonrecourse carve-outs (e.g., guarantees against fraud, misrepresentation and bankruptcy) in connection with their borrowings and (3) provide guarantees to lenders and other third parties for the completion of development projects. We customarily have agreements with our outside partners whereby the partners agree to reimburse the real estate venture or us for their share of any payments made under certain of these guarantees. Amounts that may be required to be paid in future periods in relation to budget overruns or operating losses that are also included in some of our guarantees are not estimable. Guarantees (excluding environmental) terminate either upon the satisfaction of specified circumstances or repayment of the underlying debt. At times, we have agreements with our outside partners whereby we agree to reimburse our partner for their share of any payments made by them under certain guarantees. As of December 31, 2018 , we had no principal payment guarantees for our unconsolidated real estate ventures. We also may guarantee portions of the principal, interest and other amounts in connection with the borrowings of our consolidated entities. As of December 31, 2018 , the aggregate amount of principal payment guarantees was $8.3 million for our consolidated entities. As of December 31, 2018 , we expect to fund additional capital to certain of our unconsolidated investments totaling approximately $48.6 million , which we anticipate will be primarily expended over the next two to three years. In connection with the Formation Transaction, we entered into an agreement with Vornado regarding tax matters (the "Tax Matters Agreement") that provides special rules that allocate tax liabilities if the distribution of JBG SMITH shares by Vornado, together with certain related transactions, is not tax-free. Under the Tax Matters Agreement, we may be required to indemnify Vornado against any taxes and related amounts and costs resulting from a violation by us of the Tax Matters Agreement, or from the taking of certain restricted actions by us. We are obligated under non-cancelable operating leases including ground leases on certain of our properties through 2106. As of December 31, 2018 , future minimum rental payments under non-cancelable operating leases, capital leases and lease assumption liabilities are as follows: Year ending December 31, Amount (In thousands) 2019 $ 13,991 2020 13,710 2021 13,395 2022 12,554 2023 9,489 Thereafter 55,780 Total $ 118,919 During each of the three years in the period ended December 31, 2018 , we recognized approximately $11.2 million , $4.7 million and $2.1 million of rental expense related to our non-cancelable operating and capital leases.

Transactions with Vornado and R

Transactions with Vornado and Related Parties	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	Transactions with Vornado and Related Parties Transactions with Vornado As described in Note 1, the accompanying financial statements present the operations of the Vornado Included Assets as carved-out from the financial statements of Vornado for all periods prior to July 17, 2017. Certain centralized corporate costs borne by Vornado for management and other services including, but not limited to, accounting, reporting, legal, tax, information technology and human resources have been allocated to the assets in the financial statements based on either actual costs incurred or a proportion of costs estimated to be applicable to the Vornado Included Assets based on key metrics including total revenue. The total amounts allocated during the years ended December 31, 2017 and 2016 were $13.0 million and $20.7 million . These allocated amounts are included as a component of "General and administrative expense: Corporate and other" expenses on the statements of operations and do not necessarily reflect what actual costs would have been if the Vornado Included Assets were a separate standalone public company. In connection with the Formation Transaction, we entered into an agreement with Vornado under which Vornado provides operational support for an initial period of up to two years. These services include information technology, financial reporting and payroll services. The charges for these services are based on an hourly or per transaction fee arrangement including reimbursement for overhead and out-of-pocket expenses. The total charges for the years ended December 31, 2018 and 2017 were $3.6 million and $2.2 million . Pursuant to an agreement, we are providing Vornado with leasing and property management services for certain of its assets that were not part of the Separation. The total revenue related to these services for the years ended December 31, 2018 and 2017 were $2.1 million and $779,000 . We believe that the terms of both of these agreements are comparable to those that would have been negotiated based on market rates. In connection with the Formation Transaction, we entered into a Tax Matters Agreement with Vornado. See Note 19 for additional information. In August 2014, we completed a $185.0 million financing of the Universal Buildings, a 687,000 square foot office complex located in Washington, D.C. In connection with this financing, pursuant to a note agreement dated August 12, 2014, we used a portion of the financing proceeds and made an $86.0 million loan to Vornado at LIBOR plus 2.9% due August 2019. At the Separation, Vornado repaid the outstanding balance of the loan and related accrued interest. We recognized interest income of $1.8 million and $3.3 million during the years ended December 31, 2017 and 2016 . In connection with the development of The Bartlett, prior to the Separation, we entered into various note agreements with Vornado whereby we could borrow up to a maximum of $170.0 million . Vornado contributed these note agreements along with accrued and unpaid interest to JBG SMITH at the Separation. We incurred interest expense of $4.1 million during each of the years ended December 31, 2017 and 2016 . In June 2016, the $115.0 million mortgage loan (including $608,000 of accrued interest) secured by the Bowen Building, a 231,000 square foot office building located in Washington, D.C., was repaid with the proceeds of a $115.6 million draw on our former parent's revolving credit facility. We repaid our former parent with amounts drawn under our revolving credit facility at the Combination. We incurred interest expense related to the mortgage loan of $1.3 million and $1.1 million during the years ended December 31, 2017 and 2016 . We have agreements that are terminable on the second anniversary of the Combination with Building Maintenance Services ("BMS"), a wholly owned subsidiary of Vornado, to supervise cleaning, engineering and security services at our properties. We paid BMS $20.9 million , $13.6 million and $12.1 million during each of the three years in the period ended December 31, 2018 , which are included in "Property operating expenses" in our statements of operations. We entered into a consulting agreement with Mitchell Schear, a member of our Board of Trustees and formerly the president of Vornado’s Washington, D.C. segment. The consulting agreement expired on December 31, 2017 and provided for the payment of consulting fees and expenses at the rate of $169,400 per month for the 24 months following the Separation, including after the expiration of the consulting agreement. The amount due under this consulting agreement of $4.1 million was expensed in connection with the Combination. As of December 31, 2018 , the remaining liability is $1.1 million . Additionally, in March 2017, Vornado amended Mr. Schear’s employment agreement to provide for the payment of severance, bonus and post-employment services. A total of $16.4 million was expensed in connection with the Separation during the year ended December 31, 2017 . Transactions with Real Estate Ventures Our third-party asset management and real estate services business provides fee-based real estate services to third parties and the JBG Legacy Funds. We provide services for the benefit of the JBG Legacy Funds that own interests in the assets retained by the JBG Legacy Funds. In connection with the contribution of the JBG Assets to us, it was determined that the general partner and managing member interests in the JBG Legacy Funds that were held by former JBG executives (and who became members of our management team and/or Board of Trustees) would not be transferred to us and remain under the control of these individuals. In addition, certain members of our senior management and Board of Trustees have an ownership interest in the JBG Legacy Funds and own carried interests in each fund and in certain of our real estate ventures that entitles them to receive additional compensation if the fund or real estate venture achieves certain return thresholds. This third-party real estate services revenue, including reimbursements, from these JBG Legacy Funds for the years ended December 31, 2018 and 2017 was $33.8 million and $19.9 million . As of December 31, 2018 and 2017 , we had receivables from the JBG Legacy Funds totaling $3.6 million and $3.1 million for third-party real estate services, including reimbursements. We rent our corporate offices from an unconsolidated real estate venture and incurred expenses totaling $4.9 million and $2.3 million during the years ended December 31, 2018 and 2017 , which is recorded in "General and administrative expense: Corporate and other" in our statements of operations. Registration Rights Agreements In connection with the Formation Transaction, we entered into a registration rights agreement with certain former investors in the JBG Legacy Funds that received our common shares in the Formation Transaction (the "Shares Registration Rights Agreement") and a separate registration rights agreement with the certain former investors in the JBG Legacy Funds and certain employees of JBG entities that received OP Units in the Formation Transaction (the "OP Units Registration Rights Agreement" and together with the Shares Registration Rights Agreement, the "Registration Rights Agreements"). Certain holders of common shares and OP Units who may benefit from the Registration Rights Agreements are members of our management team and/or Board of Trustees. Our obligations under the Shares Registration Rights Agreement were fully satisfied in January 2018.

Quarterly Financial Information

Quarterly Financial Information (Notes)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information [Abstract]
Quarterly Financial Information [Text Block]	Quarterly Financial Data (unaudited) 2018 First Quarter Second Quarter (1) Third Quarter (2) Fourth Quarter (3) (In thousands, except per share data) Total revenue $ 163,037 $ 159,447 $ 158,443 $ 163,255 Net income (loss) (4,786 ) 24,023 26,382 994 Net income (loss) attributable to common shareholders (4,190 ) 20,574 22,830 710 Earnings (loss) per share: Basic (0.04 ) 0.17 0.19 (0.01 ) Diluted (0.04 ) 0.17 0.19 (0.01 ) _______________ (1) During the second quarter of 2018, we recognized a gain on the sale of real estate of $33.4 million from the sale of Summit I and II and the Bowen Building, a reduction to the gain on bargain purchase of $7.6 million related to the final adjustments to the fair value of certain asset acquired and liabilities assumed in the Formation Transaction and a loss on the extinguishment of debt of $4.5 million . (2) During the third quarter of 2018, we recognized a gain of $15.5 million related to the sale of our interest in a real estate venture that owned the Investment Building and a gain on the sale of real estate of $11.9 million from the sale of Executive Tower. (3) During the fourth quarter of 2018, we recognized a gain of $20.6 million from the sale of The Warner by our unconsolidated real estate venture with CPPIB, transaction and other costs of $15.6 million related to expenses incurred in connection with the Formation Transaction (including transition services provided by our former parent, integration costs, and severance costs), costs related to the pursuit of Amazon HQ2, and costs related to other completed, potential and pursued transactions, and a gain on the sale of real estate of $6.4 million , primarily from the sale of 1233 20th Street and the out-of-service portion of Falkland Chase - North. 2017 First Quarter Second Quarter Third Quarter (1) Fourth Quarter (2) (In thousands, except per share data) Total revenue $ 116,272 $ 118,020 $ 152,350 $ 156,371 Net income (loss) 6,318 11,341 (77,991 ) (18,752 ) Net income (loss) attributable to common shareholders 6,318 11,341 (69,831 ) (16,418 ) Earnings (loss) per share: Basic 0.06 0.11 (0.61 ) (0.15 ) Diluted 0.06 0.11 (0.61 ) (0.15 ) ____________ (1) During the third quarter of 2017, we recognized transaction and other costs of $104.1 million , a gain on bargain purchase of $27.8 million and share-based compensation expense of $14.4 million in connection with the completion of the Formation Transaction. (2) During the fourth quarter of 2017, we recognized share-based compensation expense of $14.8 million and transaction and other costs of $12.6 million in connection with the completion of the Formation Transaction in the third quarter of 2017. Additionally, we recognized a reduction to the gain on bargain purchase of $3.4 million related to adjustments to the fair value of certain assets acquired and liabilities assumed in the Formation Transaction. See Note 3 for additional information.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Event In 2019 , we issued an additional 442,395 LTIP Units and 477,640 Performance-Based LTIP Units to management and employees with an estimated aggregate fair value of $24.5 million .

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts (Notes)	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	SCHEDULE II JBG SMITH PROPERTIES VALUATION AND QUALIFYING ACCOUNTS Balance at Beginning of Year Additions Charged Against Operations Adjustments to Valuation Accounts Uncollectible Accounts Written‑off Balance at End of Year (In thousands) Allowance for doubtful accounts (1) for year ended December 31: 2018 $ 6,285 $ 3,298 $ — $ (1,989 ) $ 7,594 2017 $ 4,526 $ 3,807 $ — $ (2,048 ) $ 6,285 2016 $ 4,431 $ 751 $ — $ (656 ) $ 4,526 _______________ (1) Includes allowance for doubtful accounts related to tenant and other receivables and deferred rent receivable.

Schedule III - Real Estate and

Schedule III - Real Estate and Accumulated Depreciation (Notes)	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Text Block]	SCHEDULE III JBG SMITH PROPERTIES REAL ESTATE AND ACCUMULATED DEPRECIATION December 31, 2018 Initial Cost to Company Gross Amounts at Which Carried at Close of Period Description Encumbrances (1) Land and Improvements Buildings and Improvements Costs Capitalized Subsequent to Acquisition (2) Land and Improvements Buildings and Total Accumulated Depreciation and Amortization Date of Construction (3) Date Acquired Commercial Operating Assets Universal Buildings $ 182,467 $ 69,393 $ 143,320 $ 23,829 $ 68,612 $ 167,930 $ 236,542 $ 53,606 1956 2007 2101 L Street 137,453 32,815 51,642 88,181 39,768 132,870 172,638 43,414 1975 2003 1700 M Street — 34,178 46,938 (25,937 ) 55,179 — 55,179 — 2002, 2006 1730 M Street 47,500 10,095 17,541 15,625 10,687 32,574 43,261 13,021 1964 2002 1600 K Street — 19,870 10,308 364 19,870 10,672 30,542 1,280 1950 2017 Courthouse Plaza 1 and 2 — — 105,475 50,652 — 156,127 156,127 64,721 1989 2002 2121 Crystal Drive 136,728 21,503 87,329 53,027 22,071 139,788 161,859 70,404 1985 2002 2345 Crystal Drive — 23,126 93,918 41,679 23,683 135,040 158,723 57,974 1988 2002 2231 Crystal Drive — 20,611 83,705 21,694 21,132 104,878 126,010 42,194 1987 2002 1550 Crystal Drive — 17,988 70,525 19,854 17,996 90,371 108,367 38,157 1980 2002 RTC - West 88,854 30,326 134,108 5,819 30,425 139,828 170,253 9,969 1988 2017 RTC - West Retail 6,889 2,894 — 8,338 2,894 8,338 11,232 407 2017 2017 2011 Crystal Drive — 18,940 76,921 38,777 18,991 115,647 134,638 48,727 1984 2002 2451 Crystal Drive — 16,755 68,047 28,915 17,337 96,380 113,717 38,652 1990 2002 1235 S. Clark Street 78,000 15,826 56,090 28,656 16,293 84,279 100,572 33,875 1981 2002 241 18th Street S. — 13,867 54,169 32,344 16,812 83,568 100,380 33,725 1977 2002 251 18th Street S. 34,294 12,305 49,360 56,515 15,729 102,451 118,180 39,602 1975 2002 1215 S. Clark Street — 13,636 48,380 54,601 14,017 102,600 116,617 31,987 1983 2002 201 12th Street S. 32,863 14,766 52,750 23,357 15,126 75,747 90,873 30,413 1987 2002 800 North Glebe Road 107,500 28,168 140,983 2,307 28,168 143,290 171,458 8,790 1982 2017 2200 Crystal Drive — 13,104 30,050 34,732 13,454 64,432 77,886 19,870 1968 2002 1901 South Bell Street — 11,669 36,918 21,887 12,009 58,465 70,474 26,342 1968 2002 1225 S. Clark Street — 11,176 43,495 20,292 11,490 63,473 74,963 25,616 1968 2002 Crystal City Marriott — 8,000 47,191 15,733 8,224 62,700 70,924 22,162 1968 2004 2100 Crystal Drive — 10,287 23,590 31,413 10,588 54,702 65,290 23,839 1968 2002 200 12th Street S. 16,507 8,016 30,552 20,211 8,241 50,538 58,779 20,974 1985 2002 2001 Jefferson Davis Highway — 7,300 16,746 11,870 7,481 28,435 35,916 11,411 1967 2002 1800 South Bell Street — — 28,702 7,368 212 35,858 36,070 15,602 1969 2002 Crystal City Shops at 2100 — 4,059 9,309 5,175 4,049 14,494 18,543 6,098 1968 2002 Crystal Drive Retail — — 20,465 4,461 55 24,871 24,926 11,813 2003 2004 Vienna Retail — 1,763 641 41 1,763 682 2,445 230 1981 2005 7200 Wisconsin Avenue — 34,683 92,059 4,712 34,683 96,771 131,454 5,373 1986 2017 One Democracy Plaza — — 33,628 7,873 — 41,501 41,501 23,617 1987 2002 4749 Bethesda Avenue Retail — 2,480 11,830 26 2,872 11,464 14,336 257 2016 2017 CEB Tower at Central Place 234,000 74,420 230,280 54,714 74,877 284,537 359,414 8,956 2018 2017 Commercial Construction Assets 1770 Crystal Drive — 10,771 44,276 (9,067 ) — 45,980 45,980 1,674 1974-1980 2002 Central District Retail — 4,194 — 16,388 — 20,582 20,582 5 2002 4747 Bethesda Avenue — 29,030 10,040 68,070 — 107,140 107,140 — 2017 Multifamily Operating Assets Fort Totten Square 73,600 24,390 90,404 826 24,390 91,230 115,620 5,433 2015 2017 WestEnd25 97,881 67,049 5,039 110,465 68,210 114,343 182,553 27,229 2009 2007 North End Retail — 5,847 9,333 (291 ) 5,847 9,042 14,889 481 2015 2017 RiverHouse Apartments 307,710 118,421 125,078 84,970 138,763 189,706 328,469 63,413 1960 2007 The Bartlett 220,000 41,687 — 224,948 41,867 224,768 266,635 15,988 2016 2007 220 20th Street — 8,434 19,340 100,624 8,761 119,637 128,398 31,277 2009 2017 2221 South Clark Street — 7,405 16,981 41,394 7,542 58,238 65,780 6,558 1964 2002 Initial Cost to Company Gross Amounts at Which Carried at Close of Period Description Encumbrances (1) Land and Improvements Buildings and Improvements Costs Capitalized Subsequent to Acquisition (2) Land and Improvements Buildings and Total Accumulated Depreciation and Amortization Date of Construction (3) Date Acquired Falkland Chase - South & West 41,008 18,530 44,232 570 18,530 44,802 63,332 2,941 1938 2017 Falkland Chase - North — 9,810 22,706 (2,239 ) 8,992 21,285 30,277 1,429 1938 2017 1221 Van Street — 27,386 63,775 25,293 28,182 88,272 116,454 3,613 2017 Multifamily Construction Assets West Half — 45,668 17,902 96,284 — 159,854 159,854 — 2017 965 Florida Avenue 14,306 — 42,045 — 56,351 56,351 — 2017 Atlantic Plumbing C — 47,678 13,952 66,708 — 128,338 128,338 — 2017 Future Development Assets 1900 Crystal Drive — 16,811 53,187 (25,598 ) — 44,400 44,400 243 1968 2002 Capitol Point - North — 32,730 — 18,374 50,829 275 51,104 — 2017 Metropolitan Park 6-8 — 65,259 1,326 27,777 82,898 11,464 94,362 31 2007 Pen Place - Land Parcel — 104,473 55 (30,618 ) 61,970 11,940 73,910 6 2007 Potomac Yard Land Bay G - Parcels A - F — 20,318 — 7,955 26,914 1,359 28,273 1 Potomac Yard Land Bay H — 38,369 — — 38,369 — 38,369 — RTC - West Land 1,398 29,956 — 1,792 29,956 1,792 31,748 — 2017 Square 649 — 15,550 6,451 (2,183 ) 12,672 7,146 19,818 427 2005 Other Future Development Assets — 71,686 15,286 14,629 72,394 29,207 101,601 330 Corporate — Corporate 300,000 — — 18,408 — 18,408 18,408 7,718 2017 2,144,652 1,479,777 2,606,328 1,706,629 1,371,874 4,420,860 5,792,734 1,051,875 Held for sale: Commerce Executive (4) — 13,401 58,705 31,113 13,140 90,079 103,219 34,969 2017 $ 2,144,652 $ 1,493,178 $ 2,665,033 $ 1,737,742 $ 1,385,014 $ 4,510,939 $ 5,895,953 $ 1,086,844 Note: Depreciation of the buildings and improvements is calculated over lives ranging from the life of the lease to 40 years. The net basis of our assets and liabilities for tax reporting purposes is approximately $114.0 million lower than the amounts reported in our balance sheet as of December 31, 2018 . (1) Represents the contractual debt obligations. (2) Includes asset impairments recognized, amounts written off in connection with redevelopment activities, partial sale of assets and the reclassification of the net book value of assets to construction in progress. (3) Date of original construction, many assets have had substantial renovation or additional construction. See "Costs Capitalized Subsequent to Acquisition" column. (4) In February 2019 , we sold Commerce Executive for $115.0 million . The following is a reconciliation of real estate and accumulated depreciation: Year Ended December 31, 2018 2017 2016 (In thousands) Real Estate: Balance at beginning of the year $ 6,025,797 $ 4,155,391 $ 4,038,206 Additions during the year: Land and improvements 19,431 428,702 — Buildings and improvements 282,988 1,489,409 217,261 Held for sale 94,926 8,293 — Less: Assets sold or written‑off (527,189 ) (55,998 ) (100,076 ) Balance at end of the year $ 5,895,953 $ 6,025,797 $ 4,155,391 Accumulated Depreciation: Balance at beginning of period $ 1,011,330 $ 930,769 $ 908,233 Additions during the year: Additions charged to operating expenses 116,377 136,559 122,612 Held for sale 34,969 — — Less: Accumulated depreciation on assets sold or written‑off (75,832 ) (55,998 ) (100,076 ) Balance at end of period $ 1,086,844 $ 1,011,330 $ 930,769

Organization and Basis of Pre_2

Organization and Basis of Presentation Accounting (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Accounting [Text Block]	Basis of Presentation The accompanying consolidated and combined financial statements and notes are prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"). All intercompany transactions and balances have been eliminated. The accompanying consolidated and combined financial statements include the accounts of JBG SMITH and our wholly owned subsidiaries and those other entities, including JBG SMITH LP, in which we have a controlling financial interest, including where we have been determined to be the primary beneficiary of a variable interest entity ("VIE"). See Note 7 for additional information on our VIEs. The portions of the equity and net income of consolidated subsidiaries that are not attributable to JBG SMITH are presented separately as amounts attributable to noncontrolling interests in our consolidated and combined financial statements. References to the financial statements refer to our consolidated and combined financial statements as of December 31, 2018 and 2017 , and for each of the three years in the period ended December 31, 2018 . References to the balance sheets refer to our consolidated balance sheets as of December 31, 2018 and 2017 . References to the statements of operations refer to our consolidated and combined statements of operations for each of the three years in the period ended December 31, 2018 . References to the statements of cash flows refer to our consolidated and combined statements of cash flows for each of the three years in the period ended December 31, 2018 .
Business Combinations Policy [Policy Text Block]	Formation Transaction JBG SMITH and the Vornado Included Assets were under common control of Vornado for all periods prior to the Separation. The transfer of the Vornado Included Assets from Vornado to JBG SMITH was completed prior to the Separation, at net book values (historical carrying amounts) carved out from Vornado’s books and records. For purposes of the formation of JBG SMITH, the Vornado Included Assets were designated as the predecessor and the accounting acquirer of the JBG Assets. Consequently, the financial statements of JBG SMITH, as set forth herein, represent a continuation of the financial information of the Vornado Included Assets as the predecessor and accounting acquirer such that the historical financial information included herein as of any date or for any periods on or prior to the completion of the Combination represents the pre-Combination financial information of the Vornado Included Assets. The financial statements reflect the common shares as of the date of the Separation as outstanding for all periods prior to July 17, 2017. The acquisition of the JBG Assets completed subsequently by JBG SMITH was accounted for as a business combination using the acquisition method whereby identifiable assets acquired and liabilities assumed are recorded at acquisition-date fair values and income and cash flows from the operations were consolidated into the financial statements of JBG SMITH commencing July 18, 2017. Consequently, the financial statements for the periods before and after the Formation Transaction are not directly comparable. The accompanying financial statements as of December 31, 2018 and 2017 and for the year ended December 31, 2018 include our consolidated accounts. The results of operations for the year ended December 31, 2017 reflect the aggregate operations and changes in cash flows and equity on a combined basis for all periods prior to July 17, 2017 and on a consolidated basis for all periods subsequent to July 17, 2017. The results of operations for the year ended December 31, 2016 include the Vornado Included Assets. Therefore, our results of operations, cash flows and financial condition set forth in this report are not necessarily indicative of our future results of operations, cash flows or financial condition as an independent, publicly traded company. The historical financial results for the Vornado Included Assets reflect charges for certain corporate costs allocated by the former parent, which were based on either actual costs incurred or a proportion of costs estimated to be applicable, to the Vornado Included Assets based on an analysis of key metrics, including total revenues. Such costs do not necessarily reflect what the actual costs would have been if JBG SMITH had been operating as a separate standalone public company. See Note 20 for additional information. Reclassification: To conform to the current year presentation, $7.8 million of expenses incurred in the operation and management of our properties that were previously included in "General and administrative expenses: corporate and other" for the year ended December 31, 2017 have been reclassified to "Property operating expenses". This reclassification relates to the portion of the year ended December 31, 2017 subsequent to the Formation Transaction on July 18, 2017, as general and administrative expenses incurred prior to the Formation Transaction reflect costs allocated by the former parent. Business Combinations We account for business combinations, including the acquisition of real estate, using the acquisition method pursuant to which we recognize and measure the identifiable assets acquired, liabilities assumed, and any noncontrolling interests in the acquiree at their acquisition date fair values. Accordingly, we estimate the fair values of acquired tangible assets (consisting of real estate, cash and cash equivalents, tenant and other receivables, investments in unconsolidated real estate ventures and other assets, as applicable), identified intangible assets and liabilities (consisting of the value of in-place leases, above- and below-market leases, options to enter into ground leases and management contracts, as applicable), assumed debt and other liabilities, and noncontrolling interests, as applicable, based on our evaluation of information and estimates available at that date. Based on these estimates, we allocate the purchase price to the identified assets acquired and liabilities assumed. Any excess of the purchase price over the estimated fair value of the net assets acquired is recorded as goodwill. Any excess of the fair value of assets acquired over the purchase price is recorded as a gain on bargain purchase. If, up to one year from the acquisition date, information regarding the fair value of the net assets acquired and liabilities assumed is received and estimates are refined, appropriate adjustments are made on a prospective basis to the purchase price allocation, which may include adjustments to identified assets, assumed liabilities, and goodwill or the gain on bargain purchase, as applicable. The results of operations of acquisitions are prospectively included in our financial statements beginning with the date of the acquisition. Transaction costs related to business combinations are expensed as incurred and included in "Transaction and other costs" in our statements of operations. The fair values of buildings are determined using the "as-if vacant" approach whereby we use discounted income or cash flow models with inputs and assumptions that we believe are consistent with current market conditions for similar assets. The most significant assumptions in determining the allocation of the purchase price to buildings are the exit capitalization rate, discount rate, estimated market rents and hypothetical expected lease-up periods. We assess fair value of land based on market comparisons and development projects using an income approach of cost plus a margin. The fair values of identified intangible assets are determined based on the following: • The value allocable to the above- or below-market component of an acquired in-place lease is determined based upon the present value (using a discount rate which reflects the risks associated with the acquired leases) of the difference between (i) the contractual amounts to be received pursuant to the lease over its remaining term and (ii) management’s estimate of the amounts that would be received using market rates over the remaining term of the lease. Amounts allocated to above- market leases are recorded as "Identified intangible assets" in "Other assets, net" in the balance sheets, and amounts allocated to below-market leases are recorded as "Lease intangible liabilities" in "Other liabilities, net" in the balance sheets. These intangibles are amortized to "Property rentals" in our statements of operations over the remaining terms of the respective leases. • Factors considered in determining the value allocable to in-place leases during hypothetical lease-up periods related to space that is leased at the time of acquisition include (i) lost rent and operating cost recoveries during the hypothetical lease-up period and (ii) theoretical leasing commissions required to execute similar leases. These intangible assets are recorded as "Identified intangible assets" in "Other assets, net" in the balance sheets and are amortized to "Depreciation and amortization expenses" in our statements of operations over the remaining term of the existing lease. • The fair value of the in-place property management, leasing, asset management, and development and construction management contracts is based on revenue and expense projections over the estimated life of each contract discounted using a market discount rate. These management contract intangibles are amortized to "Depreciation and amortization expenses" in our statements of operations over the weighted average life of the management contracts. The fair value of investments in unconsolidated real estate ventures and related noncontrolling interests is based on the estimated fair values of the identified assets acquired and liabilities assumed of each venture, including future expected cash flows from promote interests. The fair value of the mortgages payable assumed is determined using current market interest rates for comparable debt financings. The fair values of the interest rate swaps and caps are based on the estimated amounts we would receive or pay to terminate the contract at the acquisition date and are determined using interest rate pricing models and observable inputs. The carrying value of cash, restricted cash, working capital balances, leasehold improvements and equipment, and other assets acquired and liabilities assumed approximates fair value.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of the financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. The most significant of these estimates include: (i) the underlying cash flows used to establish the fair values recorded in connection with the Combination and used in assessing impairment and (ii) the determination of useful lives for tangible and intangible assets. Actual results could differ from these estimates.
New Accounting Pronouncements, Policy [Policy Text Block]	The following table provides a brief description of recent significant accounting pronouncements by the Financial Accounting Standards Board ("FASB") that have been or will be required to be adopted by us: Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standards adopted ASU 2014-09, Revenue from Contracts with Customers (Topic 606), as clarified and amended by ASU 2016-08, ASU 2016-10 and ASU 2016-12 This standard establishes a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most of the existing revenue recognition guidance. It requires an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services and also requires certain additional disclosures. January 2018 We utilized the modified retrospective method of adoption. The standard excludes from its scope the areas of accounting that most significantly affect our revenue recognition, including accounting for leases and financial instruments. Our evaluation determined there were no required changes to our recognition of revenue related to our third-party real estate services, tenant reimbursements, property and asset management fees, or transactional/management fees for leasing, development and construction. Our evaluation also determined there were no required changes to our recognition of promote fees and dispositions of real estate properties as we did not have any deferred gains due to continuing involvement at the time of adoption. Therefore, the adoption of this standard did not have a material impact on our financial statements. We adopted the practical expedient of this standard to only assess the recognition of revenue for open contracts at the date of adoption and there was no adjustment to the opening balance of our accumulated deficit at January 1, 2018. The comparative information has not been restated and continues to be reported under the accounting standards in effect for that period. ASU 2018-09, Codification Improvements These amendments provide clarifications and corrections to certain ASC subtopics including the following: 220-10 (Income Statement - Reporting Comprehensive Income - Overall), 470-50 (Debt - Modifications and Extinguishments), 480-10 (Distinguishing Liabilities from Equity - Overall), 718-740 (Compensation - Stock Compensation - Income Taxes), 805-740 (Business Combinations - Income Taxes), 815-10 (Derivatives and Hedging - Overall), and 820-10 (Fair Value Measurement - Overall). December 2018 The adoption and implementation of this standard did not have a material impact on our financial statements. Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standard not yet adopted ASU 2016-02, Leases (Topic 842), as clarified and amended by ASU 2018-01, ASU 2018-10, ASU 2018-11 and ASU 2018-20 This standard establishes principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. ASU 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. Lessees are required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases. Lessees will recognize expense based on the effective interest method for finance leases or on a straight-line basis for operating leases. The ASU also clarifies that an assessment of whether a land easement meets the definition of a lease under the new lease standard is required. The provisions of this standard are effective for fiscal years beginning after December 15, 2018 and should be applied through a modified retrospective transition, which includes optional practical expedients related to leases that commenced before the effective date and allows the new requirements to be applied on the date of adoption rather than the beginning of the earliest comparative period presented. January 2019 We completed our evaluation of the implementation of this standard. ASU 2016-02 will more significantly impact the accounting for leases in which we are the lessee. We have leases for which we anticipate recording operating right-of-use assets totaling $31.0 million to $41.0 million and operating lease liabilities totaling $33.0 million to $43.0 million, which are equal to the present value of the remaining minimum lease payments upon adoption of this standard. Under ASU 2016-02, initial direct costs for both lessees and lessors would include only those costs that are incremental to the arrangement and would not have been incurred if the lease had not been obtained. As a result, we will no longer be able to capitalize internal leasing costs and instead will be required to expense these costs as incurred. Capitalized internal leasing costs were $6.5 million, $2.9 million and $2.5 million for each of the three years in the period ended December 31, 2018. We will apply the modified retrospective approach of adoption and will elect the transition practical expedients, including the Relief Package for existing leases, the Easement practical expedient for existing easements, but not the Hindsight expedient.
Business Combinations Policy [Policy Text Block]	Formation Transaction JBG SMITH and the Vornado Included Assets were under common control of Vornado for all periods prior to the Separation. The transfer of the Vornado Included Assets from Vornado to JBG SMITH was completed prior to the Separation, at net book values (historical carrying amounts) carved out from Vornado’s books and records. For purposes of the formation of JBG SMITH, the Vornado Included Assets were designated as the predecessor and the accounting acquirer of the JBG Assets. Consequently, the financial statements of JBG SMITH, as set forth herein, represent a continuation of the financial information of the Vornado Included Assets as the predecessor and accounting acquirer such that the historical financial information included herein as of any date or for any periods on or prior to the completion of the Combination represents the pre-Combination financial information of the Vornado Included Assets. The financial statements reflect the common shares as of the date of the Separation as outstanding for all periods prior to July 17, 2017. The acquisition of the JBG Assets completed subsequently by JBG SMITH was accounted for as a business combination using the acquisition method whereby identifiable assets acquired and liabilities assumed are recorded at acquisition-date fair values and income and cash flows from the operations were consolidated into the financial statements of JBG SMITH commencing July 18, 2017. Consequently, the financial statements for the periods before and after the Formation Transaction are not directly comparable. The accompanying financial statements as of December 31, 2018 and 2017 and for the year ended December 31, 2018 include our consolidated accounts. The results of operations for the year ended December 31, 2017 reflect the aggregate operations and changes in cash flows and equity on a combined basis for all periods prior to July 17, 2017 and on a consolidated basis for all periods subsequent to July 17, 2017. The results of operations for the year ended December 31, 2016 include the Vornado Included Assets. Therefore, our results of operations, cash flows and financial condition set forth in this report are not necessarily indicative of our future results of operations, cash flows or financial condition as an independent, publicly traded company. The historical financial results for the Vornado Included Assets reflect charges for certain corporate costs allocated by the former parent, which were based on either actual costs incurred or a proportion of costs estimated to be applicable, to the Vornado Included Assets based on an analysis of key metrics, including total revenues. Such costs do not necessarily reflect what the actual costs would have been if JBG SMITH had been operating as a separate standalone public company. See Note 20 for additional information. Reclassification: To conform to the current year presentation, $7.8 million of expenses incurred in the operation and management of our properties that were previously included in "General and administrative expenses: corporate and other" for the year ended December 31, 2017 have been reclassified to "Property operating expenses". This reclassification relates to the portion of the year ended December 31, 2017 subsequent to the Formation Transaction on July 18, 2017, as general and administrative expenses incurred prior to the Formation Transaction reflect costs allocated by the former parent. Business Combinations We account for business combinations, including the acquisition of real estate, using the acquisition method pursuant to which we recognize and measure the identifiable assets acquired, liabilities assumed, and any noncontrolling interests in the acquiree at their acquisition date fair values. Accordingly, we estimate the fair values of acquired tangible assets (consisting of real estate, cash and cash equivalents, tenant and other receivables, investments in unconsolidated real estate ventures and other assets, as applicable), identified intangible assets and liabilities (consisting of the value of in-place leases, above- and below-market leases, options to enter into ground leases and management contracts, as applicable), assumed debt and other liabilities, and noncontrolling interests, as applicable, based on our evaluation of information and estimates available at that date. Based on these estimates, we allocate the purchase price to the identified assets acquired and liabilities assumed. Any excess of the purchase price over the estimated fair value of the net assets acquired is recorded as goodwill. Any excess of the fair value of assets acquired over the purchase price is recorded as a gain on bargain purchase. If, up to one year from the acquisition date, information regarding the fair value of the net assets acquired and liabilities assumed is received and estimates are refined, appropriate adjustments are made on a prospective basis to the purchase price allocation, which may include adjustments to identified assets, assumed liabilities, and goodwill or the gain on bargain purchase, as applicable. The results of operations of acquisitions are prospectively included in our financial statements beginning with the date of the acquisition. Transaction costs related to business combinations are expensed as incurred and included in "Transaction and other costs" in our statements of operations. The fair values of buildings are determined using the "as-if vacant" approach whereby we use discounted income or cash flow models with inputs and assumptions that we believe are consistent with current market conditions for similar assets. The most significant assumptions in determining the allocation of the purchase price to buildings are the exit capitalization rate, discount rate, estimated market rents and hypothetical expected lease-up periods. We assess fair value of land based on market comparisons and development projects using an income approach of cost plus a margin. The fair values of identified intangible assets are determined based on the following: • The value allocable to the above- or below-market component of an acquired in-place lease is determined based upon the present value (using a discount rate which reflects the risks associated with the acquired leases) of the difference between (i) the contractual amounts to be received pursuant to the lease over its remaining term and (ii) management’s estimate of the amounts that would be received using market rates over the remaining term of the lease. Amounts allocated to above- market leases are recorded as "Identified intangible assets" in "Other assets, net" in the balance sheets, and amounts allocated to below-market leases are recorded as "Lease intangible liabilities" in "Other liabilities, net" in the balance sheets. These intangibles are amortized to "Property rentals" in our statements of operations over the remaining terms of the respective leases. • Factors considered in determining the value allocable to in-place leases during hypothetical lease-up periods related to space that is leased at the time of acquisition include (i) lost rent and operating cost recoveries during the hypothetical lease-up period and (ii) theoretical leasing commissions required to execute similar leases. These intangible assets are recorded as "Identified intangible assets" in "Other assets, net" in the balance sheets and are amortized to "Depreciation and amortization expenses" in our statements of operations over the remaining term of the existing lease. • The fair value of the in-place property management, leasing, asset management, and development and construction management contracts is based on revenue and expense projections over the estimated life of each contract discounted using a market discount rate. These management contract intangibles are amortized to "Depreciation and amortization expenses" in our statements of operations over the weighted average life of the management contracts. The fair value of investments in unconsolidated real estate ventures and related noncontrolling interests is based on the estimated fair values of the identified assets acquired and liabilities assumed of each venture, including future expected cash flows from promote interests. The fair value of the mortgages payable assumed is determined using current market interest rates for comparable debt financings. The fair values of the interest rate swaps and caps are based on the estimated amounts we would receive or pay to terminate the contract at the acquisition date and are determined using interest rate pricing models and observable inputs. The carrying value of cash, restricted cash, working capital balances, leasehold improvements and equipment, and other assets acquired and liabilities assumed approximates fair value.
Real Estate, Policy [Policy Text Block]	Real Estate Real estate is carried at cost, net of accumulated depreciation and amortization. Maintenance and repairs are expensed as incurred and are included in "Property operating expenses" in our statements of operations. As real estate is undergoing redevelopment activities, all property operating expenses directly associated with and attributable to the redevelopment, including interest expense, are capitalized to the extent that we believe such costs are recoverable through the value of the property. The capitalization period ends when redevelopment activities are substantially complete. General and administrative costs are expensed as incurred. Depreciation requires an estimate of the useful life of each property and improvement as well as an allocation of the costs associated with a property to its various components. Depreciation is recognized on a straight‑line basis over estimated useful lives, which range from three to 40 years . Tenant improvements are amortized on a straight‑line basis over the lives of the related leases, which approximate the useful lives of the tenant improvements. When assets are sold or retired, their costs and related accumulated depreciation are removed from the accounts with the resulting gains or losses reflected in net income or loss for the period in “Depreciation and amortization expense.” Construction in progress, including land, is carried at cost, and no depreciation is recorded. Real estate undergoing significant renovations and improvements is considered to be under development. All direct and indirect costs related to development activities are capitalized into "Construction in progress, including land" on our balance sheets, except for certain demolition costs, which are expensed as incurred. Direct development costs incurred include: pre-development expenditures directly related to a specific project, development and construction costs, interest, insurance and real estate taxes. Indirect development costs include: employee salaries and benefits, travel and other related costs that are directly associated with the development. Our method of calculating capitalized interest expense is based upon applying our weighted average borrowing rate to the actual accumulated expenditures if the property does not have property specific debt. If the property is encumbered by specific debt, we will capitalize both the interest incurred applicable to that debt and additional interest expense using our weighted average borrowing rate for any accumulated expenditures in excess of the principal balance of the debt encumbering the property. The capitalization of such expenses ceases when the real estate is ready for its intended use, but no later than one-year from substantial completion of major construction activity. If we determine that a construction project is no longer viable, all capitalized pre-development project costs are immediately expensed. Our assets and related intangible assets are individually reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. An impairment exists when the carrying amount of an asset exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. Estimates of future cash flows are based on our current plans, intended holding periods and available market information at the time the analyses are prepared. An impairment loss is recognized if the carrying amount of the asset is not recoverable and is measured based on the excess of the property’s carrying amount over its estimated fair value. If our estimates of future cash flows, anticipated holding periods, or fair values change, based on market conditions or otherwise, our evaluation of impairment charges may be different and such differences could be material to our financial statements. Estimates of future cash flows are subjective and are based, in part, on assumptions regarding future occupancy, rental rates and capital requirements that could differ materially from actual results.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents Cash and cash equivalents consist of highly liquid investments with a purchase date life to maturity of three months or less and are carried at cost, which approximates fair value, due to their short‑term maturities.
Restrictions on Cash and Cash Equivalents [Table Text Block]	Restricted Cash Restricted cash consists primarily of proceeds from property dispositions held in escrow, security deposits held on behalf of our tenants and cash escrowed under loan agreements for debt service, real estate taxes, property insurance and capital improvements.
Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block]	Allowance for Doubtful Accounts We periodically evaluate the collectability of amounts due from tenants, including the receivable arising from deferred rent receivable, and maintain an allowance for doubtful accounts for the estimated losses resulting from the inability of tenants to make required payments under lease agreements. We exercise judgment in establishing these allowances and consider payment history and current credit status in developing these estimates.
Equity Method Investments [Policy Text Block]	Investments in and Advances to Real Estate Ventures We analyze our real estate ventures to determine whether the entities should be consolidated. If it is determined that these investments do not require consolidation because the entities are not VIEs in accordance with the Consolidation Topic of the Financial Accounting Standards Board ("FASB"), Accounting Standards Codification ("ASC"), we are not considered the primary beneficiary of the entities determined to be VIEs, we do not have voting control, and/or the limited partners (or non-managing members) have substantive participatory rights, then the selection of the accounting method used to account for our investments in unconsolidated real estate ventures is generally determined by our voting interests and the degree of influence we have over the entity. Management uses its judgment when determining if we are the primary beneficiary of, or have a controlling financial interest in, an entity in which we have a variable interest. Factors considered in determining whether we have the power to direct the activities that most significantly impact the entity’s economic performance include risk and reward sharing, experience and financial condition of the other partners, voting rights, involvement in day-to-day capital and operating decisions and the extent of our involvement in the entity. We use the equity method of accounting for investments in unconsolidated real estate ventures when we own 20% or more of the voting interests and have significant influence but do not have a controlling financial interest, or if we own less than 20% of the voting interests but have determined that we have significant influence. Under the equity method, we record our investments in and advances to these entities in our balance sheets, and our proportionate share of earnings or losses earned by the real estate venture is recognized in "Income (loss) from unconsolidated real estate ventures, net" in the accompanying statements of operations. We earn revenues from the management services we provide to unconsolidated entities. These fees are determined in accordance with the terms specific to each arrangement and may include property and asset management fees or transactional fees for leasing, acquisition, development and construction, financing, and legal services provided. We account for this revenue gross of our ownership interest in each respective real estate venture and recognize such revenue in "Third-party real estate services, including reimbursements" in our statements of operations. Our proportionate share of related expenses is recognized in "Income (loss) from unconsolidated real estate ventures, net" in our statements of operations. We may also earn incremental promote distributions if certain financial return benchmarks are achieved upon ultimate disposition of the underlying properties. Management fees are recognized when earned, and promote fees are recognized when certain earnings events have occurred, and the amount is determinable and collectible. Any promote fees are reflected in "Income (loss) from unconsolidated real estate ventures, net" in our statements of operations. With regard to distributions from unconsolidated real estate ventures, we use the information that is available to us to determine the nature of the underlying activity that generated the distributions. Using the nature of distribution approach, cash flows generated from the operations of an unconsolidated real estate venture are classified as a return on investment (cash inflow from operating activities) and cash flows that from property sales, debt refinancing or sales of our investments are classified as a return of investment (cash inflow from investing activities). On a periodic basis, we evaluate our investments in unconsolidated entities for impairment. We assess whether there are any indicators, including underlying property operating performance and general market conditions, that the value of our investments in unconsolidated real estate ventures may be impaired. An investment in a real estate venture is considered impaired if we determine that its fair value is less than the net carrying value of the investment in that real estate venture on an other-than-temporary basis. Cash flow projections for the investments consider property level factors such as expected future operating income, trends and prospects, as well as the effects of demand, competition and other factors. We consider various qualitative factors to determine if a decrease in the value of our investment is other-than-temporary. These factors include age of the venture, our intent and ability to retain our investment in the entity, financial condition and long-term prospects of the entity and relationships with our partners and banks. If we believe that the decline in the fair value of the investment is temporary, no impairment charge is recorded. If our analysis indicates that there is an other-than temporary impairment related to the investment in a particular real estate venture, the carrying value of the venture will be adjusted to an amount that reflects the estimated fair value of the investment.
Intangible Assets, Finite-Lived, Policy [Policy Text Block]	Intangibles Intangible assets consist of in-place leases, below-market ground rent obligations, above-market real estate leases and options to enter into ground leases that were recorded in connection with the acquisition of properties. Intangible assets also include management and leasing contracts acquired in the Combination. Intangible liabilities consist of above-market ground rent obligations and below-market real estate leases that are also recorded in connection with the acquisition of properties. Both intangible assets and liabilities are amortized and accreted using the straight-line method over their applicable remaining useful life. When a lease or contract is terminated early, any remaining unamortized or unaccreted balances are charged to earnings. The useful lives of intangible assets are evaluated each reporting period with any changes in estimated useful lives being accounted for over the revised remaining useful life.
Real Estate Held for Development and Sale, Policy [Policy Text Block]	Assets Held for Sale Assets, primarily consisting of real estate, are classified as held for sale when all the necessary criteria are met. The criteria include (i) management, having the authority to approve action, commits to a plan to sell the property in its present condition, (ii) the sale of the property is at a price reasonable in relation to its current fair value and (iii) the sale is probable and expected to be completed within one year. Real estate held for sale is carried at the lower of carrying amounts or estimated fair value less disposal costs. Depreciation and amortization is not recognized on real estate classified as held for sale.
Deferred Charges, Policy [Policy Text Block]	Deferred Costs Deferred financing costs consist of loan issuance costs directly related to financing transactions that are deferred and amortized over the term of the related loan as a component of interest expense. Unamortized deferred financing costs related to our mortgages payable and unsecured term loan are presented as a direct deduction from the carrying amounts of the related debt instruments, while such costs related to our revolving credit facility are included in other assets. Direct salaries, third-party fees and other costs incurred by us to originate a lease are capitalized in "Other assets, net" in the balance sheets and are amortized against the respective leases using the straight-line method over the term of the related leases.
Consolidation, Policy [Policy Text Block]	Noncontrolling Interests We identify our noncontrolling interests separately within the equity section on the balance sheets. Amounts of consolidated net income (loss) attributable to redeemable noncontrolling interests and to the noncontrolling interests in consolidated subsidiaries are presented separately in the statements of operations. Redeemable Noncontrolling Interests - Redeemable noncontrolling interests consists of OP Units issued in conjunction with the Formation Transaction and our venture partner's interest in 965 Florida Avenue. The OP Units became redeemable for our common shares or cash beginning August 1, 2018, subject to certain limitations. Redeemable noncontrolling interests are generally redeemable at the option of the holder and are presented in the mezzanine section between total liabilities and shareholders' equity on the balance sheets. The carrying amount of redeemable noncontrolling interests is adjusted to its redemption value at the end of each reporting period, but no less than its initial carrying value, with such adjustments recognized in "Additional paid-in capital". See Note 12 for additional information. Noncontrolling Interests - Noncontrolling interests represents the portion of equity that we do not own in entities we consolidate, including interests in consolidated real estate ventures.
Derivatives, Policy [Policy Text Block]	Derivative Financial Instruments and Hedge Accounting Derivative financial instruments are used at times to manage exposure to variable interest rate risk. Derivative financial instruments are recognized as either assets or liabilities and are measured at fair value. The accounting for changes in the fair value of a derivative depends on the intended use of the derivative and the resulting designation . Derivative Financial Instruments Designated as Cash Flow Hedges - Certain derivative financial instruments, consisting of interest rate swap and cap agreements, are designated as cash flow hedges, and are carried at their estimated fair value on a recurring basis. We assess the effectiveness of our cash flow hedges both at inception and on an ongoing basis. If the hedges are deemed to be effective, the fair value is recorded in accumulated other comprehensive income and is subsequently reclassified into "Interest expense" in the period that the hedged forecasted transactions affect earnings. Our cash flow hedges become less than perfectly effective if the critical terms of the hedging instrument and the forecasted transactions do not perfectly match such as notional amounts, settlement dates, reset dates, calculation period and interest rates. In addition, we evaluate the default risk of the counterparty by monitoring the creditworthiness of the counterparty. Derivative instruments and hedging activities require management to make judgments on the nature of its derivatives and their effectiveness as hedges. These judgments determine if the changes in fair value of the derivative instruments are reported in the statements of operations or as a component of comprehensive income and as a component of shareholders’ equity on the balance sheets. Derivative Financial Instruments Not Designated as Hedges - Certain derivative financial instruments, consisting of interest rate swap and cap agreements, are considered economic hedges, but not designated as accounting hedges, and are carried at their estimated fair value on a recurring basis. Realized and unrealized gains are recorded in "Interest expense" in the statements of operations in the period in which the change occurs.
Fair Value Measurement, Policy [Policy Text Block]	Fair Value of Assets and Liabilities ASC 820, Fair Value Measurement and Disclosures, defines fair value and establishes a framework for measuring fair value. The objective of fair value is to determine the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (the exit price). ASC 820 establishes a fair value hierarchy that prioritizes observable and unobservable inputs used to measure fair value into three levels: Level 1 — quoted prices (unadjusted) in active markets that are accessible at the measurement date for assets or liabilities; Level 2 — observable prices that are based on inputs not quoted in active markets, but corroborated by market data; and Level 3 — unobservable inputs that are used when little or no market data is available. The fair value hierarchy gives the highest priority to Level 1 inputs and the lowest priority to Level 3 inputs. In determining fair value, we utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as consider counterparty credit risk in our assessment of fair value.
Revenue Recognition, Policy [Policy Text Block]	Revenue Recognition Property rentals income includes base rents that each tenant pays in accordance with the terms of its respective lease and is reported on a straight-line basis over the non-cancellable term of the lease, which includes the effects of periodic step-ups in rent and rent abatements under the leases. We commence rental revenue recognition when the tenant takes possession of the leased space or controls the physical use of the leased space and the leased space is substantially ready for its intended use. In circumstances where we provide a tenant improvement allowance for improvements that are owned by the tenant, we recognize the allowance as a reduction of property rentals revenue on a straight-line basis over the term of the lease. Differences between rental income recognized and amounts due under the respective lease agreements are recorded as an increase or decrease to "Deferred rent receivable, net" on our balance sheets. Property rentals also includes the amortization/accretion of acquired above-and below-market leases. Tenant reimbursements provide for the recovery of all or a portion of the operating expenses and real estate taxes of the respective assets. Tenant reimbursements are accrued in the same periods as the related expenses are incurred. Third-party real estate services revenue, including reimbursements, is determined in accordance with the terms specific to each arrangement and may include property and asset management fees or transactional fees for leasing, acquisition, development and construction, financing, and legal services provided. These fees are determined in accordance with the terms specific to each arrangement and are recognized as the related services are performed. Development and construction fees earned from providing services to our unconsolidated real estate ventures are recorded on a percentage of completion basis.
Third-Party Real Estate Services Expenses [Policy Text Block]	Third-Party Real Estate Services Expenses Third-party real estate services expenses include the costs associated with the management services provided to our unconsolidated real estate ventures and other third parties. We allocate personnel and other overhead costs using the estimates of the time spent performing services for our third-party real estate services and other allocation methodologies.
Income Tax, Policy [Policy Text Block]	Income Taxes We have elected to be taxed as a REIT under sections 856-860 of the Internal Revenue Code of 1986, as amended (the "Code"). Under those sections, a REIT which distributes at least 90% of its REIT taxable income as dividends to its shareholders each year and which meets certain other conditions will not be taxed on that portion of its taxable income which is distributed to its shareholders. Prior to the Separation, Vornado operated as a REIT and distributed 100% of its REIT taxable income to its shareholders; accordingly, no provision for federal income taxes has been made in the accompanying financial statements for the periods prior to the Separation. We currently adhere and intend to continue to adhere to these requirements and to maintain our REIT status in future periods. As a REIT, we can reduce our taxable income by distributing all or a portion of such taxable income to shareholders. Future distributions will be declared and paid at the discretion of the Board of Trustees and will depend upon cash generated by operating activities, our financial condition, capital requirements, annual dividend requirements under the REIT provisions of the Code and such other factors as our Board of Trustees deems relevant. We also participate in the activities conducted by our subsidiary entities that have elected to be treated as taxable REIT subsidiaries ("TRS") under the Code. As such, we are subject to federal, state, and local taxes on the income from these activities. Income taxes attributable to our TRSs are accounted for under the asset and liability method. Under the asset and liability method, deferred income taxes arise from temporary differences between the tax basis of assets and liabilities and their reported amounts in the financial statements, which will result in taxable or deductible amounts in the future. We provide for a valuation allowance for deferred income tax assets if we believe all or some portion of the deferred tax asset may not be realized. Any increase or decrease in the valuation allowance that results from a change in circumstances that causes a change in the estimated ability to realize the related deferred tax asset is included in deferred tax benefit (expense). ASC 740-10, Income Taxes, provides guidance for how uncertain tax positions should be recognized, measured, presented and disclosed in the financial statements. ASC 740-10 requires the evaluation of tax positions taken in the course of preparing our tax returns to determine whether the tax positions are "more-likely-than-not" of being sustained by the applicable tax authority. Tax benefits of positions not deemed to meet the more-likely-than-not threshold are recorded as a tax expense in the current year.
Earnings Per Share, Policy [Policy Text Block]	Earnings (Loss) Per Common Share Basic earnings (loss) per common share is computed by dividing net income (loss) attributable to common shareholders by the weighted average common shares outstanding during the period. Unvested and vested share-based payment awards that entitle holders to receive non-forfeitable dividends, which include OP Units and long-term incentive partnership units ("LTIP Units"), are considered participating securities. Consequently, we are required to apply the two-class method of computing basic and diluted earnings that would otherwise have been available to common shareholders. Under the two-class method, earnings for the period are allocated between common shareholders and participating securities based on their respective rights to receive dividends. During periods of net loss, losses are allocated only to the extent the participating securities are required to absorb their share of such losses. Diluted earnings per common share reflects the potential dilution of the assumed exchange of various unit and share-based payment awards into common shares to the extent they are dilutive.
Compensation Related Costs, Policy [Policy Text Block]	Share-Based Compensation The fair value of OP Units, formation awards ("Formation Awards"), LTIP Units, LTIP Units with time-based vesting requirements ("Time-Based LTIP Units"), performance-based LTIP Units ("Performance-Based LTIP Units") and Employee Share Purchase Plan ("ESPP") common shares granted to our trustees, management and employees is determined, depending on the type of award, using the Monte Carlo or Black-Scholes methods, which is intended to estimate the fair value of the awards at the grant date using dividend yields, expected volatilities that are primarily based on available implied data and peer group companies' historical data and post-vesting restriction periods. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. The shortcut method is used for determining the expected life used in the valuation method. Compensation expense is based on the fair value of our common shares at the date of the grant and is recognized ratably over the vesting period using a graded vesting attribution model. We account for forfeitures as they occur. Distributions paid on unvested OP Units, LTIP Units, Time-Based LTIP Units and Performance-Based LTIP Units are charged to "Net income attributable to noncontrolling interests" in the statements of operations.

Organization and Basis of Pre_3

Organization and Basis of Presentation Rental Revenue from USG (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	Only the U.S. federal government accounted for 10% or more of our rental revenue, which consists of property rentals and tenant reimbursements, as follows: Year Ended December 31, (Dollars in thousands) 2018 2017 2016 Rental revenue from the U.S. federal government $ 94,822 $ 92,192 $ 103,864 Percentage of commercial segment rental revenue 22.0 % 24.0 % 29.1 % Percentage of total rental revenue 17.6 % 19.4 % 23.6 %

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of Recent Accounting Pronouncements	The following table provides a brief description of recent significant accounting pronouncements by the Financial Accounting Standards Board ("FASB") that have been or will be required to be adopted by us: Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standards adopted ASU 2014-09, Revenue from Contracts with Customers (Topic 606), as clarified and amended by ASU 2016-08, ASU 2016-10 and ASU 2016-12 This standard establishes a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most of the existing revenue recognition guidance. It requires an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services and also requires certain additional disclosures. January 2018 We utilized the modified retrospective method of adoption. The standard excludes from its scope the areas of accounting that most significantly affect our revenue recognition, including accounting for leases and financial instruments. Our evaluation determined there were no required changes to our recognition of revenue related to our third-party real estate services, tenant reimbursements, property and asset management fees, or transactional/management fees for leasing, development and construction. Our evaluation also determined there were no required changes to our recognition of promote fees and dispositions of real estate properties as we did not have any deferred gains due to continuing involvement at the time of adoption. Therefore, the adoption of this standard did not have a material impact on our financial statements. We adopted the practical expedient of this standard to only assess the recognition of revenue for open contracts at the date of adoption and there was no adjustment to the opening balance of our accumulated deficit at January 1, 2018. The comparative information has not been restated and continues to be reported under the accounting standards in effect for that period. ASU 2018-09, Codification Improvements These amendments provide clarifications and corrections to certain ASC subtopics including the following: 220-10 (Income Statement - Reporting Comprehensive Income - Overall), 470-50 (Debt - Modifications and Extinguishments), 480-10 (Distinguishing Liabilities from Equity - Overall), 718-740 (Compensation - Stock Compensation - Income Taxes), 805-740 (Business Combinations - Income Taxes), 815-10 (Derivatives and Hedging - Overall), and 820-10 (Fair Value Measurement - Overall). December 2018 The adoption and implementation of this standard did not have a material impact on our financial statements. Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standard not yet adopted ASU 2016-02, Leases (Topic 842), as clarified and amended by ASU 2018-01, ASU 2018-10, ASU 2018-11 and ASU 2018-20 This standard establishes principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. ASU 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. Lessees are required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases. Lessees will recognize expense based on the effective interest method for finance leases or on a straight-line basis for operating leases. The ASU also clarifies that an assessment of whether a land easement meets the definition of a lease under the new lease standard is required. The provisions of this standard are effective for fiscal years beginning after December 15, 2018 and should be applied through a modified retrospective transition, which includes optional practical expedients related to leases that commenced before the effective date and allows the new requirements to be applied on the date of adoption rather than the beginning of the earliest comparative period presented. January 2019 We completed our evaluation of the implementation of this standard. ASU 2016-02 will more significantly impact the accounting for leases in which we are the lessee. We have leases for which we anticipate recording operating right-of-use assets totaling $31.0 million to $41.0 million and operating lease liabilities totaling $33.0 million to $43.0 million, which are equal to the present value of the remaining minimum lease payments upon adoption of this standard. Under ASU 2016-02, initial direct costs for both lessees and lessors would include only those costs that are incremental to the arrangement and would not have been incurred if the lease had not been obtained. As a result, we will no longer be able to capitalize internal leasing costs and instead will be required to expense these costs as incurred. Capitalized internal leasing costs were $6.5 million, $2.9 million and $2.5 million for each of the three years in the period ended December 31, 2018. We will apply the modified retrospective approach of adoption and will elect the transition practical expedients, including the Relief Package for existing leases, the Easement practical expedient for existing easements, but not the Hindsight expedient.

The Combination The Combinati_2

The Combination The Combination (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The following allocation of the purchase price is based on the fair value of the assets acquired and liabilities assumed (in thousands): Fair value of purchase consideration: Common shares and OP Units $ 1,224,885 Cash 20,573 Total consideration paid $ 1,245,458 Fair value of assets acquired and liabilities assumed: Land and improvements $ 338,072 Building and improvements 609,156 Construction in progress, including land 699,800 Leasehold improvements and equipment 7,890 Real estate 1,654,918 Cash 104,529 Restricted cash 13,460 Investments in and advances to unconsolidated real estate ventures 241,142 Identified intangible assets 138,371 Notes receivable (1) 50,934 Identified intangible liabilities (8,687 ) Mortgages payable assumed (2) (768,523 ) Capital lease obligations assumed (3) (33,543 ) Lease assumption liabilities (4) (48,127 ) Deferred tax liability (5) (18,610 ) Other liabilities acquired, net (60,048 ) Noncontrolling interests in consolidated subsidiaries (3,588 ) Net assets acquired 1,262,228 Gain on bargain purchase (6) 16,770 Total consideration paid $ 1,245,458 ____________________ (1) During the year ended December 31, 2017 , we received proceeds of $50.9 million from the repayment of the notes receivable acquired in the Combination. (2) Subject to various interest rate swap and cap agreements assumed in the Combination that are considered economic hedges, but not designated as accounting hedges. (3) In the Combination, two ground leases were assumed that were determined to be capital leases. On July 25, 2017, we purchased a land parcel located in Reston, Virginia associated with one of the ground leases for $19.5 million . (4) Includes a $14.0 million payment to a tenant, which was paid in 2018, and a $34.1 million lease liability we assumed in relocating a tenant to one of our office buildings. The $34.1 million assumed lease liability is based on the contractual payments we assumed under the tenant’s previous lease, which are partially offset by estimated sub-tenant income we anticipate receiving as we actively pursue a sub-tenant. (5) Related to the management and leasing contracts acquired in the Combination. (6) The Combination resulted in a gain on bargain purchase of $24.4 million for the year ended December 31, 2017 because the fair value of the identifiable net assets acquired exceeded the purchase consideration. As a result of finalizing our fair value estimates used in the purchase price allocation related to the Combination, during the year ended December 31, 2018 , we adjusted the fair value of certain assets acquired and liabilities assumed consisting of a decrease of $468,000 to investments in and advances to unconsolidated real estate ventures, an increase of $4.7 million to lease assumption liabilities and an increase of $2.4 million to other liabilities acquired, resulting in a reduction of the gain on bargain purchase of $7.6 million for the year ended December 31, 2018 . The purchase consideration was based on the fair value of the common shares and OP Units issued in the Combination. We have concluded that all acquired assets and liabilities were recognized and that the valuation procedures and resulting estimates of fair values were appropriate.
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The fair value of the common shares and OP Units purchase consideration was determined as follows (i n thousands, except exchange ratio and price per share/unit): Outstanding common shares and common limited partnership units prior to the Combination 100,571 Exchange ratio (1) 2.71 Common shares and OP Units issued in consideration 37,164 Price per share/unit (2) $ 37.10 Fair value of common shares and OP Units issued in consideration $ 1,378,780 Fair value adjustment to OP Units due to transfer restrictions (43,304 ) Portion of consideration attributable to performance of future services (3) (110,591 ) Fair value of common shares and OP Units purchase consideration $ 1,224,885 ____________________ (1) Represents the implied exchange ratio of one common share and OP Unit of JBG SMITH for 2.71 common shares and common limited partnership units prior to the Combination. (2) Represents the volume weighted average share price on July 18, 2017. (3) OP Unit consideration paid to certain of the owners of the JBG Assets which have a fair value of $110.6 million is subject to post-combination employment with vesting over periods of either 12 or 60 months and amortization is recognized as compensation expense over the period of employment in "General and administrative expense: Share-based compensation related to Formation Transaction and special equity awards" in the statements of operations.
Schedule of Property, Plant and Equipment Acquired As Part of a Business Combination [Table Text Block]	The fair values of tangible and identified intangible assets and liabilities, which have definite lives, are as follows: Total Fair Value Weighted Average Amortization Period Useful Life (1) (In thousands) (In years) Tangible assets: Building and improvements $ 543,584 3 - 40 years Tenant improvements 65,572 Shorter of useful life or remaining life of the respective lease Total building and improvements $ 609,156 Leasehold improvements $ 4,422 Shorter of useful life or remaining life of the respective lease Equipment 3,468 5 years Total leasehold improvements and equipment $ 7,890 Identified intangible assets: In-place leases $ 60,317 6.4 Remaining life of the respective lease Above-market real estate leases 11,732 6.3 Remaining life of the respective lease Below-market ground leases 332 88.5 Remaining life of the respective lease Option to enter into ground lease 17,090 N/A Remaining life of contract Management and leasing contracts (2) 48,900 7.5 Estimated remaining life of contracts, ranging between 3 - 9 years Total identified intangible assets $ 138,371 Identified intangible liabilities: Below-market real estate leases $ 8,687 10.3 Remaining life of the respective lease ____________________ (1) In determining these useful lives, we considered the length of time the asset had been in existence, the maintenance history, as well as anticipated future maintenance, and any contractual stipulations that might limit the useful life. (2) Includes in-place property management, leasing, asset management and development management contracts.
Business Acquisition, Pro Forma Information [Table Text Block]	The following pro forma information for the year ended December 31, 2017 is presented as if the Formation Transaction had occurred on January 1, 2016. This pro forma information is based upon historical financial statements, adjusted for certain factually supported items directly related to the Formation Transaction. This pro forma information does not purport to represent what the actual results of our operations would have been, nor does it purport to predict the results of operations of future periods. The pro forma information was adjusted to exclude transaction and other costs of $127.7 million and the gain on bargain purchase of $24.4 million and their related income tax benefits for the year ended December 31, 2017 . Year Ended December 31, 2017 (In thousands) Unaudited pro forma information: Total revenue $ 637,672 Net loss attributable to common shareholders (19,343 ) The total revenue and net loss of the JBG Assets for the year ended December 31, 2017 included in our statements of operations from the acquisition date was $71.3 million and $23.1 million .

Acquisitions, Disposals and A_2

Acquisitions, Disposals and Assets Held for Sale (Tables)	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Disclosure of Long Lived Assets Held-for-sale [Table Text Block]	The following is a summary of assets held for sale: Assets Segment Location Total Square Feet Assets Held for Sale Liabilities Related to Assets Held for Sale (In thousands) December 31, 2018 Commerce Executive (1) Commercial Reston, Virginia 388,562 $ 78,981 $ 3,717 December 31, 2017 Summit - MWAA (2) Commercial Reston, Virginia — $ 1,699 $ — Potomac Yard Land Bay G (3) Other Alexandria, Virginia — 6,594 — $ 8,293 $ — _______________ (1) In July 2018, the buyer’s deposit related to the contract to sell Commerce Executive became non-refundable. In February 2019 , we sold Commerce Executive for $115.0 million . The sale also included approximately 894,000 square feet of estimated potential development density. The sale was part of a reverse 1031 like-kind exchange. See Note 7 for additional information. (2) As previously disclosed, in February 2018, Summit - MWAA was sold for $2.2 million . (3) During the second quarter of 2018, the buyer forfeited their deposit and the property was removed from assets held for sale.
Disposal Groups, Including Discontinued Operations [Table Text Block]	The following is a summary of disposition activity for the year ended December 31, 2018 : Date Disposed Assets Segment Location Total Square Feet Gross Sales Price Cash Proceeds from Sale (1) Gain on Sale of Real Estate (In thousands) February 13, 2018 Summit - MWAA Commercial Reston, Virginia — $ 2,154 $ 2,154 $ 455 April 3, 2018 Summit I and II / Summit Land (2) Commercial Reston, Virginia 284,118 95,000 35,240 6,189 May 1, 2018 Bowen Building (3) Commercial Washington, D.C. 231,402 140,000 136,488 27,207 September 21, 2018 Executive Tower (4) Commercial Washington, D.C. 129,831 121,445 113,267 12,378 October 23, 2018 1233 20th Street (5) Commercial Washington, D.C. 149,684 65,000 21,229 4,354 October 25, 2018 Falkland Chase - North (out-of-service portion) Multifamily Silver Spring, Maryland 13,284 3,819 3,819 1,600 Total 808,319 $ 427,418 $ 312,197 $ 52,183 ______________ (1) Net of related mortgage loan payments. (2) Total square feet included 700,000 square feet of estimated potential development density. In connection with the sale, we repaid the related $59.0 million mortgage loan. (3) In connection with the sale, we repaid $115.0 million of the then outstanding balance on our revolving credit facility. (4) Proceeds from the sale were held in escrow and classified as "Restricted cash" on our balance sheet as of December 31, 2018 . (5) In connection with the sale, we repaid the related $41.9 million mortgage loan.

Tenant and Other Receivables,_2

Tenant and Other Receivables, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Tenant and Other Receivables, Net [Abstract]
Schedule of Tenants and Other Receivable, Net	The following is a summary of tenant and other receivables: December 31, 2018 2017 (In thousands) Tenants $ 31,362 $ 30,672 Third-party real estate services 12,443 8,954 Other 9,463 12,992 Allowance for doubtful accounts (6,700 ) (5,884 ) Total tenant and other receivables, net $ 46,568 $ 46,734

Investments in and Advances t_2

Investments in and Advances to Unconsolidated Real Estate Ventures (Tables)	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Composition of Investments	The following is a summary of the composition of our investments in and advances to unconsolidated real estate ventures: Ownership Interest (1) December 31, Real Estate Venture Partners 2018 2017 (In thousands) CPPIB 55.0% - 68.5% $ 97,521 $ 36,317 Landmark 1.8% - 49.0% 84,320 95,368 CBREI Venture 5.0% - 64.0% 73,776 79,062 Berkshire Group 50.0% 43,937 27,761 Brandywine 30.0% 13,777 13,741 CIM Group ("CIM") and Pacific Life Insurance Company ("PacLife") 16.7% 9,339 — JP Morgan —% — 9,296 Other 128 246 Total investments in unconsolidated real estate ventures 322,798 261,791 Advances to unconsolidated real estate ventures 80 20 Total investments in and advances to unconsolidated real estate ventures $ 322,878 $ 261,811 _______________ (1) Ownership interests as of December 31, 2018 . We have multiple investments with certain venture partners with varying ownership interests. The following is a summary of the debt of our unconsolidated real estate ventures: Weighted Average Effective (1) December 31, 2018 2017 (In thousands) Variable rate (2) 5.53% $ 461,704 $ 534,500 Fixed rate (3) 4.02% 665,662 657,701 Unconsolidated real estate ventures - mortgages payable 1,127,366 1,192,201 Unamortized deferred financing costs (1,998 ) (2,000 ) Unconsolidated real estate ventures - mortgages payable, net (4) $ 1,125,368 $ 1,190,201 ______________ (1) Weighted average effective interest rate as of December 31, 2018 . (2) Includes variable rate mortgages payable with interest rate cap agreements. (3) Includes variable rate mortgages payable with interest rates fixed by interest rate swap agreements. (4) See Note 19 for additional information on guarantees of the debt of certain of our unconsolidated real estate ventures. The following is a summary of the financial information for our unconsolidated real estate ventures: December 31, 2018 2017 Combined balance sheet information: (In thousands) Real estate, net $ 2,050,985 $ 2,106,670 Other assets, net 169,264 264,731 Total assets $ 2,220,249 $ 2,371,401 Borrowings, net $ 1,125,368 $ 1,190,201 Other liabilities, net 94,845 76,416 Total liabilities 1,220,213 1,266,617 Total equity 1,000,036 1,104,784 Total liabilities and equity $ 2,220,249 $ 2,371,401 Year Ended December 31, 2018 2017 2016 Combined income statement information: (In thousands) Total revenue $ 300,032 $ 135,256 $ 68,118 Operating income (1) 56,262 14,741 19,283 Net income (loss) (1,155 ) (7,593 ) 5,234 _____________ (1) Includes gain on sale of The Warner of $32.5 million recognized by our unconsolidated real estate venture with CPPIB during the year ended December 31, 2018 .

Other Assets, Net (Tables)

Other Assets, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Summary of Other Assets, Net	The following is a summary of other assets, net: December 31, 2018 2017 (In thousands) Deferred leasing costs $ 202,066 $ 171,153 Accumulated amortization (72,465 ) (67,180 ) Deferred leasing costs, net 129,601 103,973 Identified intangible assets, net 89,859 126,467 Prepaid expenses 6,482 9,038 Deferred financing costs on credit facility, net 4,806 6,654 Deposits 3,633 6,317 Derivative agreements, at fair value 10,383 2,141 Other 20,230 9,333 Total other assets, net $ 264,994 $ 263,923
Schedule of Identified Intangible Assets, Net	The following is a summary of the composition of identified intangible assets, net: December 31, 2018 2017 Identified intangible assets: (in thousands) In-place leases $ 38,216 $ 72,086 Above-market real estate leases 9,414 12,066 Below-market ground leases 2,215 2,547 Option to enter into ground lease 17,090 17,090 Management and leasing contracts 48,900 48,900 Other 166 206 Total identified intangibles assets 116,001 152,895 Accumulated amortization: In-place leases 11,602 20,015 Above-market real estate leases 2,405 1,600 Below-market ground leases 1,448 1,365 Option to enter into ground lease 251 78 Management and leasing contracts 10,297 3,209 Other 139 161 Total accumulated amortization 26,142 26,428 Identified intangible assets, net $ 89,859 $ 126,467
Summary of Amortization Expense	The following is a summary of amortization expense included in the statements of operations related to identified intangible assets: Year Ended December 31, 2018 2017 2016 In-place lease amortization (1) $ 11,807 $ 10,216 $ 485 Above-market real estate lease amortization (2) 2,390 1,428 78 Below-market ground lease amortization (3) 85 87 85 Option to enter into ground lease amortization (3) 173 — — Management and leasing contract amortization (1) 7,088 3,209 — Other amortization (1) 18 14 92 Total identified intangible asset amortization $ 21,561 $ 14,954 $ 740 ___________________________________________ (1) Amounts are included in "Depreciation and amortization expenses" in our statements of operations. (2) Amounts are included in "Property rentals revenue" in our statements of operations. (3) Amounts are included in "Property operating expenses" in our statements of operations.
Schedule of Estimated Amortization of Identified Intangible Assets	As of December 31, 2018 , the estimated amortization of identified intangible assets is as follows for the next five years and thereafter: Year ending December 31, Amount (in thousands) 2019 $ 16,184 2020 13,720 2021 10,591 2022 9,506 2023 8,924 Thereafter 30,934 Total $ 89,859

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Maturities of Long-term Debt [Table Text Block]	s Principal maturities of debt outstanding as of December 31, 2018 , including mortgages payable and the term loans, are as follows: Year ending December 31, Amount (In thousands) 2019 $ 182,467 2020 97,141 2021 331,881 2022 327,500 2023 277,736 Thereafter 927,927 Total $ 2,144,652
Summary of Debt	The following is a summary of mortgages payable: Weighted Average (1) December 31, 2018 2017 (In thousands) Variable rate (2) 4.30% $ 308,918 $ 498,253 Fixed rate (3) 4.09% 1,535,734 1,537,706 Mortgages payable 1,844,652 2,035,959 Unamortized deferred financing costs and premium/ discount, net (6,271 ) (10,267 ) Mortgages payable, net $ 1,838,381 $ 2,025,692 __________________________ (1) Weighted average effective interest rate as of December 31, 2018 . (2) Includes variable rate mortgages payable with interest rate cap agreements. (3) Includes variable rate mortgages payable with interest rates fixed by interest rate swap agreements. . In July 2018, we drew $200.0 million under the Tranche A-2 Term Loan, in accordance with the delayed draw provisions of the credit facility. The following is a summary of amounts outstanding under the credit facility: December 31, Interest Rate (1) 2018 2017 (In thousands) Revolving credit facility (2) (3) (4) (5) 3.60% $ — $ 115,751 Tranche A-1 Term Loan 3.32% $ 100,000 $ 50,000 Tranche A-2 Term Loan 4.05% 200,000 — Unsecured term loans 300,000 50,000 Unamortized deferred financing costs, net (2,871 ) (3,463 ) Unsecured term loans, net $ 297,129 $ 46,537 __________________________ (1) Interest rate as of December 31, 2018 . (2) As of December 31, 2018 and 2017 , letters of credit with an aggregate face amount of $5.7 million were provided under our revolving credit facility. (3) As of December 31, 2018 and 2017 , net deferred financing costs related to our revolving credit facility totaling $4.8 million and $6.7 million were included in "Other assets, net." (4) In May 2018, in connection with the sale of the Bowen Building, we repaid $115.0 million of the then outstanding balance on our revolving credit facility. See Note 4 for additional information. (5) The interest rate for the revolving credit facility excludes a 0.15% facility fe

Other Liabilities, Net (Tables)

Other Liabilities, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Other Liabilities Disclosure [Abstract]
Below Market Lease, Future Amortization Income [Table Text Block]	As of December 31, 2018 , the estimated amortization of lease intangible liabilities is as follows for the next five years and thereafter: Year ending December 31, Amount (in thousands) 2019 $ 2,232 2020 2,019 2021 1,753 2022 1,734 2023 1,726 Thereafter 4,634 Total $ 14,098
Composition of Other Liabilities, Net	The following is a summary of other liabilities, net: December 31, 2018 2017 (In thousands) Lease intangible liabilities $ 40,179 $ 44,917 Accumulated amortization (26,081 ) (26,950 ) Lease intangible liabilities, net 14,098 17,967 Prepaid rent 21,998 15,751 Lease assumption liabilities and accrued tenant incentives 32,422 50,866 Capital lease obligation 15,704 15,819 Security deposits 17,696 13,618 Environmental liabilities (1) 17,898 2,900 Ground lease deferred rent payable 3,510 3,730 Net deferred tax liability 6,878 8,202 Dividends payable 45,193 31,097 Other 6,209 1,327 Total other liabilities, net $ 181,606 $ 161,277

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	December 31, 2018 2017 (in thousands) Deferred tax assets: Accrued bonus $ — $ 1,675 Net operating loss 2,326 1,710 Deferred revenue 998 71 Bad debt expense 583 111 Other 198 623 Total deferred tax assets 4,105 4,190 Valuation allowance (469 ) — Total deferred tax assets, net of valuation allowance 3,636 4,190 Deferred tax liabilities: Management and leasing contracts (9,905 ) (11,840 ) Other (609 ) (552 ) Total deferred tax liabilities (10,514 ) (12,392 ) Net deferred tax liability $ (6,878 ) $ (8,202 )
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The following is a summary of our income tax benefit (expense): Year Ended December 31, 2018 2017 2016 (in thousands) Current tax benefit (expense) $ 20 $ (496 ) $ (1,083 ) Deferred tax benefit (expense) 718 10,408 — Income tax benefit (expense) $ 738 $ 9,912 $ (1,083 )

Redeemable Noncontrolling Int_2

Redeemable Noncontrolling Interests (Tables)	12 Months Ended
	Dec. 31, 2018
Noncontrolling Interest [Abstract]
Redeemable Noncontrolling Interests	Below is a summary of the activity of redeemable noncontrolling interests: Year Ended December 31, 2018 2017 JBG SMITH LP Consolidated Real Estate Venture Total JBG SMITH LP Consolidated Real Estate Venture Total (In thousands) Balance as of beginning of period $ 603,717 $ 5,412 $ 609,129 $ — $ — $ — Fair value of OP Unit redemptions (109,208 ) — (109,208 ) — — — OP Units issued at the Separation — — — 96,632 — 96,632 OP Units issued in connection with the Combination (1) — — — 359,967 — 359,967 Net income (loss) attributable to redeemable noncontrolling interests 6,641 69 6,710 (7,320 ) (8 ) (7,328 ) Other comprehensive income 1,384 — 1,384 225 — 225 Contributions (distributions) (18,737 ) 500 (18,237 ) (9,113 ) 5,420 (3,693 ) Share-based compensation expense 52,190 — 52,190 32,634 — 32,634 Adjustment to redemption value 16,172 — 16,172 130,692 — 130,692 Balance as of end of period $ 552,159 $ 5,981 $ 558,140 $ 603,717 $ 5,412 $ 609,129 _______________________________________ (1) Excludes certain OP Units issued as part of the Combination which had an estimated fair value of $110.6 million , the vesting of which is subject to post-combination employment. See Note 13 for additional information.

Share-Based Payments (Tables)

Share-Based Payments (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]	The significant assumptions used to value these awards included: Year Ended December 31, 2018 2017 Expected volatility 20.0% to 22.0% 17.0% to 19.0% Risk-free interest rate 1.9% to 2.6% 1.3% to 1.5% Post-grant restriction periods 2 to 3 years 2 to 3 years The following table presents information regarding Granted LTIP activity: Unvested Shares Weighted Average Grant-Date Fair Value Unvested at December 31, 2017 332,207 $ 33.68 Granted 749,880 34.01 Vested (110,723 ) 32.91 Forfeited (8,702 ) 32.51 Unvested at December 31, 2018 962,662 34.03 The following table presents information regarding the OP Units activity: Unvested Shares Weighted Average Grant-Date Fair Value Unvested at December 31, 2017 3,086,962 33.49 Vested (86,975 ) 37.10 Unvested at December 31, 2018 2,999,987 33.39 The significant assumptions used to value both the Performance-Based LTIP and Special Performance-Based LTIP Units included: Year Ended December 31, 2018 2017 Expected volatility 19.9% to 26.0% 18.0 % Dividend yield 2.5% to 2.7% 2.3 % Risk-free interest rate 2.3% to 3.0% 1.5 % The following table presents information regarding the Performance-Based LTIP and Special Performance-Based LTIP Units activity: Unvested Shares Weighted Average Grant-Date Fair Value Unvested at December 31, 2017 604,522 $ 15.95 Granted 1,078,661 19.52 Forfeited (25,605 ) 16.29 Unvested at December 31, 2017 1,657,578 18.27 The significant assumptions used to value the awards included: Year Ended December 31, 2018 2017 Expected volatility 27.0% to 29.0% 26.0 % Dividend yield 2.5% to 2.7% 2.3 % Risk-free interest rate 2.8% to 3.0% 2.3 % Expected life 7 years 7 years The following table presents information regarding the Formation Awards activity: Unvested Shares Weighted Average Grant-Date Fair Value Unvested at December 31, 2017 2,673,814 $ 8.84 Granted 93,784 7.73 Vested (39,970 ) 8.32 Forfeited (72,234 ) 8.84 Unvested at December 31, 2018 2,655,394 8.81
Summary of Share-Based Compensation Expense	Share-based compensation expense is summarized as follows: Year Ended December 31, 2018 2017 2016 (In thousands) Time-Based LTIP Units $ 10,095 $ 2,211 — Performance-Based LTIP Units 5,271 1,172 — LTIP Units 794 — — Other equity awards (1) 3,826 1,526 4,502 Share-based compensation expense - other 19,986 4,909 4,502 Formation Awards 5,606 5,169 $ — OP Units (2) 29,455 21,467 — LTIP Units (2) 277 2,615 — Special Performance-Based LTIP Units 323 — — Special Time-Based LTIP Units 369 — — Share-based compensation related to Formation Transaction and special equity awards (3) 36,030 29,251 — Total share-based compensation expense 56,016 34,160 4,502 Less amount capitalized (3,341 ) (467 ) — Share-based compensation expense $ 52,675 $ 33,693 $ 4,502 ______________________________________________ (1) For the year ended December 31, 2018 , primarily includes compensation expense for certain executives who have elected to receive all or a portion of any cash bonus that may be paid in 2019, related to 2018 service, in the form of fully vested LTIP Units. For the years ended December 31, 2017 and 2016, represents share-based compensation expense related to equity awards prior to the Formation Transaction. (2) Represents share-based compensation expense for LTIP Units and OP Units subject to post-Combination employment obligations. (3) Included in "General and administrative expense: Share-based compensation related to Formation Transaction and special equity awards" in the accompanying statements of operations.

Interest Expense Interest Exp_2

Interest Expense Interest Expense (Tables)	12 Months Ended
	Dec. 31, 2018
Interest Expense [Abstract]
Interest Income and Interest Expense Disclosure [Table Text Block]	The following is a summary of interest expense included in the statements of operations: Year Ended December 31, 2018 2017 2016 (In thousands) Interest expense $ 91,651 $ 69,178 $ 54,379 Amortization of deferred financing costs 4,661 3,011 1,478 Net loss (gain) on derivative financial instruments Net unrealized (926 ) (1,348 ) — Net realized (135 ) 27 — Capitalized interest (20,804 ) (12,727 ) (4,076 ) Interest expense $ 74,447 $ 58,141 $ 51,781

Earnings (Loss) Per Common Sh_2

Earnings (Loss) Per Common Share EPS (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following summarizes the calculation of basic and diluted earnings per common share and provides a reconciliation of the amounts of net income (loss) available to common shareholders used in calculating basic and diluted earnings per common share: Year Ended December 31, 2018 2017 2016 (In thousands, except per share amounts) Net income (loss) $ 46,613 $ (79,084 ) $ 61,974 Net (income) loss attributable to redeemable noncontrolling (6,710 ) 7,328 — Net loss attributable to noncontrolling interests 21 3 — Net income (loss) attributable to common shareholders 39,924 (71,753 ) 61,974 Distributions to participating securities (2,599 ) (1,655 ) — Net income (loss) available to common shareholders — basic and diluted $ 37,325 $ (73,408 ) $ 61,974 Weighted average number of common shares outstanding — basic and diluted (1) 119,176 105,359 100,571 Earnings (loss) per common share: Basic $ 0.31 $ (0.70 ) $ 0.62 Diluted $ 0.31 $ (0.70 ) 0.62 ______________ (1) Reflects the weighted average common shares attributable to the Vornado Included Assets as of the date of the Separation for all periods prior to July 17, 2017,

Minimum Rental Income (Tables)

Minimum Rental Income (Tables)	12 Months Ended
	Dec. 31, 2018
Minimum Rental Income [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	As of December 31, 2018 , future base rental revenue under these non-cancelable operating leases excluding extension options is as follows: Year ending December 31, Amount (In thousands) 2019 $ 377,427 2020 321,205 2021 287,463 2022 256,352 2023 215,203 Thereafter 1,188,767

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following are assets and liabilities measured at fair value on a recurring basis: Fair Value Measurements Total Level 1 Level 2 Level 3 December 31, 2018 (In thousands) Derivative financial instruments designated as cash flow hedges: Classified as assets in "Other assets, net" $ 7,913 $ — $ 7,913 $ — Classified as liabilities in "Other liabilities, net" 1,723 — 1,723 — Derivative financial instruments not designated as cash flow hedges: Classified as assets in "Other assets, net" 2,470 — 2,470 — December 31, 2017 Derivative financial instruments designated as cash flow hedges: Classified as assets in "Other assets, net" $ 1,506 $ — $ 1,506 $ — Classified as liabilities in "Other liabilities, net" 2,640 — 2,640 — Derivative financial instruments not designated as cash flow hedges: Classified as assets in "Other assets, net" 635 — 635 — Classified as liabilities in "Other liabilities, net" 22 — 22 —
Schedule of Financial Instruments and Liabilities as Reflected on Balance Sheet	As of December 31, 2018 and 2017 , all financial instruments and liabilities were reflected in our balance sheets at amounts which, in our estimation, reasonably approximated their fair values, except for the following: December 31, 2018 December 31, 2017 Carrying Amount (1) Fair Value Carrying Amount (1) Fair Value (In thousands) Financial liabilities: Mortgages payable $ 1,844,652 $ 1,870,078 $ 2,035,959 $ 2,060,899 Revolving credit facility — — 115,751 115,768 Unsecured term loans 300,000 300,727 50,000 50,029 ______________________________________ ( 1) The carrying amount consists of principal only

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment information	The following table reflects the reconciliation of net income (loss) attributable to common shareholders to consolidated NOI: Year Ended December 31, 2018 2017 2016 (In thousands) Net income (loss) attributable to common shareholders $ 39,924 $ (71,753 ) $ 61,974 Add: Depreciation and amortization expense 211,436 161,659 133,343 General and administrative expense: Corporate and other 33,728 39,350 48,753 Third-party real estate services 89,826 51,919 19,066 Share-based compensation related to Formation Transaction and 36,030 29,251 — Transaction and other costs 27,706 127,739 6,476 Interest expense 74,447 58,141 51,781 Loss on extinguishment of debt 5,153 701 — Reduction of gain (gain) on bargain purchase 7,606 (24,376 ) — Income tax expense (benefit) (738 ) (9,912 ) 1,083 Net (income) loss attributable to redeemable noncontrolling interests 6,710 (7,328 ) — Less: Third-party real estate services, including reimbursements 98,699 63,236 33,882 Other income 6,358 5,167 5,381 Income (loss) from unconsolidated real estate ventures, net 39,409 (4,143 ) (947 ) Interest and other income, net 15,168 1,788 2,992 Gain on sale of real estate 52,183 — — Net loss attributable to noncontrolling interests 21 3 — Consolidated NOI $ 319,990 $ 289,340 $ 281,168 Below is a summary of NOI by segment. Items classified in other include future development assets, corporate entities and the elimination of intersegment activity. Year Ended December 31, 2018 Commercial Multifamily Other Total (In thousands) Rental revenue: Property rentals $ 395,089 $ 102,617 $ 2,129 $ 499,835 Tenant reimbursements 34,953 6,740 (2,403 ) 39,290 Total rental revenue 430,042 109,357 (274 ) 539,125 Rental expense: — Property operating 118,288 31,502 (1,709 ) 148,081 Real estate taxes 53,324 14,280 3,450 71,054 Total rental expense 171,612 45,782 1,741 219,135 Consolidated NOI $ 258,430 $ 63,575 $ (2,015 ) $ 319,990 Year Ended December 31, 2017 Commercial Multifamily Other Total (In thousands) Rental revenue: Property rentals $ 351,517 $ 86,439 $ (1,331 ) $ 436,625 Tenant reimbursements 32,380 5,130 475 37,985 Total rental revenue 383,897 91,569 (856 ) 474,610 Rental expense: Property operating 97,701 24,623 (3,488 ) 118,836 Real estate taxes 50,546 11,030 4,858 66,434 Total rental expense 148,247 35,653 1,370 185,270 Consolidated NOI $ 235,650 $ 55,916 $ (2,226 ) $ 289,340 Year Ended December 31, 2016 Commercial Multifamily Other Total (In thousands) Rental revenue: Property rentals $ 323,133 $ 63,401 $ 15,061 $ 401,595 Tenant reimbursements 33,361 3,454 846 37,661 Total rental revenue 356,494 66,855 15,907 439,256 Rental expense: — Property operating 91,148 17,238 (8,082 ) 100,304 Real estate taxes 46,115 6,993 4,676 57,784 Total rental expense 137,263 24,231 (3,406 ) 158,088 Consolidated NOI $ 219,231 $ 42,624 $ 19,313 $ 281,168 The following is a summary of certain balance sheet data by segment: Commercial Multifamily Other Total December 31, 2018 (In thousands) Real estate, at cost $ 3,634,472 $ 1,656,974 $ 501,288 $ 5,792,734 Investments in and advances to unconsolidated real estate ventures 177,173 109,232 36,473 322,878 Total assets (1) 3,707,255 1,528,177 761,853 5,997,285 December 31, 2017 Real estate, at cost $ 4,023,544 $ 1,480,812 $ 513,148 $ 6,017,504 Investments in and advances to unconsolidated real estate ventures 134,138 98,835 28,838 261,811 Total assets (1) 3,612,947 1,403,452 1,055,408 6,071,807 __________________________ (1) Includes assets held for sale. See Note 4 for additional information.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments for Capital and Operating Leases [Table Text Block]	As of December 31, 2018 , future minimum rental payments under non-cancelable operating leases, capital leases and lease assumption liabilities are as follows: Year ending December 31, Amount (In thousands) 2019 $ 13,991 2020 13,710 2021 13,395 2022 12,554 2023 9,489 Thereafter 55,780 Total $ 118,919

Quarterly Financial Informati_2

Quarterly Financial Information (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information [Abstract]
Quarterly Financial Information [Table Text Block]	2018 First Quarter Second Quarter (1) Third Quarter (2) Fourth Quarter (3) (In thousands, except per share data) Total revenue $ 163,037 $ 159,447 $ 158,443 $ 163,255 Net income (loss) (4,786 ) 24,023 26,382 994 Net income (loss) attributable to common shareholders (4,190 ) 20,574 22,830 710 Earnings (loss) per share: Basic (0.04 ) 0.17 0.19 (0.01 ) Diluted (0.04 ) 0.17 0.19 (0.01 ) _______________ (1) During the second quarter of 2018, we recognized a gain on the sale of real estate of $33.4 million from the sale of Summit I and II and the Bowen Building, a reduction to the gain on bargain purchase of $7.6 million related to the final adjustments to the fair value of certain asset acquired and liabilities assumed in the Formation Transaction and a loss on the extinguishment of debt of $4.5 million . (2) During the third quarter of 2018, we recognized a gain of $15.5 million related to the sale of our interest in a real estate venture that owned the Investment Building and a gain on the sale of real estate of $11.9 million from the sale of Executive Tower. (3) During the fourth quarter of 2018, we recognized a gain of $20.6 million from the sale of The Warner by our unconsolidated real estate venture with CPPIB, transaction and other costs of $15.6 million related to expenses incurred in connection with the Formation Transaction (including transition services provided by our former parent, integration costs, and severance costs), costs related to the pursuit of Amazon HQ2, and costs related to other completed, potential and pursued transactions, and a gain on the sale of real estate of $6.4 million , primarily from the sale of 1233 20th Street and the out-of-service portion of Falkland Chase - North. 2017 First Quarter Second Quarter Third Quarter (1) Fourth Quarter (2) (In thousands, except per share data) Total revenue $ 116,272 $ 118,020 $ 152,350 $ 156,371 Net income (loss) 6,318 11,341 (77,991 ) (18,752 ) Net income (loss) attributable to common shareholders 6,318 11,341 (69,831 ) (16,418 ) Earnings (loss) per share: Basic 0.06 0.11 (0.61 ) (0.15 ) Diluted 0.06 0.11 (0.61 ) (0.15 ) ____________ (1) During the third quarter of 2017, we recognized transaction and other costs of $104.1 million , a gain on bargain purchase of $27.8 million and share-based compensation expense of $14.4 million in connection with the completion of the Formation Transaction. (2) During the fourth quarter of 2017, we recognized share-based compensation expense of $14.8 million and transaction and other costs of $12.6 million in connection with the completion of the Formation Transaction in the third quarter of 2017. Additionally, we recognized a reduction to the gain on bargain purchase of $3.4 million related to adjustments to the fair value of certain assets acquired and liabilities assumed in the Formation Transaction. See Note 3 for additional information.

Organization and Basis of Pre_4

Organization and Basis of Presentation - Narrative (Details) shares in Thousands, $ in Thousands	Jul. 18, 2017ft²building_unitpropertiesshares	Jul. 17, 2017shares	Dec. 31, 2018USD ($)ft²building_unitpropertiesshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)
Real Estate Properties [Line Items]
Common Stock, Shares, Issued | shares		94,700	120,937	117,955
Limited Partners' Capital Account, Units Issued | shares		5,800
Outstanding common shares and common limited partnership units prior to the Combination | shares	118,000		120,937	117,955
Limited Partners' Capital Account, Units Outstanding | shares	19,800
Number of Real Estate Properties			62
Cost of Other Property Operating Expense | $			$ 148,081	$ 118,836	$ 100,304
Asset under Construction
Real Estate Properties [Line Items]
Number of Real Estate Properties			9
Future Development
Real Estate Properties [Line Items]
Number of Real Estate Properties			41
Area of real estate property (in square feet) | ft²			23,100,000
Commercial Real Estate [Member]
Real Estate Properties [Line Items]
Number of Real Estate Properties			46
Area of real estate property (in square feet) | ft²			12,900,000
Commercial Real Estate [Member] | Asset under Construction
Real Estate Properties [Line Items]
Number of Real Estate Properties			5
Area of real estate property (in square feet) | ft²			1,200,000
Multifamily
Real Estate Properties [Line Items]
Number of Real Estate Properties			16
Number of Units in Real Estate Property | building_unit			6,315
Multifamily | Asset under Construction
Real Estate Properties [Line Items]
Number of Real Estate Properties			4
Number of Units in Real Estate Property | building_unit			1,476
Wholly Owned Properties | Future Development
Real Estate Properties [Line Items]
Area of real estate property (in square feet) | ft²			19,600,000
Wholly Owned Properties | Commercial Real Estate [Member]
Real Estate Properties [Line Items]
Area of real estate property (in square feet) | ft²			11,300,000
Wholly Owned Properties | Commercial Real Estate [Member] | Asset under Construction
Real Estate Properties [Line Items]
Area of real estate property (in square feet) | ft²			927,000
Wholly Owned Properties | Multifamily
Real Estate Properties [Line Items]
Number of Units in Real Estate Property | building_unit			4,531
Wholly Owned Properties | Multifamily | Asset under Construction
Real Estate Properties [Line Items]
Area of real estate property (in square feet) | ft²			1,298
JBG Smith, LP
Real Estate Properties [Line Items]
Ownership interest by parent			87.80%
JBG Companies
Real Estate Properties [Line Items]
Common shares and OP Units issued in consideration | shares	37,164
Outstanding common shares and common limited partnership units prior to the Combination | shares		100,571
Number of Real Estate Properties	30
JBG Companies | Commercial Real Estate [Member]
Real Estate Properties [Line Items]
Number of Real Estate Properties	21
Area of real estate property (in square feet) | ft²	4,100,000
JBG Companies | Multifamily
Real Estate Properties [Line Items]
Number of Real Estate Properties	9
Number of Units in Real Estate Property | building_unit	2,883
JBG Companies | Wholly Owned Properties | Commercial Real Estate [Member]
Real Estate Properties [Line Items]
Area of real estate property (in square feet) | ft²	2,400,000
JBG Companies | Wholly Owned Properties | Multifamily
Real Estate Properties [Line Items]
Number of Units in Real Estate Property | building_unit	1,099
JBG Companies | Common Shares
Real Estate Properties [Line Items]
Common shares and OP Units issued in consideration | shares	23,200
JBG Companies | Partnership Interest [Member]
Real Estate Properties [Line Items]
Common shares and OP Units issued in consideration | shares	13,900
Affiliated Entity [Member] | Vornado Realty Trust [Member]
Real Estate Properties [Line Items]
Percentage of Outstanding Common Shares Distributed		100.00%
Restatement Adjustment [Member]
Real Estate Properties [Line Items]
Cost of Other Property Operating Expense | $				$ 7,800

Organization and Basis of Pre_5

Organization and Basis of Presentation Schedule of Revenue by Major Customer (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Total revenue	$ 163,255	$ 158,443	$ 159,447	$ 163,037	$ 156,371	$ 152,350	$ 118,020	$ 116,272	$ 644,182	$ 543,013	$ 478,519
Government Contract [Member]
Disaggregation of Revenue [Line Items]
Total revenue									$ 94,822	$ 92,192	$ 103,864
Sales Revenue, Segment [Member] | Government Contracts Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage									22.00%	24.00%	29.10%
Sales Revenue, Net [Member] | Government Contracts Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage									17.60%	19.40%	23.60%
Annualized Rent [Domain] | Government Contracts Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage									27.00%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Capitalization of internal leasing costs - YTD	$ 6.5	$ 2.9	$ 2.5
Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Operating Lease, Right-of-Use Asset	$ 28
Contractual Obligation	$ 30
Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Operating Lease, Right-of-Use Asset	$ 38
Contractual Obligation	$ 40

The Combination Narrative (Deta

The Combination Narrative (Details) $ in Thousands	3 Months Ended			12 Months Ended
	Dec. 31, 2018USD ($)ft²building_unitproperties	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2018USD ($)ft²building_unitproperties	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Jul. 18, 2017USD ($)ft²building_unitproperties
Number of Real Estate Properties | properties	62			62
Transaction and other costs | $	$ 15,600	$ 12,600	$ 104,100	$ 27,706	$ 127,739	$ 6,476
Business Acquisition, Transaction Costs | $	9,000			9,000
Costs Related to Pursuit of Amazon Headquarters | $				2,800
JBG Companies [Member]
Number of Real Estate Properties | properties							30
Number of Unrelated Owners							20
Number of Former Owners Turned Employees							19
Number of Former Owners Turned Board Members							3
Business Acquisition, Transaction Costs | $	$ 15,900			$ 15,900			$ 40,800
Investment Banking Fees Paid | $					33,600
Legal Fees | $					13,900
Professional Fees | $					$ 10,800
Commercial Real Estate [Member]
Number of Real Estate Properties | properties	46			46
Area of real estate property (in square feet)	12,900,000			12,900,000
Commercial Real Estate [Member] | JBG Companies [Member]
Number of Real Estate Properties | properties							21
Area of real estate property (in square feet)							4,100,000
Multifamily
Number of Real Estate Properties | properties	16			16
Number of Units in Real Estate Property | building_unit	6,315			6,315
Multifamily | JBG Companies [Member]
Number of Real Estate Properties | properties							9
Number of Units in Real Estate Property | building_unit							2,883
Asset under Construction | JBG Companies [Member]
Number of Real Estate Properties | properties							11
Area of real estate property (in square feet)							2,500,000
Near-Term Development [Member] | JBG Companies [Member]
Number of Real Estate Properties | properties							2
Area of real estate property (in square feet)							401,000
Future Development | JBG Companies [Member]
Number of Real Estate Properties | properties							26
Area of real estate property (in square feet)							11,700,000
Wholly Owned Properties | Commercial Real Estate [Member]
Area of real estate property (in square feet)	11,300,000			11,300,000
Wholly Owned Properties | Commercial Real Estate [Member] | JBG Companies [Member]
Area of real estate property (in square feet)							2,400,000
Wholly Owned Properties | Multifamily
Number of Units in Real Estate Property | building_unit	4,531			4,531
Wholly Owned Properties | Multifamily | JBG Companies [Member]
Number of Units in Real Estate Property | building_unit							1,099
Wholly Owned Properties | Asset under Construction | JBG Companies [Member]
Area of real estate property (in square feet)							2,200,000
Wholly Owned Properties | Near-Term Development [Member] | JBG Companies [Member]
Area of real estate property (in square feet)							242,000
Wholly Owned Properties | Future Development | JBG Companies [Member]
Area of real estate property (in square feet)							8,500,000

The Combination Fair Value of A

The Combination Fair Value of Assets Acquired and Liabilities Assumed (Details)	Jul. 25, 2017USD ($)	Jul. 18, 2017USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Noncontrolling interests in consolidated subsidiaries						$ (5,550,000)
Proceeds from Collection of Notes Receivable						0	$ 50,934,000	$ 0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Bargain Purchase, Reduction Of Gain			$ (7,600,000)	$ (3,400,000)	$ 27,800,000	(7,606,000)	24,376,000	$ 0
JBG Companies [Member]
Fair value of common shares and OP Units purchase consideration		$ 1,224,885,000
Cash		20,573,000
Total consideration paid		1,245,458,000
Land and improvements		338,072,000
Building and improvements		609,156,000
Construction in progress, including land		699,800,000
Leasehold improvements and equipment		7,890,000
Real estate		1,654,918,000
Cash		104,529,000
Restricted cash		13,460,000
Investments in and advances to unconsolidated real estate ventures		241,142,000
Identified intangible assets		138,371,000
Notes receivable (1)		50,934,000
Identified intangible liabilities		(8,687,000)
Mortgages payable assumed (2)		(768,523,000)
Capital lease obligations assumed (3)		(33,543,000)
Lease assumption liabilities (4)		(48,127,000)
Deferred tax liability (5)		(18,610,000)
Other liabilities acquired, net		(60,048,000)
Noncontrolling interests in consolidated subsidiaries		(3,588,000)
Net assets acquired		1,262,228,000
Gain on bargain purchase (6)		$ 16,770,000
Proceeds from Collection of Notes Receivable							$ 50,900,000
Capital Leased Assets, Number of Units		2
Business Combination, Recognized Indentifiable Acquired and Liabilities Assumed, Lease Liabilities, Future Payments		$ 14,000,000
Business Combination, Recognized Indentifiable Acquired and Liabilities Assumed, Lease Liabilities, Relocation of Tenants		$ 34,100,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Real Estate Investments, Unconsolidated Real Estate And Other Joint Ventures						468,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Lease Liabilities						(4,700,000)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Current Liabilities, Other						$ 2,400,000
Reston, Virginia [Member] | JBG Companies [Member]
Capital Leased Assets, Number of Units	1
Payments to Acquire Land	$ 19,500,000

The Combination Fair Value of C

The Combination Fair Value of Common Shares and OP Units Purchase Consideration (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	Jul. 18, 2017	Dec. 31, 2018	Dec. 31, 2017	Jul. 17, 2017
Outstanding common shares and common limited partnership units prior to the Combination	118,000	120,937	117,955
Portion of consideration attributable to performance of future services (3)		$ (110,600)
JBG Companies [Member]
Outstanding common shares and common limited partnership units prior to the Combination				100,571
Exchange ratio (1)	271.00%
Common shares and OP Units issued in consideration	37,164
Fair value of common shares and OP Units issued in consideration	$ 1,378,780
Fair value adjustment to OP Units due to transfer restrictions	(43,304)
Portion of consideration attributable to performance of future services (3)	(110,591)
Fair value of common shares and OP Units purchase consideration	$ 1,224,885
Formation Awards [Member]
Price per share/unit (2)		$ 34.40
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		10 years
Formation Awards [Member] | JBG Companies [Member]
Price per share/unit (2)	$ 37.10
Minimum | OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	12 months
Maximum | OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	60 months

The Combination Fair Value of T

The Combination Fair Value of Tangible Assets Acquired and Identified Intangible Assets (Details) - USD ($) $ in Thousands	Jul. 18, 2017	Dec. 31, 2018
JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Buildings and Improvements	$ 543,584
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tenant Improvements	65,572
Building and improvements	609,156
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Leasehold Improvements	4,422
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Equipment	3,468
Leasehold improvements and equipment	7,890
Identified intangible assets	138,371
Identified intangible liabilities	$ 8,687
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years 3 months 18 days
In-place leases | JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 60,317
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 5 months
Above-market real estate leases | JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 11,732
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 3 months
Below-market ground leases | JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 332
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	88 years 6 months
Option to enter into ground lease | JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 17,090
Management and leasing contracts | JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 48,900
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	7 years 6 months
Minimum
Finite-Lived Intangible Assets [Line Items]
Property, Plant and Equipment, Useful Life		3 years
Minimum | Leasing Arrangement [Member] | JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Property, Plant and Equipment, Useful Life		40 years
Maximum | Leasing Arrangement [Member] | JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	9 years
Building and Building Improvements [Member] | Minimum | JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Building and Building Improvements [Member] | Maximum | JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Equipment [Member] | JBG Companies [Member]
Finite-Lived Intangible Assets [Line Items]
Property, Plant and Equipment, Useful Life	5 years

The Combination Pro Forma Infor

The Combination Pro Forma Information (Details) - USD ($) $ in Thousands	Jul. 18, 2017	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Transaction and other costs		$ 15,600	$ 12,600	$ 104,100	$ 27,706	$ 127,739	$ 6,476
Business Acquisition, Pro Forma Revenue						637,672
Business Acquisition, Pro Forma Net Income (Loss)						(19,343)
JBG Companies [Member]
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual						71,300
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual						$ 23,100
Gain on bargain purchase (6)	$ 16,770

Acquisitions, Disposals and A_3

Acquisitions, Disposals and Assets Held for Sale Acquisitions (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2018USD ($)a	Dec. 31, 2018USD ($)a	Dec. 31, 2017USD ($)
Environmental liabilities (1)	$ 17,898	$ 17,898	$ 2,900
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	$ 5,550	$ 5,550
Potomac Land Bay H [Member]
Area of Land in Acres | a	4.25	4.25
Potomac Land Bay H [Member] | Alexandria, VA [Member]
Payments to Acquire Land	$ 23,000
Potomac Land Bay H [Member] | Land [Member]
Environmental liabilities (1)	$ 15,100	$ 15,100
West Half [Member]
Business Acquisition, Percentage of Voting Interests Acquired	3.10%	3.10%
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	$ 5,000	$ 5,000
Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions		100.00%

Acquisitions, Disposals and A_4

Acquisitions, Disposals and Assets Held for Sale Dispositions and Assets Held for Sale (Details) $ in Thousands	1 Months Ended						3 Months Ended			12 Months Ended
	Feb. 26, 2019USD ($)	Dec. 31, 2018USD ($)ft²	Oct. 31, 2018USD ($)	May 31, 2018USD ($)	Apr. 30, 2018USD ($)	Feb. 28, 2018USD ($)	Dec. 31, 2018USD ($)ft²	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)ft²	Dec. 31, 2017USD ($)ft²	Dec. 31, 2016USD ($)	Feb. 01, 2019ft²	Aug. 31, 2018ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Property Held-for-sale										$ 427,418
Proceeds from sale of real estate										312,197
Gains (Losses) on Sales of Investment Real Estate							$ 6,400		$ 33,400	52,183	$ 0	$ 0
Assets Held-for-sale, Not Part of Disposal Group		$ 78,981					78,981			78,981	8,293
Liabilities related to assets held for sale		$ 3,717					$ 3,717			3,717	0
Mortgages payable
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Repayments of Secured Debt										$ 298,100	$ 250,000
Revolving credit facility
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Repayments of Secured Debt				$ 115,000
Summit I and II [Member] | Mortgages payable
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Repayments of Secured Debt					$ 59,000
Executive Tower [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gains (Losses) on Sales of Investment Real Estate								$ 11,900
1233 20th Street [Member] | Mortgages payable
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Repayments of Secured Debt			$ 41,900
JP Morgan [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²														401,000
Equity Method Investment, Ownership Percentage		0.00%					0.00%			0.00%				5.00%
Summit I and II, Bowen Bldg & Executive Tower [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²		808,319					808,319			808,319
Reston, Virginia [Member] | Summit I & II Land [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Property Held-for-sale						$ 2,200
Reston, Virginia [Member] | Summit I & II Land [Member] | Commercial Segment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²											0
Proceeds from Sale of Property Held-for-sale										$ 2,154
Proceeds from sale of real estate										2,154
Gains (Losses) on Sales of Investment Real Estate										$ 455
Assets Held-for-sale, Not Part of Disposal Group											$ 1,699
Liabilities related to assets held for sale											0
Reston, Virginia [Member] | Summit I and II [Member] | Commercial Segment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²		284,118					284,118			284,118
Proceeds from Sale of Property Held-for-sale										$ 95,000
Proceeds from sale of real estate										35,240
Gains (Losses) on Sales of Investment Real Estate										$ 6,189
Reston, Virginia [Member] | Commerce Executive [Member] | Commercial Segment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²		388,562					388,562			388,562
Assets Held-for-sale, Not Part of Disposal Group		$ 78,981					$ 78,981			$ 78,981
Liabilities related to assets held for sale		$ 3,717					$ 3,717			$ 3,717
Reston, Virginia [Member] | Subsequent Event [Member] | Commerce Executive [Member] | Commercial Segment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Property Held-for-sale	$ 115,000
Washington, D.C. [Member] | Bowen Building, Washington DC [Member] | Commercial Segment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²		231,402					231,402			231,402
Proceeds from Sale of Property Held-for-sale										$ 140,000
Proceeds from sale of real estate										136,488
Gains (Losses) on Sales of Investment Real Estate										$ 27,207
Washington, D.C. [Member] | Executive Tower [Member] | Commercial Segment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²		129,831					129,831			129,831
Proceeds from Sale of Property Held-for-sale										$ 121,445
Proceeds from sale of real estate										113,267
Gains (Losses) on Sales of Investment Real Estate										$ 12,378
Washington, D.C. [Member] | 1233 20th Street [Member] | Commercial Segment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²		149,684					149,684			149,684
Proceeds from Sale of Property Held-for-sale										$ 65,000
Proceeds from sale of real estate										21,229
Gains (Losses) on Sales of Investment Real Estate										$ 4,354
Downtown Silver Spring, MD [Member] | Falkland Chase-North [Member] | Multifamily
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²		13,284					13,284			13,284
Proceeds from Sale of Property Held-for-sale										$ 3,819
Proceeds from sale of real estate										3,819
Gains (Losses) on Sales of Investment Real Estate										$ 1,600
Alexandria, VA [Member] | Potomac Land Bay G [Member] | Commercial Segment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets Held-for-sale, Not Part of Disposal Group											6,594
Liabilities related to assets held for sale											$ 0
Future Development
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²		23,100,000					23,100,000			23,100,000
Future Development | Summit I and II [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²		700,000					700,000			700,000
Future Development | Subsequent Event [Member] | Commerce Executive [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²													894,000
Canadian Pension Plan Investment Board (CPPIB) | The Warner [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of real estate property (in square feet) | ft²		583,000					583,000			583,000
Repayments of Secured Debt		$ 270,500
Gains (Losses) on Sales of Investment Real Estate		$ 32,500

Tenant and Other Receivables,_3

Tenant and Other Receivables, Net (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tenant and Other Receivables, Net [Abstract]
Tenants	$ 31,362,000	$ 30,672,000
Third-party real estate services	12,443,000	8,954,000
Other	9,463,000	12,992,000
Allowance for doubtful accounts	(6,700,000)	(5,884,000)
Total tenant and other receivables, net	46,568,000	46,734,000
Bad debt expense	$ 3,298,000	$ 3,807,000	$ 750,600

Investments in and Advances t_3

Investments in and Advances to Unconsolidated Real Estate Ventures - Summary of Composition of Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Aug. 31, 2018	Jan. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Total investments in unconsolidated real estate ventures	$ 322,798			$ 261,791
Advances to unconsolidated real estate ventures	80			20
Total investments in and advances to unconsolidated real estate ventures	322,878			261,811
Canadian Pension Plan Investment Board (CPPIB)
Schedule of Equity Method Investments [Line Items]
Total investments in unconsolidated real estate ventures	97,521			36,317
Landmark
Schedule of Equity Method Investments [Line Items]
Total investments in unconsolidated real estate ventures	84,320			95,368
CBREI Venture
Schedule of Equity Method Investments [Line Items]
Total investments in unconsolidated real estate ventures	$ 73,776			79,062
Berkshire Group [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Total investments in unconsolidated real estate ventures	$ 43,937			27,761
Brandywine
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	30.00%
Total investments in unconsolidated real estate ventures	$ 13,777			13,741
CIM/PacLife [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	16.70%		16.67%
Total investments in unconsolidated real estate ventures	$ 9,339			0
JP Morgan
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	0.00%	5.00%
Total investments in unconsolidated real estate ventures	$ 0			9,296
Other
Schedule of Equity Method Investments [Line Items]
Total investments in unconsolidated real estate ventures	$ 128			$ 246
Minimum | Canadian Pension Plan Investment Board (CPPIB)
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	55.00%
Minimum | Landmark
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	1.80%
Minimum | CBREI Venture
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	5.00%
Maximum | Canadian Pension Plan Investment Board (CPPIB)
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	68.50%
Maximum | Landmark
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	49.00%
Maximum | CBREI Venture
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	64.00%

Investments in and Advances t_4

Investments in and Advances to Unconsolidated Real Estate Ventures - Narrative (Details) $ in Thousands	1 Months Ended				3 Months Ended			12 Months Ended
	Dec. 31, 2018USD ($)ft²	Aug. 31, 2018USD ($)ft²	Feb. 28, 2018USD ($)	Jan. 31, 2018USD ($)	Dec. 31, 2018USD ($)ft²	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)ft²	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Schedule of Equity Method Investments [Line Items]
Deconsolidation of 1900 N Street	$ 95,923				$ 95,923			$ 95,923	$ 0	$ 0
Return on capital from unconsolidated real estate ventures								7,827	2,563	1,520
Real Estate Investments, Unconsolidated Real Estate and Other Joint Ventures, Excluding Advances	$ 322,798				322,798			322,798	261,791
Income (Loss) from Equity Method Investments								39,409	(4,143)	(947)
Distribution of capital from sale of interest in an unconsolidated real estate venture								80,279	0	0
Proceeds from Sale of Real Estate								413,077	0	0
Gains (Losses) on Sales of Investment Real Estate					$ 6,400		$ 33,400	$ 52,183	0	$ 0
CIM/PacLife [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	16.70%			16.67%	16.70%			16.70%
Payments to Acquire Interest in Joint Venture				$ 10,100
Real Estate Investments, Unconsolidated Real Estate and Other Joint Ventures, Excluding Advances	$ 9,339				$ 9,339			$ 9,339	0
Canadian Pension Plan Investment Board (CPPIB)
Schedule of Equity Method Investments [Line Items]
Real Estate Investments, Unconsolidated Real Estate and Other Joint Ventures, Excluding Advances	$ 97,521				$ 97,521			$ 97,521	36,317
1900 N Street
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			100.00%
Equity Method Investment, Ownership Percentage After Funding Of Contributions			55.00%
1101 17th Street [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage After Funding Of Contributions	55.00%				55.00%			55.00%
Return on capital from unconsolidated real estate ventures								$ 5,400
Real Estate Investments, Unconsolidated Real Estate and Other Joint Ventures, Excluding Advances	$ 0				$ 0			0
Income (Loss) from Equity Method Investments								$ 8,300
JP Morgan [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	0.00%	5.00%			0.00%			0.00%
Real Estate Investments, Unconsolidated Real Estate and Other Joint Ventures, Excluding Advances	$ 0				$ 0			$ 0	$ 9,296
Distribution of capital from sale of interest in an unconsolidated real estate venture		$ 24,600
Equity Method Investment, Realized Gain (Loss) on Disposal						$ 15,500		15,500
Area of real estate property (in square feet) | ft²		401,000
The Warner [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Realized Gain (Loss) on Disposal					$ 20,600			$ 20,600
Legacy JBG Funds [Member] | CIM/PacLife [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage				47.64%
Canadian Pension Plan Investment Board (CPPIB) | 1900 N Street
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			45.00%
Deconsolidation of 1900 N Street			$ 95,900
Long-term Purchase Commitment, Amount			$ 101,300
Canadian Pension Plan Investment Board (CPPIB) | The Warner [Member]
Schedule of Equity Method Investments [Line Items]
Area of real estate property (in square feet) | ft²	583,000				583,000			583,000
Proceeds from Sale of Real Estate	$ 376,500
Gains (Losses) on Sales of Investment Real Estate	32,500
Repayments of Secured Debt	$ 270,500

Investments in and Advances t_5

Investments in and Advances to Unconsolidated Real Estate Ventures - Summary of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Variable rate, weighted average interest rate	5.53%
Variable rate	$ 461,704	$ 534,500
Fixed rate, weighted average interest rate	4.02%
Fixed rate	$ 665,662	657,701
Unconsolidated real estate ventures - mortgages payable	1,127,366	1,192,201
Unamortized deferred financing costs	(1,998)	(2,000)
Unconsolidated real estate ventures - mortgages payable, net	$ 1,125,368	$ 1,190,201

Investments in and Advances t_6

Investments in and Advances to Unconsolidated Real Estate Ventures - Condensed Combined Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Combined balance sheet information:
Real estate, net	$ 2,050,985	$ 2,106,670
Other assets, net	169,264	264,731
Total assets	2,220,249	2,371,401
Mortgages payable, net	1,125,368	1,190,201
Other liabilities, net	94,845	76,416
Total liabilities	1,220,213	1,266,617
Total equity	1,000,036	1,104,784
Total liabilities and equity	2,220,249	2,371,401
Combined income statement information:
Total revenue	300,032	135,256	$ 68,118
Operating income	56,262	14,741	19,283
Net loss	$ (1,155)	$ (7,593)	$ 5,234

Variable Interest Entities (Det

Variable Interest Entities (Details) $ in Millions	Dec. 31, 2018USD ($)properties	Dec. 31, 2017USD ($)
Variable Interest Entity [Line Items]
Number of Real Estate Properties | properties	62
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	$ 232.8	$ 163.5
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	94.8	111
Liabilities	$ 43.4	$ 8.8
Number of Real Estate Properties	2	2

Other Assets, Net Summary of Ot

Other Assets, Net Summary of Other Assets, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred leasing costs	$ 202,066	$ 171,153
Accumulated amortization	(72,465)	(67,180)
Deferred leasing costs, net	129,601	103,973
Identified intangible assets, net	89,859	126,467
Prepaid expenses	6,482	9,038
Deferred financing costs on credit facility, net	4,806	6,654
Deposits	3,633	6,317
Derivative agreements, at fair value	10,383	2,141
Other	20,230	9,333
Total other assets, net	$ 264,994	$ 263,923

Other Assets, Net Schedule of I

Other Assets, Net Schedule of Identified Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Total identified intangibles assets	$ 116,001	$ 152,895
Total accumulated amortization	26,142	26,428
Identified intangible assets, net	89,859	126,467
In-place leases
Finite-Lived Intangible Assets [Line Items]
Total identified intangibles assets	38,216	72,086
Total accumulated amortization	11,602	20,015
Above-market real estate leases
Finite-Lived Intangible Assets [Line Items]
Total identified intangibles assets	9,414	12,066
Total accumulated amortization	2,405	1,600
Below-market ground leases
Finite-Lived Intangible Assets [Line Items]
Total identified intangibles assets	2,215	2,547
Total accumulated amortization	1,448	1,365
Option to enter into ground lease
Finite-Lived Intangible Assets [Line Items]
Total identified intangibles assets	17,090	17,090
Total accumulated amortization	251	78
Management and leasing contracts
Finite-Lived Intangible Assets [Line Items]
Total identified intangibles assets	48,900	48,900
Total accumulated amortization	10,297	3,209
Other
Finite-Lived Intangible Assets [Line Items]
Total identified intangibles assets	166	206
Total accumulated amortization	$ 139	$ 161

Other Assets, Net Summary of Am

Other Assets, Net Summary of Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 21,561	$ 14,954	$ 740
In-place leases
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	11,807	10,216	485
Above-market real estate leases
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	2,390	1,428	78
Below-market ground leases
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	85	87	85
Option to enter into ground lease
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	173	0	0
Management and leasing contracts
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	7,088	3,209	0
Other
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 18	$ 14	$ 92

Other Assets, Net Schedule of E

Other Assets, Net Schedule of Estimated Amortization of Identified Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
2,019	$ 16,184
2,020	13,720
2,021	10,591
2,022	9,506
2,023	8,924
Thereafter	30,934
Identified intangible assets, net	$ 89,859	$ 126,467

Debt - Schedule of Mortgages Pa

Debt - Schedule of Mortgages Payable (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Debt, gross	$ 2,144,652
Mortgages payable
Debt Instrument [Line Items]
Variable interest rate	4.30%
Variable rate amount	$ 308,918	$ 498,253
Fixed interest rate	4.09%
Fixed rate amount	$ 1,535,734	1,537,706
Debt, gross	1,844,652	2,035,959
Unamortized deferred financing costs and premium/ discount, net	(6,271)	(10,267)
Debt, net	$ 1,838,381	$ 2,025,692

Debt - Narrative (Details)

Debt - Narrative (Details)	Jul. 18, 2017USD ($)	Jul. 31, 2018USD ($)	Jan. 31, 2018USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Line of Credit Facility [Line Items]
Borrowings under mortgages payable					$ 118,141,000	$ 366,239,000	$ 0
Loss on extinguishment of debt				$ (4,500,000)	(5,153,000)	(701,000)	0
Borrowings under revolving credit facility					35,000,000	115,751,000	$ 0
Debt, gross					2,144,652,000
Mortgages payable
Line of Credit Facility [Line Items]
Proceeds from Issuance of Secured Debt						79,300,000
Secured Debt, Additional Borrowing Capacity						143,700,000
Net carrying value of real estate collateralizing the mortgages payable					2,300,000,000
Repayment of mortgages payable					298,100,000	250,000,000
Derivative, notional amount					1,300,000,000	1,400,000,000
Derivatives Entered Into, Notional Value					381,300,000
Debt, gross					1,844,652,000	2,035,959,000
Line of credit
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity					1,400,000,000
Debt Instrument, Fee Amount	$ 11,200,000
Line of credit | Revolving credit facility
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity					$ 1,000,000,000
Debt Instrument, Number Of Term Extension Options					2
Debt Instrument, Extension Option, Term					6 months
Line of credit | Tranche A-1 Term Loan
Line of Credit Facility [Line Items]
Derivative, notional amount					$ 100,000,000	50,000,000
Credit facility, maximum borrowing capacity					200,000,000
Borrowings under revolving credit facility			$ 50,000,000
Debt, gross					100,000,000	50,000,000
Line of credit | Tranche A-2 Term Loan Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity					200,000,000
Borrowings under revolving credit facility		$ 200,000,000
Debt, gross					$ 200,000,000	$ 0
Minimum | LIBOR | Line of credit | Revolving credit facility
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.10%
Minimum | LIBOR | Line of credit | Tranche A-1 Term Loan
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.20%				2.12%	1.97%
Minimum | LIBOR | Line of credit | Tranche A-2 Term Loan Credit Facility [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.55%
Maximum | LIBOR | Line of credit | Revolving credit facility
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Maximum | LIBOR | Line of credit | Tranche A-1 Term Loan
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.70%
Maximum | LIBOR | Line of credit | Tranche A-2 Term Loan Credit Facility [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.35%
JBG Companies [Member]
Line of Credit Facility [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	$ 768,523,000
JBG Companies [Member] | Mortgages payable
Line of Credit Facility [Line Items]
Repayment of mortgages payable						$ 64,800,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	$ 768,500,000
1730 M Street [Member]
Line of Credit Facility [Line Items]
Borrowings under mortgages payable					$ 47,500,000

Debt - Summary of Amounts Outst

Debt - Summary of Amounts Outstanding under the Credit Facility (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Debt, gross		$ 2,144,652
Debt Issuance Costs, Line of Credit Arrangements, Net		4,806	$ 6,654
Tranche A-1 and A-2 Loans [Member]
Line of Credit Facility [Line Items]
Debt, gross		300,000	50,000
Unamortized deferred financing costs, net		(2,871)	(3,463)
Debt, net		$ 297,129	46,537
Line of credit | Revolving credit facility
Line of Credit Facility [Line Items]
Interest Rate (1)		3.60%
Debt, net		$ 0	115,751
Letters of Credit Outstanding, Amount		$ 5,700	5,700
Line of Credit Facility, Commitment Fee Percentage		0.15%
Line of credit | Tranche A-1 Term Loan
Line of Credit Facility [Line Items]
Interest Rate (1)		3.32%
Debt, gross		$ 100,000	50,000
Line of credit | Tranche A-2 Term Loan Credit Facility [Member]
Line of Credit Facility [Line Items]
Interest Rate (1)		4.05%
Debt, gross		$ 200,000	$ 0
Revolving credit facility
Line of Credit Facility [Line Items]
Repayments of Secured Debt	$ 115,000

Debt - Schedule of Principal Ma

Debt - Schedule of Principal Maturities Outstanding (Details) $ in Thousands	Dec. 31, 2018USD ($)
Debt Disclosure [Abstract]
2,019	$ 182,467
2,020	97,141
2,021	331,881
2,022	327,500
2,023	277,736
Thereafter	927,927
Debt, gross	$ 2,144,652

Other Liabilities, Net Summary

Other Liabilities, Net Summary of Other Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Other Liabilities [Line Items]
Lease intangible liabilities	$ 40,179	$ 44,917
Accumulated amortization	(26,081)	(26,950)
Lease intangible liabilities, net	14,098	17,967
Prepaid rent	21,998	15,751
Lease assumption liabilities and accrued tenant incentives	32,422	50,866
Capital lease obligation	15,704	15,819
Security deposits	17,696	13,618
Environmental liabilities (1)	17,898	2,900
Ground lease deferred rent payable	3,510	3,730
Net deferred tax liability	6,878	8,202
Dividends payable	45,193	31,097
Other	6,209	1,327
Total other liabilities, net	181,606	161,277
Amortization of Intangible Liabilities	2,600	$ 2,300	$ 1,400
Potomac Land Bay H [Member] | Land [Member]
Schedule of Other Liabilities [Line Items]
Environmental liabilities (1)	$ 15,100

Other Liabilities, Net Amortiza

Other Liabilities, Net Amortization of Intangible Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
2,019	$ 2,232
2,020	2,019
2,021	1,753
2,022	1,734
2,023	1,726
Thereafter	4,634
Below Market Lease, Net	$ 14,098	$ 17,967

Income Taxes Narrative (Details

Income Taxes Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Expense (Benefit)	$ (738,000)	$ (9,912,000)	$ 1,083,000
Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Liability, Income Taxes		3,900,000
Operating Loss Carryforwards	6,800,000
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Federal Income Tax Basis Difference	114,000,000
Deferred Tax Liabilities, Net	$ 6,878,000	$ 8,202,000
Common Stock, Dividends, Per Share, Declared	$ 1	$ 0.45	$ 0
Common Stock, Dividends, Per Share, Indicated Annual Amount	0.90
Common Stock, Dividends, Per Share, Additional Declared	0.10
Common Stock, Dividends, Per Share, Declared, Taxable As Ordinary Income in Current Year	0.42	0.385
Common Stock, Dividends, Per Share, Declared, Taxable As Return of Capital	0.355	$ 0.065
Common Stock, Dividends, Per Share, Declared, Taxable Status to be Determined in Next Year	$ 0.225
Subsidiaries
Income Tax Expense (Benefit)	$ 0
Minimum
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2037
Maximum
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2038

Income Taxes Schedule of Compon

Income Taxes Schedule of Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Current Income Tax Expense (Benefit)	$ 20	$ (496)	$ (1,083)
Deferred Income Tax Expense (Benefit)	718	10,408	0
Income Tax Expense (Benefit)	$ 738	$ 9,912	$ (1,083)

Income Taxes Schedule of Deferr

Income Taxes Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Accrued bonus	$ 0	$ 1,675
Net operating loss	2,326	1,710
Deferred revenue	998	71
Bad debt expense	583	111
Other	198	623
Total deferred tax assets	4,105	4,190
Valuation allowance	(469)	0
Total deferred tax assets, net of valuation allowance	3,636	4,190
Management and leasing contracts	(9,905)	(11,840)
Other	(609)	(552)
Total deferred tax liabilities	10,514	12,392
Net deferred tax liability	$ 6,878	$ 8,202

Redeemable Noncontrolling Int_3

Redeemable Noncontrolling Interests - Narrative (Details) - USD ($) shares in Thousands, $ in Millions	Jul. 18, 2017	Feb. 26, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Common Shares Issued During Period in Connection with Redemption of OP Units			2,962
Business Combination, Contingent Consideration, Liability			$ 110.6
JBG Smith, LP
Noncontrolling Interest [Line Items]
Ownership interest by parent			87.80%
Consolidated Real Estate Venture
Noncontrolling Interest [Line Items]
Ownership interest by parent			88.10%
Ownership interest by parent, threshold for capital contributions to cease			97.00%
OP Units [Member]
Noncontrolling Interest [Line Items]
Common shares and OP Units issued in consideration	19,800		16,800
Common Shares Issued During Period in Connection with Redemption of OP Units			3,000
OP Units [Member] | JBG Smith, LP
Noncontrolling Interest [Line Items]
Ownership interest by parent			12.20%
Minimum
Noncontrolling Interest [Line Items]
Redemption period			2 years
Maximum
Noncontrolling Interest [Line Items]
Redemption period			7 years
Subsequent Event [Member] | OP Units [Member]
Noncontrolling Interest [Line Items]
Common Shares Issued During Period in Connection with Redemption of OP Units		1,700

Redeemable Noncontrolling Int_4

Redeemable Noncontrolling Interests - Summary of the Activity of Redeemable Noncontrolling Interests (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Temporary Equity
Beginning Balance	$ 609,129	$ 0
Fair value of OP Unit redemptions	(109,208)	0	$ 0
Issuance of common limited partnership units at the Separation	0	96,632	0
OP Units issued in connection with the Combination (1)	0	359,967
Net income (loss) attributable to redeemable noncontrolling interests	6,710	(7,328)
Other comprehensive income	1,384	225
Contributions (distributions)	(18,237)	(3,693)
Share-based compensation expense	52,190	32,634
Adjustment to redemption value	16,172	130,692
Ending Balance	558,140	609,129	0
Business Combination, Contingent Consideration, Liability	110,600
JBG Smith, LP
Temporary Equity
Beginning Balance	603,717	0
Fair value of OP Unit redemptions	(109,208)	0
Issuance of common limited partnership units at the Separation	0	96,632
OP Units issued in connection with the Combination (1)	0	359,967
Net income (loss) attributable to redeemable noncontrolling interests	6,641	(7,320)
Other comprehensive income	1,384	225
Contributions (distributions)	(18,737)	(9,113)
Share-based compensation expense	52,190	32,634
Adjustment to redemption value	16,172	130,692
Ending Balance	552,159	603,717	0
Consolidated Real Estate Venture
Temporary Equity
Beginning Balance	5,412	0
Fair value of OP Unit redemptions	0	0
Issuance of common limited partnership units at the Separation	0	0
OP Units issued in connection with the Combination (1)	0	0
Net income (loss) attributable to redeemable noncontrolling interests	69	(8)
Other comprehensive income	0	0
Contributions (distributions)	500	5,420
Share-based compensation expense	0	0
Adjustment to redemption value	0	0
Ending Balance	$ 5,981	$ 5,412	$ 0

Share-Based Payments - OP Units

Share-Based Payments - OP Units (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 18, 2017	Dec. 31, 2018	Dec. 31, 2017
Business Combination, Contingent Consideration, Liability		$ 110,600
OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		2,999,987	3,086,962
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(86,975)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 33.39	$ 33.49
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		$ 37.10
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value		$ 3,200	$ 7,200
JBG Companies [Member]
Business Combination, Contingent Consideration, Liability	$ 110,591
JBG Companies [Member] | OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	3,300,000
Minimum | OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	12 months
Maximum | OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	60 months
Measurement Input, Price Volatility [Member] | OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum	18.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum	27.00%
Measurement Input, Risk Free Interest Rate [Member] | OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum	1.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum	1.50%
Measurement Input, Expected Term [Member] | Minimum | OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	1 year
Measurement Input, Expected Term [Member] | Maximum | OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	3 years

Share-Based Payments - Formatio

Share-Based Payments - Formation Awards (Details) - USD ($)	Jul. 18, 2017	Dec. 31, 2018	Dec. 31, 2017	Jul. 17, 2017
Compensation expense recognition period (in years)		2 years 9 months
Formation Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		93,784
Price per share/unit (2)		$ 34.40
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		10 years
Deferred Compensation Arrangement with Individual, Fair Value of Shares Issued		$ 725,000	$ 23,700,000
Compensation expense recognition period (in years)		5 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		2,655,394	2,673,814
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 8.81	$ 8.84
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 7.73
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(39,970)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		$ 8.32
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		(72,234)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value		$ 8.84
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value		$ 333,000
Formation Awards [Member] | JBG Companies [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	2,700,000
Stock Granted, Value, Share-based Compensation, Gross	$ 100,000,000	$ 3,200,000
Price per share/unit (2)	$ 37.10
Measurement Input, Price Volatility [Member] | Formation Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate			26.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum		27.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate			2.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate			2.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term		7 years	7 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum		29.00%
Measurement Input, Risk Free Interest Rate [Member] | Formation Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum		2.80%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum		3.00%
Omnibus Share Plan, 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		4,800,000		10,300,000
Maximum | Measurement Input, Expected Dividend Rate [Member] | Formation Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate		2.70%
Minimum | Measurement Input, Expected Dividend Rate [Member] | Formation Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate		2.50%
Share-based Compensation Award, Tranche One [Member] | Formation Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		25.00%
Share-based Compensation Award, Tranche One [Member] | Formation Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		25.00%
Share-based Compensation Award, Tranche Three [Member] | Formation Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		50.00%

Share-Based Payments - LTIP and

Share-Based Payments - LTIP and Time-Based LTIP Units (Details)	Jul. 18, 2017USD ($)shares	May 31, 2018USD ($)shares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Compensation expense recognition period (in years)			2 years 9 months
Time-Based LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Equity grants (in shares)			367,519	302,518
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			25.00%
Compensation expense recognition period (in years)			4 years
Weighted Average Grant-Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares			$ 31.48	$ 33.71
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights			P4Y	P4Y
Special Time-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Equity grants (in shares)			356,591
Compensation expense recognition period (in years)			5 years
Weighted Average Grant-Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares			$ 36.84
Special Time-Based LTIP Units [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			50.00%
LTIP and Time-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number			962,662	332,207
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value | $			$ 3,600,000	$ 2,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Equity grants (in shares)			749,880
Fair value of awards on grant date | $			$ 25,500,000	$ 13,700,000
Weighted Average Grant-Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares			$ 34.01
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares			$ 34.03	$ 33.68
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period			(110,723)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value | $ / shares			$ 32.91
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period			(8,702)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value | $ / shares			$ 32.51
Trustee | LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Equity grants (in shares)	47,166	25,770
Deferred Compensation Arrangement With Individual, Number of Individuals	7
Fair value of awards on grant date | $	$ 250,000	$ 794,000
Management [Member] | LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Equity grants (in shares)	59,927
Management [Member] | LTIP Units [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
Management [Member] | LTIP Units [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
Measurement Input, Price Volatility [Member] | LTIP and Time-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum			20.00%	17.00%
Weighted Average Grant-Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum			22.00%	19.00%
Measurement Input, Risk Free Interest Rate [Member] | LTIP and Time-Based LTIP Units [Member]
Weighted Average Grant-Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum			1.90%	1.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum			2.60%	1.50%
Minimum | Measurement Input, Expected Term [Member] | LTIP and Time-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term			2 years	2 years
Maximum | Measurement Input, Expected Term [Member] | LTIP and Time-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term			3 years	3 years

Share-Based Payments - Performa

Share-Based Payments - Performance-Based LTIP Units (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognition period (in years)	2 years 9 months
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity grants (in shares)	567,106	605,072
Compensation expense recognition period (in years)	4 years
Performance Shares [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
Performance Shares [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
Special Performance-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity grants (in shares)	511,555
Compensation expense recognition period (in years)	5 years
Special Performance-Based LTIP Units [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
Special Performance-Based LTIP Units [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
Performance Shares and Special-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	1,657,578	604,522
Equity grants (in shares)	1,078,661
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Fair value of awards on grant date	$ 21.1	$ 9.7
Weighted Average Grant-Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 19.52
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 18.27	$ 15.95
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(25,605)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value	$ 16.29
Measurement Input, Price Volatility [Member] | Performance Shares and Special-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum	19.90%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum	26.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate		18.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate		2.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		1.50%
Measurement Input, Risk Free Interest Rate [Member] | Performance Shares and Special-Based LTIP Units [Member]
Weighted Average Grant-Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum	2.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum	3.00%
Minimum | Measurement Input, Expected Dividend Rate [Member] | Performance Shares and Special-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	2.50%
Maximum | Measurement Input, Expected Dividend Rate [Member] | Performance Shares and Special-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	2.70%

Share-Based Payments - Employee

Share-Based Payments - Employee Share Purchase Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock Issued During Period, Shares, Employee Stock Purchase Plans	20,000
Proceeds from common stock issued pursuant to Employee Share Purchase Plan	$ 597,000	$ 0	$ 0
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	2,100,000
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date	15.00%
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Value of Share Per Employee	$ 25,000
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Outstanding Stock Maximum	0.10%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	206,600
Stock Issued During Period, Shares, Employee Stock Purchase Plans	20,178
Proceeds from common stock issued pursuant to Employee Share Purchase Plan	$ 597,000
Allocated Share-based Compensation Expense	$ 144,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	2,000,000
Measurement Input, Price Volatility [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	21.00%
Measurement Input, Expected Dividend Rate [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	2.50%
Measurement Input, Expected Term [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	6 months
Measurement Input, Risk Free Interest Rate [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.00%

Share-Based Payments - Summary

Share-Based Payments - Summary of Share-Based Compensation Expense (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business Combination, Contingent Consideration, Liability			$ 110,600
Share-based compensation related to Formation Transaction	$ 14,800	$ 14,400	36,030	$ 29,251	$ 0
Allocated Share-based Compensation Expense, Before Capitalization			56,016	34,160	4,502
Less amount capitalized			(3,341)	(467)	0
Share-based compensation expense			52,675	33,693	4,502
Total unrecognized compensation expense			$ 119,000
Compensation expense recognition period (in years)			2 years 9 months
Defined Contribution Plan, Cost			$ 1,800	3,600	2,400
Time-Based LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			$ 10,095	2,211	0
Compensation expense recognition period (in years)			4 years
Performance-Based LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			$ 5,271	1,172	0
Compensation expense recognition period (in years)			4 years
LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			$ 794	0	0
Other Equity Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			3,826	1,526	4,502
Share-based compensation expense - other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			$ 19,986	4,909	4,502
Formation Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period			10 years
Price per share/unit (2)			$ 34.40
Allocated Share-based Compensation Expense			$ 5,606	5,169	0
Compensation expense recognition period (in years)			5 years
OP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			$ 29,455	21,467	0
LTIP Units Related to Formation Transaction And Other [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			277	2,615	0
Special Performance-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			$ 323	0	0
Compensation expense recognition period (in years)			5 years
Special Time-Based LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			$ 369	0	0
Compensation expense recognition period (in years)			5 years
Share-based compensation related to Formation Transaction
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation related to Formation Transaction			$ 36,030	$ 29,251	$ 0

Interest Expense Interest Exp_3

Interest Expense Interest Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest expense	$ 91,651,000	$ 69,178,000	$ 54,379,000
Amortization of deferred financing costs	4,661,000	3,011,000	1,478,000
Unrealized gain on interest rate swaps and caps	(926,000)	(1,348,000)	0
Derivative, Gain (Loss) on Derivative, Net	(135,000)	27,000	0
Capitalized interest	(20,804,000)	(12,727,000)	(4,076,000)
Interest Expense	$ 74,447,000	$ 58,141,000	$ 51,781,000

Earnings (Loss) Per Common Sh_3

Earnings (Loss) Per Common Share - Schedule of Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income (loss)									$ 46,613	$ (79,084)	$ 61,974
Net (income) loss attributable to redeemable noncontrolling interests									6,710	(7,328)	0
Net loss attributable to noncontrolling interests									(21)	(3)	0
Net income (loss) attributable to common shareholders									(39,924)	71,753	(61,974)
Distributions to participating securities									(2,599)	(1,655)	0
Net income (loss) available to common shareholders — basic and diluted	$ 710	$ 22,830	$ 20,574	$ (4,190)	$ (16,418)	$ (69,831)	$ 11,341	$ 6,318	$ 37,325	$ (73,408)	$ 61,974
Weighted average number of common shares outstanding — basic and diluted (1)									119,176	105,359	100,571
Earnings (loss) per common share:
Earnings Per Share, Basic	$ (0.01)	$ 0.19	$ 0.17	$ (0.04)	$ (0.15)	$ (0.61)	$ 0.11	$ 0.06	$ 0.31	$ (0.70)	$ 0.62
Earnings Per Share, Diluted	$ (0.01)	$ 0.19	$ 0.17	$ (0.04)	$ (0.15)	$ (0.61)	$ 0.11	$ 0.06	$ 0.31	$ (0.70)	$ 0.62

Earnings (Loss) Per Common Sh_4

Earnings (Loss) Per Common Share - Narrative (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	3.9	3.3

Earnings (Loss) Per Common Sh_5

Earnings (Loss) Per Common Share - Antidilutive Securities Excluded (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	3.9	3.3

Minimum Rental Income (Details)

Minimum Rental Income (Details) $ in Thousands	Dec. 31, 2018USD ($)ft²
2,019	$ 377,427
2,020	321,205
2,021	287,463
2,022	256,352
2,023	215,203
Thereafter	$ 1,188,767
1700 M Street [Member]
Lessor, Operating Lease, Term of Contract	99 years
Future Development
Area of real estate property (in square feet) | ft²	23,100,000
Future Development | 1700 M Street [Member]
Area of real estate property (in square feet) | ft²	34,000

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Net unrealized gain on derivative designated as cash flow hedge	$ 8,300,000	$ 1,800,000
Gain expected to be reclassified into interest expense within the next 12 months	3,500,000
Unrealized Gain (Loss) on Derivatives	$ (926,000)	$ (1,348,000)	$ 0

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - Interest rate swap and caps - Recurring - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Assets, Net | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as assets in Other assets, net	$ 7,913	$ 1,506
Other Assets, Net | Designated as Hedging Instrument | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as assets in Other assets, net	0	0
Other Assets, Net | Designated as Hedging Instrument | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as assets in Other assets, net	7,913	1,506
Other Assets, Net | Designated as Hedging Instrument | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as assets in Other assets, net	0	0
Other Assets, Net | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as assets in Other assets, net	2,470	635
Other Assets, Net | Not Designated as Hedging Instrument | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as assets in Other assets, net	0	0
Other Assets, Net | Not Designated as Hedging Instrument | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as assets in Other assets, net	2,470	635
Other Assets, Net | Not Designated as Hedging Instrument | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as assets in Other assets, net	0	0
Other Liabilities, Net | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as liabilities in Other liabilities, net	1,723	2,640
Other Liabilities, Net | Designated as Hedging Instrument | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as liabilities in Other liabilities, net	0	0
Other Liabilities, Net | Designated as Hedging Instrument | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as liabilities in Other liabilities, net	1,723	2,640
Other Liabilities, Net | Designated as Hedging Instrument | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as liabilities in Other liabilities, net	$ 0	0
Other Liabilities, Net | Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as liabilities in Other liabilities, net		22
Other Liabilities, Net | Not Designated as Hedging Instrument | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as liabilities in Other liabilities, net		0
Other Liabilities, Net | Not Designated as Hedging Instrument | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as liabilities in Other liabilities, net		22
Other Liabilities, Net | Not Designated as Hedging Instrument | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Classified as liabilities in Other liabilities, net		$ 0

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Mortgages payable | Carrying Amount
Financial liabilities:
Financial liabilities	$ 1,844,652	$ 2,035,959
Mortgages payable | Fair Value
Financial liabilities:
Financial liabilities	1,870,078	2,060,899
Revolving credit facility | Carrying Amount
Financial liabilities:
Financial liabilities	0	115,751
Revolving credit facility | Fair Value
Financial liabilities:
Financial liabilities	0	115,768
Unsecured term loans | Carrying Amount
Financial liabilities:
Financial liabilities	300,000	50,000
Unsecured term loans | Fair Value
Financial liabilities:
Financial liabilities	$ 300,727	$ 50,029

Segment Information - Narrative

Segment Information - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)segment
Segment Reporting Information [Line Items]
Number of reportable segments | segment	3	3
Other assets, net	$ 264,994	$ 263,923
Third-Party Real Estate Services Segment
Segment Reporting Information [Line Items]
Other assets, net	$ 38,600	$ 45,700

Segment Information - Schedule

Segment Information - Schedule of Reconciliation of Net Income Attributable to Parent (Details) - USD ($)	3 Months Ended				12 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Net income (loss) attributable to common shareholders					$ 39,924,000	$ (71,753,000)	$ 61,974,000
Depreciation and amortization					211,436,000	161,659,000	133,343,000
Corporate and other					33,728,000	39,350,000	48,753,000
Third-party real estate services					89,826,000	51,919,000	19,066,000
Share-based compensation related to Formation Transaction			$ 14,800,000	$ 14,400,000	36,030,000	29,251,000	0
Transaction and other costs	$ 15,600,000		12,600,000	104,100,000	27,706,000	127,739,000	6,476,000
Interest expense					74,447,000	58,141,000	51,781,000
Loss on extinguishment of debt		$ 4,500,000			5,153,000	701,000	0
Reduction of gain (gain) on bargain purchase		7,600,000	$ 3,400,000	$ (27,800,000)	7,606,000	(24,376,000)	0
Income tax benefit					(738,000)	(9,912,000)	1,083,000
Net (income) loss attributable to redeemable noncontrolling interests					6,710,000	(7,328,000)	0
Third-party real estate services, including reimbursements					98,699,000	63,236,000	33,882,000
Other income					6,358,000	5,167,000	5,381,000
Income (loss) from unconsolidated real estate ventures, net					39,409,000	(4,143,000)	(947,000)
Interest and other income (loss), net					15,168,000	1,788,000	2,992,000
Gains (Losses) on Sales of Investment Real Estate	$ 6,400,000	$ 33,400,000			52,183,000	0	0
Net loss attributable to noncontrolling interests					21,000	3,000	0
Consolidated NOI					$ 319,990,000	$ 289,340,000	$ 281,168,000

Segment Information - Summary o

Segment Information - Summary of NOI by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Property rentals	$ 499,835	$ 436,625	$ 401,595
Reimbursements from Tenants	39,290	37,985	37,661
Property operating	148,081	118,836	100,304
Real estate taxes	71,054	66,434	57,784
Operating Segments
Segment Reporting Information [Line Items]
Property rentals	499,835	436,625	401,595
Reimbursements from Tenants	39,290	37,985	37,661
Total rental revenue	539,125	474,610	439,256
Property operating	148,081	118,836	100,304
Real estate taxes	71,054	66,434	57,784
Total rental expense	219,135	185,270	158,088
Consolidated NOI	319,990	289,340	281,168
Operating Segments | Commercial Segment [Member]
Segment Reporting Information [Line Items]
Property rentals	395,089	351,517	323,133
Reimbursements from Tenants	34,953	32,380	33,361
Total rental revenue	430,042	383,897	356,494
Property operating	118,288	97,701	91,148
Real estate taxes	53,324	50,546	46,115
Total rental expense	171,612	148,247	137,263
Consolidated NOI	258,430	235,650	219,231
Operating Segments | Multifamily
Segment Reporting Information [Line Items]
Property rentals	102,617	86,439	63,401
Reimbursements from Tenants	6,740	5,130	3,454
Total rental revenue	109,357	91,569	66,855
Property operating	31,502	24,623	17,238
Real estate taxes	14,280	11,030	6,993
Total rental expense	45,782	35,653	24,231
Consolidated NOI	63,575	55,916	42,624
Operating Segments | Other
Segment Reporting Information [Line Items]
Property rentals	2,129	(1,331)	15,061
Reimbursements from Tenants	(2,403)	475	846
Total rental revenue	(274)	(856)	15,907
Property operating	(1,709)	(3,488)	(8,082)
Real estate taxes	3,450	4,858	4,676
Total rental expense	1,741	1,370	(3,406)
Consolidated NOI	$ (2,015)	$ (2,226)	$ 19,313

Segment Information - Summary_2

Segment Information - Summary of Certain Balance Sheet Data by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Real estate, at cost	$ 5,792,734	$ 6,017,504
Investments in and advances to unconsolidated real estate ventures	322,878	261,811
Total assets (1)	5,997,285	6,071,807
Operating Segments | Commercial Segment [Member]
Segment Reporting Information [Line Items]
Real estate, at cost	3,634,472	4,023,544
Investments in and advances to unconsolidated real estate ventures	177,173	134,138
Total assets (1)	3,707,255	3,612,947
Operating Segments | Multifamily
Segment Reporting Information [Line Items]
Real estate, at cost	1,656,974	1,480,812
Investments in and advances to unconsolidated real estate ventures	109,232	98,835
Total assets (1)	1,528,177	1,403,452
Operating Segments | Other
Segment Reporting Information [Line Items]
Real estate, at cost	501,288	513,148
Investments in and advances to unconsolidated real estate ventures	36,473	28,838
Total assets (1)	$ 761,853	$ 1,055,408

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Real Estate Properties [Line Items]
General liability insurance limit	$ 200,000,000
Property and rental value insurance coverage limit	2,000,000,000
Terrorist acts insurance coverage limit	2,000,000,000
Purchase obligation	519,400,000
Environmental liabilities (1)	17,898,000	$ 2,900,000
Additional capital funding committed amount	48,600,000
Operating Leases, Rent Expense And Interest Expense, Lessee, Assets Under Capital Lease	11,200,000	$ 4,700,000	$ 2,100,000
Consolidated Properties
Real Estate Properties [Line Items]
Purchase obligation	440,900,000
Principal payment guarantees	8,300,000
Unconsolidated Properties
Real Estate Properties [Line Items]
Purchase obligation	78,500,000
Principal payment guarantees	$ 0
Minimum
Real Estate Properties [Line Items]
Commitment amortization period	2 years
Minimum | Unconsolidated Properties
Real Estate Properties [Line Items]
Commitment amortization period	2 years
Maximum
Real Estate Properties [Line Items]
Commitment amortization period	3 years
Maximum | Unconsolidated Properties
Real Estate Properties [Line Items]
Commitment amortization period	3 years

Commitments and Contingencies S

Commitments and Contingencies Summary of Future Minimum Rental Payments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,019	$ 13,991
2,020	13,710
2,021	13,395
2,022	12,554
2,023	9,489
Thereafter	55,780
Total	$ 118,919

Transactions with Vornado and_2

Transactions with Vornado and Related Parties (Details)	Jul. 18, 2017USD ($)	Jul. 17, 2017USD ($)	Aug. 12, 2014USD ($)	Jun. 30, 2016USD ($)ft²	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Aug. 31, 2014USD ($)ft²
Related Party Transaction [Line Items]
Borrowings under revolving credit facility					$ 35,000,000	$ 115,751,000	$ 0
Third-party real estate services, including reimbursements					98,699,000	63,236,000	33,882,000
Corporate and other					33,728,000	39,350,000	48,753,000
Universal Buildings, Washington DC
Related Party Transaction [Line Items]
Area of real estate property (in square feet) | ft²								687,000
Bowen Building, Washington DC [Member]
Related Party Transaction [Line Items]
Area of real estate property (in square feet) | ft²				231,000
Financing of the Universal Buildings
Related Party Transaction [Line Items]
Debt instrument, face amount								$ 185
Affiliated Entity [Member] | Vornado Realty Trust [Member] | Vornado's revolving credit facility
Related Party Transaction [Line Items]
Interest expense to Vornado						1,300,000	1,100,000
Borrowings under revolving credit facility				$ 115,600,000
Affiliated Entity [Member] | Vornado Realty Trust [Member] | Mortgage loan secured by Bowen Building
Related Party Transaction [Line Items]
Repayment of mortgages payable				115,000,000
Accrued interest on mortgage loan				$ 608,000
Affiliated Entity [Member] | Legacy JBG Funds [Member]
Related Party Transaction [Line Items]
Corporate and other					4,900,000	2,300,000
Affiliated Entity [Member] | Allocations of centralized corporate costs | Vornado Realty Trust [Member]
Related Party Transaction [Line Items]
Allocated amounts included in general and administrative expense						13,000,000	20,700,000
Affiliated Entity [Member] | Financing transactions | Vornado Realty Trust [Member] | Financing of the Universal Buildings
Related Party Transaction [Line Items]
Loan to Vornado			$ 0
Interest Income on loan receivable from Vornado						1,800,000	3,300,000
Affiliated Entity [Member] | Financing transactions | Vornado Realty Trust [Member] | Financing of the Universal Buildings | LIBOR
Related Party Transaction [Line Items]
Mortgage loan interest rate			2.90%
Affiliated Entity [Member] | Financing transactions | Vornado Realty Trust [Member] | Note agreement for development of Bartlett
Related Party Transaction [Line Items]
Debt instrument, face amount	$ 170,000,000
Interest expense to Vornado						4,100,000	4,100,000
Affiliated Entity [Member] | Supervise cleaning, engineering and security services | BMS
Related Party Transaction [Line Items]
Related party transaction amount					20,900,000	13,600,000	$ 12,100,000
Affiliated Entity [Member] | Separation and Combination transaction | Vornado Realty Trust [Member]
Related Party Transaction [Line Items]
Expenses from related parties					3,600,000	2,200,000
Revenue from related parties					2,100,000	779,000
Affiliated Entity [Member] | Fees from Legacy JBG Funds | Legacy JBG Funds [Member]
Related Party Transaction [Line Items]
Third-party real estate services, including reimbursements					33,800,000	19,900,000
Accounts Receivable, Related Parties					3,600,000	3,100,000
Trustee | Consulting agreement
Related Party Transaction [Line Items]
Expenses from related parties						$ 16,400,000
Transaction services, initial period (in months)		24 years
Related party transaction, monthly amount		$ 169,400
JBG Companies [Member]
Related Party Transaction [Line Items]
Liability incurred in connection with the Combination	$ 4,100,000				$ 1,100,000

Quarterly Financial Informati_3

Quarterly Financial Information (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total revenue	$ 163,255,000	$ 158,443,000	$ 159,447,000	$ 163,037,000	$ 156,371,000	$ 152,350,000	$ 118,020,000	$ 116,272,000	$ 644,182,000	$ 543,013,000	$ 478,519,000
Net income (loss)	994,000	26,382,000	24,023,000	(4,786,000)	(18,752,000)	(77,991,000)	11,341,000	6,318,000	39,903,000	(71,756,000)	61,974,000
Net income (loss) attributable to common shareholders	$ 710,000	$ 22,830,000	$ 20,574,000	$ (4,190,000)	$ (16,418,000)	$ (69,831,000)	$ 11,341,000	$ 6,318,000	$ 37,325,000	$ (73,408,000)	$ 61,974,000
Earnings Per Share, Basic	$ (0.01)	$ 0.19	$ 0.17	$ (0.04)	$ (0.15)	$ (0.61)	$ 0.11	$ 0.06	$ 0.31	$ (0.70)	$ 0.62
Earnings Per Share, Diluted	$ (0.01)	$ 0.19	$ 0.17	$ (0.04)	$ (0.15)	$ (0.61)	$ 0.11	$ 0.06	$ 0.31	$ (0.70)	$ 0.62
Gains (Losses) on Sales of Investment Real Estate	$ 6,400,000		$ 33,400,000						$ 52,183,000	$ 0	$ 0
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Bargain Purchase, Reduction Of Gain			(7,600,000)		$ (3,400,000)	$ 27,800,000			(7,606,000)	24,376,000	0
Loss on extinguishment of debt			$ (4,500,000)						(5,153,000)	(701,000)	0
Transaction and other costs	15,600,000				12,600,000	104,100,000			27,706,000	127,739,000	6,476,000
Share-based compensation related to Formation Transaction					$ 14,800,000	$ 14,400,000			36,030,000	$ 29,251,000	$ 0
The Warner [Member]
Equity Method Investment, Realized Gain (Loss) on Disposal	$ 20,600,000								20,600,000
Executive Tower [Member]
Gains (Losses) on Sales of Investment Real Estate		$ 11,900,000
JP Morgan [Member]
Equity Method Investment, Realized Gain (Loss) on Disposal		$ 15,500,000							$ 15,500,000

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Performance-Based LTIP Units
Subsequent Event [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		567,106	605,072
Subsequent Event [Member]
Subsequent Event [Line Items]
Stock Granted, Value, Share-based Compensation, Gross	$ 24.5
Subsequent Event [Member] | Time-Based LTIP Units
Subsequent Event [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	442,395
Subsequent Event [Member] | Performance-Based LTIP Units
Subsequent Event [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	477,640

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - SEC Schedule, 12-09, Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	$ 6,285	$ 4,526	$ 4,431
Additions Charged Against Operations	3,298	3,807	751
Adjustments to Valuation Accounts	0	0	0
Uncollectible Accounts Written‑off	(1,989)	(2,048)	(656)
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	$ 7,594	$ 6,285	$ 4,526

Schedule III - Real Estate an_2

Schedule III - Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 26, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Federal Income Tax Basis Difference		$ 114,000
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		2,144,652
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		1,479,777
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		2,606,328
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		1,706,629
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		1,371,874
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		4,420,860
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		5,792,734	$ 6,025,797	$ 4,155,391	$ 4,038,206
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Other Acquisition		19,431	428,702	0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Improvements		282,988	1,489,409	217,261
SEC Schedule, 12-28, Real Estate, Held for Sale		94,926	8,293	0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Write-down or Reserve, Amount		(527,189)	(55,998)	(100,076)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		1,051,875	1,011,330	930,769	$ 908,233
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Depreciation Expense		116,377	136,559	122,612
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Investment in Real Estate Sold		(75,832)	$ (55,998)	$ (100,076)
Operating and Held for Sale [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		2,144,652
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		1,493,178
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		2,665,033
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		1,737,742
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		1,385,014
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		4,510,939
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		5,895,953
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		1,086,844
Universal Buildings, Washington DC
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		182,467
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		69,393
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		143,320
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		23,829
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		68,612
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		167,930
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		236,542
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		53,606
2101 L Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		137,453
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		32,815
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		51,642
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		88,181
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		39,768
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		132,870
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		172,638
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		43,414
1700 M Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		34,178
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		46,938
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		(25,937)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		55,179
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		55,179
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		0
1730 M Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		47,500
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		10,095
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		17,541
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		15,625
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		10,687
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		32,574
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		43,261
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		13,021
1600 K Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		19,870
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		10,308
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		364
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		19,870
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		10,672
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		30,542
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		1,280
Courthouse Plaza 1 and 2 [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		105,475
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		50,652
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		156,127
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		156,127
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		64,721
2121 Crystal Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		136,728
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		21,503
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		87,329
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		53,027
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		22,071
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		139,788
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		161,859
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		70,404
2345 Crystal Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		23,126
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		93,918
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		41,679
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		23,683
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		135,040
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		158,723
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		57,974
2231 Crystal Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		20,611
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		83,705
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		21,694
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		21,132
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		104,878
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		126,010
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		42,194
1550 Crystal Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		17,988
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		70,525
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		19,854
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		17,996
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		90,371
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		108,367
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		38,157
RTC - West [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		88,854
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		30,326
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		134,108
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		5,819
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		30,425
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		139,828
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		170,253
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		9,969
RTC - West Retail [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		6,889
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		2,894
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		8,338
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		2,894
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		8,338
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		11,232
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		407
2011 Crystal Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		18,940
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		76,921
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		38,777
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		18,991
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		115,647
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		134,638
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		48,727
2451 Crystal Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		16,755
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		68,047
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		28,915
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		17,337
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		96,380
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		113,717
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		38,652
1235 S. Clark Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		78,000
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		15,826
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		56,090
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		28,656
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		16,293
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		84,279
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		100,572
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		33,875
241 18th Street S. [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		13,867
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		54,169
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		32,344
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		16,812
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		83,568
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		100,380
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		33,725
251 18th Street S. [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		34,294
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		12,305
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		49,360
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		56,515
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		15,729
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		102,451
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		118,180
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		39,602
1215 S. Clark Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		13,636
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		48,380
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		54,601
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		14,017
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		102,600
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		116,617
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		31,987
201 12th Street S. [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		32,863
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		14,766
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		52,750
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		23,357
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		15,126
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		75,747
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		90,873
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		30,413
800 North Glebe Road [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		107,500
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		28,168
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		140,983
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		2,307
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		28,168
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		143,290
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		171,458
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		8,790
2200 Crystal Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		13,104
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		30,050
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		34,732
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		13,454
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		64,432
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		77,886
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		19,870
1901 South Bell Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		11,669
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		36,918
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		21,887
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		12,009
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		58,465
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		70,474
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		26,342
1225 S. Clark Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		11,176
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		43,495
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		20,292
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		11,490
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		63,473
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		74,963
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		25,616
Crystal City Marriott [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		8,000
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		47,191
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		15,733
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		8,224
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		62,700
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		70,924
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		22,162
2100 Crystal Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		10,287
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		23,590
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		31,413
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		10,588
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		54,702
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		65,290
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		23,839
200 12th Street S. [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		16,507
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		8,016
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		30,552
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		20,211
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		8,241
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		50,538
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		58,779
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		20,974
2001 Jefferson Davis Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		7,300
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		16,746
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		11,870
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		7,481
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		28,435
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		35,916
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		11,411
1800 South Bell Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		28,702
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		7,368
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		212
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		35,858
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		36,070
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		15,602
Crystal City Shops at 2100 [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		4,059
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		9,309
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		5,175
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		4,049
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		14,494
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		18,543
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		6,098
Crystal Drive Retail [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		20,465
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		4,461
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		55
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		24,871
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		24,926
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		11,813
Vienna Retail [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		1,763
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		641
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		41
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		1,763
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		682
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		2,445
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		230
7200 Wisconsin Avenue [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		34,683
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		92,059
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		4,712
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		34,683
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		96,771
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		131,454
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		5,373
One Democracy Plaza [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		33,628
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		7,873
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		41,501
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		41,501
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		23,617
4749 Bethesda Avenue [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		2,480
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		11,830
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		26
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		2,872
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		11,464
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		14,336
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		257
CEB Tower at Central Place [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		234,000
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		74,420
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		230,280
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		54,714
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		74,877
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		284,537
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		359,414
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		8,956
1770 Crystal Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		10,771
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		44,276
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		(9,067)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		45,980
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		45,980
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		1,674
Central District Retail [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		4,194
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		16,388
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		20,582
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		20,582
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		5
4747 Bethesda Avenue [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		29,030
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		10,040
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		68,070
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		107,140
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		107,140
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		0
Fort Totten Square [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		73,600
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		24,390
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		90,404
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		826
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		24,390
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		91,230
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		115,620
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		5,433
WestEnd25 [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		97,881
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		67,049
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		5,039
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		110,465
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		68,210
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		114,343
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		182,553
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		27,229
North End Retail [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		5,847
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		9,333
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		(291)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		5,847
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		9,042
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		14,889
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		481
RiverHouse Apartments [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		307,710
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		118,421
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		125,078
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		84,970
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		138,763
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		189,706
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		328,469
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		63,413
The Bartlett [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		220,000
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		41,687
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		224,948
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		41,867
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		224,768
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		266,635
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		15,988
220 20th Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		8,434
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		19,340
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		100,624
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		8,761
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		119,637
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		128,398
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		31,277
2221 South Clark Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		7,405
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		16,981
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		41,394
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		7,542
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		58,238
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		65,780
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		6,558
Falkland Chase - South & West [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		41,008
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		18,530
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		44,232
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		570
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		18,530
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		44,802
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		63,332
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		2,941
Falkland Chase-North [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		9,810
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		22,706
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		(2,239)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		8,992
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		21,285
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		30,277
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		1,429
1221 Van Street [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		27,386
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		63,775
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		25,293
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		28,182
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		88,272
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		116,454
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		3,613
West Half [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		45,668
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		17,902
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		96,284
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		159,854
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		159,854
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		0
965 Florida Avenue [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		14,306
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		42,045
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		56,351
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		56,351
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		0
Atlantic Plumbing C [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		47,678
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		13,952
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		66,708
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		128,338
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		128,338
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		0
1900 Crystal Drive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		16,811
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		53,187
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		(25,598)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		44,400
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		44,400
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		243
Capitol Point - North [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		32,730
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		18,374
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		50,829
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		275
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		51,104
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		0
Metropolitan Park 6 - 8 [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		65,259
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		1,326
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		27,777
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		82,898
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		11,464
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		94,362
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		31
Pen Place - Land Parcel [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		104,473
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		55
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		(30,618)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		61,970
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		11,940
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		73,910
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		6
Potomac Yard Land Bay G - Parcels A-F [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		20,318
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		7,955
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		26,914
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		1,359
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		28,273
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		1
Potomac Land Bay H [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		38,369
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		38,369
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		38,369
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		0
RTC - West Land [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		1,398
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		29,956
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		1,792
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		29,956
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		1,792
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		31,748
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		0
Square 649 [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		15,550
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		6,451
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		(2,183)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		12,672
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		7,146
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		19,818
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		427
Other Future Development Assets [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		71,686
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		15,286
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		14,629
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		72,394
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		29,207
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		101,601
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		330
Corporation [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		300,000
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		18,408
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		18,408
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		18,408
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		7,718
Commerce Executive [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Land		13,401
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Initial Cost of Building and Improvements		58,705
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Cost Capitalized Subsequent to Acquisition, Cost		31,113
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Land, Amount		13,140
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Building and Improvements, Amount		90,079
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Gross		103,219
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation		$ 34,969
Maximum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Property, Plant and Equipment, Useful Life		40 years
Reston, Virginia [Member] | Commerce Executive [Member] | Commercial Segment [Member] | Subsequent Event [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Proceeds from Sale of Property Held-for-sale	$ 115,000

Uncategorized Items - jbgs-2018

Label	Element	Value
Interest Payable	us-gaap_InterestPayableCurrentAndNoncurrent	$ 0
Interest Payable	us-gaap_InterestPayableCurrentAndNoncurrent	3,714,000
Interest Payable	us-gaap_InterestPayableCurrentAndNoncurrent	3,216,000
Dividends Payable, Redeemable Noncontrolling Interest	jbgs_DividendsPayableRedeemableNoncontrollingInterest	0
Dividends Payable, Redeemable Noncontrolling Interest	jbgs_DividendsPayableRedeemableNoncontrollingInterest	4,557,000
Dividends Payable, Redeemable Noncontrolling Interest	jbgs_DividendsPayableRedeemableNoncontrollingInterest	5,896,000
Dividends Payable, Common Shareholders	jbgs_DividendsPayableCommonShareholders	0
Dividends Payable, Common Shareholders	jbgs_DividendsPayableCommonShareholders	26,540,000
Dividends Payable, Common Shareholders	jbgs_DividendsPayableCommonShareholders	$ 39,298,000