Federal Realty Investment Trust (FRT) 10-K 10 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2019	Feb. 05, 2020	Jun. 30, 2019
Entity Information [Line Items]
Document Annual Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	MD
Entity Registrant Name	FEDERAL REALTY INVESTMENT TRUST
Entity Central Index Key	0000034903
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		75,651,842
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 9.7
Entity File Number	1-07533
Entity Tax Identification Number	52-0782497
Entity Address, Address Line One	1626 East Jefferson Street
Entity Address, City or Town	Rockville
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20852
City Area Code	301)
Local Phone Number	998-8100
Entity Interactive Data Current	Yes
New York Stock Exchange, Inc. | Common Shares Of Beneficial Interest
Entity Information [Line Items]
Title of 12(b) Security	Common Shares of Beneficial Interest
Trading Symbol	FRT
Security Exchange Name	NYSE
New York Stock Exchange, Inc. | Depositary Shares
Entity Information [Line Items]
Title of 12(b) Security	Depositary Shares, each representing 1/1000 of a share
Trading Symbol	FRT-C
Security Exchange Name	NYSE

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
ASSETS
Operating (including $1,676,866 and $1,701,804 of consolidated variable interest entities, respectively)	$ 7,535,983	$ 7,307,622
Construction-in-progress (including $102,583 and $51,313 of consolidated variable interest entities, respectively)	760,420	495,274
Assets held for sale	1,729	16,576
Real estate, at cost, total	8,298,132	7,819,472
Less accumulated depreciation and amortization (including $296,165 and $292,374 of consolidated variable interest entities, respectively)	(2,215,413)	(2,059,143)
Net real estate	6,082,719	5,760,329
Cash and cash equivalents	127,432	64,087
Accounts and notes receivable	152,572	142,237
Mortgage notes receivable, net	30,429	30,429
Investment in partnerships	28,604	26,859
Operating Lease, Right-of-Use Asset	93,774	0
Finance Lease, Right-of-Use Asset	52,402	0
Prepaid expenses and other assets	227,060	265,703
TOTAL ASSETS	6,794,992	6,289,644
Liabilities
Mortgages payable, net (including $469,184 and $444,388 of consolidated variable interest entities, respectively)	545,679	474,379
Capital lease obligations	0	71,519
Notes payable	3,781	279,027
Senior notes and debentures, net	2,807,134	2,404,279
Accounts payable and accrued expenses	255,503	177,922
Dividends payable	81,676	78,207
Security deposits payable	21,701	17,875
Operating Lease, Liability	73,628	0
Finance Lease, Liability	72,062	0
Other liabilities and deferred credits	157,938	182,898
Total liabilities	4,019,102	3,686,106
Commitments and contingencies (Note 7)
Redeemable noncontrolling interests	139,758	136,208
Shareholders’ equity
Common shares of beneficial interest, $.01 par, 100,000,000 shares authorized, 75,540,804 and 74,249,633 shares issued and outstanding, respectively	759	745
Additional paid-in capital	3,166,522	3,004,442
Accumulated dividends in excess of net income	(791,124)	(818,877)
Accumulated other comprehensive loss	(813)	(416)
Total shareholders’ equity of the Trust	2,535,341	2,345,891
Noncontrolling interests	100,791	121,439
Total shareholders’ equity	2,636,132	2,467,330
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	6,794,992	6,289,644
5.0% Series C Cumulative Redeemable Preferred Shares, (stated at liquidation preference $25,000 per share), 6,000 shares issued and outstanding
Shareholders’ equity
Preferred shares, authorized 15,000,000 shares, $.01 par:	150,000	150,000
5.417% Series 1 Cumulative Convertible Preferred Shares, (stated at liquidation preference $25 per share), 399,896 shares issued and outstanding
Shareholders’ equity
Preferred shares, authorized 15,000,000 shares, $.01 par:	$ 9,997	$ 9,997

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating real estate, consolidated variable interest entities	$ 1,676,866	$ 1,701,804
Construction-in-progress, consolidated variable interest entities	102,583	51,313
Accumulated depreciation and amortization, consolidated variable interest entities	296,165	292,374
Mortgages payable, consolidated variable interest entities	$ 469,184	$ 444,388
Preferred shares, authorized	15,000,000	15,000,000
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, percentage	5.00%	5.00%
Common shares of beneficial interest, par value	$ 0.01	$ 0.01
Common shares of beneficial interest, shares authorized	100,000,000	100,000,000
Common shares of beneficial interest, shares issued	75,540,804	74,249,633
Common shares of beneficial interest, shares outstanding	75,540,804	74,249,633
5.417% Series 1 Cumulative Convertible Preferred Shares, (stated at liquidation preference $25 per share), 399,896 shares issued and outstanding
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, percentage	5.417%	5.417%
Preferred Shares, liquidation preference per share	$ 25	$ 25
Preferred shares, shares issued	399,896	399,896
Preferred shares, shares outstanding	399,896	399,896
5.0% Series C Cumulative Redeemable Preferred Shares, (stated at liquidation preference $25,000 per share), 6,000 shares issued and outstanding
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, percentage	5.00%	5.00%
Preferred Shares, liquidation preference per share	$ 25,000	$ 25,000
Preferred shares, shares issued	6,000	6,000
Preferred shares, shares outstanding	6,000	6,000

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
REVENUE
Rental Income	$ 932,738	$ 912,287	$ 854,286
Mortgage interest income	3,050	3,149	3,062
Total revenue	935,788	915,436	857,348
EXPENSES
Rental expenses	187,831	173,094	164,890
Real estate taxes	110,927	114,776	107,839
General and administrative	42,754	33,600	36,281
Depreciation and amortization	239,758	244,245	216,050
Total operating expenses	581,270	565,715	525,060
Gain on sale of real estate, net	116,393	11,915	77,922
OPERATING INCOME	470,911	361,636	410,210
Other interest income	1,266	942	475
Interest expense	(109,623)	(110,154)	(100,125)
Early extinguishment of debt	0	0	(12,273)
(Loss) income from real estate partnerships	(2,012)	(3,398)	(417)
Net income	360,542	249,026	297,870
Net income attributable to noncontrolling interests	(6,676)	(7,119)	(7,956)
NET INCOME ATTRIBUTABLE TO THE TRUST	353,866	241,907	289,914
Dividends on preferred shares	(8,042)	(8,042)	(2,458)
NET INCOME AVAILABLE FOR COMMON SHAREHOLDERS	$ 345,824	$ 233,865	$ 287,456
EARNINGS PER COMMON SHARE, BASIC
Net income available for common shareholders	$ 4.61	$ 3.18	$ 3.97
Weighted average common shares outstanding, basic	74,766	73,274	72,117
EARNINGS PER COMMON SHARE, DILUTED
Net income available for common shareholders	$ 4.61	$ 3.18	$ 3.97
Weighted average number of common shares	74,766	73,302	72,233
Comprehensive Income
Net income	$ 360,542	$ 249,026	$ 297,870
Other comprehensive (loss) income - change in value of interest rate swaps	(397)	(438)	2,599
COMPREHENSIVE INCOME	360,145	248,588	300,469
Comprehensive income attributable to noncontrolling interests	(6,676)	(7,119)	(7,956)
COMPREHENSIVE INCOME ATTRIBUTABLE TO THE TRUST	$ 353,469	$ 241,469	$ 292,513

Consolidated Statement Of Share

Consolidated Statement Of Shareholders' Equity - USD ($) $ in Thousands	Total	Preferred Shares	Common shares	Additional Paid-in Capital	Accumulated Dividends in Excess of Net Income	Accumulated Other Comprehensive Income/(Loss)	Noncontrolling Interests	Common shares	Preferred Shares	Preferred SharesAdditional Paid-in Capital
Beginning balance (in shares) at Dec. 31, 2016		399,896	71,995,897
Beginning balance at Dec. 31, 2016	$ 2,075,835	$ 9,997	$ 722	$ 2,718,325	$ (749,734)	$ (2,577)	$ 99,102
Increase (Decrease) in Stockholders' Equity [Roll Forward]
January 1 adoption of new accounting standard - See Note 2	0			83	(83)
Net income, excluding amount attributable to redeemable noncontrolling interests	293,996				289,914		4,082
Other comprehensive (loss) income - change in value of interest rate swaps	2,599					2,599
Dividends declared to common shareholders	(287,006)				(287,006)
Dividends declared to preferred shareholders	(2,458)				(2,458)
Distributions declared to noncontrolling interests	(5,560)						(5,560)
Shares issued (in shares)		6,000	826,592
Shares issued		$ 150,000	$ 8	108,240				$ 108,248	$ 144,965	$ (5,035)
Exercise of stock options (in shares)			152,634
Exercise of stock options	$ 9,979		$ 2	9,977
Shares issued under dividend reinvestment plan (in shares)	17,911		17,911
Shares issued under dividend reinvestment plan	$ 2,373			2,373
Share-based compensation expense, net of forfeitures (in shares)			107,522
Share-based compensation expense, net of forfeitures	12,371		$ 1	12,370
Shares withheld for employee taxes (in shares)			(29,709)
Shares withheld for employee taxes	(4,229)			(4,229)
Conversion and redemption of OP units (in shares)			20,030
Conversion and redemption of OP units	0		$ 0	2,569			(2,569)
Purchase of noncontrolling interests	(5,536)			42			(5,578)
Contributions from noncontrolling interests	35,331						35,331
Adjustment to redeemable noncontrolling interests	10,606			10,606
Ending balance (in shares) at Dec. 31, 2017		405,896	73,090,877
Ending balance at Dec. 31, 2017	2,391,514	$ 159,997	$ 733	2,855,321	(749,367)	22	124,808
Increase (Decrease) in Stockholders' Equity [Roll Forward]
January 1 adoption of new accounting standard - See Note 2	(6,028)				(6,028)
Net income, excluding amount attributable to redeemable noncontrolling interests	245,161				241,907		3,254
Other comprehensive (loss) income - change in value of interest rate swaps	(438)					(438)
Dividends declared to common shareholders	(297,347)				(297,347)
Dividends declared to preferred shareholders	(8,042)				(8,042)
Distributions declared to noncontrolling interests	(5,175)						(5,175)
Shares issued (in shares)			987,461
Shares issued	126,071		$ 10	126,061
Exercise of stock options (in shares)			105,803
Exercise of stock options	$ 4,572		$ 1	4,571
Shares issued under dividend reinvestment plan (in shares)	17,952		17,952
Shares issued under dividend reinvestment plan	$ 2,159			2,159
Share-based compensation expense, net of forfeitures (in shares)			55,223
Share-based compensation expense, net of forfeitures	12,736		$ 1	12,735
Shares withheld for employee taxes (in shares)			(8,432)
Shares withheld for employee taxes	(958)			(958)
Conversion and redemption of OP units (in shares)			749
Conversion and redemption of OP units	(6,012)		$ 0	(544)			(5,468)
Contributions from noncontrolling interests	4,020						4,020
Adjustment to redeemable noncontrolling interests	5,097			5,097
Ending balance (in shares) at Dec. 31, 2018		405,896	74,249,633
Ending balance at Dec. 31, 2018	2,467,330	$ 159,997	$ 745	3,004,442	(818,877)	(416)	121,439
Increase (Decrease) in Stockholders' Equity [Roll Forward]
January 1 adoption of new accounting standard - See Note 2	(7,098)				(7,098)
Net income, excluding amount attributable to redeemable noncontrolling interests	357,112				353,866		3,246
Other comprehensive (loss) income - change in value of interest rate swaps	(397)					(397)
Dividends declared to common shareholders	(310,973)				(310,973)
Dividends declared to preferred shareholders	(8,042)				(8,042)
Distributions declared to noncontrolling interests	(9,961)						(9,961)
Shares issued (in shares)			1,069,740
Shares issued	$ 142,716		$ 11	142,705
Exercise of stock options (in shares)	0
Shares issued under dividend reinvestment plan (in shares)	15,909		15,909
Shares issued under dividend reinvestment plan	$ 2,095			2,095
Share-based compensation expense, net of forfeitures (in shares)			111,555
Share-based compensation expense, net of forfeitures	13,330		$ 1	13,329
Shares withheld for employee taxes (in shares)			(34,320)
Shares withheld for employee taxes	(4,626)			(4,626)
Conversion and redemption of OP units (in shares)			128,287
Conversion and redemption of OP units	(72)		$ 2	14,102			(14,176)
Contributions from noncontrolling interests	243						243
Adjustment to redeemable noncontrolling interests	(5,525)			(5,525)
Ending balance (in shares) at Dec. 31, 2019		405,896	75,540,804
Ending balance at Dec. 31, 2019	$ 2,636,132	$ 159,997	$ 759	$ 3,166,522	$ (791,124)	$ (813)	$ 100,791

Consolidated Statement Of Sha_2

Consolidated Statement Of Shareholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Amounts attributable to redeemable noncontrolling interest	$ 3,430	$ 3,865	$ 3,874

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES
Net income	$ 360,542	$ 249,026	$ 297,870
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	239,758	244,245	216,050
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	(116,393)	(11,915)	(77,922)
Early extinguishment of debt	0	0	12,273
Loss from partnerships	2,012	3,398	417
Other, net	169	4,147	(2,674)
Changes in assets and liabilities, net of effects of acquisitions and dispositions:
Proceeds from new market tax credit transaction, net of deferred costs	0	12,353	0
(Increase) decrease in accounts receivable, net	(16,128)	917	2,059
Increase in prepaid expenses and other assets	(10,253)	(2,070)	(3,695)
Increase in accounts payable and accrued expenses	2,327	2,650	14,242
(Decrease) increase in security deposits and other liabilities	(115)	13,937	208
Net cash provided by operating activities	461,919	516,688	458,828
INVESTING ACTIVITIES
Acquisition of real estate	(204,516)	(13,503)	(437,772)
Capital expenditures - development and redevelopment	(327,074)	(302,120)	(441,984)
Capital expenditures - other	(82,836)	(66,138)	(76,952)
Proceeds from sale of real estate	321,997	177,775	136,055
Proceeds from partnership formation	0	37,998	0
Investment in partnerships	(1,052)	(1,037)	(696)
Distribution from partnerships in excess of earnings	2,765	275	1,729
Leasing costs	(25,459)	(25,430)	(16,656)
Issuance of mortgage and other notes receivable, net	(357)	(67)	(1,646)
Net cash used in investing activities	(316,532)	(192,247)	(837,922)
FINANCING ACTIVITIES
Net (repayments) borrowings under revolving credit facility, including costs	(4,012)	(41,000)	41,000
Issuance of senior notes, net of costs	399,913	0	572,134
Redemption and retirement of senior notes	0	0	(161,930)
Repayment of mortgages, finance leases, and notes payable	(301,029)	(16,620)	(56,328)
Issuance of common shares, net of costs	143,027	130,918	118,583
Issuance of preferred shares, net of costs	0	0	144,991
Dividends paid to common and preferred shareholders	(313,649)	(301,194)	(282,995)
Shares withheld for employee taxes	(4,626)	(958)	(4,229)
Proceeds from Noncontrolling Interests	404	2,838	13,449
Distributions to and redemptions of noncontrolling interests	(20,133)	(15,293)	(15,230)
Net cash (used in) provided by financing activities	(100,105)	(241,309)	369,445
Increase (decrease) in cash, cash equivalents, and restricted cash	45,282	83,132	(9,649)
Cash, cash equivalents, and restricted cash at beginning of year	108,332	25,200	34,849
Cash, cash equivalents, and restricted cash at end of year	$ 153,614	$ 108,332	$ 25,200

Business And Organization

Business And Organization	12 Months Ended
	Dec. 31, 2019
Nature Of Operations [Abstract]
BUSINESS AND ORGANIZATION	BUSINESS AND ORGANIZATION Federal Realty Investment Trust (the “Trust”) is an equity real estate investment trust (“REIT”) specializing in the ownership, management, and redevelopment of retail and mixed-use properties. Our properties are located primarily in densely populated and affluent communities in strategically selected metropolitan markets in the Mid-Atlantic and Northeast regions of the United States, California, and South Florida. As of December 31, 2019 , we owned or had a majority interest in community and neighborhood shopping centers and mixed-use properties which are operated as 104 predominantly retail real estate projects. We operate in a manner intended to enable us to qualify as a REIT for federal income tax purposes. A REIT that distributes at least 90% of its taxable income to its shareholders each year and meets certain other conditions is not taxed on that portion of its taxable income which is distributed to its shareholders.

Summary Of Significant Accounti

Summary Of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation Our consolidated financial statements include the accounts of the Trust, its corporate subsidiaries, and all entities in which the Trust has a controlling interest or has been determined to be the primary beneficiary of a variable interest entity (“VIE”). The equity interests of other investors are reflected as noncontrolling interests or redeemable noncontrolling interests. All significant intercompany transactions and balances are eliminated in consolidation. We account for our interests in joint ventures, which we do not control, using the equity method of accounting. Certain 2018 and 2017 amounts have been reclassified to conform to current period presentation. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America, referred to as “GAAP,” requires management to make estimates and assumptions that in certain circumstances affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities, and revenues and expenses. These estimates are prepared using management’s best judgment, after considering past, current and expected events and economic conditions. Actual results could differ from these estimates. Revenue Recognition and Accounts Receivable Policy beginning January 1, 2019, with our adoption of Accounting Standards Codification (ASC) 842, "Leases" Our leases with our tenants are classified as operating leases. When collection of substantially all lease payments during the lease term is considered probable, the lease qualifies for accrual accounting. Lease payments are recognized on a straight-line basis from when the tenant controls the space through the term of the related lease. Variable lease payments relating to percentage rent are recognized at the end of the lease year or earlier if we have determined the required sales level is achieved. Real estate tax and other cost reimbursements are recognized on an accrual basis over the periods in which the related expenditures are incurred. For a tenant to terminate its lease agreement prior to the end of the agreed term, we may require that they pay a fee to cancel the lease agreement. Lease termination fees for which the tenant has relinquished control of the space are generally recognized on the termination date. When a lease is terminated early but the tenant continues to control the space under a modified lease agreement, the lease termination fee is generally recognized evenly over the remaining term of the modified lease agreement. When collection of substantially all lease payments during the lease term is not considered probable, total lease revenue is limited to the lesser of revenue recognized under accrual accounting or cash received. Determining the probability of collection of substantially all lease payments during lease term requires judgment. This determination is impacted by numerous factors including our assessment of the tenant’s credit worthiness, economic conditions, our historical experience with the tenant and tenants operating in the same industry, and the length of the lease term. If leases currently classified as probable are subsequently reclassified as not probable, any outstanding lease receivables (including straight-line rent receivables) would be written-off with a corresponding decrease in rental income. Policy prior to January 1, 2019 Prior to January 1, 2019, management estimates of collectability were considered when reserving for billed and accrued lease receivables and straight-line rent receivables. Full and partial reserves were recorded when determined to be appropriate with a corresponding charge to bad debt expense. The primary impact of the adoption of ASC 842, “Leases,” on our recognition of lease revenue relates to the upfront and ongoing assessment of the collectability of substantially all lease payments required by the new standard. Other revenue recognition policies In 2018, we completed construction on 221 condominium units at our Assembly Row and Pike & Rose properties. Beginning on January 1, 2018, with the adoption of ASU 2014-09, "Revenue from Contracts with Customers," gains or losses on the sale of these condominium units are recognized as the condominium units are legally sold. In 2017, we accounted for contracted condominium sales under the percentage-of completion method, based on an evaluation of the criteria specified in ASC Topic 360-20, “Property, Plant and Equipment – Real Estate Sales,” including: the legal commitment of the purchaser in the real estate contract, whether the construction of the project was beyond a preliminary phase, whether sufficient units had been contracted to ensure the project would not revert to a rental project, the ability to reasonably estimate the aggregate project sale proceeds and aggregate project costs, and the determination that the buyer had made an adequate initial and continuing cash investment under the contract. When the percentage-of-completion criteria had not been met, no profit was recognized. The application of these criteria can be complex and required us to make assumptions. When we enter into a transaction to sell a property or a portion of a property, we evaluate the recognition of the sale under ASC 610-20, "Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets." In accordance with ASC 610-20, we apply the guidance in ASC 606, "Revenue from Contracts with Customers," to determine whether and when control transfers and how to measure the associated gain or loss. We determine the transaction price based on the consideration we expect to receive. Variable consideration is included in the transaction price to the extent it is probable that a significant reversal of a gain recognized will not occur. We analyze the risk of a significant gain reversal and if necessary limit the amount of variable consideration recognized in order to mitigate this risk. The estimation of variable consideration requires us to make assumptions and apply significant judgment. Real Estate Land, buildings and improvements are recorded at cost. Depreciation is computed using the straight-line method. Estimated useful lives range generally from 35 years to a maximum of 50 years on buildings and major improvements. Minor improvements, furniture and equipment are capitalized and depreciated over useful lives ranging from 2 to 20 years. Maintenance and repairs that do not improve or extend the useful lives of the related assets are charged to operations as incurred. Tenant improvements are capitalized and depreciated over the life of the related lease or their estimated useful life, whichever is shorter. If a tenant vacates its space prior to contractual termination of its lease, the undepreciated balance of any tenant improvements are written off if they are replaced or have no future value. In 2019 , 2018 and 2017 , real estate depreciation expense was $215.4 million , $216.0 million and $193.3 million , respectively, including amounts from real estate sold. Effective January 1, 2018, (upon the adoption of ASU 2014-09, "Revenue from Contracts with Customers," as amended and interpreted) sales of real estate are recognized generally upon the transfer of control, which usually occurs when the real estate is legally sold. Prior to January 1, 2018, sales of real estate were recognized only when sufficient down payments had been obtained, possession and other attributes of ownership had been transferred to the buyer and we had no significant continuing involvement. The application of these criteria can be complex and required us to make assumptions. We believe the relevant criteria were met for all real estate sold during the periods presented. Our methodology of allocating the cost of acquisitions to assets acquired and liabilities assumed is based on estimated fair values, replacement cost and/or appraised values. When we acquire operating real estate properties, the purchase price is allocated to land, building, improvements, leasing costs, intangibles such as in-place leases, assumed debt, if any, and to current assets and liabilities acquired, if any. The value allocated to in-place leases is amortized over the related lease term and reflected as rental income in the consolidated statements of comprehensive income. We consider qualitative and quantitative factors in evaluating the likelihood of a tenant exercising a below market renewal option and include such renewal options in the calculation of in-place lease value when we consider these to be bargain renewal options. If the value of below market lease intangibles includes renewal option periods, we include such renewal periods in the amortization period utilized. If a tenant vacates its space prior to contractual termination of its lease, the unamortized balance of any in-place lease value is written off to rental income. Transaction costs related to asset acquisitions, such as broker fees, transfer taxes, legal, accounting, valuation, and other professional and consulting fees, are capitalized as part of the acquisition cost. The acquisition of an operating shopping center typically qualifies as an asset acquisition. Prior to the adoption of ASU 2016-02, "Leases," when applicable, as lessee, we classify our leases of land and building as operating or capital leases. We are required to use judgment and make estimates in determining the lease term, the estimated economic life of the property and the interest rate to be used in determining whether or not the lease meets the qualification of a capital lease. Subsequently, capital leases are now considered "finance leases," see "Recent Accounting Pronouncements," for an explanation of the impact to our consolidated balance sheet. We capitalize certain costs related to the development and redevelopment of real estate including pre-construction costs, real estate taxes, insurance, construction costs and salaries and related costs of personnel directly involved, are capitalized. Additionally, we capitalize interest costs related to development and redevelopment activities. Capitalization of these costs begin when the activities and related expenditures commence and cease when the project is substantially complete and ready for its intended use at which time the project is placed in service and depreciation commences. Additionally, we make estimates as to the probability of certain development and redevelopment projects being completed. If we determine the development or redevelopment is no longer probable of completion, we expense all capitalized costs which are not recoverable. We review for impairment on a property by property basis. Impairment is recognized on properties held for use when the expected undiscounted cash flows for a property are less than its carrying amount, at which time, the property is written-down to fair value. Properties held for sale are recorded at the lower of the carrying amount or the expected sales price less costs to sell. Cash and Cash Equivalents We define cash and cash equivalents as cash on hand, demand deposits with financial institutions and short term liquid investments with an initial maturity, when purchased, under three months. Cash balances in individual banks may exceed the federally insured limit by the Federal Deposit Insurance Corporation (the “FDIC”). At December 31, 2019 , we had $131.5 million in excess of the FDIC insured limit. Prepaid Expenses and Other Assets Prepaid expenses and other assets consist primarily of lease costs, prepaid property taxes and acquired above market leases. Capitalized lease costs are incremental direct costs incurred which were essential to originate a successful leasing arrangement and would not have been incurred had the leasing transaction not taken place. Capitalized lease costs are amortized over the life of the related lease. If a tenant vacates its space prior to the contractual termination of its lease, the unamortized balance of any previously capitalized lease costs are written off. Debt Issuance Costs Costs related to the issuance of debt instruments are deferred and are amortized as interest expense over the estimated life of the related issue using the straight-line method which approximates the effective interest method. If a debt instrument is paid off prior to its original maturity date, the unamortized balance of debt issuance costs are written off to interest expense or, if significant, included in “early extinguishment of debt.” Debt issuance costs related to our revolving credit facility are classified as an asset and are included in "prepaid expenses and other assets" in our consolidated balance sheets. All other debt issuance costs are presented as a direct deduction from the carrying amount of the debt liability. Derivative Instruments We may use derivative instruments to manage exposure to variable interest rate risk. We generally enter into interest rate swaps to manage our exposure to variable interest rate risk and treasury locks to manage the risk of interest rates rising prior to the issuance of debt. We enter into derivative instruments that qualify as cash flow hedges and do not enter into derivative instruments for speculative purposes. Interest rate swaps associated with cash flow hedges are recorded at fair value on a recurring basis. Effectiveness of cash flow hedges is assessed both at inception and on an ongoing basis. The effective portion of changes in fair value of the interest rate swaps associated with cash flow hedges is recorded in other comprehensive income (loss) which is included in accumulated other comprehensive income (loss) on the balance sheet and statement of shareholders' equity. Cash flow hedges become ineffective if critical terms of the hedging instrument and the debt instrument do not perfectly match such as notional amounts, settlement dates, reset dates, calculation period and LIBOR rate. In addition, the default risk of the counterparty is evaluated by monitoring the credit worthiness of the counterparty which includes reviewing debt ratings and financial performance. If a cash flow hedge is deemed ineffective, the ineffective portion of changes in fair value of the interest rate swaps associated with cash flow hedges is recognized in earnings in the period affected. During 2019 , we entered into two interest rate swap agreements that effectively fix the interest rate on a mortgage payable associated with our Hoboken acquisition at 3.67% . Both swaps were designated and qualify for cash flow hedge accounting. As of December 31, 2019 , our Assembly Row hotel joint venture is a party to two interest rate swap agreements that effectively fix the interest rate on the joint venture's mortgage debt at 5.206% . Both swaps were designated and qualify as cash flow hedges. Hedge ineffectiveness has not impacted earnings in 2019 , 2018 and 2017 . Mortgage Notes Receivable We have made certain mortgage loans that, because of their nature, qualify as loan receivables. At the time the loans were made, we did not intend for the arrangement to be anything other than a financing and did not contemplate a real estate investment. We evaluate each investment to determine whether the loan arrangement qualifies as a loan, joint venture or real estate investment and the appropriate accounting thereon. Such determination affects our balance sheet classification of these investments and the recognition of interest income derived therefrom. We receive additional interest, however, we never receive in excess of 50% of the residual profit in the project, and because the borrower has either a substantial investment in the project or has guaranteed all or a portion of our loan (or a combination thereof), the loans qualify for loan accounting. The amounts under these arrangements are presented as mortgage notes receivable at December 31, 2019 and 2018 . Mortgage notes receivable are recorded at cost, net of any valuation adjustments. Interest income is accrued as earned. Mortgage notes receivable are considered past due based on the contractual terms of the note agreement. On a quarterly basis, we evaluate the collectability of each mortgage note receivable based on various factors which may include payment history, expected fair value of the collateral securing the loan, internal and external credit information and/or economic trends. A loan is considered impaired when, based upon current information and events, it is probable that we will be unable to collect all amounts due under the existing contractual terms. When a loan is considered impaired, the amount of the loss accrual is calculated by comparing the carrying amount of the mortgage note receivable to the present value of expected future cash flows. Since our loans are collateralized by a first mortgage, the loans have risk characteristics similar to the risks in owning commercial real estate. At December 31, 2019 and 2018 , we had two mortgage notes receivable, with aggregate carrying amounts of $30.4 million , and weighted average interest rates of 10.0% and 10.3% , respectively, which were secured by first mortgages on retail buildings. Share Based Compensation We grant share based compensation awards to employees and trustees typically in the form of restricted common shares, common shares, and options. We measure share based compensation expense based on the grant date fair value of the award and recognize the expense ratably over the requisite service period, which is typically the vesting period. See Note 12 for further discussion regarding our share based compensation plans and policies. Variable Interest Entities Certain entities that do not have sufficient equity at risk for the entity to finance its activities without additional subordinated financial support from other parties or in which equity investors do not have the characteristics of a controlling financial interest qualify as VIEs. VIEs are required to be consolidated by their primary beneficiary. The primary beneficiary of a VIE has both the power to direct the activities that most significantly impact economic performance of the VIE and the obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. Our equity method investments in the Pike & Rose hotel joint venture, the Assembly Row hotel joint venture, and the La Alameda shopping center are also considered variable interests in a VIE. As we do not control the activities that most significantly impact the economic performance of the joint ventures, we are not the primary beneficiary and do not consolidate. As of December 31, 2019 and 2018 , our investment in these joint ventures and maximum exposure to loss was $23.4 million and $26.9 million , respectively. In addition, we have 18 entities that meet the criteria of a VIE in which we hold a variable interest. For each of these entities, we control the significant operating decisions and consequently have the power to direct the activities that most significantly impact the economic performance of the entities. As we also have the obligation to absorb the majority of the losses and/or the right to receive a majority of the benefits for each of these entities, all are consolidated in our financial statements. Net real estate assets related to VIEs included in our consolidated balance sheets were approximately $1.5 billion for both December 31, 2019 and 2018 , and mortgages related to VIEs included in our consolidated balance sheets were approximately $469.2 million and $444.4 million , as of December 31, 2019 and 2018 , respectively. We have also evaluated our mortgage notes receivable investments and determined that the entities obligated under the mortgage notes are not VIEs. Our equity method investments and mortgage notes receivable balances are presented separately in our consolidated balance sheets. Redeemable Noncontrolling Interests We have certain noncontrolling interests that are redeemable for cash upon the occurrence of an event that is not solely in our control and therefore are classified outside of permanent equity. We adjust the carrying amounts of these noncontrolling interests that are currently redeemable to redemption value at the balance sheet date. Adjustments to the carrying amount to reflect changes in redemption value are recorded as adjustments to additional paid-in capital in shareholders' equity. These amounts are classified within the mezzanine section of the consolidated balance sheets. The following table provides a rollforward of the redeemable noncontrolling interests: Year Ended December 31, 2019 2018 (In thousands) Beginning balance $ 136,208 $ 141,157 Contributions 9,961 354 Net Income 3,430 3,865 Distributions & Redemptions (15,366 ) (4,071 ) Change in redemption value 5,525 (5,097 ) Ending balance $ 139,758 $ 136,208 On August 2, 2019 , we acquired the 10.1% redeemable noncontrolling interest in the partnership that owns our Montrose Crossing Shopping Center for $10.0 million , bringing our ownership interest to 100% . Income Taxes We operate in a manner intended to enable us to qualify as a REIT for federal income tax purposes. A REIT that distributes at least 90% of its taxable income to its shareholders each year and meets certain other conditions is not taxed on that portion of its taxable income which is distributed to its shareholders. Therefore, federal income taxes on our taxable income have been and are generally expected to be immaterial. We are obligated to pay state taxes, generally consisting of franchise or gross receipts taxes in certain states. Such state taxes also have not been material. We have elected to treat certain of our subsidiaries as taxable REIT subsidiaries, which we refer to as a TRS. In general, a TRS may engage in any real estate business and certain non-real estate businesses, subject to certain limitations under the Internal Revenue Code of 1986, as amended (the “Code”). A TRS is subject to federal and state income taxes. Our TRS activities have not been material. With few exceptions, we are no longer subject to U.S. federal, state, and local tax examinations by tax authorities for years before 2016 . As of December 31, 2019 and 2018 , we had no material unrecognized tax benefits. While we currently have no material unrecognized tax benefits, as a policy, we recognize penalties and interest accrued related to unrecognized tax benefits as income tax expense. Segment Information Our primary business is the ownership, management, and redevelopment of retail and mixed-use properties. We review operating and financial information for each property on an individual basis and therefore, each property represents an individual operating segment. We evaluate financial performance using property operating income, which consists of rental income, other property income and mortgage interest income, less rental expenses and real estate taxes. No individual commercial or residential property constitutes more than 10% of our revenues or property operating income and we have no operations outside of the United States of America. Therefore, we have aggregated our properties into one reportable segment as the properties share similar long-term economic characteristics and have other similarities including the fact that they are operated using consistent business strategies, are typically located in major metropolitan areas, and have similar tenant mixes. Recent Accounting Pronouncements Standard Description Date of Adoption Effect on the financial statements or significant matters Recently adopted: Leases (Topic 842) and related updates: Topic 842, Leases ASU 2019-01, March 2019, Leases (Topic 842), Codification Improvements ASC 842 significantly changes the accounting for leases by requiring lessees to recognize assets and liabilities for leases greater than 12 months on their balance sheet. The larger changes to the lessor model include: a change to the definition of initial direct costs of leases (resulting in the upfront expensing of more leasing related costs), the requirement to make an upfront and ongoing assessment of whether collection of substantially all of the lease payments required for the term of the lease is probable (if not probable, lease revenue is effectively recongnized when cash is collected), certain presentation changes, and the elimination of real estate specific guidance. January 2019 We have elected to apply the transition provisions of ASC Topic 842 at the beginning of the period of adoption (i.e., January 1, 2019), and therefore, did not retrospectively adjust prior periods presented. We have also elected to apply certain adoption related practical expedients for all leases that commenced prior to the effective date. These practical expedients include not reassessing whether any expired or existing contracts are or contain leases; not reassessing the lease classification for any expired or existing leases; and not reassessing initial direct costs for any existing leases. We have also elected the practical expedient allowing lessors to combine non-lease and lease components (primarily impacts common area maintenance recoveries). Standard Description Date of Adoption Effect on the financial statements or significant matters Adopted subsequent to December 31, 2019: Financial Instruments - Credit Losses (Topic 326) and related updates: 2016, Financial Instruments - Credit Losses (Topic 326) November 2018, Codification Topic 326, Financial Instruments - Credit Losses This ASU changes the impairment model for most financial assets and certain other instruments, requiring the use of an "expected credit loss" model and adding more disclosure requirements. ASU 2018-19 clarifies that impairment of of receivables arising from operating leases should accounted for in accordance with Topic 842, Leases. January 2020 While our mortgage notes receivable and certain other accounts receivables are impacted by this standard, the adoption of this standard will not have a significant impact to our consolidated financial statements. ASU 2018-15, August 2018, Intangibles - Goodwill and Other Internal Use Software: Customers Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract This ASU requires a customer in a cloud computing arrangement (i.e. hosting arrangement) that is a service contract to follow the internal-use software guidance in ASC 350-40 to determine which implementation costs to capitalize as assets. Capitalized implementation costs related to a hosting arrangement that is a service contract will be amortized over the term of the hosting arrangement. Entities will expense costs during the preliminary project and post-implementation stages as they are incurred. The guidance can be applied prospectively to all implementation costs incurred after the date of adoption or retrospectively in accordance with ASC 250-10-45-5 through ASC 250-10-45-10. January 2020 The adoption of this standard will not have a significant impact to our consolidated financial statements. The following table provides additional information on our operating and finance leases where we are the lessee: Year Ended December 31, 2019 (In thousands) LEASE COST: Finance lease cost: Amortization of right-of-use assets $ 1,284 Interest on lease liabilities 5,824 Operating lease cost 6,063 Variable lease cost 487 Total lease cost $ 13,658 OTHER INFORMATION: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows for finance leases 5,759 Operating cash flows for operating leases 5,561 Financing cash flows for finance leases 47 December 31, 2019 Weighted-average remaining term - finance leases 18.2 years Weighted-average remaining term - operating leases 53.7 years Weighted-average discount rate - finance leases 8.0 % Weighted-average discount rate - operating leases 4.5 % Consolidated Statements of Cash Flows—Supplemental Disclosures The following table provides supplemental disclosures related to the Consolidated Statements of Cash Flows: Year Ended December 31, 2019 2018 2017 (In thousands) SUPPLEMENTAL DISCLOSURES: Total interest costs incurred $ 130,110 $ 129,001 $ 125,684 Interest capitalized (20,487 ) (18,847 ) (25,559 ) Interest expense $ 109,623 $ 110,154 $ 100,125 Cash paid for interest, net of amounts capitalized $ 106,180 $ 107,494 $ 105,201 Cash paid for income taxes $ 483 $ 675 $ 352 NON-CASH INVESTING AND FINANCING TRANSACTIONS (1): Mortgage loans refinanced $ — $ — $ 166,823 Mortgage loans assumed/entered into with acquisition $ 98,041 $ — $ 79,401 DownREIT operating partnership units issued with acquisition $ — $ — $ 5,918 DownREIT operating partnership units redeemed for common shares $ 14,105 $ 101 $ 2,569 Settlement of partner loan receivable via dilution of partner interests $ 5,379 $ — $ — Shares issued under dividend reinvestment plan $ 1,784 $ 1,884 $ 2,017 Contribution from noncontrolling interest $ — $ 1,435 $ — (1) See Note 5 for additional disclosures relating to the mortgages entered into and assumed as a result of the Hoboken acquisition in 2019. In addition, see Note 3 for additional disclosures relating to our investment in the Assembly Row hotel joint venture in 2018. Capitalized lease costs are incremental direct costs incurred which were essential to originate a lease and would not have been incurred had the leasing transaction not taken place. These costs include third party commissions related to obtaining a lease. Capitalized lease costs are amortized over the initial term of the related lease which generally ranges from three to ten years. We view these lease costs as part of the up-front initial investment we made in order to generate a long-term cash inflow and therefore, we classify cash outflows related to leasing costs as an investing activity in our consolidated statements of cash flows. See the "Recent Accounting Pronouncements" section in this note for further discussion regarding the change in accounting for lease costs as well as the operating lease right of use assets and lease liabilities recorded in connection with our adoption of ASC Topic 842. December 31, 2019 2018 (In thousands) RECONCILIATION OF CASH, CASH EQUIVALENTS, AND RESTRICTED CASH: Cash and cash equivalents $ 127,432 $ 64,087 Restricted cash (1) 26,182 44,245 Total cash, cash equivalents, and restricted cash $ 153,614 $ 108,332 (1) Restricted cash balances are included in "prepaid expenses and other assets" on our consolidated balance sheets.

Real Estate

Real Estate	12 Months Ended
	Dec. 31, 2019
Real Estate [Abstract]
REAL ESTATE	2019 Property Dispositions On December 11, 2019 , w e received $154.7 million in net proceeds related to the sale under the threat of condemnation of 11.7 acres of San Antonio Center to a local school district ("the condemning authority"). As part of the transaction, the condemning authority will commence condemnation proceedings in order to terminate all existing leases they assumed at closing. We have indemnified the condemning authority for all costs incurred related to the condemnation proceedings including any payments required to tenants at the property and expect the process will take several years to complete. The consideration in the transaction is considered variable because we have agreed to indemnify the condemning authority for these costs. Consequently, we have recorded a liability of $45.5 million to reflect our estimate of the final consideration, net of estimated condemnation proceeding costs and other transaction related costs. The resulting net gain on sale is approximately $85.1 million . During the year ended December 31, 2019 , we sold three properties and one land parcel for a net sales price of $149.0 million , which resulted in a net gain of $28.3 million . During the year ended December 31, 2019 , we closed on the sale of 43 condominium units at our Assembly Row and Pike & Rose properties (combined), received proceeds net of closing costs of $20.1 million , and recognized a gain of $2.6 million , net of income taxes. The cost basis for the remaining condominium units as of December 31, 2019 is $1.7 million , and is included in "assets held for sale" on our consolidated balance sheet. 2018 Property Acquisitions and Dispositions On June 15, 2018 , we formed a new joint venture to develop Freedom Plaza (formerly known as Jordan Downs Plaza) which, when completed, will be an approximately 113,000 square foot grocery anchored shopping center located in Los Angeles County, California. We initially invested $34.4 million as a result of a pre-funding requirement for equity to be advanced prior to the start of construction. We own approximately 91% of the venture, and control the 9.4 acre land parcel on which the shopping center will be constructed under a long-term ground lease that expires June 15, 2093 (including two 10-year option periods which may be exercised at our option). The Freedom Plaza development is expected to generate income tax credits under the New Market Tax Credit Program ("NMTC") which was provided for in the Community Renewal Tax Relief Act of 2000 ("the Act") and is intended to induce investment in underserved areas of the United States. The Act permits taxpayers to claim credits against their Federal income taxes for qualified investments. A third party bank contributed $13.9 million to the development, and is entitled to the related tax credit benefits, but they do not have an interest in the underlying economics of the property. The transaction also includes a put/call provision whereby we may be obligated or entitled to purchase the third party bank’s interest. We believe the put will be exercised at its $1,000 strike price. Based on our assessment of control, we concluded that the project and certain other transaction related entities should be consolidated. The $13.9 million in proceeds received in exchange for the transfer of the tax credits has been deferred and will be recognized when the tax benefits are delivered to the third party bank without risk of recapture. Direct and incremental costs of $1.6 million incurred in structuring the NMTC transaction have also been deferred. The Trust anticipates recognizing the net cash received as revenue upon completion of the seven-year NMTC compliance period. Cash in escrow at December 31, 2019 of $12.6 million , reflects remaining cash that will ultimately be used for the development of the shopping center, and is included in "prepaid expenses and other assets" on our consolidated balance sheets. The cash is held in escrow pursuant to the new market tax credit transaction documents and will be released as qualified development expenditures are incurred. In August 2018 , we contributed hotel related assets valued at $44.0 million to our Assembly Row hotel joint venture, and received a cash distribution of $38.0 million . At December 31, 2019 , our investment in the venture was $3.2 million . The joint venture is considered a variable interest entity controlled by our partner, and as a result, we are using the equity method to account for our investment. During the year ended December 31, 2018, we sold two properties for a net sales price of $42.2 million , which resulted in a net gain of $4.7 million . On November 29, 2018 , we acquired a 40,000 square foot building adjacent to our Bell Gardens property for $9.6 million . During the year ended December 31, 2018 , we closed on the sale of 176 condominium units at our Assembly Row and Pike & Rose properties (combined) and received proceeds net of closing costs of $133.5 million , For the year ended December 31, 2018 , we recognized a gain of $7.2 million , net of $1.6 million of income taxes. The cost basis for remaining condominium units that were ready for their intended use as of December 31, 2018 was $16.6 million , and is included in "assets held for sale" on our consolidated balance sheet.

Acquired In-Place Leases

Acquired In-Place Leases	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
ACQUIRED IN-PLACE LEASES	ACQUIRED IN-PLACE LEASES Acquired lease assets comprise above market leases where we are the lessor and below market leases where we are the lessee. Acquired lease liabilities comprise below market leases where we are the lessor and above market leases where we are the lessee. As a lessor, acquired above market leases are included in prepaid expenses and other assets, and acquired below market leases are included in other liabilities and deferred credits. In accordance with our adoption of ASC Topic 842, acquired below market leases and acquired above market leases where we are the lessee are included in right of use assets. The following is a summary of our acquired lease assets and liabilities: December 31, 2019 December 31, 2018 Cost Accumulated Amortization Cost Accumulated Amortization (in thousands) Above market leases, lessor $ 48,530 $ (32,833 ) $ 49,128 $ (33,843 ) Below market leases, lessee 34,604 (3,362 ) 34,604 (2,533 ) Total $ 83,134 $ (36,195 ) $ 83,732 $ (36,376 ) Below market leases, lessor $ (177,512 ) $ 66,419 $ (189,379 ) $ 65,408 Above market leases, lessee (9,084 ) 1,590 (9,084 ) 1,065 Total $ (186,596 ) $ 68,009 $ (198,463 ) $ 66,473 The value allocated to in-place leases where we are the lessor is amortized over the related lease term and reflected as additional rental income for below market leases or a reduction of rental income for above market leases in the consolidated statements of comprehensive income. The related amortization of in-place leases where we are the lessee is reflected as additional rental expense for below market leases or a reduction of rental expenses for above market leases in the consolidated statements of comprehensive income. The following is a summary of acquired lease amortization: Year Ended December 31, 2019 2018 2017 (in thousands) Amortization of above market leases, lessor $ (3,239 ) $ (5,608 ) $ (6,005 ) Amortization of below market leases, lessor 9,623 12,445 10,726 Net increase in rental income $ 6,384 $ 6,837 $ 4,721 Amortization of below market leases, lessee $ 828 $ 828 $ 781 Amortization of above market leases, lessee (525 ) (505 ) (290 ) Net increase in rental expense $ 303 $ 323 $ 491 The following is a summary of the remaining weighted average amortization period for our acquired lease assets and acquired lease liabilities: December 31, 2019 Above market leases, lessor 3.7 years Below market leases, lessee 39.6 years Below market leases, lessor 18.1 years Above market leases, lessee 14.4 years The amortization for acquired in-place leases during the next five years and thereafter, assuming no early lease terminations, is as follows: Acquired Lease Assets Acquired Lease Liabilities (In thousands) Year ending December 31, 2020 $ 4,350 $ 8,235 2021 3,370 7,687 2022 2,716 7,394 2023 2,488 7,134 2024 2,223 6,603 Thereafter 31,792 81,534 $ 46,939 $ 118,587

Debt

Debt	12 Months Ended
	Dec. 31, 2019
Debt Instruments [Abstract]
DEBT	DEBT The following is a summary of our total debt outstanding as of December 31, 2019 and 2018 : Principal Balance as of December 31, Stated Interest Rate as of Stated Maturity Date as of Description of Debt 2019 2018 December 31, 2019 December 31, 2019 Mortgages payable (Dollars in thousands) Rollingwood Apartments $ — $ 20,331 5.54 % May 1, 2019 The Shops at Sunset Place 61,987 64,453 5.62 % September 1, 2020 29th Place 3,878 4,117 5.91 % January 31, 2021 Sylmar Towne Center 16,630 17,006 5.39 % June 6, 2021 Plaza Del Sol 8,230 8,409 5.23 % December 1, 2021 THE AVENUE at White Marsh 52,705 52,705 3.35 % January 1, 2022 Montrose Crossing 67,492 69,310 4.20 % January 10, 2022 Azalea 40,000 40,000 3.73 % November 1, 2025 Bell Gardens 12,677 12,936 4.06 % August 1, 2026 Plaza El Segundo 125,000 125,000 3.83 % June 5, 2027 The Grove at Shrewsbury (East) 43,600 43,600 3.77 % September 1, 2027 Brook 35 11,500 11,500 4.65 % July 1, 2029 Hoboken (24 Buildings) 56,450 — LIBOR + 1.95% December 15, 2029 Various Hoboken (12 Buildings) 24,627 — Various (1) Various through 2029 Chelsea 5,597 5,941 5.36 % January 15, 2031 Hoboken (1 Building) 16,874 — 3.75 % July 1, 2042 Subtotal 547,247 475,308 Net unamortized premium and debt issuance costs (1,568 ) (929 ) Total mortgages payable 545,679 474,379 Notes payable Term loan — 275,000 LIBOR + 0.90% November 21, 2019 Revolving credit facility — — LIBOR + 0.775% January 19, 2024 Various 3,843 4,392 11.31 % Various through 2028 Subtotal 3,843 279,392 Net unamortized debt issuance costs (62 ) (365 ) Total notes payable 3,781 279,027 Senior notes and debentures 2.55% notes 250,000 250,000 2.55 % January 15, 2021 3.00% notes 250,000 250,000 3.00 % August 1, 2022 2.75% notes 275,000 275,000 2.75 % June 1, 2023 3.95% notes 300,000 300,000 3.95 % January 15, 2024 7.48% debentures 29,200 29,200 7.48 % August 15, 2026 3.25% notes 475,000 475,000 3.25 % July 15, 2027 6.82% medium term notes 40,000 40,000 6.82 % August 1, 2027 3.20% notes 400,000 — 3.20 % June 15, 2029 4.50% notes 550,000 550,000 4.50 % December 1, 2044 3.625% notes 250,000 250,000 3.625 % August 1, 2046 Subtotal 2,819,200 2,419,200 Net unamortized discount and debt issuance costs (12,066 ) (14,921 ) Total senior notes and debentures 2,807,134 2,404,279 Various — 71,519 Various Various through 2106 Total debt and capital lease obligations $ 3,356,594 $ 3,229,204 _____________________ 1) The interest rates on these mortgages range from 3.91% to 5.00% . On January 31, 2019 , we repaid the $20.3 million mortgage loan on Rollingwood Apartments, at par, prior to its original maturity date. On June 7, 2019 , we issued $300.0 million of fixed rate senior unsecured notes that mature on June 15, 2029 and bear interest at 3.20% . The notes were offered at 99.838% of the principal amount with a yield to maturity of 3.219% . On August 21, 2019 , we issued an additional $100.0 million senior notes of the same series and with the same terms. The August notes were offered at 103.813% of the principal amount, with a yield to maturity of 2.744% . The combined net proceeds from the note offerings after net issuance premium, underwriting fees, and other costs were $399.9 million , which were primarily used to repay our $275.0 million unsecured term loan, at par, on June 7, 2019 and for general corporate purposes. On July 25, 2019 , we amended our revolving credit facility to increase our borrowing capacity to $1.0 billion and extend the maturity date to January 19, 2024, plus two six-month extensions at our option. Under the amended facility, the spread over LIBOR is 77.5 basis points based on our current credit rating. In addition, we have an option (subject to bank approval) to increase the credit facility through an accordion feature to $1.5 billion . During 2019 , 2018 and 2017 , the maximum amount of borrowings outstanding under our revolving credit facility was $116.5 million , $177.0 million and $344.0 million , respectively. The weighted average amount of borrowings outstanding was $26.8 million , $83.1 million and $147.5 million , respectively, and the weighted average interest rate, before amortization of debt fees, was 3.2% , 2.7% and 1.9% , respectively. The revolving credit facility requires an annual facility fee of $1.0 million . At December 31, 2019 and 2018 , our revolving credit facility had no balance outstanding. In connection with our Hoboken, New Jersey acquisitions in 2019 , we assumed mortgage loans with a face amount of $41.6 million and a fair value of $42.9 million , and entered into a new mortgage loan with a face amount of $56.5 million . The mortgage loans associated with our Hoboken acquisitions have the following contractual terms: Principal Stated Interest Rate Maturity Date (in millions) September 18, 2019 (date assumed) $ 17.0 3.75 % July 1, 2042 November 26, 2019 (date originated) $ 56.5 LIBOR + 1.95% (1) December 15, 2029 November 26, 2019 (date assumed) $ 5.7 Various (2) Various (2) December 19, 2019 (date assumed) $ 18.9 Various (3) Various (3) _____________________ (1) The interest rate is effectively fixed at 3.67% as a result of two interest rate swap agreements. (2) The interest rates on these mortgages range from 3.91% to 5.00% and have maturity dates ranging from January 9, 2025 to May 31, 2029. (3) The interests rates on these mortgages range from 4.00% to 4.38% and have maturity dates ranging from October 1, 2025 to July 1, 2026. Our revolving credit facility and certain notes require us to comply with various financial covenants, including the maintenance of minimum shareholders’ equity and debt coverage ratios and a maximum ratio of debt to net worth. As of December 31, 2019 , we were in compliance with all default related debt covenants. Scheduled principal payments on mortgages payable, notes payable, senior notes and debentures as of December 31, 2019 are as follows: Mortgages Payable Notes Payable Senior Notes and Debentures Total Principal (In thousands) Year ending December 31, 2020 $ 66,252 $ 613 $ — $ 66,865 2021 31,519 680 250,000 282,199 2022 119,460 756 250,000 370,216 2023 3,293 775 275,000 279,068 2024 3,421 665 (1) 300,000 304,086 Thereafter 323,302 354 1,744,200 2,067,856 $ 547,247 $ 3,843 $ 2,819,200 $ 3,370,290 (2) _____________________ (1) Our $1.0 billion revolving credit facility matures on January 19, 2024 , plus two six-month extensions at our option. As of December 31, 2019 , there was no outstanding balance under this credit facility. (2) The total debt maturities differ from the total reported on the consolidated balance sheet due to the unamortized net premium/discount and debt issuance costs on mortgage loans, notes payable, and senior notes as of December 31, 2019 .

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	NOTE 6 —FAIR VALUE OF FINANCIAL INSTRUMENTS A fair value measurement is based on the assumptions that market participants would use in pricing an asset or liability in an orderly transaction. The hierarchy for inputs used in measuring fair value are as follows: 1. Level 1 Inputs—quoted prices in active markets for identical assets or liabilities 2. Level 2 Inputs—observable inputs other than quoted prices in active markets for identical assets and liabilities 3. Level 3 Inputs—prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, for disclosure purposes, the level within which the fair value measurement is categorized is based on the lowest level input that is significant to the fair value measurement. Except as disclosed below, the carrying amount of our financial instruments approximates their fair value. The fair value of our mortgages payable, notes payable and senior notes and debentures is sensitive to fluctuations in interest rates. Quoted market prices (Level 1) were used to estimate the fair value of our marketable senior notes and debentures and discounted cash flow analysis (Level 2) is generally used to estimate the fair value of our mortgages and notes payable. Considerable judgment is necessary to estimate the fair value of financial instruments. The estimates of fair value presented herein are not necessarily indicative of the amounts that could be realized upon disposition of the financial instruments. A summary of the carrying amount and fair value of our mortgages payable, notes payable and senior notes and debentures is as follows: December 31, 2019 December 31, 2018 Carrying Value Fair Value Carrying Value Fair Value (In thousands) Mortgages and notes payable $ 549,460 $ 562,049 $ 753,406 $ 751,361 Senior notes and debentures $ 2,807,134 $ 3,001,216 $ 2,404,279 $ 2,371,392 During 2019 , we entered into two interest rate swap agreements with notional amounts of $56.5 million that are measured at fair value on a recurring basis. The interest rate swap agreements fix the interest rate on $56.5 million of mortgage payables associated with our Hoboken acquisition at 3.67% through December 15, 2029 . The fair values of the interest rate swap agreements 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 interest rate related observable inputs. The fair value of our swaps at December 31, 2019 was an asset of $0.1 million and is included in "prepaid expenses and other assets" on our consolidated balance sheet. During 2019 , we reclassified less than $0.1 million from other comprehensive income as an increase to interest expense. A summary of our financial assets that are measured at fair value on a recurring basis, by level within the fair value hierarchy is as follows: December 31, 2019 December 31, 2018 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (In thousands) Interest rate swaps $ — $ 130 $ — $ 130 $ — $ — $ — $ — One of our equity method investees has two interest rate swaps which qualify as cash flow hedges. At December 31, 2019 and December 31, 2018, our share of the decrease in fair value of the related swaps included in "accumulated other comprehensive loss" was $0.9 million and $0.4 million , respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES We are sometimes involved in lawsuits, warranty claims, and environmental matters arising in the ordinary course of business. Management makes assumptions and estimates concerning the likelihood and amount of any potential loss relating to these matters. We are currently a party to various legal proceedings. We accrue a liability for litigation if an unfavorable outcome is probable and the amount of loss can be reasonably estimated. If an unfavorable outcome is probable and a reasonable estimate of the loss is a range, we accrue the best estimate within the range; however, if no amount within the range is a better estimate than any other amount, the minimum within the range is accrued. Legal fees related to litigation are expensed as incurred. Other than as described below, we do not believe that the ultimate outcome of these matters, either individually or in the aggregate, could have a material adverse effect on our financial position or overall trends in results of operations; however, litigation is subject to inherent uncertainties. Also under our leases, tenants are typically obligated to indemnify us from and against all liabilities, costs and expenses imposed upon or asserted against us (1) as owner of the properties due to certain matters relating to the operation of the properties by the tenant, and (2) where appropriate, due to certain matters relating to the ownership of the properties prior to their acquisition by us. We are self-insured for general liability costs up to predetermined retained amounts per claim, and we believe that we maintain adequate accruals to cover our retained liability. We currently do not maintain third party stop-loss insurance policies to cover liability costs in excess of predetermined retained amounts. Our accrual for self-insurance liability is determined by management and is based on claims filed and an estimate of claims incurred but not yet reported. Management considers a number of factors, including third-party actuarial analysis, previous experience in our portfolio, and future increases in costs of claims, when making these determinations. If our liability costs exceed these accruals, it will reduce our net income. We reserve for estimated losses, if any, associated with warranties given to a buyer at the time real estate is sold or other potential liabilities relating to that sale, taking any insurance policies into account. These warranties may extend up to ten years and require significant judgment. If changes in facts and circumstances indicate that warranty reserves are understated, we will accrue additional reserves at such time a liability has been incurred and the costs can be reasonably estimated. Warranty reserves are released once the legal liability period has expired or all related work has been substantially completed. At December 31, 2019 and 2018 , our reserves for general liability costs were $3.0 million and $3.1 million , respectively, and are included in “accounts payable and accrued expenses” in our consolidated balance sheets. Any potential losses which exceed our estimates would result in a decrease in our net income. During 2019 and 2018 , we made payments from these reserves of $1.3 million and $1.4 million , respectively. Although we consider the reserve to be adequate, there can be no assurance that the reserve will prove to be adequate over-time to cover losses due to the difference between the assumptions used to estimate the reserve and actual losses. At December 31, 2019 , we had letters of credit outstanding of approximately $4.3 million . As of December 31, 2019 in connection with capital improvement, development, and redevelopment projects, the Trust has contractual obligations of approximately $572.4 million . Future minimum lease payments and their present value for properties under finance leases as of December 31, 2019 , are as follows: (In thousands) Year ending December 31, 2020 $ 5,800 2021 5,800 2022 5,810 2023 60,013 2024 1,013 Thereafter 81,849 160,285 Less amount representing interest (88,808 ) Add straight line lease obligation 585 Present value $ 72,062 We are obligated under operating lease agreements on several shopping centers requiring minimum annual payments as follows, as of December 31, 2019 : (In thousands) Year ending December 31, 2020 $ 4,824 2021 4,832 2022 4,948 2023 4,988 2024 4,951 Thereafter 179,896 $ 204,439 A master lease for Mercer Mall includes a fixed purchase price option for $55 million in 2023 . If we fail to exercise our purchase option, the owner of Mercer Mall has a put option which would require us to purchase Mercer Mall for $60 million in 2025 . Under the terms of the Congressional Plaza partnership agreement, a minority partner has the right to require us and the other minority partner to purchase its 26.63% interest in Congressional Plaza at the interest’s then-current fair market value. If the other minority partner defaults in their obligation, we must purchase the full interest. Based on management’s current estimate of fair market value as of December 31, 2019 , our estimated maximum liability upon exercise of the put option would range from approximately $79 million to $84 million . A master lease for Melville Mall includes a fixed purchase price option in 2021 for $5 million . If we fail to exercise our purchase option, the owner of Melville Mall has a put option which would require us to purchase Melville Mall in 2023 for $5 million . Two of the members in Plaza El Segundo have the right to require us to purchase their 10.0% and 11.8% ownership interests at the interests' then-current fair market value. If the members fail to exercise their put options, we have the right to purchase each of their interests on or after December 30, 2026 at fair market value. Based on management’s current estimate of fair market value as of December 31, 2019 , our estimated maximum liability upon exercise of the put option would range from approximately $30 million to $33 million . The other member in The Grove at Shrewsbury and Brook 35 has the right to require us to purchase all of its approximately 4.1% interest in The Grove at Shrewsbury and approximately 6.5% interest in Brook 35 at the interests' then-current fair market value. Based on management's current estimate of fair market value as of December 31, 2019 , our estimated maximum liability upon exercise of the put option would range from $7 million to $8 million . Effective September 18, 2023, the other member in Hoboken has the right to require us to purchase all of its 10.0% ownership interest at the interest's then-current fair market value. Based on management's current estimate of fair market value as of December 31, 2019 , our estimated maximum liability upon exercise of the put option would range from $9 million to $10 million . Under the terms of certain partnership agreements, the partners have the right to exchange their operating partnership units for cash or the same number of our common shares, at our option. A total of 609,584 downREIT operating partnership units are outstanding which have a total fair value of $78.5 million , based on our closing stock price on December 31, 2019 .

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
SHAREHOLDERS’ EQUITY	SHAREHOLDERS’ EQUITY We have a Dividend Reinvestment Plan (the “Plan”), whereby shareholders may use their dividends and optional cash payments to purchase shares. In 2019 , 2018 and 2017 , 15,909 shares, 17,952 shares and 17,911 shares, respectively, were issued under the Plan. On September 29, 2017 , we issued 6,000,000 Depositary Shares, each representing 1/1000th interest of 5.0% Series C Cumulative Redeemable Preferred Share, par value $0.01 per share ("Series C Preferred Shares"), at the liquidation preference of $25.00 per depositary share (or $25,000 per Series C Preferred share) in an underwritten public offering, which were outstanding as of December 31, 2019 , 2018 , and 2017. The Series C Preferred Shares accrue dividends at a rate of 5.0% of the $25,000 liquidation preference per year and are redeemable at our option on or after September 29, 2022 . Additionally, they are not convertible and holders of these shares generally have no voting rights, unless we fail to pay dividends for six or more quarters. The net proceeds after underwriting fees and other costs were approximately $145.0 million for the year ended December 31, 2017. As of December 31, 2019 , 2018 , and 2017 , we had 399,896 shares of 5.417% Series 1 Cumulative Convertible Preferred Shares (“Series 1 Preferred Shares”) outstanding that have a liquidation preference of $25 per share and par value $0.01 per share. The Series 1 Preferred Shares accrue dividends at a rate of 5.417% per year and are convertible at any time by the holders to our common shares at a conversion rate of $104.69 per share. The Series 1 Preferred Shares are also convertible under certain circumstances at our election. The holders of the Series 1 Preferred Shares have no voting rights. On May 7, 2018, we replaced our existing at-the-market (“ATM”) equity program with a new ATM equity program in which we may from time to time offer and sell common shares having an aggregate offering price of up to $400.0 million . We intend to use the net proceeds to fund potential acquisition opportunities, fund our development and redevelopment pipeline, repay amounts of outstanding under our revolving credit facility and/or for general corporate purposes. For the year ended December 31, 2019 , we issued 1,069,699 common shares at a weighted average price per share of $134.71 for net cash proceeds of $142.7 million and paid $1.2 million in commissions and $0.2 million in additional offering expenses related to the sales of these common shares. For the year ended December 31, 2018 , we issued 987,383 common shares at a weighted average price per share of $129.19 for net cash proceeds of $126.1 million and paid $1.3 million in commissions and $0.2 million in additional offering expenses related to the sales of these common shares. As of December 31, 2019 , we had the capacity to issue up to $128.3 million in common shares under our ATM equity program.

Dividends

Dividends	12 Months Ended
	Dec. 31, 2019
Dividends [Abstract]
DIVIDENDS	DIVIDENDS The following table provides a summary of dividends declared and paid per share: Year Ended December 31, 2019 2018 2017 Declared Paid Declared Paid Declared Paid Common shares $ 4.140 $ 4.110 $ 4.040 $ 4.020 $ 3.960 $ 3.940 5.417% Series 1 Cumulative Convertible Preferred shares $ 1.354 $ 1.354 $ 1.354 $ 1.354 $ 1.354 $ 1.354 5.0% Series C Cumulative Redeemable Preferred shares (1) $ 1.250 $ 1.250 $ 1.250 $ 1.306 $ 0.368 $ — (1) Amount represents dividends per depositary share, each representing 1/1000th of a share. A summary of the income tax status of dividends per share paid is as follows: Year Ended December 31, 2019 2018 2017 Common shares Ordinary dividend $ 4.110 $ 3.859 $ 3.940 Ordinary dividend eligible for 15% rate — 0.161 — $ 4.110 $ 4.020 $ 3.940 5.417% Series 1 Cumulative Convertible Preferred shares Ordinary dividend $ 1.354 $ 1.300 $ 1.354 Ordinary dividend eligible for 15% rate — 0.054 — $ 1.354 $ 1.354 $ 1.354 5.0% Series C Cumulative Redeemable Preferred shares Ordinary dividend $ 1.250 $ 1.254 $ — Ordinary dividend eligible for 15% rate — 0.052 $ — $ 1.250 $ 1.306 $ — On October 30, 2019 , the Trustees declared a quarterly cash dividend of $1.05 per common share, payable January 15, 2020 to common shareholders of record on January 2, 2020 .

Operating Leases

Operating Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
OPERATING LEASES	OPERATING LEASES At December 31, 2019 , our 104 predominantly retail shopping center and mixed-use properties are located in 12 states and the District of Columbia. There are approximately 3,000 commercial leases and 2,700 residential leases. Our commercial tenants range from sole proprietorships to national retailers and corporations. At December 31, 2019 , no one tenant or corporate group of tenants accounted for more than 2.6% of annualized base rent. Our leases with commercial property and residential tenants are classified as operating leases. Commercial property leases generally range from three to ten years (certain leases with anchor tenants may be longer), and in addition to minimum rents, may provide for percentage rents based on the tenant’s level of sales achieved and cost recoveries for the tenant’s share of certain operating costs. Leases on apartments are generally for a period of 1 year or less. As of December 31, 2019 , future minimum rentals from noncancelable commercial operating leases (excluding both tenant reimbursements of operating expenses and percentage rent based on tenants' sales) are as follows: (In thousands) Year ending December 31, 2020 $ 616,760 2021 565,835 2022 498,438 2023 422,729 2024 352,221 Thereafter 1,528,699 $ 3,984,682

Components Of Rental Expense

Components Of Rental Expense	12 Months Ended
	Dec. 31, 2019
Components Of Rental Expense [Abstract]
COMPONENTS OF RENTAL EXPENSE	COMPONENTS OF RENTAL EXPENSE The principal components of rental expenses are as follows: Year Ended December 31, 2019 2018 2017 (In thousands) Repairs and maintenance $ 73,179 $ 67,745 $ 67,996 Utilities 27,729 27,635 25,763 Management fees and costs 24,930 24,024 22,297 Payroll 16,485 16,140 14,922 Insurance 9,036 7,547 7,762 Marketing 7,427 7,935 9,007 Ground rent 4,803 4,697 3,826 Bad debt (1) — 4,708 2,591 Other operating (2) 24,242 12,663 10,726 Total rental expenses $ 187,831 $ 173,094 $ 164,890 _____________________ (1) Collectibility adjustments are now presented as a reduction of rental income rather than rental expense in accordance with our adoption of the new lease standard (see Note 2 for additional disclosure). (2) Other operating for the year ended December 31, 2019 includes an $11.9 million charge relating to the buyout of a lease at Assembly Square Marketplace.

Share-Based Compensation Plans

Share-Based Compensation Plans	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
SHARE-BASED COMPENSATION PLANS	SHARE-BASED COMPENSATION PLANS A summary of share-based compensation expense included in net income is as follows: Year Ended December 31, 2019 2018 2017 (In thousands) Grants of common shares and options $ 13,330 $ 12,736 $ 12,371 Capitalized share-based compensation (1,054 ) (1,017 ) (1,385 ) Share-based compensation expense $ 12,276 $ 11,719 $ 10,986 We have grants outstanding under our shareholder approved 2010 Performance Incentive Plan, as amended (the "2010 Plan”), which authorized the grant of share options, common shares and other share-based awards for up to 2,450,000 common shares of beneficial interest. Option awards under the plan are required to have an exercise price at least equal to the closing trading price of our common shares on the date of grant. Options and restricted share awards under the plan generally vest over three to seven years and option awards typically have a ten -year contractual term. We pay dividends on unvested shares. Certain options and share awards provide for accelerated vesting if there is a change in control. Additionally, the vesting on certain option and share awards can accelerate in part or in full upon retirement based on the age of the retiree or upon termination without cause. The fair value of each option award is estimated on the date of grant using the Black-Scholes model. Expected volatilities, term, dividend yields, employee exercises and estimated forfeitures are primarily based on historical data. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. The fair value of each share award is determined based on the closing trading price of our common shares on the grant date. No options were granted in 2019 and 2017 . The following table provides a summary of the assumptions used to value options granted in 2018: Year Ended December 31, 2018 Volatility 18.0 % Expected dividend yield 3.6 % Expected term (in years) 7.5 Risk free interest rate 2.8 % The following table provides a summary of option activity for 2019 : Shares Under Option Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value (In years) (In thousands) Outstanding at December 31, 2018 682 $ 152.34 Granted — — Exercised — — Forfeited or expired — — Outstanding at December 31, 2019 682 $ 152.34 6.1 $ — Exercisable at December 31, 2019 409 $ 152.34 6.1 $ — The weighted-average grant-date fair value of options granted in 2018 was $14.42 per share, which were later forfeited during 2018. The total cash received from options exercised during 2018 and 2017 was $4.6 million and $10.0 million , respectively. The total intrinsic value of options exercised during the years ended December 31, 2018 and 2017 was $8.2 million and $10.7 million , respectively. The following table provides a summary of restricted share activity for 2019 : Shares Weighted-Average Grant-Date Fair Value Unvested at December 31, 2018 206,100 $ 130.46 Granted 122,056 133.30 Vested (97,077 ) 133.35 Forfeited (10,501 ) 151.22 Unvested at December 31, 2019 220,578 $ 129.78 The weighted-average grant-date fair value of stock awarded in 2019 , 2018 and 2017 was $133.30 , $112.88 and $139.31 , respectively. The total vesting-date fair value of shares vested during the year ended December 31, 2019 , 2018 and 2017 , was $13.0 million , $9.7 million and $12.5 million , respectively. As of December 31, 2019 , there was $17.1 million of total unrecognized compensation cost related to unvested share-based compensation arrangements (i.e. options and unvested shares) granted under our plans. This cost is expected to be recognized over the next 4.9 years with a weighted-average period of 2.4 years . Subsequent to December 31, 2019 , common shares were awarded under various compensation plans as follows: Date Award Vesting Term Beneficiary January 2, 2020 5,591 Shares Immediate Trustees February 4, 2020 101,981 Restricted Shares 1-7 years Officers and key employees

Savings and Retirement Plans

Savings and Retirement Plans	12 Months Ended
	Dec. 31, 2019
Savings and Retirement Plans [Abstract]
SAVINGS AND RETIREMENT PLANS	SAVINGS AND RETIREMENT PLANS We have a savings and retirement plan in accordance with the provisions of Section 401(k) of the Code. Generally, employees can elect, at their discretion, to contribute a portion of their compensation up to a maximum of $19,000 for 2019 , $18,500 for 2018 , and 18,000 for 2017 . Under the plan, we contribute 50% of each employee’s elective deferrals up to 5% of eligible earnings. In addition, we may make discretionary contributions within the limits of deductibility set forth by the Code. Our full-time employees are immediately eligible to become plan participants. Employees are eligible to receive matching contributions immediately on their participation; however, these matching payments will not vest until their third anniversary of employment. Our expense for the years ended December 31, 2019 , 2018 and 2017 was approximately $764,000 , $688,000 and $632,000 , respectively. A non-qualified deferred compensation plan for our officers and certain other employees was established in 1994 that allows the participants to defer a portion of their income. As of December 31, 2019 and 2018 , we are liable to participants for approximately $14.7 million and $12.0 million , respectively, under this plan. Although this is an unfunded plan, we have purchased certain investments to match this obligation. Our obligation under this plan and the related investments are both included in the accompanying consolidated financial statements.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE We have calculated earnings per share (“EPS”) under the two-class method. The two-class method is an earnings allocation methodology whereby EPS for each class of common stock and participating securities is calculated according to dividends declared and participation rights in undistributed earnings. For 2019 , 2018 , and 2017 we had 0.2 million weighted average unvested shares outstanding, which are considered participating securities. Therefore, we have allocated our earnings for basic and diluted EPS between common shares and unvested shares; the portion of earnings allocated to the unvested shares is reflected as “earnings allocated to unvested shares” in the reconciliation below. In the dilutive EPS calculation, dilutive stock options were calculated using the treasury stock method consistent with prior periods. There were 682 anti-dilutive stock options in 2019 , 2018 , and 2017 , respectively. The conversions of downREIT operating partnership units and 5.417% Series 1 Cumulative Convertible Preferred Shares are anti-dilutive for all periods presented and accordingly, have been excluded from the weighted average common shares used to compute diluted EPS. Year Ended December 31, 2019 2018 2017 (In thousands, except per share data) NUMERATOR Net income $ 360,542 $ 249,026 $ 297,870 Less: Preferred share dividends (8,042 ) (8,042 ) (2,458 ) Less: Income from operations attributable to noncontrolling interests (6,676 ) (7,119 ) (7,956 ) Less: Earnings allocated to unvested shares (1,007 ) (930 ) (942 ) Net income available for common shareholders, basic and diluted $ 344,817 $ 232,935 $ 286,514 DENOMINATOR Weighted average common shares outstanding—basic 74,766 73,274 72,117 Stock options — 28 116 Weighted average common shares outstanding—diluted 74,766 73,302 72,233 EARNINGS PER COMMON SHARE, BASIC Net income available for common shareholders $ 4.61 $ 3.18 $ 3.97 EARNINGS PER COMMON SHARE, DILUTED Net income available for common shareholders $ 4.61 $ 3.18 $ 3.97

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)	SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) Summarized quarterly financial data is as follows: First Quarter Second Quarter Third Quarter Fourth Quarter (In thousands, except per share data) 2019 Revenue $ 232,227 $ 230,465 $ 233,947 $ 239,149 Operating income (1) $ 91,093 $ 109,579 $ 94,018 $ 176,221 Net income (1) $ 61,803 $ 82,667 $ 67,106 $ 148,966 Net income attributable to the Trust (1) $ 60,144 $ 80,902 $ 65,465 $ 147,355 Net income available for common shareholders (1) $ 58,134 $ 78,891 $ 63,455 $ 145,344 Earnings per common share—basic (1) $ 0.78 $ 1.05 $ 0.84 $ 1.92 Earnings per common share—diluted (1) $ 0.78 $ 1.05 $ 0.84 $ 1.92 First Quarter Second Quarter Third Quarter Fourth Quarter (In thousands, except per share data) 2018 Revenue $ 225,405 $ 224,902 $ 229,753 $ 235,376 Operating income (2) $ 89,461 $ 93,868 $ 93,467 $ 84,840 Net income (2) $ 62,931 $ 65,533 $ 64,180 $ 56,382 Net income attributable to the Trust (2) $ 61,247 $ 63,595 $ 62,558 $ 54,507 Net income available for common shareholders (2) $ 59,237 $ 61,584 $ 60,548 $ 52,496 Earnings per common share—basic (2) $ 0.81 $ 0.84 $ 0.82 $ 0.71 Earnings per common share—diluted (2) $ 0.81 $ 0.84 $ 0.82 $ 0.71 (1) Second and third quarter 2019 include net gains of $16.2 million and $14.3 million , respectively, related to the sale of two properties and one parcel of land, as well as condominiums sold at our Assembly Row and Pike & Rose properties. Third quarter 2019 also includes an $11.9 million charge related to the buyout of a lease at Assembly Square Marketplace. Fourth quarter 2019 includes an $85.1 million net gain on sale under the threat of condemnation of a portion of San Antonio Center . All of these transactions are further discussed in Note 3. (2) First and second quarter 2018 include net gains of $3.3 million and $4.0 million , respectively, related to condominiums sold at our Assembly Row and Pike & Rose properties. Third and fourth quarter 2018 include gains of $3.1 million and $1.6 million , respectively, related to the sale of one residential building and one property. All of these transactions are further discussed in Note 3.

Subsequent Event (Notes)

Subsequent Event (Notes)	12 Months Ended
	Dec. 31, 2019
Subsequent Event [Line Items]
Subsequent Event	SUBSEQUENT EVENT On January 10, 2020 , we acquired a 49,000 square foot shopping center in Fairfax, Virginia for $22.3 million . This acquisition was funded by 163,322 downREIT operating partnership units.

Schedule III - Summary of Real

Schedule III - Summary of Real Estate and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Schedule III - Summary of Real Estate and Accumulated Depreciation	FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total 29TH PLACE (Virginia) $ 3,868 $ 10,211 $ 18,863 $ 11,985 $ 10,195 $ 30,864 $ 41,059 $ 14,953 1975 - 2001 5/30/2007 (1) ANDORRA (Pennsylvania) 2,432 12,346 11,718 2,432 24,064 26,496 20,382 1953 1/12/1988 (1) ASSEMBLY ROW/ASSEMBLY SQUARE MARKETPLACE (Massachusetts) 93,252 34,196 662,720 69,421 720,747 790,168 72,687 2005, 2012-2019 2005-2013 (1) AZALEA (California) 39,702 40,219 67,117 (3 ) 40,219 67,114 107,333 6,109 2014 8/2/2017 (1) BALA CYNWYD (Pennsylvania) 3,565 14,466 39,175 2,683 54,523 57,206 23,062 1955 9/22/1993 (1) BARCROFT PLAZA (Virginia) 12,617 29,603 6,515 12,617 36,118 48,735 4,513 1963, 1972, 1990, & 2000 1/13/16 & 11/7/16 (1) BARRACKS ROAD (Virginia) 4,363 16,459 48,764 4,363 65,223 69,586 47,069 1958 12/31/1985 (1) BELL GARDENS (California) 12,292 24,406 85,947 589 24,406 86,536 110,942 10,215 1990, 2003, 2006 8/2/17 & 11/29/18 (1) BETHESDA ROW (Maryland) 46,579 35,406 151,640 43,904 189,721 233,625 85,602 1945-2008 12/31/93, 6/2/97, 1/20/06, 9/25/08, 9/30/08, & 12/27/10 (1) BRICK PLAZA (New Jersey) — 24,715 72,050 4,094 92,671 96,765 52,749 1958 12/28/1989 (1) BRISTOL PLAZA (Connecticut) 3,856 15,959 11,786 3,856 27,745 31,601 19,149 1959 9/22/1995 (1) BROOK 35 (New Jersey) 11,304 7,128 38,355 2,792 7,128 41,147 48,275 8,360 1986/2004 1/1/2014 (1) CAMPUS PLAZA (Massachusetts) 16,710 13,412 315 16,710 13,727 30,437 2,415 1970 1/13/2016 (1) CHELSEA COMMONS (Massachusetts) 5,402 8,689 19,466 2,126 8,669 21,612 30,281 8,382 1962/1969/2008 8/25/06, 1/30/07, & 7/16/08 (1) COCOWALK (Florida) 35,063 71,476 47,158 34,406 119,291 153,697 10,175 1990/1994, 1922-1973, 2018-2019 5/4/15, 7/1/15, 12/16/15, 7/26/16, 6/30/17, & 8/10/17 (1) COLORADO BLVD (California) 5,262 4,071 10,375 5,262 14,446 19,708 11,507 1905-1988 12/31/96 & 8/14/98 (1) CONGRESSIONAL PLAZA (Maryland) 2,793 7,424 95,064 2,793 102,488 105,281 58,521 1965/2003 4/1/1965 (1) FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total COURTHOUSE CENTER (Maryland) 1,750 1,869 3,106 1,750 4,975 6,725 2,408 1975 12/17/1997 (1) CROSSROADS (Illinois) 4,635 11,611 19,462 4,635 31,073 35,708 18,708 1959 7/19/1993 (1) CROW CANYON COMMONS (California) 27,245 54,575 8,392 27,245 62,967 90,212 25,878 Late 1970's/ 12/29/05 & 2/28/07 (1) DARIEN (Connecticut) 30,368 19,523 7,214 30,368 26,737 57,105 4,351 1920-2009 4/3/13 & 7/20/18 (1) DEDHAM PLAZA (Massachusetts) 16,658 13,964 15,825 16,658 29,789 46,447 17,108 1959 12/31/93, 12/14/16, 1/29/19, & 3/12/19 (1) DEL MAR VILLAGE (Florida) 15,624 41,712 15,821 15,587 57,570 73,157 24,154 1982/1994/2007 5/30/08, 7/11/08, & 10/14/14 (1) EAST BAY BRIDGE (California) 29,069 138,035 11,839 29,069 149,874 178,943 36,029 1994-2001, 2011/2012 12/21/2012 (1) EASTGATE CROSSING (North Carolina) 1,608 5,775 27,806 1,608 33,581 35,189 21,822 1963 12/18/1986 (1) ELLISBURG (New Jersey) 4,028 11,309 19,277 4,013 30,601 34,614 21,832 1959 10/16/1992 (1) ESCONDIDO PROMENADE (California) 19,117 15,829 17,942 19,117 33,771 52,888 19,105 1987 12/31/96 & 11/10/10 (1) FAIRFAX JUNCTION (Virgina) 10,229 11,321 25 10,229 11,346 21,575 548 1981/2000 2/8/2019 (1) FALLS PLAZA (Virginia) 1,798 1,270 11,370 1,819 12,619 14,438 9,078 1960/1962 9/30/67 & 10/05/72 (1) FEDERAL PLAZA (Maryland) 10,216 17,895 42,396 10,216 60,291 70,507 46,693 1970 6/29/1989 (1) FINLEY SQUARE (Illinois) 9,252 9,544 22,645 9,252 32,189 41,441 22,071 1974 4/27/1995 (1) FLOURTOWN (Pennsylvania) 1,345 3,943 11,795 1,507 15,576 17,083 7,028 1957 4/25/1980 (1) FOURTH STREET (California) 13,978 9,909 2,345 13,978 12,254 26,232 1,014 1948,1975 5/19/2017 (1) FREEDOM PLAZA (California) — 3,255 35,623 — 38,878 38,878 — 2018-2019 6/15/2018 (1) FRESH MEADOWS (New York) 24,625 25,255 43,297 24,633 68,544 93,177 43,607 1946-1949 12/5/1997 (1) FRIENDSHIP CENTER (District of Columbia) 12,696 20,803 4,662 12,696 25,465 38,161 13,970 1998 9/21/2001 (1) GAITHERSBURG SQUARE (Maryland) 7,701 5,271 15,692 5,973 22,691 28,664 18,933 1966 4/22/1993 (1) GARDEN MARKET (Illinois) 2,677 4,829 7,295 2,677 12,124 14,801 8,640 1958 7/28/1994 (1) FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total GEORGETOWNE SHOPPING CENTER (New York) 30,738 50,103 946 32,199 49,588 81,787 295 1969/2006/2015 11/15/2019 (1) GOVERNOR PLAZA (Maryland) 2,068 4,905 20,620 2,068 25,525 27,593 22,092 1963 10/1/1985 (1) GRAHAM PARK PLAZA (Virginia) 1,237 15,096 20,518 1,169 35,682 36,851 28,526 1971 7/21/1983 (1) GRATIOT PLAZA (Michigan) 525 1,601 17,996 525 19,597 20,122 18,005 1964 3/29/1973 (1) GREENLAWN PLAZA (New York) 10,590 20,869 412 10,590 21,281 31,871 3,468 1975/2004 1/13/2016 (1) GREENWICH AVENUE (Connecticut) 7,484 5,445 10,819 7,484 16,264 23,748 4,824 1968 4/12/1995 (1) HASTINGS RANCH PLAZA (California) — 22,393 438 — 22,831 22,831 2,272 1958, 1984, 2006, 2007 2/1/2017 (1) HAUPPAUGE (New York) 8,791 15,262 5,388 8,419 21,022 29,441 13,170 1963 8/6/1998 (1) HOBOKEN (New Jersey) 98,224 45,385 150,905 952 43,450 153,792 197,242 628 1887-2006 9/18/19, 11/26/19, & 12/19/19 (1) HOLLYWOOD BLVD (California) 8,300 16,920 26,745 8,370 43,595 51,965 16,783 1929/1991 3/22/99 & 6/18/99 (1) HUNTINGTON (New York) 12,194 16,008 18,484 12,194 34,492 46,686 17,431 1962 12/12/88, 10/26/07, & 11/24/15 (1) HUNTINGTON SQUARE (New York) — 10,075 3,148 506 12,717 13,223 4,238 1980/2004-2007 8/16/2010 (1) IDYLWOOD PLAZA (Virginia) 4,308 10,026 2,779 4,308 12,805 17,113 9,716 1991 4/15/1994 (1) KINGS COURT (California) — 10,714 866 — 11,580 11,580 9,545 1960 8/24/1998 (1) LANCASTER (Pennsylvania) — 2,103 6,116 432 7,787 8,219 6,008 1958 4/24/1980 (1) LANGHORNE SQUARE (Pennsylvania) 720 2,974 18,992 720 21,966 22,686 16,661 1966 1/31/1985 (1) LAUREL (Maryland) 7,458 22,525 28,273 7,462 50,794 58,256 40,417 1956 8/15/1986 (1) LAWRENCE PARK (Pennsylvania) 6,150 8,491 19,621 6,161 28,101 34,262 23,385 1972 7/23/1980 & 4/3/17 (1) LEESBURG PLAZA (Virginia) 8,184 10,722 18,165 8,184 28,887 37,071 16,067 1967 9/15/1998 (1) LINDEN SQUARE (Massachusetts) 79,382 19,247 51,735 79,346 71,018 150,364 26,947 1960-2008 8/24/2006 (1) MELVILLE MALL (New York) 35,622 32,882 31,450 35,622 64,332 99,954 17,028 1974 10/16/2006 (1) MERCER MALL (New Jersey) 5,917 18,358 48,524 5,917 66,882 72,799 33,340 1975 10/14/03 & 1/31/17 (1) FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total MONTROSE CROSSING (Maryland) 67,492 48,624 91,819 22,110 48,624 113,929 162,553 32,948 1960s, 1970s, 1996 & 2011 12/27/11 & 12/19/13 (1) MOUNT VERNON/SOUTH VALLEY/7770 RICHMOND HWY. (Virginia) 10,068 33,501 42,942 10,150 76,361 86,511 39,734 1966/1972/1987/2001 3/31/03, 3/21/03, & 1/27/06 (1) NORTH DARTMOUTH (Massachusetts) 9,366 — 3 9,366 3 9,369 1 2004 8/24/2006 (1) NORTHEAST (Pennsylvania) 938 8,779 22,027 939 30,805 31,744 19,120 1959 8/30/1983 (1) OLD KEENE MILL (Virginia) 638 998 11,093 638 12,091 12,729 6,017 1968 6/15/1976 (1) OLD TOWN CENTER (California) 3,420 2,765 29,348 3,420 32,113 35,533 22,722 1962, 1997-1998 10/22/1997 (1) OLIVO AT MISSION HILLS (California) 15,048 46,732 17,869 15,048 64,601 79,649 3,016 2017-2018 8/2/2017 (1) PAN AM (Virginia) 8,694 12,929 8,314 8,695 21,242 29,937 16,292 1979 2/5/1993 (1) PENTAGON ROW (Virginia) — 2,955 103,383 — 106,338 106,338 52,509 1999 - 2002 1998 & 11/22/10 (1) PERRING PLAZA (Maryland) 2,800 6,461 22,943 2,800 29,404 32,204 24,834 1963 10/1/1985 (1) PIKE & ROSE (Maryland) 31,471 10,335 579,682 27,929 593,559 621,488 50,600 1963, 2012-2019 5/18/82, 10/26/07, & 7/31/12 (1) PIKE 7 PLAZA (Virginia) 14,970 22,799 11,569 14,914 34,424 49,338 18,736 1968 3/31/97 & 7/8/15 (1) PLAZA DEL MERCADO (Maryland) 10,305 21,553 14,859 10,305 36,412 46,717 5,571 1969 1/13/2016 (1) PLAZA DEL SOL (California) 8,308 5,605 12,331 — 5,605 12,331 17,936 1,185 2009 8/2/2017 (1) PLAZA EL SEGUNDO/THE POINT (California) 124,336 62,127 153,556 77,079 64,788 227,974 292,762 54,745 2006/2007/2016 12/30/11, 6/14/13, 7/26/13, & 12/27/13 (1) QUEEN ANNE PLAZA (Massachusetts) 3,319 8,457 6,166 3,319 14,623 17,942 10,580 1967 12/23/1994 (1) QUINCE ORCHARD (Maryland) 3,197 7,949 30,386 2,928 38,604 41,532 22,770 1975 4/22/1993 (1) RIVERPOINT CENTER (Illinois) 15,422 104,572 1,930 15,422 106,502 121,924 9,487 1989, 2012 3/31/2017 (1) ROCKVILLE TOWN SQUARE (Maryland) — 8,092 39,639 — 47,731 47,731 20,001 2005 - 2007 2006 - 2007 (1) ROLLINGWOOD APTS. (Maryland) 552 2,246 8,575 774 10,599 11,373 9,940 1960 1/15/1971 (1) FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total SAM'S PARK & SHOP (District of Columbia) 4,840 6,319 3,022 4,840 9,341 14,181 5,912 1930 12/1/1995 (1) SAN ANTONIO CENTER (California) 26,400 18,462 1,141 26,400 19,603 46,003 3,752 1958, 1964-1965, 1974-1975, 1995-1997 1/9/2015, 9/13/19 (1) SANTANA ROW (California) 66,682 7,502 976,080 53,217 997,047 1,050,264 221,350 1999-2006, 2009, 2011, 2014, 2016-2019 3/5/97, 7/13/12, 9/6/12, 4/30/13 & 9/23/13 (1) SAUGUS PLAZA (Massachusetts) 4,383 8,291 4,501 4,383 12,792 17,175 7,557 1976 10/1/1996 (1) SYLMAR TOWNE CENTER (California) 16,854 18,522 24,636 679 18,522 25,315 43,837 2,205 1973 8/2/2017 (1) THE AVENUE AT WHITE MARSH (Maryland) 52,597 20,682 72,432 29,311 20,685 101,740 122,425 38,923 1997 3/8/2007 (1) THE GROVE AT SHREWSBURY (New Jersey) 42,874 18,016 103,115 5,419 18,021 108,529 126,550 20,825 1988/1993/2007 1/1/2014 & 10/6/14 (1) THE SHOPPES AT NOTTINGHAM SQUARE (Maryland) 4,441 12,849 735 4,441 13,584 18,025 5,889 2005 - 2006 3/8/2007 (1) THE SHOPS AT SUNSET PLACE (Florida) 62,426 64,499 50,853 8,944 64,499 59,797 124,296 10,136 1999 10/1/2015 (1) THIRD STREET PROMENADE (California) 22,645 12,709 45,863 25,125 56,092 81,217 36,201 1888-2000 1996-2000 (1) TOWER SHOPPNG CENTER (Virginia) 7,170 10,518 4,797 7,280 15,205 22,485 9,921 1953-1960 8/24/1998 (1) TOWER SHOPS (Florida) 29,940 43,390 24,855 29,962 68,223 98,185 21,085 1989 1/19/11 & 6/13/14 (1) TOWN CENTER OF NEW BRITAIN (Pennsylvania) 1,282 12,285 2,888 1,535 14,920 16,455 5,931 1969 6/29/2006 (1) TOWSON RESIDENTIAL (FLATS 703) (Maryland) 2,328 — 20,042 2,328 20,042 22,370 1,454 2016-2017 3/8/2007 (1) TROY HILLS (New Jersey) 3,126 5,193 32,655 5,865 35,109 40,974 23,135 1966 7/23/1980 (1) TYSON'S STATION (Virginia) 388 453 4,170 493 4,518 5,011 3,939 1954 1/17/1978 (1) VILLAGE AT SHIRLINGTON (Virginia) 9,761 14,808 38,771 4,234 59,106 63,340 30,187 1940, 2006-2009 12/21/1995 (1) WESTGATE CENTER (California) 6,319 107,284 43,870 6,319 151,154 157,473 61,106 1960-1966 3/31/2004 (1) WHITE MARSH PLAZA (Maryland) 3,478 21,413 1,028 3,478 22,441 25,919 9,736 1987 3/8/2007 (1) FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total WHITE MARSH OTHER (Maryland) 29,725 1,843 146 29,754 1,960 31,714 913 1985 3/8/2007 (1) WILDWOOD (Maryland) 9,111 1,061 15,905 9,111 16,966 26,077 9,208 1958 5/5/1969 (1) WILLOW GROVE (Pennsylvania) 1,499 6,643 22,061 1,499 28,704 30,203 27,812 1953 11/20/1984 (1) WILLOW LAWN (Virginia) 3,192 7,723 91,838 7,790 94,963 102,753 62,087 1957 12/5/1983 (1) WYNNEWOOD (Pennsylvania) 8,055 13,759 21,272 8,055 35,031 43,086 25,668 1948 10/29/1996 (1) TOTALS $ 545,679 $ 1,449,865 $ 2,526,772 $ 4,321,495 $ 1,414,814 $ 6,883,318 $ 8,298,132 $ 2,215,413 (1) Depreciation of building and improvements is calculated based on useful lives ranging from the life of the lease to 50 years . FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION - CONTINUED Three Years Ended December 31, 2019 Reconciliation of Total Cost (in thousands) Balance, December 31, 2016 $ 6,759,073 Additions during period Acquisitions 555,476 Improvements 492,541 Deduction during period—dispositions and retirements of property (172,029 ) Balance, December 31, 2017 7,635,061 Additions during period Acquisitions 14,940 Improvements 407,225 Deduction during period—dispositions and retirements of property (237,754 ) Balance, December 31, 2018 7,819,472 January 1, 2019 adoption of new accounting standard - See Note 2 (71,859 ) Additions during period Acquisitions 309,921 Improvements 441,703 Deduction during period—dispositions and retirements of property (201,105 ) Balance, December 31, 2019 (1) $ 8,298,132 _____________________ (1) For Federal tax purposes, the aggregate cost basis is approximately $7.4 billion as of December 31, 2019 . FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION - CONTINUED Three Years Ended December 31, 2019 Reconciliation of Accumulated Depreciation and Amortization (in thousands) Balance, December 31, 2016 $ 1,729,234 Additions during period—depreciation and amortization expense 193,340 Deductions during period—dispositions and retirements of property (46,030 ) Balance, December 31, 2017 1,876,544 Additions during period—depreciation and amortization expense 215,969 Deductions during period—dispositions and retirements of property (33,370 ) Balance, December 31, 2018 2,059,143 January 1, 2019 adoption of new accounting standard - See Note 2 (18,173 ) Additions during period—depreciation and amortization expense 215,382 Deductions during period—dispositions and retirements of property (40,939 ) Balance, December 31, 2019 $ 2,215,413

Schedule III Part II - Summary

Schedule III Part II - Summary of Real Estate and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Schedule III - Summary of Real Estate and Accumulated Depreciation	FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total 29TH PLACE (Virginia) $ 3,868 $ 10,211 $ 18,863 $ 11,985 $ 10,195 $ 30,864 $ 41,059 $ 14,953 1975 - 2001 5/30/2007 (1) ANDORRA (Pennsylvania) 2,432 12,346 11,718 2,432 24,064 26,496 20,382 1953 1/12/1988 (1) ASSEMBLY ROW/ASSEMBLY SQUARE MARKETPLACE (Massachusetts) 93,252 34,196 662,720 69,421 720,747 790,168 72,687 2005, 2012-2019 2005-2013 (1) AZALEA (California) 39,702 40,219 67,117 (3 ) 40,219 67,114 107,333 6,109 2014 8/2/2017 (1) BALA CYNWYD (Pennsylvania) 3,565 14,466 39,175 2,683 54,523 57,206 23,062 1955 9/22/1993 (1) BARCROFT PLAZA (Virginia) 12,617 29,603 6,515 12,617 36,118 48,735 4,513 1963, 1972, 1990, & 2000 1/13/16 & 11/7/16 (1) BARRACKS ROAD (Virginia) 4,363 16,459 48,764 4,363 65,223 69,586 47,069 1958 12/31/1985 (1) BELL GARDENS (California) 12,292 24,406 85,947 589 24,406 86,536 110,942 10,215 1990, 2003, 2006 8/2/17 & 11/29/18 (1) BETHESDA ROW (Maryland) 46,579 35,406 151,640 43,904 189,721 233,625 85,602 1945-2008 12/31/93, 6/2/97, 1/20/06, 9/25/08, 9/30/08, & 12/27/10 (1) BRICK PLAZA (New Jersey) — 24,715 72,050 4,094 92,671 96,765 52,749 1958 12/28/1989 (1) BRISTOL PLAZA (Connecticut) 3,856 15,959 11,786 3,856 27,745 31,601 19,149 1959 9/22/1995 (1) BROOK 35 (New Jersey) 11,304 7,128 38,355 2,792 7,128 41,147 48,275 8,360 1986/2004 1/1/2014 (1) CAMPUS PLAZA (Massachusetts) 16,710 13,412 315 16,710 13,727 30,437 2,415 1970 1/13/2016 (1) CHELSEA COMMONS (Massachusetts) 5,402 8,689 19,466 2,126 8,669 21,612 30,281 8,382 1962/1969/2008 8/25/06, 1/30/07, & 7/16/08 (1) COCOWALK (Florida) 35,063 71,476 47,158 34,406 119,291 153,697 10,175 1990/1994, 1922-1973, 2018-2019 5/4/15, 7/1/15, 12/16/15, 7/26/16, 6/30/17, & 8/10/17 (1) COLORADO BLVD (California) 5,262 4,071 10,375 5,262 14,446 19,708 11,507 1905-1988 12/31/96 & 8/14/98 (1) CONGRESSIONAL PLAZA (Maryland) 2,793 7,424 95,064 2,793 102,488 105,281 58,521 1965/2003 4/1/1965 (1) FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total COURTHOUSE CENTER (Maryland) 1,750 1,869 3,106 1,750 4,975 6,725 2,408 1975 12/17/1997 (1) CROSSROADS (Illinois) 4,635 11,611 19,462 4,635 31,073 35,708 18,708 1959 7/19/1993 (1) CROW CANYON COMMONS (California) 27,245 54,575 8,392 27,245 62,967 90,212 25,878 Late 1970's/ 12/29/05 & 2/28/07 (1) DARIEN (Connecticut) 30,368 19,523 7,214 30,368 26,737 57,105 4,351 1920-2009 4/3/13 & 7/20/18 (1) DEDHAM PLAZA (Massachusetts) 16,658 13,964 15,825 16,658 29,789 46,447 17,108 1959 12/31/93, 12/14/16, 1/29/19, & 3/12/19 (1) DEL MAR VILLAGE (Florida) 15,624 41,712 15,821 15,587 57,570 73,157 24,154 1982/1994/2007 5/30/08, 7/11/08, & 10/14/14 (1) EAST BAY BRIDGE (California) 29,069 138,035 11,839 29,069 149,874 178,943 36,029 1994-2001, 2011/2012 12/21/2012 (1) EASTGATE CROSSING (North Carolina) 1,608 5,775 27,806 1,608 33,581 35,189 21,822 1963 12/18/1986 (1) ELLISBURG (New Jersey) 4,028 11,309 19,277 4,013 30,601 34,614 21,832 1959 10/16/1992 (1) ESCONDIDO PROMENADE (California) 19,117 15,829 17,942 19,117 33,771 52,888 19,105 1987 12/31/96 & 11/10/10 (1) FAIRFAX JUNCTION (Virgina) 10,229 11,321 25 10,229 11,346 21,575 548 1981/2000 2/8/2019 (1) FALLS PLAZA (Virginia) 1,798 1,270 11,370 1,819 12,619 14,438 9,078 1960/1962 9/30/67 & 10/05/72 (1) FEDERAL PLAZA (Maryland) 10,216 17,895 42,396 10,216 60,291 70,507 46,693 1970 6/29/1989 (1) FINLEY SQUARE (Illinois) 9,252 9,544 22,645 9,252 32,189 41,441 22,071 1974 4/27/1995 (1) FLOURTOWN (Pennsylvania) 1,345 3,943 11,795 1,507 15,576 17,083 7,028 1957 4/25/1980 (1) FOURTH STREET (California) 13,978 9,909 2,345 13,978 12,254 26,232 1,014 1948,1975 5/19/2017 (1) FREEDOM PLAZA (California) — 3,255 35,623 — 38,878 38,878 — 2018-2019 6/15/2018 (1) FRESH MEADOWS (New York) 24,625 25,255 43,297 24,633 68,544 93,177 43,607 1946-1949 12/5/1997 (1) FRIENDSHIP CENTER (District of Columbia) 12,696 20,803 4,662 12,696 25,465 38,161 13,970 1998 9/21/2001 (1) GAITHERSBURG SQUARE (Maryland) 7,701 5,271 15,692 5,973 22,691 28,664 18,933 1966 4/22/1993 (1) GARDEN MARKET (Illinois) 2,677 4,829 7,295 2,677 12,124 14,801 8,640 1958 7/28/1994 (1) FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total GEORGETOWNE SHOPPING CENTER (New York) 30,738 50,103 946 32,199 49,588 81,787 295 1969/2006/2015 11/15/2019 (1) GOVERNOR PLAZA (Maryland) 2,068 4,905 20,620 2,068 25,525 27,593 22,092 1963 10/1/1985 (1) GRAHAM PARK PLAZA (Virginia) 1,237 15,096 20,518 1,169 35,682 36,851 28,526 1971 7/21/1983 (1) GRATIOT PLAZA (Michigan) 525 1,601 17,996 525 19,597 20,122 18,005 1964 3/29/1973 (1) GREENLAWN PLAZA (New York) 10,590 20,869 412 10,590 21,281 31,871 3,468 1975/2004 1/13/2016 (1) GREENWICH AVENUE (Connecticut) 7,484 5,445 10,819 7,484 16,264 23,748 4,824 1968 4/12/1995 (1) HASTINGS RANCH PLAZA (California) — 22,393 438 — 22,831 22,831 2,272 1958, 1984, 2006, 2007 2/1/2017 (1) HAUPPAUGE (New York) 8,791 15,262 5,388 8,419 21,022 29,441 13,170 1963 8/6/1998 (1) HOBOKEN (New Jersey) 98,224 45,385 150,905 952 43,450 153,792 197,242 628 1887-2006 9/18/19, 11/26/19, & 12/19/19 (1) HOLLYWOOD BLVD (California) 8,300 16,920 26,745 8,370 43,595 51,965 16,783 1929/1991 3/22/99 & 6/18/99 (1) HUNTINGTON (New York) 12,194 16,008 18,484 12,194 34,492 46,686 17,431 1962 12/12/88, 10/26/07, & 11/24/15 (1) HUNTINGTON SQUARE (New York) — 10,075 3,148 506 12,717 13,223 4,238 1980/2004-2007 8/16/2010 (1) IDYLWOOD PLAZA (Virginia) 4,308 10,026 2,779 4,308 12,805 17,113 9,716 1991 4/15/1994 (1) KINGS COURT (California) — 10,714 866 — 11,580 11,580 9,545 1960 8/24/1998 (1) LANCASTER (Pennsylvania) — 2,103 6,116 432 7,787 8,219 6,008 1958 4/24/1980 (1) LANGHORNE SQUARE (Pennsylvania) 720 2,974 18,992 720 21,966 22,686 16,661 1966 1/31/1985 (1) LAUREL (Maryland) 7,458 22,525 28,273 7,462 50,794 58,256 40,417 1956 8/15/1986 (1) LAWRENCE PARK (Pennsylvania) 6,150 8,491 19,621 6,161 28,101 34,262 23,385 1972 7/23/1980 & 4/3/17 (1) LEESBURG PLAZA (Virginia) 8,184 10,722 18,165 8,184 28,887 37,071 16,067 1967 9/15/1998 (1) LINDEN SQUARE (Massachusetts) 79,382 19,247 51,735 79,346 71,018 150,364 26,947 1960-2008 8/24/2006 (1) MELVILLE MALL (New York) 35,622 32,882 31,450 35,622 64,332 99,954 17,028 1974 10/16/2006 (1) MERCER MALL (New Jersey) 5,917 18,358 48,524 5,917 66,882 72,799 33,340 1975 10/14/03 & 1/31/17 (1) FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total MONTROSE CROSSING (Maryland) 67,492 48,624 91,819 22,110 48,624 113,929 162,553 32,948 1960s, 1970s, 1996 & 2011 12/27/11 & 12/19/13 (1) MOUNT VERNON/SOUTH VALLEY/7770 RICHMOND HWY. (Virginia) 10,068 33,501 42,942 10,150 76,361 86,511 39,734 1966/1972/1987/2001 3/31/03, 3/21/03, & 1/27/06 (1) NORTH DARTMOUTH (Massachusetts) 9,366 — 3 9,366 3 9,369 1 2004 8/24/2006 (1) NORTHEAST (Pennsylvania) 938 8,779 22,027 939 30,805 31,744 19,120 1959 8/30/1983 (1) OLD KEENE MILL (Virginia) 638 998 11,093 638 12,091 12,729 6,017 1968 6/15/1976 (1) OLD TOWN CENTER (California) 3,420 2,765 29,348 3,420 32,113 35,533 22,722 1962, 1997-1998 10/22/1997 (1) OLIVO AT MISSION HILLS (California) 15,048 46,732 17,869 15,048 64,601 79,649 3,016 2017-2018 8/2/2017 (1) PAN AM (Virginia) 8,694 12,929 8,314 8,695 21,242 29,937 16,292 1979 2/5/1993 (1) PENTAGON ROW (Virginia) — 2,955 103,383 — 106,338 106,338 52,509 1999 - 2002 1998 & 11/22/10 (1) PERRING PLAZA (Maryland) 2,800 6,461 22,943 2,800 29,404 32,204 24,834 1963 10/1/1985 (1) PIKE & ROSE (Maryland) 31,471 10,335 579,682 27,929 593,559 621,488 50,600 1963, 2012-2019 5/18/82, 10/26/07, & 7/31/12 (1) PIKE 7 PLAZA (Virginia) 14,970 22,799 11,569 14,914 34,424 49,338 18,736 1968 3/31/97 & 7/8/15 (1) PLAZA DEL MERCADO (Maryland) 10,305 21,553 14,859 10,305 36,412 46,717 5,571 1969 1/13/2016 (1) PLAZA DEL SOL (California) 8,308 5,605 12,331 — 5,605 12,331 17,936 1,185 2009 8/2/2017 (1) PLAZA EL SEGUNDO/THE POINT (California) 124,336 62,127 153,556 77,079 64,788 227,974 292,762 54,745 2006/2007/2016 12/30/11, 6/14/13, 7/26/13, & 12/27/13 (1) QUEEN ANNE PLAZA (Massachusetts) 3,319 8,457 6,166 3,319 14,623 17,942 10,580 1967 12/23/1994 (1) QUINCE ORCHARD (Maryland) 3,197 7,949 30,386 2,928 38,604 41,532 22,770 1975 4/22/1993 (1) RIVERPOINT CENTER (Illinois) 15,422 104,572 1,930 15,422 106,502 121,924 9,487 1989, 2012 3/31/2017 (1) ROCKVILLE TOWN SQUARE (Maryland) — 8,092 39,639 — 47,731 47,731 20,001 2005 - 2007 2006 - 2007 (1) ROLLINGWOOD APTS. (Maryland) 552 2,246 8,575 774 10,599 11,373 9,940 1960 1/15/1971 (1) FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total SAM'S PARK & SHOP (District of Columbia) 4,840 6,319 3,022 4,840 9,341 14,181 5,912 1930 12/1/1995 (1) SAN ANTONIO CENTER (California) 26,400 18,462 1,141 26,400 19,603 46,003 3,752 1958, 1964-1965, 1974-1975, 1995-1997 1/9/2015, 9/13/19 (1) SANTANA ROW (California) 66,682 7,502 976,080 53,217 997,047 1,050,264 221,350 1999-2006, 2009, 2011, 2014, 2016-2019 3/5/97, 7/13/12, 9/6/12, 4/30/13 & 9/23/13 (1) SAUGUS PLAZA (Massachusetts) 4,383 8,291 4,501 4,383 12,792 17,175 7,557 1976 10/1/1996 (1) SYLMAR TOWNE CENTER (California) 16,854 18,522 24,636 679 18,522 25,315 43,837 2,205 1973 8/2/2017 (1) THE AVENUE AT WHITE MARSH (Maryland) 52,597 20,682 72,432 29,311 20,685 101,740 122,425 38,923 1997 3/8/2007 (1) THE GROVE AT SHREWSBURY (New Jersey) 42,874 18,016 103,115 5,419 18,021 108,529 126,550 20,825 1988/1993/2007 1/1/2014 & 10/6/14 (1) THE SHOPPES AT NOTTINGHAM SQUARE (Maryland) 4,441 12,849 735 4,441 13,584 18,025 5,889 2005 - 2006 3/8/2007 (1) THE SHOPS AT SUNSET PLACE (Florida) 62,426 64,499 50,853 8,944 64,499 59,797 124,296 10,136 1999 10/1/2015 (1) THIRD STREET PROMENADE (California) 22,645 12,709 45,863 25,125 56,092 81,217 36,201 1888-2000 1996-2000 (1) TOWER SHOPPNG CENTER (Virginia) 7,170 10,518 4,797 7,280 15,205 22,485 9,921 1953-1960 8/24/1998 (1) TOWER SHOPS (Florida) 29,940 43,390 24,855 29,962 68,223 98,185 21,085 1989 1/19/11 & 6/13/14 (1) TOWN CENTER OF NEW BRITAIN (Pennsylvania) 1,282 12,285 2,888 1,535 14,920 16,455 5,931 1969 6/29/2006 (1) TOWSON RESIDENTIAL (FLATS 703) (Maryland) 2,328 — 20,042 2,328 20,042 22,370 1,454 2016-2017 3/8/2007 (1) TROY HILLS (New Jersey) 3,126 5,193 32,655 5,865 35,109 40,974 23,135 1966 7/23/1980 (1) TYSON'S STATION (Virginia) 388 453 4,170 493 4,518 5,011 3,939 1954 1/17/1978 (1) VILLAGE AT SHIRLINGTON (Virginia) 9,761 14,808 38,771 4,234 59,106 63,340 30,187 1940, 2006-2009 12/21/1995 (1) WESTGATE CENTER (California) 6,319 107,284 43,870 6,319 151,154 157,473 61,106 1960-1966 3/31/2004 (1) WHITE MARSH PLAZA (Maryland) 3,478 21,413 1,028 3,478 22,441 25,919 9,736 1987 3/8/2007 (1) FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION DECEMBER 31, 2019 (Dollars in thousands) COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E COLUMN F COLUMN G COLUMN H COLUMN I Descriptions Encumbrance Initial cost to company Cost Capitalized Subsequent to Acquisition Gross amount at which carried at close of period Accumulated Depreciation and Amortization Date of Construction Date Acquired Life on which depreciation in latest income statements is computed Land Building and Improvements Land Building and Improvements Total WHITE MARSH OTHER (Maryland) 29,725 1,843 146 29,754 1,960 31,714 913 1985 3/8/2007 (1) WILDWOOD (Maryland) 9,111 1,061 15,905 9,111 16,966 26,077 9,208 1958 5/5/1969 (1) WILLOW GROVE (Pennsylvania) 1,499 6,643 22,061 1,499 28,704 30,203 27,812 1953 11/20/1984 (1) WILLOW LAWN (Virginia) 3,192 7,723 91,838 7,790 94,963 102,753 62,087 1957 12/5/1983 (1) WYNNEWOOD (Pennsylvania) 8,055 13,759 21,272 8,055 35,031 43,086 25,668 1948 10/29/1996 (1) TOTALS $ 545,679 $ 1,449,865 $ 2,526,772 $ 4,321,495 $ 1,414,814 $ 6,883,318 $ 8,298,132 $ 2,215,413 (1) Depreciation of building and improvements is calculated based on useful lives ranging from the life of the lease to 50 years . FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION - CONTINUED Three Years Ended December 31, 2019 Reconciliation of Total Cost (in thousands) Balance, December 31, 2016 $ 6,759,073 Additions during period Acquisitions 555,476 Improvements 492,541 Deduction during period—dispositions and retirements of property (172,029 ) Balance, December 31, 2017 7,635,061 Additions during period Acquisitions 14,940 Improvements 407,225 Deduction during period—dispositions and retirements of property (237,754 ) Balance, December 31, 2018 7,819,472 January 1, 2019 adoption of new accounting standard - See Note 2 (71,859 ) Additions during period Acquisitions 309,921 Improvements 441,703 Deduction during period—dispositions and retirements of property (201,105 ) Balance, December 31, 2019 (1) $ 8,298,132 _____________________ (1) For Federal tax purposes, the aggregate cost basis is approximately $7.4 billion as of December 31, 2019 . FEDERAL REALTY INVESTMENT TRUST SCHEDULE III SUMMARY OF REAL ESTATE AND ACCUMULATED DEPRECIATION - CONTINUED Three Years Ended December 31, 2019 Reconciliation of Accumulated Depreciation and Amortization (in thousands) Balance, December 31, 2016 $ 1,729,234 Additions during period—depreciation and amortization expense 193,340 Deductions during period—dispositions and retirements of property (46,030 ) Balance, December 31, 2017 1,876,544 Additions during period—depreciation and amortization expense 215,969 Deductions during period—dispositions and retirements of property (33,370 ) Balance, December 31, 2018 2,059,143 January 1, 2019 adoption of new accounting standard - See Note 2 (18,173 ) Additions during period—depreciation and amortization expense 215,382 Deductions during period—dispositions and retirements of property (40,939 ) Balance, December 31, 2019 $ 2,215,413

Schedule IV - Mortgage Loans on

Schedule IV - Mortgage Loans on Real Estate	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Abstract]
Schedule IV - Mortgage Loans on Real Estate	FEDERAL REALTY INVESTMENT TRUST SCHEDULE IV MORTGAGE LOANS ON REAL ESTATE Year Ended December 31, 2019 (Dollars in thousands) Column A Column B Column C Column D Column E Column F Column G Column H Description of Lien Interest Rate Maturity Date Periodic Payment Prior Face Amount Carrying Principal Mortgage on 8% or 10% May 2021 Interest only $ — $ 21,179 $ 21,179 (2) $ — Mortgage on retail buildings in Philadelphia, PA 10% plus participation May 2021 Interest only monthly; — 9,250 9,250 — $ — $ 30,429 $ 30,429 $ — _____________________ (1) For Federal tax purposes, the aggregate tax basis is approximately $30.4 million as of December 31, 2019 . (2) This mortgage is available for up to $25.0 million . FEDERAL REALTY INVESTMENT TRUST SCHEDULE IV MORTGAGE LOANS ON REAL ESTATE - CONTINUED Three Years Ended December 31, 2019 Reconciliation of Carrying Amount (in thousands) Balance, December 31, 2016 $ 29,904 Additions during period: Issuance of loans 525 Balance, December 31, 2017 30,429 Balance, December 31, 2018 30,429 Balance, December 31, 2019 $ 30,429

Summary Of Significant Accoun_2

Summary Of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation Our consolidated financial statements include the accounts of the Trust, its corporate subsidiaries, and all entities in which the Trust has a controlling interest or has been determined to be the primary beneficiary of a variable interest entity (“VIE”). The equity interests of other investors are reflected as noncontrolling interests or redeemable noncontrolling interests. All significant intercompany transactions and balances are eliminated in consolidation. We account for our interests in joint ventures, which we do not control, using the equity method of accounting. Certain 2018 and 2017 amounts have been reclassified to conform to current period presentation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America, referred to as “GAAP,” requires management to make estimates and assumptions that in certain circumstances affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities, and revenues and expenses. These estimates are prepared using management’s best judgment, after considering past, current and expected events and economic conditions. Actual results could differ from these estimates.
Revenue Recognition and Accounts Receivable	Revenue Recognition and Accounts Receivable Policy beginning January 1, 2019, with our adoption of Accounting Standards Codification (ASC) 842, "Leases" Our leases with our tenants are classified as operating leases. When collection of substantially all lease payments during the lease term is considered probable, the lease qualifies for accrual accounting. Lease payments are recognized on a straight-line basis from when the tenant controls the space through the term of the related lease. Variable lease payments relating to percentage rent are recognized at the end of the lease year or earlier if we have determined the required sales level is achieved. Real estate tax and other cost reimbursements are recognized on an accrual basis over the periods in which the related expenditures are incurred. For a tenant to terminate its lease agreement prior to the end of the agreed term, we may require that they pay a fee to cancel the lease agreement. Lease termination fees for which the tenant has relinquished control of the space are generally recognized on the termination date. When a lease is terminated early but the tenant continues to control the space under a modified lease agreement, the lease termination fee is generally recognized evenly over the remaining term of the modified lease agreement. When collection of substantially all lease payments during the lease term is not considered probable, total lease revenue is limited to the lesser of revenue recognized under accrual accounting or cash received. Determining the probability of collection of substantially all lease payments during lease term requires judgment. This determination is impacted by numerous factors including our assessment of the tenant’s credit worthiness, economic conditions, our historical experience with the tenant and tenants operating in the same industry, and the length of the lease term. If leases currently classified as probable are subsequently reclassified as not probable, any outstanding lease receivables (including straight-line rent receivables) would be written-off with a corresponding decrease in rental income. Policy prior to January 1, 2019 Prior to January 1, 2019, management estimates of collectability were considered when reserving for billed and accrued lease receivables and straight-line rent receivables. Full and partial reserves were recorded when determined to be appropriate with a corresponding charge to bad debt expense. The primary impact of the adoption of ASC 842, “Leases,” on our recognition of lease revenue relates to the upfront and ongoing assessment of the collectability of substantially all lease payments required by the new standard. Other revenue recognition policies In 2018, we completed construction on 221 condominium units at our Assembly Row and Pike & Rose properties. Beginning on January 1, 2018, with the adoption of ASU 2014-09, "Revenue from Contracts with Customers," gains or losses on the sale of these condominium units are recognized as the condominium units are legally sold. In 2017, we accounted for contracted condominium sales under the percentage-of completion method, based on an evaluation of the criteria specified in ASC Topic 360-20, “Property, Plant and Equipment – Real Estate Sales,” including: the legal commitment of the purchaser in the real estate contract, whether the construction of the project was beyond a preliminary phase, whether sufficient units had been contracted to ensure the project would not revert to a rental project, the ability to reasonably estimate the aggregate project sale proceeds and aggregate project costs, and the determination that the buyer had made an adequate initial and continuing cash investment under the contract. When the percentage-of-completion criteria had not been met, no profit was recognized. The application of these criteria can be complex and required us to make assumptions.
Real Estate	Real Estate Land, buildings and improvements are recorded at cost. Depreciation is computed using the straight-line method. Estimated useful lives range generally from 35 years to a maximum of 50 years on buildings and major improvements. Minor improvements, furniture and equipment are capitalized and depreciated over useful lives ranging from 2 to 20 years. Maintenance and repairs that do not improve or extend the useful lives of the related assets are charged to operations as incurred. Tenant improvements are capitalized and depreciated over the life of the related lease or their estimated useful life, whichever is shorter. If a tenant vacates its space prior to contractual termination of its lease, the undepreciated balance of any tenant improvements are written off if they are replaced or have no future value. In 2019 , 2018 and 2017 , real estate depreciation expense was $215.4 million , $216.0 million and $193.3 million , respectively, including amounts from real estate sold. Effective January 1, 2018, (upon the adoption of ASU 2014-09, "Revenue from Contracts with Customers," as amended and interpreted) sales of real estate are recognized generally upon the transfer of control, which usually occurs when the real estate is legally sold. Prior to January 1, 2018, sales of real estate were recognized only when sufficient down payments had been obtained, possession and other attributes of ownership had been transferred to the buyer and we had no significant continuing involvement. The application of these criteria can be complex and required us to make assumptions. We believe the relevant criteria were met for all real estate sold during the periods presented. Our methodology of allocating the cost of acquisitions to assets acquired and liabilities assumed is based on estimated fair values, replacement cost and/or appraised values. When we acquire operating real estate properties, the purchase price is allocated to land, building, improvements, leasing costs, intangibles such as in-place leases, assumed debt, if any, and to current assets and liabilities acquired, if any. The value allocated to in-place leases is amortized over the related lease term and reflected as rental income in the consolidated statements of comprehensive income. We consider qualitative and quantitative factors in evaluating the likelihood of a tenant exercising a below market renewal option and include such renewal options in the calculation of in-place lease value when we consider these to be bargain renewal options. If the value of below market lease intangibles includes renewal option periods, we include such renewal periods in the amortization period utilized. If a tenant vacates its space prior to contractual termination of its lease, the unamortized balance of any in-place lease value is written off to rental income. Transaction costs related to asset acquisitions, such as broker fees, transfer taxes, legal, accounting, valuation, and other professional and consulting fees, are capitalized as part of the acquisition cost. The acquisition of an operating shopping center typically qualifies as an asset acquisition. Prior to the adoption of ASU 2016-02, "Leases," when applicable, as lessee, we classify our leases of land and building as operating or capital leases. We are required to use judgment and make estimates in determining the lease term, the estimated economic life of the property and the interest rate to be used in determining whether or not the lease meets the qualification of a capital lease. Subsequently, capital leases are now considered "finance leases," see "Recent Accounting Pronouncements," for an explanation of the impact to our consolidated balance sheet. We capitalize certain costs related to the development and redevelopment of real estate including pre-construction costs, real estate taxes, insurance, construction costs and salaries and related costs of personnel directly involved, are capitalized. Additionally, we capitalize interest costs related to development and redevelopment activities. Capitalization of these costs begin when the activities and related expenditures commence and cease when the project is substantially complete and ready for its intended use at which time the project is placed in service and depreciation commences. Additionally, we make estimates as to the probability of certain development and redevelopment projects being completed. If we determine the development or redevelopment is no longer probable of completion, we expense all capitalized costs which are not recoverable. We review for impairment on a property by property basis. Impairment is recognized on properties held for use when the expected undiscounted cash flows for a property are less than its carrying amount, at which time, the property is written-down to fair value. Properties held for sale are recorded at the lower of the carrying amount or the expected sales price less costs to sell.
Cash and Cash Equivalents	Cash and Cash Equivalents We define cash and cash equivalents as cash on hand, demand deposits with financial institutions and short term liquid investments with an initial maturity, when purchased, under three months. Cash balances in individual banks may exceed the federally insured limit by the Federal Deposit Insurance Corporation (the “FDIC”). At December 31, 2019 , we had $131.5 million in excess of the FDIC insured limit.
Prepaid Expenses and Other Assets	Prepaid Expenses and Other Assets Prepaid expenses and other assets consist primarily of lease costs, prepaid property taxes and acquired above market leases. Capitalized lease costs are incremental direct costs incurred which were essential to originate a successful leasing arrangement and would not have been incurred had the leasing transaction not taken place. Capitalized lease costs are amortized over the life of the related lease. If a tenant vacates its space prior to the contractual termination of its lease, the unamortized balance of any previously capitalized lease costs are written off.
Debt Issuance Costs	Debt Issuance Costs Costs related to the issuance of debt instruments are deferred and are amortized as interest expense over the estimated life of the related issue using the straight-line method which approximates the effective interest method. If a debt instrument is paid off prior to its original maturity date, the unamortized balance of debt issuance costs are written off to interest expense or, if significant, included in “early extinguishment of debt.” Debt issuance costs related to our revolving credit facility are classified as an asset and are included in "prepaid expenses and other assets" in our consolidated balance sheets. All other debt issuance costs are presented as a direct deduction from the carrying amount of the debt liability.
Derivative Instruments	Derivative Instruments We may use derivative instruments to manage exposure to variable interest rate risk. We generally enter into interest rate swaps to manage our exposure to variable interest rate risk and treasury locks to manage the risk of interest rates rising prior to the issuance of debt. We enter into derivative instruments that qualify as cash flow hedges and do not enter into derivative instruments for speculative purposes. Interest rate swaps associated with cash flow hedges are recorded at fair value on a recurring basis. Effectiveness of cash flow hedges is assessed both at inception and on an ongoing basis. The effective portion of changes in fair value of the interest rate swaps associated with cash flow hedges is recorded in other comprehensive income (loss) which is included in accumulated other comprehensive income (loss) on the balance sheet and statement of shareholders' equity. Cash flow hedges become ineffective if critical terms of the hedging instrument and the debt instrument do not perfectly match such as notional amounts, settlement dates, reset dates, calculation period and LIBOR rate. In addition, the default risk of the counterparty is evaluated by monitoring the credit worthiness of the counterparty which includes reviewing debt ratings and financial performance. If a cash flow hedge is deemed ineffective, the ineffective portion of changes in fair value of the interest rate swaps associated with cash flow hedges is recognized in earnings in the period affected. During 2019 , we entered into two interest rate swap agreements that effectively fix the interest rate on a mortgage payable associated with our Hoboken acquisition at 3.67% . Both swaps were designated and qualify for cash flow hedge accounting. As of December 31, 2019 , our Assembly Row hotel joint venture is a party to two interest rate swap agreements that effectively fix the interest rate on the joint venture's mortgage debt at 5.206% . Both swaps were designated and qualify as cash flow hedges. Hedge ineffectiveness has not impacted earnings in 2019 , 2018 and 2017 .
Mortgage Notes Receivable	Mortgage Notes Receivable We have made certain mortgage loans that, because of their nature, qualify as loan receivables. At the time the loans were made, we did not intend for the arrangement to be anything other than a financing and did not contemplate a real estate investment. We evaluate each investment to determine whether the loan arrangement qualifies as a loan, joint venture or real estate investment and the appropriate accounting thereon. Such determination affects our balance sheet classification of these investments and the recognition of interest income derived therefrom. We receive additional interest, however, we never receive in excess of 50% of the residual profit in the project, and because the borrower has either a substantial investment in the project or has guaranteed all or a portion of our loan (or a combination thereof), the loans qualify for loan accounting. The amounts under these arrangements are presented as mortgage notes receivable at December 31, 2019 and 2018 . Mortgage notes receivable are recorded at cost, net of any valuation adjustments. Interest income is accrued as earned. Mortgage notes receivable are considered past due based on the contractual terms of the note agreement. On a quarterly basis, we evaluate the collectability of each mortgage note receivable based on various factors which may include payment history, expected fair value of the collateral securing the loan, internal and external credit information and/or economic trends. A loan is considered impaired when, based upon current information and events, it is probable that we will be unable to collect all amounts due under the existing contractual terms. When a loan is considered impaired, the amount of the loss accrual is calculated by comparing the carrying amount of the mortgage note receivable to the present value of expected future cash flows. Since our loans are collateralized by a first mortgage, the loans have risk characteristics similar to the risks in owning commercial real estate. At December 31, 2019 and 2018 , we had two mortgage notes receivable, with aggregate carrying amounts of $30.4 million , and weighted average interest rates of 10.0% and 10.3% , respectively, which were secured by first mortgages on retail buildings.
Share Based Compensation	Share Based Compensation We grant share based compensation awards to employees and trustees typically in the form of restricted common shares, common shares, and options. We measure share based compensation expense based on the grant date fair value of the award and recognize the expense ratably over the requisite service period, which is typically the vesting period. See Note 12 for further discussion regarding our share based compensation plans and policies.
Variable Interest Entities	Variable Interest Entities Certain entities that do not have sufficient equity at risk for the entity to finance its activities without additional subordinated financial support from other parties or in which equity investors do not have the characteristics of a controlling financial interest qualify as VIEs. VIEs are required to be consolidated by their primary beneficiary. The primary beneficiary of a VIE has both the power to direct the activities that most significantly impact economic performance of the VIE and the obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. Our equity method investments in the Pike & Rose hotel joint venture, the Assembly Row hotel joint venture, and the La Alameda shopping center are also considered variable interests in a VIE. As we do not control the activities that most significantly impact the economic performance of the joint ventures, we are not the primary beneficiary and do not consolidate. As of December 31, 2019 and 2018 , our investment in these joint ventures and maximum exposure to loss was $23.4 million and $26.9 million , respectively. In addition, we have 18 entities that meet the criteria of a VIE in which we hold a variable interest. For each of these entities, we control the significant operating decisions and consequently have the power to direct the activities that most significantly impact the economic performance of the entities. As we also have the obligation to absorb the majority of the losses and/or the right to receive a majority of the benefits for each of these entities, all are consolidated in our financial statements. Net real estate assets related to VIEs included in our consolidated balance sheets were approximately $1.5 billion for both December 31, 2019 and 2018 , and mortgages related to VIEs included in our consolidated balance sheets were approximately $469.2 million and $444.4 million , as of December 31, 2019 and 2018 , respectively. We have also evaluated our mortgage notes receivable investments and determined that the entities obligated under the mortgage notes are not VIEs. Our equity method investments and mortgage notes receivable balances are presented separately in our consolidated balance sheets.
Redeemable Noncontrolling Interests	Redeemable Noncontrolling Interests We have certain noncontrolling interests that are redeemable for cash upon the occurrence of an event that is not solely in our control and therefore are classified outside of permanent equity. We adjust the carrying amounts of these noncontrolling interests that are currently redeemable to redemption value at the balance sheet date. Adjustments to the carrying amount to reflect changes in redemption value are recorded as adjustments to additional paid-in capital in shareholders' equity. These amounts are classified within the mezzanine section of the consolidated balance sheets. The following table provides a rollforward of the redeemable noncontrolling interests: Year Ended December 31, 2019 2018 (In thousands) Beginning balance $ 136,208 $ 141,157 Contributions 9,961 354 Net Income 3,430 3,865 Distributions & Redemptions (15,366 ) (4,071 ) Change in redemption value 5,525 (5,097 ) Ending balance $ 139,758 $ 136,208
Income Taxes	Income Taxes We operate in a manner intended to enable us to qualify as a REIT for federal income tax purposes. A REIT that distributes at least 90% of its taxable income to its shareholders each year and meets certain other conditions is not taxed on that portion of its taxable income which is distributed to its shareholders. Therefore, federal income taxes on our taxable income have been and are generally expected to be immaterial. We are obligated to pay state taxes, generally consisting of franchise or gross receipts taxes in certain states. Such state taxes also have not been material. We have elected to treat certain of our subsidiaries as taxable REIT subsidiaries, which we refer to as a TRS. In general, a TRS may engage in any real estate business and certain non-real estate businesses, subject to certain limitations under the Internal Revenue Code of 1986, as amended (the “Code”). A TRS is subject to federal and state income taxes. Our TRS activities have not been material. With few exceptions, we are no longer subject to U.S. federal, state, and local tax examinations by tax authorities for years before 2016 . As of December 31, 2019 and 2018 , we had no material unrecognized tax benefits. While we currently have no material unrecognized tax benefits, as a policy, we recognize penalties and interest accrued related to unrecognized tax benefits as income tax expense.
Segment Information	Segment Information Our primary business is the ownership, management, and redevelopment of retail and mixed-use properties. We review operating and financial information for each property on an individual basis and therefore, each property represents an individual operating segment. We evaluate financial performance using property operating income, which consists of rental income, other property income and mortgage interest income, less rental expenses and real estate taxes. No individual commercial or residential property constitutes more than 10% of our revenues or property operating income and we have no operations outside of the United States of America. Therefore, we have aggregated our properties into one reportable segment as the properties share similar long-term economic characteristics and have other similarities including the fact that they are operated using consistent business strategies, are typically located in major metropolitan areas, and have similar tenant mixes.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Standard Description Date of Adoption Effect on the financial statements or significant matters Recently adopted: Leases (Topic 842) and related updates: Topic 842, Leases ASU 2019-01, March 2019, Leases (Topic 842), Codification Improvements ASC 842 significantly changes the accounting for leases by requiring lessees to recognize assets and liabilities for leases greater than 12 months on their balance sheet. The larger changes to the lessor model include: a change to the definition of initial direct costs of leases (resulting in the upfront expensing of more leasing related costs), the requirement to make an upfront and ongoing assessment of whether collection of substantially all of the lease payments required for the term of the lease is probable (if not probable, lease revenue is effectively recongnized when cash is collected), certain presentation changes, and the elimination of real estate specific guidance. January 2019 We have elected to apply the transition provisions of ASC Topic 842 at the beginning of the period of adoption (i.e., January 1, 2019), and therefore, did not retrospectively adjust prior periods presented. We have also elected to apply certain adoption related practical expedients for all leases that commenced prior to the effective date. These practical expedients include not reassessing whether any expired or existing contracts are or contain leases; not reassessing the lease classification for any expired or existing leases; and not reassessing initial direct costs for any existing leases. We have also elected the practical expedient allowing lessors to combine non-lease and lease components (primarily impacts common area maintenance recoveries). Standard Description Date of Adoption Effect on the financial statements or significant matters Adopted subsequent to December 31, 2019: Financial Instruments - Credit Losses (Topic 326) and related updates: 2016, Financial Instruments - Credit Losses (Topic 326) November 2018, Codification Topic 326, Financial Instruments - Credit Losses This ASU changes the impairment model for most financial assets and certain other instruments, requiring the use of an "expected credit loss" model and adding more disclosure requirements. ASU 2018-19 clarifies that impairment of of receivables arising from operating leases should accounted for in accordance with Topic 842, Leases. January 2020 While our mortgage notes receivable and certain other accounts receivables are impacted by this standard, the adoption of this standard will not have a significant impact to our consolidated financial statements. ASU 2018-15, August 2018, Intangibles - Goodwill and Other Internal Use Software: Customers Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract This ASU requires a customer in a cloud computing arrangement (i.e. hosting arrangement) that is a service contract to follow the internal-use software guidance in ASC 350-40 to determine which implementation costs to capitalize as assets. Capitalized implementation costs related to a hosting arrangement that is a service contract will be amortized over the term of the hosting arrangement. Entities will expense costs during the preliminary project and post-implementation stages as they are incurred. The guidance can be applied prospectively to all implementation costs incurred after the date of adoption or retrospectively in accordance with ASC 250-10-45-5 through ASC 250-10-45-10. January 2020 The adoption of this standard will not have a significant impact to our consolidated financial statements.

Summary Of Significant Accoun_3

Summary Of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Lease, Cost [Table Text Block]	The following table provides additional information on our operating and finance leases where we are the lessee: Year Ended December 31, 2019 (In thousands) LEASE COST: Finance lease cost: Amortization of right-of-use assets $ 1,284 Interest on lease liabilities 5,824 Operating lease cost 6,063 Variable lease cost 487 Total lease cost $ 13,658 OTHER INFORMATION: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows for finance leases 5,759 Operating cash flows for operating leases 5,561 Financing cash flows for finance leases 47 December 31, 2019 Weighted-average remaining term - finance leases 18.2 years Weighted-average remaining term - operating leases 53.7 years Weighted-average discount rate - finance leases 8.0 % Weighted-average discount rate - operating leases 4.5 %
Rollforward table of the redeemable noncontrolling interest	The following table provides a rollforward of the redeemable noncontrolling interests: Year Ended December 31, 2019 2018 (In thousands) Beginning balance $ 136,208 $ 141,157 Contributions 9,961 354 Net Income 3,430 3,865 Distributions & Redemptions (15,366 ) (4,071 ) Change in redemption value 5,525 (5,097 ) Ending balance $ 139,758 $ 136,208
Schedule of supplemental disclosures related to the Consolidated Statements Of Cash Flows	The following table provides supplemental disclosures related to the Consolidated Statements of Cash Flows: Year Ended December 31, 2019 2018 2017 (In thousands) SUPPLEMENTAL DISCLOSURES: Total interest costs incurred $ 130,110 $ 129,001 $ 125,684 Interest capitalized (20,487 ) (18,847 ) (25,559 ) Interest expense $ 109,623 $ 110,154 $ 100,125 Cash paid for interest, net of amounts capitalized $ 106,180 $ 107,494 $ 105,201 Cash paid for income taxes $ 483 $ 675 $ 352 NON-CASH INVESTING AND FINANCING TRANSACTIONS (1): Mortgage loans refinanced $ — $ — $ 166,823 Mortgage loans assumed/entered into with acquisition $ 98,041 $ — $ 79,401 DownREIT operating partnership units issued with acquisition $ — $ — $ 5,918 DownREIT operating partnership units redeemed for common shares $ 14,105 $ 101 $ 2,569 Settlement of partner loan receivable via dilution of partner interests $ 5,379 $ — $ — Shares issued under dividend reinvestment plan $ 1,784 $ 1,884 $ 2,017 Contribution from noncontrolling interest $ — $ 1,435 $ — (1) See Note 5 for additional disclosures relating to the mortgages entered into and assumed as a result of the Hoboken acquisition in 2019. In addition, see Note 3 for additional disclosures relating to our investment in the Assembly Row hotel joint venture in 2018.
Reconcilition of cash, cash equivalents, and restricted cash	December 31, 2019 2018 (In thousands) RECONCILIATION OF CASH, CASH EQUIVALENTS, AND RESTRICTED CASH: Cash and cash equivalents $ 127,432 $ 64,087 Restricted cash (1) 26,182 44,245 Total cash, cash equivalents, and restricted cash $ 153,614 $ 108,332 (1) Restricted cash balances are included in "prepaid expenses and other assets" on our consolidated balance sheets.

Real Estate (Tables)

Real Estate (Tables)	12 Months Ended
	Dec. 31, 2019
Real Estate [Abstract]
2019 Acquisitions	Date Acquired Property City/State Gross Leasable Area (GLA) Purchase Price (in square feet) (in millions) February 8, 2019 Fairfax Junction Fairfax, Virginia 75,000 $ 22.5 (1) September 13, 2019 San Antonio Center Mountain View, California 6,000 $ 6.5 November 15, 2019 Georgetowne Shopping Center Brooklyn, New York 147,000 $ 83.7 (2) Various 2019 Hoboken (37 mixed-use buildings) Hoboken, New Jersey 158,000 $ 189.2 (3)

Acquired In-Place Leases (Table

Acquired In-Place Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The following is a summary of our acquired lease assets and liabilities: December 31, 2019 December 31, 2018 Cost Accumulated Amortization Cost Accumulated Amortization (in thousands) Above market leases, lessor $ 48,530 $ (32,833 ) $ 49,128 $ (33,843 ) Below market leases, lessee 34,604 (3,362 ) 34,604 (2,533 ) Total $ 83,134 $ (36,195 ) $ 83,732 $ (36,376 ) Below market leases, lessor $ (177,512 ) $ 66,419 $ (189,379 ) $ 65,408 Above market leases, lessee (9,084 ) 1,590 (9,084 ) 1,065 Total $ (186,596 ) $ 68,009 $ (198,463 ) $ 66,473
Finite-lived Intangible Assets Amortization Expense [Table Text Block]	The following is a summary of acquired lease amortization: Year Ended December 31, 2019 2018 2017 (in thousands) Amortization of above market leases, lessor $ (3,239 ) $ (5,608 ) $ (6,005 ) Amortization of below market leases, lessor 9,623 12,445 10,726 Net increase in rental income $ 6,384 $ 6,837 $ 4,721 Amortization of below market leases, lessee $ 828 $ 828 $ 781 Amortization of above market leases, lessee (525 ) (505 ) (290 ) Net increase in rental expense $ 303 $ 323 $ 491 The following is a summary of the remaining weighted average amortization period for our acquired lease assets and acquired lease liabilities: December 31, 2019 Above market leases, lessor 3.7 years Below market leases, lessee 39.6 years Below market leases, lessor 18.1 years Above market leases, lessee 14.4 years
Amortization for acquired in-place leases during the next five years and thereafter	The amortization for acquired in-place leases during the next five years and thereafter, assuming no early lease terminations, is as follows: Acquired Lease Assets Acquired Lease Liabilities (In thousands) Year ending December 31, 2020 $ 4,350 $ 8,235 2021 3,370 7,687 2022 2,716 7,394 2023 2,488 7,134 2024 2,223 6,603 Thereafter 31,792 81,534 $ 46,939 $ 118,587

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Instruments [Abstract]
Summary of total debt outstanding	The following is a summary of our total debt outstanding as of December 31, 2019 and 2018 : Principal Balance as of December 31, Stated Interest Rate as of Stated Maturity Date as of Description of Debt 2019 2018 December 31, 2019 December 31, 2019 Mortgages payable (Dollars in thousands) Rollingwood Apartments $ — $ 20,331 5.54 % May 1, 2019 The Shops at Sunset Place 61,987 64,453 5.62 % September 1, 2020 29th Place 3,878 4,117 5.91 % January 31, 2021 Sylmar Towne Center 16,630 17,006 5.39 % June 6, 2021 Plaza Del Sol 8,230 8,409 5.23 % December 1, 2021 THE AVENUE at White Marsh 52,705 52,705 3.35 % January 1, 2022 Montrose Crossing 67,492 69,310 4.20 % January 10, 2022 Azalea 40,000 40,000 3.73 % November 1, 2025 Bell Gardens 12,677 12,936 4.06 % August 1, 2026 Plaza El Segundo 125,000 125,000 3.83 % June 5, 2027 The Grove at Shrewsbury (East) 43,600 43,600 3.77 % September 1, 2027 Brook 35 11,500 11,500 4.65 % July 1, 2029 Hoboken (24 Buildings) 56,450 — LIBOR + 1.95% December 15, 2029 Various Hoboken (12 Buildings) 24,627 — Various (1) Various through 2029 Chelsea 5,597 5,941 5.36 % January 15, 2031 Hoboken (1 Building) 16,874 — 3.75 % July 1, 2042 Subtotal 547,247 475,308 Net unamortized premium and debt issuance costs (1,568 ) (929 ) Total mortgages payable 545,679 474,379 Notes payable Term loan — 275,000 LIBOR + 0.90% November 21, 2019 Revolving credit facility — — LIBOR + 0.775% January 19, 2024 Various 3,843 4,392 11.31 % Various through 2028 Subtotal 3,843 279,392 Net unamortized debt issuance costs (62 ) (365 ) Total notes payable 3,781 279,027 Senior notes and debentures 2.55% notes 250,000 250,000 2.55 % January 15, 2021 3.00% notes 250,000 250,000 3.00 % August 1, 2022 2.75% notes 275,000 275,000 2.75 % June 1, 2023 3.95% notes 300,000 300,000 3.95 % January 15, 2024 7.48% debentures 29,200 29,200 7.48 % August 15, 2026 3.25% notes 475,000 475,000 3.25 % July 15, 2027 6.82% medium term notes 40,000 40,000 6.82 % August 1, 2027 3.20% notes 400,000 — 3.20 % June 15, 2029 4.50% notes 550,000 550,000 4.50 % December 1, 2044 3.625% notes 250,000 250,000 3.625 % August 1, 2046 Subtotal 2,819,200 2,419,200 Net unamortized discount and debt issuance costs (12,066 ) (14,921 ) Total senior notes and debentures 2,807,134 2,404,279 Various — 71,519 Various Various through 2106 Total debt and capital lease obligations $ 3,356,594 $ 3,229,204 _____________________ 1) The interest rates on these mortgages range from 3.91% to 5.00% .
Schedule of principal payments on mortgages payable, notes payable, senior notes and debentures	Scheduled principal payments on mortgages payable, notes payable, senior notes and debentures as of December 31, 2019 are as follows: Mortgages Payable Notes Payable Senior Notes and Debentures Total Principal (In thousands) Year ending December 31, 2020 $ 66,252 $ 613 $ — $ 66,865 2021 31,519 680 250,000 282,199 2022 119,460 756 250,000 370,216 2023 3,293 775 275,000 279,068 2024 3,421 665 (1) 300,000 304,086 Thereafter 323,302 354 1,744,200 2,067,856 $ 547,247 $ 3,843 $ 2,819,200 $ 3,370,290 (2) _____________________ (1) Our $1.0 billion revolving credit facility matures on January 19, 2024 , plus two six-month extensions at our option. As of December 31, 2019 , there was no outstanding balance under this credit facility. (2) The total debt maturities differ from the total reported on the consolidated balance sheet due to the unamortized net premium/discount and debt issuance costs on mortgage loans, notes payable, and senior notes as of December 31, 2019 .

Fair Value Of Financial Instr_2

Fair Value Of Financial Instruments Fair Value Of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Summary of carrying amount and fair value of financial instruments	A summary of the carrying amount and fair value of our mortgages payable, notes payable and senior notes and debentures is as follows: December 31, 2019 December 31, 2018 Carrying Value Fair Value Carrying Value Fair Value (In thousands) Mortgages and notes payable $ 549,460 $ 562,049 $ 753,406 $ 751,361 Senior notes and debentures $ 2,807,134 $ 3,001,216 $ 2,404,279 $ 2,371,392
Summary of financial assets/(liabilities) measured at fair value on a recurring basis	A summary of our financial assets that are measured at fair value on a recurring basis, by level within the fair value hierarchy is as follows: December 31, 2019 December 31, 2018 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (In thousands) Interest rate swaps $ — $ 130 $ — $ 130 $ — $ — $ — $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Lease Payments	Future minimum lease payments and their present value for properties under finance leases as of December 31, 2019 , are as follows: (In thousands) Year ending December 31, 2020 $ 5,800 2021 5,800 2022 5,810 2023 60,013 2024 1,013 Thereafter 81,849 160,285 Less amount representing interest (88,808 ) Add straight line lease obligation 585 Present value $ 72,062
Minimum annual payments	We are obligated under operating lease agreements on several shopping centers requiring minimum annual payments as follows, as of December 31, 2019 : (In thousands) Year ending December 31, 2020 $ 4,824 2021 4,832 2022 4,948 2023 4,988 2024 4,951 Thereafter 179,896 $ 204,439

Dividends (Tables)

Dividends (Tables)	12 Months Ended
	Dec. 31, 2019
Dividends [Abstract]
Summary of dividends declared and paid per share	The following table provides a summary of dividends declared and paid per share: Year Ended December 31, 2019 2018 2017 Declared Paid Declared Paid Declared Paid Common shares $ 4.140 $ 4.110 $ 4.040 $ 4.020 $ 3.960 $ 3.940 5.417% Series 1 Cumulative Convertible Preferred shares $ 1.354 $ 1.354 $ 1.354 $ 1.354 $ 1.354 $ 1.354 5.0% Series C Cumulative Redeemable Preferred shares (1) $ 1.250 $ 1.250 $ 1.250 $ 1.306 $ 0.368 $ — (1) Amount represents dividends per depositary share, each representing 1/1000th of a share.
Summary of income tax status of dividends per share paid	A summary of the income tax status of dividends per share paid is as follows: Year Ended December 31, 2019 2018 2017 Common shares Ordinary dividend $ 4.110 $ 3.859 $ 3.940 Ordinary dividend eligible for 15% rate — 0.161 — $ 4.110 $ 4.020 $ 3.940 5.417% Series 1 Cumulative Convertible Preferred shares Ordinary dividend $ 1.354 $ 1.300 $ 1.354 Ordinary dividend eligible for 15% rate — 0.054 — $ 1.354 $ 1.354 $ 1.354 5.0% Series C Cumulative Redeemable Preferred shares Ordinary dividend $ 1.250 $ 1.254 $ — Ordinary dividend eligible for 15% rate — 0.052 $ — $ 1.250 $ 1.306 $ —

Operating Leases (Tables)

Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Schedule of minimum future commercial property rentals from noncancelable operating leases	As of December 31, 2019 , future minimum rentals from noncancelable commercial operating leases (excluding both tenant reimbursements of operating expenses and percentage rent based on tenants' sales) are as follows: (In thousands) Year ending December 31, 2020 $ 616,760 2021 565,835 2022 498,438 2023 422,729 2024 352,221 Thereafter 1,528,699 $ 3,984,682

Components of Rental Expense (T

Components of Rental Expense (Tables)	12 Months Ended
	Dec. 31, 2019
Components Of Rental Expense [Abstract]
Schedule of principal components of rental expenses	The principal components of rental expenses are as follows: Year Ended December 31, 2019 2018 2017 (In thousands) Repairs and maintenance $ 73,179 $ 67,745 $ 67,996 Utilities 27,729 27,635 25,763 Management fees and costs 24,930 24,024 22,297 Payroll 16,485 16,140 14,922 Insurance 9,036 7,547 7,762 Marketing 7,427 7,935 9,007 Ground rent 4,803 4,697 3,826 Bad debt (1) — 4,708 2,591 Other operating (2) 24,242 12,663 10,726 Total rental expenses $ 187,831 $ 173,094 $ 164,890 _____________________ (1) Collectibility adjustments are now presented as a reduction of rental income rather than rental expense in accordance with our adoption of the new lease standard (see Note 2 for additional disclosure). (2) Other operating for the year ended December 31, 2019 includes an $11.9 million charge relating to the buyout of a lease at Assembly Square Marketplace.

Share-Based Compensation Plans

Share-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Summary of share-based compensation expense	A summary of share-based compensation expense included in net income is as follows: Year Ended December 31, 2019 2018 2017 (In thousands) Grants of common shares and options $ 13,330 $ 12,736 $ 12,371 Capitalized share-based compensation (1,054 ) (1,017 ) (1,385 ) Share-based compensation expense $ 12,276 $ 11,719 $ 10,986
Summary of weighted average assumptions used to value options granted	The following table provides a summary of the assumptions used to value options granted in 2018: Year Ended December 31, 2018 Volatility 18.0 % Expected dividend yield 3.6 % Expected term (in years) 7.5 Risk free interest rate 2.8 %
Summary of option activity	The following table provides a summary of option activity for 2019 : Shares Under Option Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term Aggregate Intrinsic Value (In years) (In thousands) Outstanding at December 31, 2018 682 $ 152.34 Granted — — Exercised — — Forfeited or expired — — Outstanding at December 31, 2019 682 $ 152.34 6.1 $ — Exercisable at December 31, 2019 409 $ 152.34 6.1 $ —
Summary of restricted share activity	The following table provides a summary of restricted share activity for 2019 : Shares Weighted-Average Grant-Date Fair Value Unvested at December 31, 2018 206,100 $ 130.46 Granted 122,056 133.30 Vested (97,077 ) 133.35 Forfeited (10,501 ) 151.22 Unvested at December 31, 2019 220,578 $ 129.78
Schedule of common shares awarded under various compensation plans	Subsequent to December 31, 2019 , common shares were awarded under various compensation plans as follows: Date Award Vesting Term Beneficiary January 2, 2020 5,591 Shares Immediate Trustees February 4, 2020 101,981 Restricted Shares 1-7 years Officers and key employees

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of earnings per share	In the dilutive EPS calculation, dilutive stock options were calculated using the treasury stock method consistent with prior periods. There were 682 anti-dilutive stock options in 2019 , 2018 , and 2017 , respectively. The conversions of downREIT operating partnership units and 5.417% Series 1 Cumulative Convertible Preferred Shares are anti-dilutive for all periods presented and accordingly, have been excluded from the weighted average common shares used to compute diluted EPS. Year Ended December 31, 2019 2018 2017 (In thousands, except per share data) NUMERATOR Net income $ 360,542 $ 249,026 $ 297,870 Less: Preferred share dividends (8,042 ) (8,042 ) (2,458 ) Less: Income from operations attributable to noncontrolling interests (6,676 ) (7,119 ) (7,956 ) Less: Earnings allocated to unvested shares (1,007 ) (930 ) (942 ) Net income available for common shareholders, basic and diluted $ 344,817 $ 232,935 $ 286,514 DENOMINATOR Weighted average common shares outstanding—basic 74,766 73,274 72,117 Stock options — 28 116 Weighted average common shares outstanding—diluted 74,766 73,302 72,233 EARNINGS PER COMMON SHARE, BASIC Net income available for common shareholders $ 4.61 $ 3.18 $ 3.97 EARNINGS PER COMMON SHARE, DILUTED Net income available for common shareholders $ 4.61 $ 3.18 $ 3.97

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Summary of quarterly financial data	Summarized quarterly financial data is as follows: First Quarter Second Quarter Third Quarter Fourth Quarter (In thousands, except per share data) 2019 Revenue $ 232,227 $ 230,465 $ 233,947 $ 239,149 Operating income (1) $ 91,093 $ 109,579 $ 94,018 $ 176,221 Net income (1) $ 61,803 $ 82,667 $ 67,106 $ 148,966 Net income attributable to the Trust (1) $ 60,144 $ 80,902 $ 65,465 $ 147,355 Net income available for common shareholders (1) $ 58,134 $ 78,891 $ 63,455 $ 145,344 Earnings per common share—basic (1) $ 0.78 $ 1.05 $ 0.84 $ 1.92 Earnings per common share—diluted (1) $ 0.78 $ 1.05 $ 0.84 $ 1.92 First Quarter Second Quarter Third Quarter Fourth Quarter (In thousands, except per share data) 2018 Revenue $ 225,405 $ 224,902 $ 229,753 $ 235,376 Operating income (2) $ 89,461 $ 93,868 $ 93,467 $ 84,840 Net income (2) $ 62,931 $ 65,533 $ 64,180 $ 56,382 Net income attributable to the Trust (2) $ 61,247 $ 63,595 $ 62,558 $ 54,507 Net income available for common shareholders (2) $ 59,237 $ 61,584 $ 60,548 $ 52,496 Earnings per common share—basic (2) $ 0.81 $ 0.84 $ 0.82 $ 0.71 Earnings per common share—diluted (2) $ 0.81 $ 0.84 $ 0.82 $ 0.71 (1) Second and third quarter 2019 include net gains of $16.2 million and $14.3 million , respectively, related to the sale of two properties and one parcel of land, as well as condominiums sold at our Assembly Row and Pike & Rose properties. Third quarter 2019 also includes an $11.9 million charge related to the buyout of a lease at Assembly Square Marketplace. Fourth quarter 2019 includes an $85.1 million net gain on sale under the threat of condemnation of a portion of San Antonio Center . All of these transactions are further discussed in Note 3. (2) First and second quarter 2018 include net gains of $3.3 million and $4.0 million , respectively, related to condominiums sold at our Assembly Row and Pike & Rose properties. Third and fourth quarter 2018 include gains of $3.1 million and $1.6 million , respectively, related to the sale of one residential building and one property. All of these transactions are further discussed in Note 3.

Business And Organization (Deta

Business And Organization (Details)	12 Months Ended
	Dec. 31, 2019project
Nature Of Operations [Abstract]
Number of real estate properties	104
Minimum percentage of taxable income distributed to shareholders	90.00%

Summary Of Significant Accoun_4

Summary Of Significant Accounting Policies (Revenue Recognition and Accounts Receivable) (Details)	Dec. 31, 2019condominiums
Condominiums | Assembly Row and Pike & Rose
Real estate property
Number of Units in Real Estate Property	221

Summary Of Significant Accoun_5

Summary Of Significant Accounting Policies (Real Estate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation Expense Real Estate	$ 215.4	$ 216	$ 193.3
Building and Building Improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	35 years
Building and Building Improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	50 years
Minor Improvements, Furniture and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Minor Improvements, Furniture and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years

Summary Of Significant Accoun_6

Summary Of Significant Accounting Policies (Cash and Cash Equivalents) (Details) $ in Millions	Dec. 31, 2019USD ($)
Accounting Policies [Abstract]
Cash in excess of the FDIC insured limit	$ 131.5

Summary Of Significant Accoun_7

Summary Of Significant Accounting Policies (Derivative Instruments and Mortgage Notes Receivable) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Derivatives, Fair Value [Line Items]
Residual profit maximum	50.00%
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Number of Loans	2
Aggregate tax basis for Federal tax purposes	$ 30.4	$ 30.4
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Interest Rate	10.00%	10.30%
Hoboken
Derivatives, Fair Value [Line Items]
Number of interest rate swap agreements	2
Assembly Row Hotel
Derivatives, Fair Value [Line Items]
Number of interest rate swap agreements	2
Equity Method Investee | Assembly Row Hotel
Derivatives, Fair Value [Line Items]
Fixed interest rate of derivative instrument	5.206%
Hoboken | Mortgages Payable
Derivatives, Fair Value [Line Items]
Number of interest rate swap agreements	2
Fixed interest rate of derivative instrument	3.67%

Summary Of Significant Accoun_8

Summary Of Significant Accounting Policies (Variable Interest Entities) (Details) $ in Thousands	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Variable Interest Entity [Line Items]
Number of consolidated variable interest entities	18
Net real estate assets of consolidated VIEs	$ 1,500,000	$ 1,500,000
Mortgage Payable From Consolidated Variable Interest Entities	469,184	444,388
Unconsolidated variable interest entities
Variable Interest Entity [Line Items]
Maximum exposure to loss in variable interest entity	$ 23,400	$ 26,900

Summary Of Significant Accoun_9

Summary Of Significant Accounting Policies (Redeemable Noncontrolling Interests) (Details) - USD ($) $ in Thousands	Aug. 02, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Rollforward of Redeemable Noncontrolling Interests
Beginning balance		$ 136,208	$ 141,157
Contributions		9,961	354
Net income		3,430	3,865	$ 3,874
Distributions & Redemptions		(15,366)	(4,071)
Change in redemption value		5,525	(5,097)
Ending balance		$ 139,758	$ 136,208	$ 141,157
Montrose Crossing
Redeemable Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	10.10%
Purchase Price Under Option	$ 10,000
Ownership interest subsequent to redemption	100.00%

Summary Of Significant Accou_10

Summary Of Significant Accounting Policies (Income Taxes and Segments) (Details)	12 Months Ended
	Dec. 31, 2019USD ($)segmentproperty
Accounting Policies [Abstract]
Minimum percentage of taxable income distributed to shareholders	90.00%
Material unrecognized tax benefits | $	$ 0
Number of properties exceeding segment reporting threshold | property	0
Segment Reporting, Factors Used to Identify Entity's Reportable Segments	10% of our revenues or property operating income
Number of segments | segment	1

Summary Of Significant Accou_11

Summary Of Significant Accounting Policies (Recent Accounting Pronouncements) (Details) $ in Millions	Jan. 01, 2019USD ($)	Dec. 31, 2019USD ($)property	Dec. 31, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of Properties Subject to Ground Leases | property		14
Cumulative Effect on Retained Earnings, Tax	$ 7.1
Capitalized internal leasing and external legal leasing costs		$ 2.2	$ 7.5

Summary Of Significant Accou_12

Summary Of Significant Accounting Policies (Supplemental Cash Flow Disclosures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Total interest costs incurred	$ 130,110	$ 129,001	$ 125,684
Interest capitalized	20,487	18,847	25,559
Interest expense	109,623	110,154	100,125
Cash paid for interest, net of amounts capitalized	106,180	107,494	105,201
Cash paid for income taxes	483	675	352
NON-CASH INVESTING AND FINANCING TRANSACTIONS (1):
Mortgage loans refinanced	0	0	166,823
Mortgage loans assumed with acquisition	98,041	0	79,401
DownREIT operating partnership units issued with acquisition	0	0	5,918
DownREIT operating partnership units redeemed for common shares	14,105	101	2,569
Settlement of partner loan via dilution	5,379	0	0
Shares issued under dividend reinvestment plan	1,784	1,884	2,017
Contribution of noncontrolling interest	$ 0	$ 1,435	$ 0
Minimum | Retail and commercial
Operating Leased Assets [Line Items]
Operating lease, term	3 years
Maximum | Retail and commercial
Operating Leased Assets [Line Items]
Operating lease, term	10 years

Summary Of Significant Accou_13

Summary Of Significant Accounting Policies Consolidated Statement of Cash Flows - Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents		$ 127,432	$ 64,087
Restricted cash	[1]	26,182	44,245
Total cash, cash equivalents, and restricted cash		$ 153,614	$ 108,332	$ 25,200	$ 34,849
[1]	(1) Restricted cash balances are included in "prepaid expenses and other assets" on our consolidated balance sheets.

Summary Of Significant Accou_14

Summary Of Significant Accounting Policies Lease Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Lease Information [Abstract]
Finance Lease, Right-of-Use Asset, Amortization	$ 1,284
Finance Lease, Interest Expense	5,824
Operating Lease, Cost	6,063
Variable Lease, Cost	487
Lease, Cost	13,658
Finance Lease, Interest Payment on Liability	5,759
Operating Lease, Payments	5,561
Finance Lease, Principal Payments	$ 47
Finance Lease, Weighted Average Remaining Lease Term	18 years 2 months 12 days
Operating Lease, Weighted Average Remaining Lease Term	53 years 8 months 12 days
Finance Lease, Weighted Average Discount Rate, Percent	8.00%
Operating Lease, Weighted Average Discount Rate, Percent	4.50%

Real Estate (Significant Acquis

Real Estate (Significant Acquisitions and Dispositions) (Details)		Dec. 11, 2019USD ($)a	Nov. 15, 2019USD ($)ft²	Sep. 13, 2019USD ($)ft²	Feb. 08, 2019USD ($)ft²	Nov. 29, 2018USD ($)ft²	Jun. 15, 2018USD ($)aft²	Aug. 31, 2018USD ($)	Dec. 31, 2019USD ($)ft²condominiums	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)ft²condominiums	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Business Acquisition and Disposition
Distribution from partnerships in excess of earnings												$ 2,765,000	$ 275,000	$ 1,729,000
Our investment in joint venture									$ 28,604,000			28,604,000	26,859,000
Assets held for sale									$ 1,729,000			1,729,000	16,576,000
Mortgage loans assumed with acquisition												98,041,000	0	79,401,000
Gain on sale of real estate, net of income taxes												$ 116,393,000	11,915,000	$ 77,922,000
Fairfax Junction
Business Acquisition and Disposition
Square footage of real estate property | ft²					75,000
Purchase price of real estate acquisition	[1]				$ 22,500,000
Georgetowne Shopping Center
Business Acquisition and Disposition
Square footage of real estate property | ft²			147,000
Purchase price of real estate acquisition	[2]		$ 83,700,000
Hoboken
Business Acquisition and Disposition
Square footage of real estate property | ft²									158,000			158,000
Purchase price of real estate acquisition	[3]											$ 189,200,000
Mortgage loans assumed with acquisition												$ 98,000,000
Number of Units in Real Estate Property									123			123
Ownership percentage in partnership									90.00%			90.00%
Freedom Plaza
Business Acquisition and Disposition
Square footage of real estate property | ft²							113,000
Construction pre-funding investment							$ 34,400,000
Controlling interest percentage							91.00%
Land parcel acre on which the shopping center will be constructed | a							9.4
Contribution from third party bank							$ 13,900,000
Strike price of put option							1,000
Direct and incremental costs of structuring the NMTC transaction							$ 1,600,000
Cash in escrow to be used for development									$ 12,600,000			$ 12,600,000
Two Properties [Member]
Business Acquisition and Disposition
Proceeds from sale													42,200,000
Gain on sale of real estate, net													4,700,000
A building adjacent to Bell Gardens
Business Acquisition and Disposition
Square footage of real estate property | ft²						40,000
Purchase price of real estate acquisition						$ 9,600,000
San Antonio Center
Business Acquisition and Disposition
Square footage of real estate property		11.7		6,000
Estimated Litigation Liability		$ 45,500,000
Proceeds from sale		$ 154,700,000
Gain on sale									85,100,000
Purchase price of real estate acquisition				$ 6,500,000
Three properties [Member]
Business Acquisition and Disposition
Proceeds from sale												149,000,000
Gain on sale												28,300,000
Other Assets | Above Market Leases | Fairfax Junction
Business Acquisition and Disposition
Net assets acquired allocated to intangible lease assets or liabilities					600,000
Other Assets | Above Market Leases | Georgetowne Shopping Center
Business Acquisition and Disposition
Net assets acquired allocated to intangible lease assets or liabilities			2,000,000
Other Assets | Above Market Leases | Hoboken
Business Acquisition and Disposition
Net assets acquired allocated to intangible lease assets or liabilities												3,600,000
Other Liabilities | Fairfax Junction
Business Acquisition and Disposition
Net assets acquired allocated to below market leases					$ 400,000
Other Liabilities | Georgetowne Shopping Center
Business Acquisition and Disposition
Net assets acquired allocated to below market leases			$ 400,000
Other Liabilities | Hoboken
Business Acquisition and Disposition
Net assets acquired allocated to below market leases												8,100,000
Condominiums | Assembly Row and Pike & Rose
Business Acquisition and Disposition
Proceeds from sale												$ 20,100,000	$ 133,500,000
Number of condominium units sold												43	176
Taxes related to the sale of condominiums													$ 1,600,000
Assets held for sale									$ 1,700,000			$ 1,700,000	16,600,000
Number of Units in Real Estate Property | condominiums									221			221
Gain on sale of real estate, net of income taxes										$ 4,000,000	$ 3,300,000	$ 2,600,000	$ 7,200,000
Equity method investments | Hotel | Assembly Row Hotel
Business Acquisition and Disposition
Contribution of Property								$ 44,000,000
Distribution from partnerships in excess of earnings								$ 38,000,000
Our investment in joint venture									$ 3,200,000			$ 3,200,000
[1]	Approximately $0.6 million and $0.4 million of net assets acquired were allocated to other assets for "above market leases," and other liabilities for "below market leases," respectively.
[2]	Approximately $2.0 million and $0.4 million of net assets acquired were allocated to other assets for "above market leases," and other liabilities for "below market leases," respectively.
[3]	These acquisitions were completed through a newly formed joint venture, for which we own a 90% interest. The purchase price includes new and assumptions of mortgage debt totaling approximately $98.0 million . This property includes 123 residential units in addition to the GLA in the table above. Approximately $3.6 million and $8.1 million of net assets acquired were allocated to other assets for "above market leases," and other liabilities for "below market leases," respectively.

Acquired In-Place Leases Acqur

Acquired In-Place Leases Acqured Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Total	$ 83,134	$ 83,732
Finite-Lived Intangible Assets, Accumulated Amortization	(36,195)	(36,376)
Finite-Lived Intangible Liabilities, Total	(186,596)	(198,463)
Finite-Lived Intangible Liabilities, Accumulated Amortization	68,009	66,473
Amortization of below market leases, lessor	9,623	12,445	$ 10,726
Net increase in rental income	6,384	6,837	4,721
Amortization of Below Market Lease, Lessee	828	828	781
Net increase in rental expense	303	323	491
Acquired Lease Liabilities
2020	8,235
2021	7,687
2022	7,394
2023	7,134
2024	6,603
Thereafter	81,534
Total future amortization expense from acquired below market leases	118,587
Above Market Leases
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of above market leases, lessor	(3,239)	(5,608)	(6,005)
Amortization of above market leases, lessee	$ (525)	(505)	$ (290)
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years 8 months 12 days
Acquired Finite-Lived Intangible Liabilities, Weighted Average Useful Life	18 years 1 month 6 days
Acquired Lease Assets
2020	$ 4,350
2021	3,370
2022	2,716
2023	2,488
2024	2,223
Thereafter	31,792
Acquired Lease Liabilities
Finite-Lived Intangible Assets, Net	46,939
Above Market Leases, Lessor
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Total	48,530	49,128
Finite-Lived Intangible Assets, Accumulated Amortization	(32,833)	(33,843)
Below Market Leases, Lessee
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Total	34,604	34,604
Finite-Lived Intangible Assets, Accumulated Amortization	$ (3,362)	(2,533)
Below Market Lease
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	39 years 7 months 6 days
Acquired Finite-Lived Intangible Liabilities, Weighted Average Useful Life	14 years 4 months 24 days
Below Market Leases, Lessor
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Liabilities, Total	$ (177,512)	(189,379)
Finite-Lived Intangible Liabilities, Accumulated Amortization	66,419	65,408
Above Market Leases, Lessee
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Liabilities, Total	(9,084)	(9,084)
Finite-Lived Intangible Liabilities, Accumulated Amortization	$ 1,590	$ 1,065

Debt (Summary Of Debt Outstandi

Debt (Summary Of Debt Outstanding) (Details) - USD ($) $ in Thousands	Jul. 25, 2019	Dec. 31, 2019	Aug. 21, 2019	Jun. 07, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Mortgages payable		$ 545,679			$ 474,379
Revolving credit facility		0			0
Notes payable		3,781			279,027
Net unamortized discount and debt issuance costs		(62)			(365)
Senior notes and debentures, net		2,807,134			2,404,279
Capital lease obligations		0			71,519
Total debt and capital lease obligations		3,356,594			3,229,204
Mortgages Payable
Debt Instrument [Line Items]
Principal balance		547,247			475,308
Net unamortized (discount) premium and debt issuance costs		(1,568)			(929)
Notes Payable
Debt Instrument [Line Items]
Notes payable		3,843			279,392
Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		2,819,200			2,419,200
Net unamortized (discount) premium and debt issuance costs		(12,066)			(14,921)
Rollingwood Apartments | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 0			20,331
Interest rate		5.54%
The Shops at Sunset Place | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 61,987			64,453
Interest rate		5.62%
29th Place | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 3,878			4,117
Interest rate		5.91%
Sylmar Towne Center | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 16,630			17,006
Interest rate		5.39%
Plaza Del Sol | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 8,230			8,409
Interest rate		5.23%
THE AVENUE at White Marsh | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 52,705			52,705
Interest rate		3.35%
Montrose Crossing | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 67,492			69,310
Interest rate		4.20%
Azalea | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 40,000			40,000
Interest rate		3.73%
Bell Gardens | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 12,677			12,936
Interest rate		4.06%
Plaza El Segundo | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 125,000			125,000
Interest rate		3.83%
The Grove at Shrewsbury (East) | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 43,600			43,600
Interest rate		3.77%
Brook 35 | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 11,500			11,500
Interest rate		4.65%
Hoboken (24 Buildings) | Mortgages Payable
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.95%
Principal balance		$ 56,450			0
Hoboken (12 Buildings) | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		24,627			0
Chelsea | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 5,597			5,941
Interest rate		5.36%
Hoboken (1 Building) | Mortgages Payable
Debt Instrument [Line Items]
Principal balance		$ 16,874			0
Interest rate		3.75%
Term Loan | Notes Payable
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		0.90%
Other Notes Payable		$ 0			275,000
Revolving credit facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.775%
Revolving credit facility | Notes Payable
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		0.775%
Various | Notes Payable
Debt Instrument [Line Items]
Interest rate		11.31%
Other Notes Payable		$ 3,843			4,392
2.55% notes | Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		$ 250,000			250,000
Interest rate		2.55%
3.00% notes | Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		$ 250,000			250,000
Interest rate		3.00%
2.75% notes | Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		$ 275,000			275,000
Interest rate		2.75%
3.95% notes | Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		$ 300,000			300,000
Interest rate		3.95%
7.48% debentures | Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		$ 29,200			29,200
Interest rate		7.48%
3.25% Senior notes | Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		$ 475,000			475,000
Interest rate		3.25%
6.82% medium term notes | Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		$ 40,000			40,000
Interest rate		6.82%
3.2% Senior Note
Debt Instrument [Line Items]
Senior notes and debentures, net			$ 100,000	$ 300,000
3.2% Senior Note | Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		$ 400,000			0
Interest rate		3.20%		3.20%
4.50% notes | Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		$ 550,000			550,000
Interest rate		4.50%
3.625% Senior notes | Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		$ 250,000			$ 250,000
Interest rate		3.625%
Minimum | Hoboken (12 Buildings) | Mortgages Payable
Debt Instrument [Line Items]
Interest rate		3.91%
Maximum | Hoboken (12 Buildings) | Mortgages Payable
Debt Instrument [Line Items]
Interest rate		5.00%

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($) $ in Thousands	Dec. 19, 2019	Nov. 26, 2019	Sep. 18, 2019	Jul. 25, 2019	Jun. 07, 2019	Jan. 31, 2019	Aug. 21, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Senior notes								$ 2,807,134	$ 2,404,279
Issuance of senior notes, net of costs								399,913	0	$ 572,134
Revolving credit facility								0	0
Maximum borrowing capacity under revolving credit facility				$ 1,000,000				1,000,000
Maximum amount of borrowings outstanding								116,500	177,000	344,000
Weighted average amount of borrowings outstanding								$ 26,800	$ 83,100	$ 147,500
Weighted average interest rate before amortization of debt fees								3.20%	2.70%	1.90%
Line of credit facility, annual facility fee								$ 1,000
Mortgage loans assumed with acquisition								$ 98,041	$ 0	$ 79,401
Option to increase credit facility through accordion feature
Debt Instrument [Line Items]
Maximum borrowing capacity under revolving credit facility				$ 1,500,000
Rollingwood Apartments | Mortgages Payable
Debt Instrument [Line Items]
Repayments of mortgage loan						$ 20,300
Stated Interest Rate								5.54%
3.2% Senior Note
Debt Instrument [Line Items]
Senior notes					$ 300,000		$ 100,000
3.2% Senior Note | Senior Notes and Debentures
Debt Instrument [Line Items]
Stated Interest Rate					3.20%			3.20%
Note Offering Percent					99.838%		103.813%
Debt yield to maturity percent					3.219%		2.744%
Issuance of senior notes, net of costs							$ 399,900
Term Loan | Notes Payable
Debt Instrument [Line Items]
Repayment of Term Loan					$ 275,000
Debt Instrument, Basis Spread on Variable Rate								0.90%
Revolving credit facility
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				0.775%
Revolving credit facility | Notes Payable
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate								0.775%
Hoboken | Mortgages Payable
Debt Instrument [Line Items]
Stated Interest Rate			3.75%
Debt Instrument, Basis Spread on Variable Rate		1.95%
Mortgage loans assumed with acquisition	$ 18,900	$ 5,700	$ 17,000					$ 41,600
Mortgage loan originated with acquisition		$ 56,500
Fair value of long-term debt								$ 42,900
Fixed interest rate of derivative instrument								3.67%
Hoboken | Minimum | Mortgages Payable
Debt Instrument [Line Items]
Stated Interest Rate	4.00%	3.91%
Hoboken | Maximum | Mortgages Payable
Debt Instrument [Line Items]
Stated Interest Rate	4.38%	5.00%

Debt (Principal Payments On Mor

Debt (Principal Payments On Mortgage Payable, Notes Payable, Senior Notes and Debentures) (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Jul. 25, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
2020		$ 66,865
2021		282,199
2022		370,216
2023		279,068
2024		304,086
Thereafter		2,067,856
Long-term Debt	[1]	3,370,290
Maximum borrowing capacity under revolving credit facility		1,000,000	$ 1,000,000
Revolving credit facility		0		$ 0
Mortgages Payable
Debt Instrument [Line Items]
Principal balance		547,247		475,308
2020		66,252
2021		31,519
2022		119,460
2023		3,293
2024		3,421
Thereafter		323,302
Long-term Debt		547,247
Notes Payable
Debt Instrument [Line Items]
2020		613
2021		680
2022		756
2023		775
2024	[2]	665
Thereafter		354
Long-term Debt		3,843
Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance		2,819,200		$ 2,419,200
2020		0
2021		250,000
2022		250,000
2023		275,000
2024		300,000
Thereafter		1,744,200
Long-term Debt		$ 2,819,200
[1]	The total debt maturities differ from the total reported on the consolidated balance sheet due to the unamortized net premium/discount and debt issuance costs on mortgage loans, notes payable, and senior notes as of December 31, 2019 .
[2]	Our $1.0 billion revolving credit facility matures on January 19, 2024 , plus two six-month extensions at our option. As of December 31, 2019 , there was no outstanding balance under this credit facility.

Fair Value Of Financial Instr_3

Fair Value Of Financial Instruments (Summary Of Carrying Amount And Fair Value Of Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Mortgages payable and notes payable | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value of long-term debt	$ 549,460	$ 753,406
Mortgages payable and notes payable | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value of long-term debt	562,049	751,361
Senior notes and debentures | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value of long-term debt	2,807,134	2,404,279
Senior notes and debentures | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value of long-term debt	$ 3,001,216	$ 2,371,392

Fair Value Of Financial Instr_4

Fair Value Of Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Interest expense reclassified from other comprehensive income (less than for 2019)	$ 100
Other comprehensive loss - change in value of interest rate swaps	(397)	$ (438)	$ 2,599
Prepaid expenses and other assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value of interest rate swaps	100
Fair Value, Measurements, Recurring | Interest Rate Swap
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value of interest rate swaps	130	0
Accumulated Other Comprehensive Income (loss)
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Other comprehensive loss - change in value of interest rate swaps	(397)	(438)	$ 2,599
Accumulated Other Comprehensive Income (loss) | Equity Method Investee
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Other comprehensive loss - change in value of interest rate swaps	900	400
Mortgage Payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Mortgage payable	$ 547,247	$ 475,308
Hoboken | Mortgage Payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Number of interest rate swap agreements	2
Notional amount of interest rate swap agreements	$ 56,500
Mortgage payable	$ 56,500
Fixed interest rate of derivative instrument	3.67%

Fair Value Of Financial Instr_5

Fair Value Of Financial Instruments (Summary of Financial Liabilities Measured At Fair Value On A Recurring Basis) (Details) - Interest Rate Swap - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative financial asset	$ 130	$ 0
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative financial asset	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative financial asset	130	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative financial asset	$ 0	$ 0

Commitments and Contingencies_2

Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2025	Oct. 16, 2023	Sep. 30, 2023	Oct. 16, 2021
Loss Contingencies [Line Items]
Reserves for warranties and general liability	$ 3	$ 3.1
Payments from reserves	1.3	$ 1.4
Letters of credit outstanding, amount	$ 4.3
DownREIT operating partnership units, outstanding	609,584
Operating partnership units outstanding, fair value	$ 78.5
Congressional Plaza | Put Option
Loss Contingencies [Line Items]
Indexed ownership interest percentage	26.63%
Maximum partnership percentage required to purchase	100.00%
Congressional Plaza | Put Option | Minimum
Loss Contingencies [Line Items]
Estimated maximum liability upon exercise of the put option	$ 79
Congressional Plaza | Put Option | Maximum
Loss Contingencies [Line Items]
Estimated maximum liability upon exercise of the put option	$ 84
Plaza El Segundo | Put Option
Loss Contingencies [Line Items]
Number of members with purchase options	2
Plaza El Segundo | Put Option | Minimum
Loss Contingencies [Line Items]
Estimated maximum liability upon exercise of the put option	$ 30
Plaza El Segundo | Put Option | Maximum
Loss Contingencies [Line Items]
Estimated maximum liability upon exercise of the put option	$ 33
The Grove at Shrewsbury | Put Option
Loss Contingencies [Line Items]
Indexed ownership interest percentage	4.10%
Brook 35 | Put Option
Loss Contingencies [Line Items]
Indexed ownership interest percentage	6.50%
Grove at Shrewsbury and Brook 35 | Put Option | Minimum
Loss Contingencies [Line Items]
Estimated maximum liability upon exercise of the put option	$ 7
Grove at Shrewsbury and Brook 35 | Put Option | Maximum
Loss Contingencies [Line Items]
Estimated maximum liability upon exercise of the put option	$ 8
Hoboken | Put Option
Loss Contingencies [Line Items]
Indexed ownership interest percentage	10.00%
Hoboken | Put Option | Minimum
Loss Contingencies [Line Items]
Estimated maximum liability upon exercise of the put option	$ 9
Hoboken | Put Option | Maximum
Loss Contingencies [Line Items]
Estimated maximum liability upon exercise of the put option	$ 10
Scenario, Forecast | Mercer Mall
Loss Contingencies [Line Items]
Purchase price under option					$ 55
Scenario, Forecast | Mercer Mall | Put Option
Loss Contingencies [Line Items]
Purchase price under option			$ 60
Scenario, Forecast | Melville Mall
Loss Contingencies [Line Items]
Purchase price under option						$ 5
Scenario, Forecast | Melville Mall | Put Option
Loss Contingencies [Line Items]
Purchase price under option				$ 5
Member One In Plaza El Segundo | Plaza El Segundo | Put Option
Loss Contingencies [Line Items]
Indexed ownership interest percentage	10.00%
Member Two In Plaza El Segundo | Plaza El Segundo | Put Option
Loss Contingencies [Line Items]
Indexed ownership interest percentage	11.80%
Capital Improvement, Development, and Redevelopment Projects
Loss Contingencies [Line Items]
Contractual obligations	$ 572.4

Commitments and Contingencies_3

Commitments and Contingencies (Schedule of Lease Payments) (Details) $ in Thousands	Dec. 31, 2019USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2020	$ 4,824
2021	4,832
2022	4,948
2023	4,988
2024	4,951
Thereafter	179,896
Total	$ 204,439

Commitments and Contingencies F

Commitments and Contingencies Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finance Lease, Liability, Payment, Due [Abstract]
2020	$ 5,800
2021	5,800
2022	5,810
2023	60,013
2024	1,013
Thereafter	81,849
Future minimum lease payments	160,285
Less amount representing interest	(88,808)
Add straight line lease obligation	585
Present value	$ 72,062	$ 0

Shareholders' Equity (Details)

Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 29, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 07, 2018
Class of Stock [Line Items]
Shares issued under dividend reinvestment plan (in shares)		15,909	17,952	17,911
Preferred shares, percentage		5.00%	5.00%	5.00%
Preferred shares, par value		$ 0.01	$ 0.01
Issuance of preferred shares, net of costs		$ 0	$ 0	$ 144,991
Net cash proceeds of common stock		$ 143,027	$ 130,918	$ 118,583
At The Market Equity Program
Class of Stock [Line Items]
Shares issued		1,069,699	987,383
Aggregate offering price of common shares					$ 400,000
Net cash proceeds of common stock		$ 142,700	$ 126,100
Weighted average price per common share		$ 134.71	$ 129.19
Remaining capacity to issue		$ 128,300
At The Market Equity Program | Commissions
Class of Stock [Line Items]
Commissions related to sales of common shares		1,200	$ 1,300
At The Market Equity Program | Other Offering Costs
Class of Stock [Line Items]
Commissions related to sales of common shares		$ 200	$ 200
5.0% Series C Cumulative Redeemable Preferred Shares
Class of Stock [Line Items]
Preferred shares, percentage	5.00%	5.00%	5.00%	5.00%
Preferred shares, par value	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Preferred shares, liquidation preference per share	$ 25,000	$ 25,000	$ 25,000	$ 25,000
Issuance of preferred shares, net of costs	$ 145,000
Preferred shares, shares outstanding		6,000	6,000
5.417% Series 1 Cumulative Convertible Preferred Shares
Class of Stock [Line Items]
Preferred shares, percentage		5.417%	5.417%	5.417%
Preferred shares, par value		$ 0.01	$ 0.01	$ 0.01
Preferred shares, liquidation preference per share		$ 25	$ 25	$ 25
Preferred shares, shares outstanding		399,896	399,896	399,896
Conversion price per share		$ 104.69
Depositary Shares | 5.0% Series C Cumulative Redeemable Preferred Shares
Class of Stock [Line Items]
Preferred shares, liquidation preference per share	$ 25	$ 25	$ 25	$ 25
Preferred Shares
Class of Stock [Line Items]
Shares issued				6,000
Preferred Shares | Depositary Shares | 5.0% Series C Cumulative Redeemable Preferred Shares
Class of Stock [Line Items]
Shares issued	6,000,000
Preferred shares, shares outstanding		6,000,000	6,000,000	6,000,000

Dividends (Details)

Dividends (Details) - $ / shares	Oct. 30, 2019	Sep. 29, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Preferred shares, percentage			5.00%	5.00%	5.00%
Common shares, declared	$ 1.05		$ 4.140	$ 4.040	$ 3.960
Common shares, paid			4.110	4.020	3.940
Payments of ordinary dividends, common stock			4.110	3.859	3.940
Common shares, ordinary dividend eligible for 15% rate			$ 0	$ 0.161	$ 0
Common shares, qualified dividends, tax rate			15.00%	15.00%	15.00%
Preferred stock, qualified dividends, tax rate			15.00%	15.00%	15.00%
5.417% Series 1 Cumulative Convertible Preferred Shares
Class of Stock [Line Items]
Preferred shares, percentage			5.417%	5.417%	5.417%
Preferred shares, declared			$ 1.354	$ 1.354	$ 1.354
Preferred shares, paid			1.354	1.354	1.354
Payment of ordinary dividends, preferred stock			1.354	1.300	1.354
Preferred shares, ordinary dividend eligible for 15% rate			$ 0	$ 0.054	$ 0
5.0% Series C Cumulative Redeemable Preferred Shares
Class of Stock [Line Items]
Preferred shares, percentage		5.00%	5.00%	5.00%	5.00%
Preferred shares, declared			$ 1.250	$ 1.250	$ 0.368
Preferred shares, paid			1.250	1.306	0
Payment of ordinary dividends, preferred stock			1.250	1.254	0
Preferred shares, ordinary dividend eligible for 15% rate			$ 0	$ 0.052	$ 0

Operating Leases (Details)

Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)projectleasestate
Property Subject to or Available for Operating Lease [Line Items]
Number of real estate properties | project	104
Number of states in which entity has properties | state	12
Percent of annualized base rent	2.60%
Operating Leases, Future Minimum Payments Receivable [Abstract]
2020	$ 616,760
2021	565,835
2022	498,438
2023	422,729
2024	352,221
Thereafter	1,528,699
Total	$ 3,984,682
Retail and commercial
Property Subject to or Available for Operating Lease [Line Items]
Number of leases | lease	3,000
Retail and commercial | Minimum
Property Subject to or Available for Operating Lease [Line Items]
Operating lease, term	3 years
Retail and commercial | Maximum
Property Subject to or Available for Operating Lease [Line Items]
Operating lease, term	10 years
Residential
Property Subject to or Available for Operating Lease [Line Items]
Number of leases	2,700
Residential | Maximum
Property Subject to or Available for Operating Lease [Line Items]
Operating lease, term	1 year

Components of Rental Expense (C

Components of Rental Expense (Components Of Rental Expenses) (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Repairs and maintenance			$ 73,179	$ 67,745	$ 67,996
Utilities			27,729	27,635	25,763
Management fees and costs			24,930	24,024	22,297
Payroll			16,485	16,140	14,922
Insurance			9,036	7,547	7,762
Marketing			7,427	7,935	9,007
Ground rent			4,803	4,697	3,826
Bad debt	[1]		0	4,708	2,591
Other operating	[2]		24,242	12,663	10,726
Total rental expenses			187,831	$ 173,094	$ 164,890
Assembly Square Marketplace
Charge related to the buyout of a lease		$ 11,900	$ 11,900
[1]	Collectibility adjustments are now presented as a reduction of rental income rather than rental expense in accordance with our adoption of the new lease standard (see Note 2 for additional disclosure).
[2]	Other operating for the year ended December 31, 2019 includes an $11.9 million charge relating to the buyout of a lease at Assembly Square Marketplace.

Share-Based Compensation Plan_2

Share-Based Compensation Plans (Allocated Share-Based Compensation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Abstract]
Grants of common shares and options	$ 13,330	$ 12,736	$ 12,371
Capitalized share-based compensation	(1,054)	(1,017)	(1,385)
Share-based compensation expense	$ 12,276	$ 11,719	$ 10,986

Share-Based Compensation Plan_3

Share-Based Compensation Plans (Weighted Average Assumptions Used to Value Option Granted) (Details)	12 Months Ended
	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Volatility	18.00%
Expected dividend yield	3.60%
Expected term (in years)	7 years 6 months
Risk free interest rate	2.80%

Share-Based Compensation Plan_4

Share-Based Compensation Plans (Schedule of Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at the beginning of year (in shares)	682
Granted (in shares)	0	0
Exercised (in shares)	0
Forfeited or expired (in shares)	0
Outstanding at the end of year (in shares)	682
Exercisable at the end of year (in shares)	409
Outstanding at the beginning of year, Weighted-Average Exercise Price (in dollars per share)	$ 152.34
Granted, Weighted-Average Exercise Price (in dollars per share)	0
Exercised, Weighted-Average Exercise Price (in dollars per share)	0
Forfeited or Expired, Weighted-Average Exercise Price (in dollars per share)	0
Outstanding at the end of year, Weighted-Average Exercise Price (in dollars per share)	152.34
Exercisable at the end of the year, Weighted-Average Exercise Price (in dollars per share)	$ 152.34
Outstanding at the end of year, Weighted-Average Remaining Contractual Term (in years)	6 years 1 month 6 days
Exercisable at the end of year, Weighted-Average Remaining Contractual Term (in years)	6 years 1 month 6 days
Outstanding at the end of year, Aggregate Intrinsic Value	$ 0
Exercisable at the end of year, Aggregate Intrinsic Value	$ 0

Share-Based Compensation Plan_5

Share-Based Compensation Plans (Restricted Share Activity) (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested at the beginning of year (in shares)	206,100
Granted (in shares)	122,056
Vested (in shares)	(97,077)
Forfeited (in shares)	(10,501)
Unvested at the end of year (in shares)	220,578	206,100
Unvested at the beginning of year, Weighted-Average Grant-Date Fair Value (in dollars per share)	$ 130.46
Granted, Weighted-Average Grant-Date Fair Value (in dollars per share)	133.30	$ 112.88	$ 139.31
Vested, Weighted-Average Grant-Date Fair Value (in dollars per share)	133.35
Forfeited, Weighted-Average Grant-Date Fair Value (in dollars per share)	151.22
Unvested at the end of year, Weighted-Average Grant-Date Fair Value (in dollars per share)	$ 129.78	$ 130.46

Share-Based Compensation Plan_6

Share-Based Compensation Plans (Common Shares Awarded Under Various Compensation Plans) (Details) - Restricted Stock - shares	Feb. 04, 2020	Jan. 02, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			122,056
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	101,981	5,591
Subsequent Event | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Term	1 year
Subsequent Event | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Term	7 years

Share-Based Compensation Plan_7

Share-Based Compensation Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted in period	0		0
Weighted average grant date fair value of options granted		$ 14.42
Total cash received from options exercised		$ 4.6	$ 10
Total intrinsic value of options exercised		$ 8.2	$ 10.7
Total unrecognized compensation cost related to unvested share-based compensation arrangements	$ 17.1
Period for recognition (in years)	4 years 10 months 24 days
Weighted-average period for recognition	2 years 4 months 24 days
Performance Incentive Plan 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	2,450,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of stock awarded	$ 133.30	$ 112.88	$ 139.31
Total vesting-date fair value of shares vested during the year	$ 13	$ 9.7	$ 12.5
Grants of common shares and options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Term	3 years
Grants of common shares and options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Term	7 years
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term (in years)	10 years

Savings and Retirement Plans (D

Savings and Retirement Plans (Details) - 401(K) and Deferred Compensation Plan - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
401(k) Maximum annual contribution per employee	$ 19,000	$ 18,500	$ 18,000
401(k) Employer match	50.00%	50.00%	50.00%
401(k) Employer contribution expense	$ 764,000	$ 688,000	$ 632,000
Deferred compensation liability to participants	$ 14,700,000	$ 12,000,000
Maximum
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
401(k) Maximum of employer match as a percentage of employee eligible earnings	5.00%	5.00%	5.00%

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share Narrative [Line Items]
Weighted average unvested shares outstanding	200,000	200,000	200,000
Anti-dilutive stock options excluded from dilutive earnings per share calculation	682	682	682
Cumulative convertible preferred share, dividend rate	5.00%	5.00%	5.00%
5.417% Series 1 Cumulative Convertible Preferred Shares
Earnings Per Share Narrative [Line Items]
Cumulative convertible preferred share, dividend rate	5.417%	5.417%	5.417%

Earnings Per Share (Schedule Of

Earnings Per Share (Schedule Of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2019	[1]	Sep. 30, 2019	[1]	Jun. 30, 2019	[1]	Mar. 31, 2019	[1]	Dec. 31, 2018	[2]	Sep. 30, 2018	[2]	Jun. 30, 2018	[2]	Mar. 31, 2018	[2]	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 148,966		$ 67,106		$ 82,667		$ 61,803		$ 56,382		$ 64,180		$ 65,533		$ 62,931		$ 360,542	$ 249,026	$ 297,870
Less: Preferred share dividends																	(8,042)	(8,042)	(2,458)
Net income attributable to noncontrolling interests																	(6,676)	(7,119)	(7,956)
Less: Earnings allocated to unvested shares																	(1,007)	(930)	(942)
Net income available for common shareholders, basic and diluted																	$ 344,817	$ 232,935	$ 286,514
Weighted average common shares outstanding—basic																	74,766	73,274	72,117
Stock options																	0	28	116
Weighted average common shares outstanding—diluted																	74,766	73,302	72,233
Earnings Per Common Share, Basic	$ 1.92		$ 0.84		$ 1.05		$ 0.78		$ 0.71		$ 0.82		$ 0.84		$ 0.81		$ 4.61	$ 3.18	$ 3.97
Earnings Per Common Share, Diluted	$ 1.92		$ 0.84		$ 1.05		$ 0.78		$ 0.71		$ 0.82		$ 0.84		$ 0.81		$ 4.61	$ 3.18	$ 3.97
[1]	Second and third quarter 2019 include net gains of $16.2 million and $14.3 million , respectively, related to the sale of two properties and one parcel of land, as well as condominiums sold at our Assembly Row and Pike & Rose properties. Third quarter 2019 also includes an $11.9 million charge related to the buyout of a lease at Assembly Square Marketplace. Fourth quarter 2019 includes an $85.1 million net gain on sale under the threat of condemnation of a portion of San Antonio Center . All of these transactions are further discussed in Note 3.
[2]	First and second quarter 2018 include net gains of $3.3 million and $4.0 million , respectively, related to condominiums sold at our Assembly Row and Pike & Rose properties. Third and fourth quarter 2018 include gains of $3.1 million and $1.6 million , respectively, related to the sale of one residential building and one property. All of these transactions are further discussed in Note 3.

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) Summary Of Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 239,149		$ 233,947		$ 230,465		$ 232,227		$ 235,376		$ 229,753		$ 224,902		$ 225,405		$ 935,788	$ 915,436	$ 857,348
Operating income	176,221	[1]	94,018	[1]	109,579	[1]	91,093	[1]	84,840	[2]	93,467	[2]	93,868	[2]	89,461	[2]	470,911	361,636	410,210
Net income	148,966	[1]	67,106	[1]	82,667	[1]	61,803	[1]	56,382	[2]	64,180	[2]	65,533	[2]	62,931	[2]	360,542	249,026	297,870
Net income attributable to the Trust	147,355	[1]	65,465	[1]	80,902	[1]	60,144	[1]	54,507	[2]	62,558	[2]	63,595	[2]	61,247	[2]	353,866	241,907	289,914
Net income available for common shareholders	$ 145,344	[1]	$ 63,455	[1]	$ 78,891	[1]	$ 58,134	[1]	$ 52,496	[2]	$ 60,548	[2]	$ 61,584	[2]	$ 59,237	[2]	$ 345,824	$ 233,865	$ 287,456
Earnings Per Common Share, Basic	$ 1.92	[1]	$ 0.84	[1]	$ 1.05	[1]	$ 0.78	[1]	$ 0.71	[2]	$ 0.82	[2]	$ 0.84	[2]	$ 0.81	[2]	$ 4.61	$ 3.18	$ 3.97
Earnings Per Common Share, Diluted	$ 1.92	[1]	$ 0.84	[1]	$ 1.05	[1]	$ 0.78	[1]	$ 0.71	[2]	$ 0.82	[2]	$ 0.84	[2]	$ 0.81	[2]	$ 4.61	$ 3.18	$ 3.97
[1]	Second and third quarter 2019 include net gains of $16.2 million and $14.3 million , respectively, related to the sale of two properties and one parcel of land, as well as condominiums sold at our Assembly Row and Pike & Rose properties. Third quarter 2019 also includes an $11.9 million charge related to the buyout of a lease at Assembly Square Marketplace. Fourth quarter 2019 includes an $85.1 million net gain on sale under the threat of condemnation of a portion of San Antonio Center . All of these transactions are further discussed in Note 3.
[2]	First and second quarter 2018 include net gains of $3.3 million and $4.0 million , respectively, related to condominiums sold at our Assembly Row and Pike & Rose properties. Third and fourth quarter 2018 include gains of $3.1 million and $1.6 million , respectively, related to the sale of one residential building and one property. All of these transactions are further discussed in Note 3.

Selected Quarterly Financial _4

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ in Thousands	3 Months Ended							12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of real estate, net								$ 116,393	$ 11,915	$ 77,922
Assembly Square Marketplace
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Charge related to the buyout of a lease		$ 11,900						11,900
Portion of San Antonio Center under threat of condemnation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale	$ 85,100
Two properties, one parcel of land, and condominiums sold at our Assembly Row and Pike & Rose properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of real estate, net		$ 14,300	$ 16,200
Condominiums | Assembly Row and Pike & Rose
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of real estate, net						$ 4,000	$ 3,300	$ 2,600	$ 7,200
Residential
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale					$ 3,100
One property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale				$ 1,600

Subsequent Event (Details)

Subsequent Event (Details) - Shopping center in Fairfax, Virginia - Subsequent Event $ in Millions	Jan. 10, 2020USD ($)ft²shares
Subsequent Event [Line Items]
Square footage of real estate property | ft²	49,000
Purchase price of real estate acquisition | $	$ 22.3
DownREIT operating partnership units issued to fund acquisition | shares	163,322

Schedule III - Summary of Rea_2

Schedule III - Summary of Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 545,679
Initial cost to company, Land	1,449,865
Initial cost to company, Buildings and Improvements	2,526,772
Cost Capitalized Subsequent to Acquisition	4,321,495
Gross amount at which carried at close of period, Land	1,414,814
Gross amount at which carried at close of period, Buildings and Improvements	6,883,318
Gross amount at which carried at close of period, Total	8,298,132	$ 7,819,472	$ 7,635,061	$ 6,759,073
Accumulated Depreciation and Amortization	$ 2,215,413	$ 2,059,143	$ 1,876,544	$ 1,729,234
Maximum
Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statements is computed	50 years
29th Place
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 3,868
Initial cost to company, Land	10,211
Initial cost to company, Buildings and Improvements	18,863
Cost Capitalized Subsequent to Acquisition	11,985
Gross amount at which carried at close of period, Land	10,195
Gross amount at which carried at close of period, Buildings and Improvements	30,864
Gross amount at which carried at close of period, Total	41,059
Accumulated Depreciation and Amortization	14,953
Andorra
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	2,432
Initial cost to company, Buildings and Improvements	12,346
Cost Capitalized Subsequent to Acquisition	11,718
Gross amount at which carried at close of period, Land	2,432
Gross amount at which carried at close of period, Buildings and Improvements	24,064
Gross amount at which carried at close of period, Total	26,496
Accumulated Depreciation and Amortization	20,382
Assembly Row/Assembly Square Market Place
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	93,252
Initial cost to company, Buildings and Improvements	34,196
Cost Capitalized Subsequent to Acquisition	662,720
Gross amount at which carried at close of period, Land	69,421
Gross amount at which carried at close of period, Buildings and Improvements	720,747
Gross amount at which carried at close of period, Total	790,168
Accumulated Depreciation and Amortization	72,687
Azalea
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	39,702
Initial cost to company, Land	40,219
Initial cost to company, Buildings and Improvements	67,117
Cost Capitalized Subsequent to Acquisition	(3)
Gross amount at which carried at close of period, Land	40,219
Gross amount at which carried at close of period, Buildings and Improvements	67,114
Gross amount at which carried at close of period, Total	107,333
Accumulated Depreciation and Amortization	6,109
Bala Cynwyd
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	3,565
Initial cost to company, Buildings and Improvements	14,466
Cost Capitalized Subsequent to Acquisition	39,175
Gross amount at which carried at close of period, Land	2,683
Gross amount at which carried at close of period, Buildings and Improvements	54,523
Gross amount at which carried at close of period, Total	57,206
Accumulated Depreciation and Amortization	23,062
Barcroft Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	12,617
Initial cost to company, Buildings and Improvements	29,603
Cost Capitalized Subsequent to Acquisition	6,515
Gross amount at which carried at close of period, Land	12,617
Gross amount at which carried at close of period, Buildings and Improvements	36,118
Gross amount at which carried at close of period, Total	48,735
Accumulated Depreciation and Amortization	4,513
Barracks Road
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	4,363
Initial cost to company, Buildings and Improvements	16,459
Cost Capitalized Subsequent to Acquisition	48,764
Gross amount at which carried at close of period, Land	4,363
Gross amount at which carried at close of period, Buildings and Improvements	65,223
Gross amount at which carried at close of period, Total	69,586
Accumulated Depreciation and Amortization	47,069
Bell Gardens
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	12,292
Initial cost to company, Land	24,406
Initial cost to company, Buildings and Improvements	85,947
Cost Capitalized Subsequent to Acquisition	589
Gross amount at which carried at close of period, Land	24,406
Gross amount at which carried at close of period, Buildings and Improvements	86,536
Gross amount at which carried at close of period, Total	110,942
Accumulated Depreciation and Amortization	10,215
Bethesda Row
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	46,579
Initial cost to company, Buildings and Improvements	35,406
Cost Capitalized Subsequent to Acquisition	151,640
Gross amount at which carried at close of period, Land	43,904
Gross amount at which carried at close of period, Buildings and Improvements	189,721
Gross amount at which carried at close of period, Total	233,625
Accumulated Depreciation and Amortization	85,602
Brick Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	0
Initial cost to company, Buildings and Improvements	24,715
Cost Capitalized Subsequent to Acquisition	72,050
Gross amount at which carried at close of period, Land	4,094
Gross amount at which carried at close of period, Buildings and Improvements	92,671
Gross amount at which carried at close of period, Total	96,765
Accumulated Depreciation and Amortization	52,749
Bristol Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	3,856
Initial cost to company, Buildings and Improvements	15,959
Cost Capitalized Subsequent to Acquisition	11,786
Gross amount at which carried at close of period, Land	3,856
Gross amount at which carried at close of period, Buildings and Improvements	27,745
Gross amount at which carried at close of period, Total	31,601
Accumulated Depreciation and Amortization	19,149
Brook 35
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	11,304
Initial cost to company, Land	7,128
Initial cost to company, Buildings and Improvements	38,355
Cost Capitalized Subsequent to Acquisition	2,792
Gross amount at which carried at close of period, Land	7,128
Gross amount at which carried at close of period, Buildings and Improvements	41,147
Gross amount at which carried at close of period, Total	48,275
Accumulated Depreciation and Amortization	8,360
Campus Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	16,710
Initial cost to company, Buildings and Improvements	13,412
Cost Capitalized Subsequent to Acquisition	315
Gross amount at which carried at close of period, Land	16,710
Gross amount at which carried at close of period, Buildings and Improvements	13,727
Gross amount at which carried at close of period, Total	30,437
Accumulated Depreciation and Amortization	2,415
Chelsea Commons
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	5,402
Initial cost to company, Land	8,689
Initial cost to company, Buildings and Improvements	19,466
Cost Capitalized Subsequent to Acquisition	2,126
Gross amount at which carried at close of period, Land	8,669
Gross amount at which carried at close of period, Buildings and Improvements	21,612
Gross amount at which carried at close of period, Total	30,281
Accumulated Depreciation and Amortization	8,382
CocoWalk
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	35,063
Initial cost to company, Buildings and Improvements	71,476
Cost Capitalized Subsequent to Acquisition	47,158
Gross amount at which carried at close of period, Land	34,406
Gross amount at which carried at close of period, Buildings and Improvements	119,291
Gross amount at which carried at close of period, Total	153,697
Accumulated Depreciation and Amortization	10,175
Colorado Blvd
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	5,262
Initial cost to company, Buildings and Improvements	4,071
Cost Capitalized Subsequent to Acquisition	10,375
Gross amount at which carried at close of period, Land	5,262
Gross amount at which carried at close of period, Buildings and Improvements	14,446
Gross amount at which carried at close of period, Total	19,708
Accumulated Depreciation and Amortization	11,507
Congressional Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	2,793
Initial cost to company, Buildings and Improvements	7,424
Cost Capitalized Subsequent to Acquisition	95,064
Gross amount at which carried at close of period, Land	2,793
Gross amount at which carried at close of period, Buildings and Improvements	102,488
Gross amount at which carried at close of period, Total	105,281
Accumulated Depreciation and Amortization	58,521
Courthouse Center
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	1,750
Initial cost to company, Buildings and Improvements	1,869
Cost Capitalized Subsequent to Acquisition	3,106
Gross amount at which carried at close of period, Land	1,750
Gross amount at which carried at close of period, Buildings and Improvements	4,975
Gross amount at which carried at close of period, Total	6,725
Accumulated Depreciation and Amortization	2,408
Crossroads
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	4,635
Initial cost to company, Buildings and Improvements	11,611
Cost Capitalized Subsequent to Acquisition	19,462
Gross amount at which carried at close of period, Land	4,635
Gross amount at which carried at close of period, Buildings and Improvements	31,073
Gross amount at which carried at close of period, Total	35,708
Accumulated Depreciation and Amortization	18,708
Crow Canyon Commons
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	27,245
Initial cost to company, Buildings and Improvements	54,575
Cost Capitalized Subsequent to Acquisition	8,392
Gross amount at which carried at close of period, Land	27,245
Gross amount at which carried at close of period, Buildings and Improvements	62,967
Gross amount at which carried at close of period, Total	90,212
Accumulated Depreciation and Amortization	25,878
Darien
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	30,368
Initial cost to company, Buildings and Improvements	19,523
Cost Capitalized Subsequent to Acquisition	7,214
Gross amount at which carried at close of period, Land	30,368
Gross amount at which carried at close of period, Buildings and Improvements	26,737
Gross amount at which carried at close of period, Total	57,105
Accumulated Depreciation and Amortization	4,351
Dedham Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	16,658
Initial cost to company, Buildings and Improvements	13,964
Cost Capitalized Subsequent to Acquisition	15,825
Gross amount at which carried at close of period, Land	16,658
Gross amount at which carried at close of period, Buildings and Improvements	29,789
Gross amount at which carried at close of period, Total	46,447
Accumulated Depreciation and Amortization	17,108
Del Mar Village
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	15,624
Initial cost to company, Buildings and Improvements	41,712
Cost Capitalized Subsequent to Acquisition	15,821
Gross amount at which carried at close of period, Land	15,587
Gross amount at which carried at close of period, Buildings and Improvements	57,570
Gross amount at which carried at close of period, Total	73,157
Accumulated Depreciation and Amortization	24,154
East Bay Bridge
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	29,069
Initial cost to company, Buildings and Improvements	138,035
Cost Capitalized Subsequent to Acquisition	11,839
Gross amount at which carried at close of period, Land	29,069
Gross amount at which carried at close of period, Buildings and Improvements	149,874
Gross amount at which carried at close of period, Total	178,943
Accumulated Depreciation and Amortization	36,029
Eastgate Crossing
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	1,608
Initial cost to company, Buildings and Improvements	5,775
Cost Capitalized Subsequent to Acquisition	27,806
Gross amount at which carried at close of period, Land	1,608
Gross amount at which carried at close of period, Buildings and Improvements	33,581
Gross amount at which carried at close of period, Total	35,189
Accumulated Depreciation and Amortization	21,822
Elllisburg
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	4,028
Initial cost to company, Buildings and Improvements	11,309
Cost Capitalized Subsequent to Acquisition	19,277
Gross amount at which carried at close of period, Land	4,013
Gross amount at which carried at close of period, Buildings and Improvements	30,601
Gross amount at which carried at close of period, Total	34,614
Accumulated Depreciation and Amortization	21,832
Escondido Promenade
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	19,117
Initial cost to company, Buildings and Improvements	15,829
Cost Capitalized Subsequent to Acquisition	17,942
Gross amount at which carried at close of period, Land	19,117
Gross amount at which carried at close of period, Buildings and Improvements	33,771
Gross amount at which carried at close of period, Total	52,888
Accumulated Depreciation and Amortization	19,105
Fairfax Junction
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	10,229
Initial cost to company, Buildings and Improvements	11,321
Cost Capitalized Subsequent to Acquisition	25
Gross amount at which carried at close of period, Land	10,229
Gross amount at which carried at close of period, Buildings and Improvements	11,346
Gross amount at which carried at close of period, Total	21,575
Accumulated Depreciation and Amortization	548
Falls Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	1,798
Initial cost to company, Buildings and Improvements	1,270
Cost Capitalized Subsequent to Acquisition	11,370
Gross amount at which carried at close of period, Land	1,819
Gross amount at which carried at close of period, Buildings and Improvements	12,619
Gross amount at which carried at close of period, Total	14,438
Accumulated Depreciation and Amortization	9,078
Federal Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	10,216
Initial cost to company, Buildings and Improvements	17,895
Cost Capitalized Subsequent to Acquisition	42,396
Gross amount at which carried at close of period, Land	10,216
Gross amount at which carried at close of period, Buildings and Improvements	60,291
Gross amount at which carried at close of period, Total	70,507
Accumulated Depreciation and Amortization	46,693
Finley Square
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	9,252
Initial cost to company, Buildings and Improvements	9,544
Cost Capitalized Subsequent to Acquisition	22,645
Gross amount at which carried at close of period, Land	9,252
Gross amount at which carried at close of period, Buildings and Improvements	32,189
Gross amount at which carried at close of period, Total	41,441
Accumulated Depreciation and Amortization	22,071
Flourtown
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	1,345
Initial cost to company, Buildings and Improvements	3,943
Cost Capitalized Subsequent to Acquisition	11,795
Gross amount at which carried at close of period, Land	1,507
Gross amount at which carried at close of period, Buildings and Improvements	15,576
Gross amount at which carried at close of period, Total	17,083
Accumulated Depreciation and Amortization	7,028
Fourth Street
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	13,978
Initial cost to company, Buildings and Improvements	9,909
Cost Capitalized Subsequent to Acquisition	2,345
Gross amount at which carried at close of period, Land	13,978
Gross amount at which carried at close of period, Buildings and Improvements	12,254
Gross amount at which carried at close of period, Total	26,232
Accumulated Depreciation and Amortization	1,014
Freedom Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	0
Initial cost to company, Buildings and Improvements	3,255
Cost Capitalized Subsequent to Acquisition	35,623
Gross amount at which carried at close of period, Land	0
Gross amount at which carried at close of period, Buildings and Improvements	38,878
Gross amount at which carried at close of period, Total	38,878
Accumulated Depreciation and Amortization	0
Fresh Meadows
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	24,625
Initial cost to company, Buildings and Improvements	25,255
Cost Capitalized Subsequent to Acquisition	43,297
Gross amount at which carried at close of period, Land	24,633
Gross amount at which carried at close of period, Buildings and Improvements	68,544
Gross amount at which carried at close of period, Total	93,177
Accumulated Depreciation and Amortization	43,607
Friendship Center
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	12,696
Initial cost to company, Buildings and Improvements	20,803
Cost Capitalized Subsequent to Acquisition	4,662
Gross amount at which carried at close of period, Land	12,696
Gross amount at which carried at close of period, Buildings and Improvements	25,465
Gross amount at which carried at close of period, Total	38,161
Accumulated Depreciation and Amortization	13,970
Gaithersburg Square
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	7,701
Initial cost to company, Buildings and Improvements	5,271
Cost Capitalized Subsequent to Acquisition	15,692
Gross amount at which carried at close of period, Land	5,973
Gross amount at which carried at close of period, Buildings and Improvements	22,691
Gross amount at which carried at close of period, Total	28,664
Accumulated Depreciation and Amortization	18,933
Garden Market
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	2,677
Initial cost to company, Buildings and Improvements	4,829
Cost Capitalized Subsequent to Acquisition	7,295
Gross amount at which carried at close of period, Land	2,677
Gross amount at which carried at close of period, Buildings and Improvements	12,124
Gross amount at which carried at close of period, Total	14,801
Accumulated Depreciation and Amortization	8,640
Georgetowne Shopping Center
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	30,738
Initial cost to company, Buildings and Improvements	50,103
Cost Capitalized Subsequent to Acquisition	946
Gross amount at which carried at close of period, Land	32,199
Gross amount at which carried at close of period, Buildings and Improvements	49,588
Gross amount at which carried at close of period, Total	81,787
Accumulated Depreciation and Amortization	295
Governor Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	2,068
Initial cost to company, Buildings and Improvements	4,905
Cost Capitalized Subsequent to Acquisition	20,620
Gross amount at which carried at close of period, Land	2,068
Gross amount at which carried at close of period, Buildings and Improvements	25,525
Gross amount at which carried at close of period, Total	27,593
Accumulated Depreciation and Amortization	22,092
Graham Park Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	1,237
Initial cost to company, Buildings and Improvements	15,096
Cost Capitalized Subsequent to Acquisition	20,518
Gross amount at which carried at close of period, Land	1,169
Gross amount at which carried at close of period, Buildings and Improvements	35,682
Gross amount at which carried at close of period, Total	36,851
Accumulated Depreciation and Amortization	28,526
Gratiot Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	525
Initial cost to company, Buildings and Improvements	1,601
Cost Capitalized Subsequent to Acquisition	17,996
Gross amount at which carried at close of period, Land	525
Gross amount at which carried at close of period, Buildings and Improvements	19,597
Gross amount at which carried at close of period, Total	20,122
Accumulated Depreciation and Amortization	18,005
Greenlawn Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	10,590
Initial cost to company, Buildings and Improvements	20,869
Cost Capitalized Subsequent to Acquisition	412
Gross amount at which carried at close of period, Land	10,590
Gross amount at which carried at close of period, Buildings and Improvements	21,281
Gross amount at which carried at close of period, Total	31,871
Accumulated Depreciation and Amortization	3,468
Greenwich Avenue
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	7,484
Initial cost to company, Buildings and Improvements	5,445
Cost Capitalized Subsequent to Acquisition	10,819
Gross amount at which carried at close of period, Land	7,484
Gross amount at which carried at close of period, Buildings and Improvements	16,264
Gross amount at which carried at close of period, Total	23,748
Accumulated Depreciation and Amortization	4,824
Hastings Ranch Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	0
Initial cost to company, Buildings and Improvements	22,393
Cost Capitalized Subsequent to Acquisition	438
Gross amount at which carried at close of period, Land	0
Gross amount at which carried at close of period, Buildings and Improvements	22,831
Gross amount at which carried at close of period, Total	22,831
Accumulated Depreciation and Amortization	2,272
Hauppauge
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	8,791
Initial cost to company, Buildings and Improvements	15,262
Cost Capitalized Subsequent to Acquisition	5,388
Gross amount at which carried at close of period, Land	8,419
Gross amount at which carried at close of period, Buildings and Improvements	21,022
Gross amount at which carried at close of period, Total	29,441
Accumulated Depreciation and Amortization	13,170
Hoboken
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	98,224
Initial cost to company, Land	45,385
Initial cost to company, Buildings and Improvements	150,905
Cost Capitalized Subsequent to Acquisition	952
Gross amount at which carried at close of period, Land	43,450
Gross amount at which carried at close of period, Buildings and Improvements	153,792
Gross amount at which carried at close of period, Total	197,242
Accumulated Depreciation and Amortization	628
Hollywood Blvd.
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	8,300
Initial cost to company, Buildings and Improvements	16,920
Cost Capitalized Subsequent to Acquisition	26,745
Gross amount at which carried at close of period, Land	8,370
Gross amount at which carried at close of period, Buildings and Improvements	43,595
Gross amount at which carried at close of period, Total	51,965
Accumulated Depreciation and Amortization	16,783
Huntington
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	12,194
Initial cost to company, Buildings and Improvements	16,008
Cost Capitalized Subsequent to Acquisition	18,484
Gross amount at which carried at close of period, Land	12,194
Gross amount at which carried at close of period, Buildings and Improvements	34,492
Gross amount at which carried at close of period, Total	46,686
Accumulated Depreciation and Amortization	17,431
Huntington Square
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	0
Initial cost to company, Buildings and Improvements	10,075
Cost Capitalized Subsequent to Acquisition	3,148
Gross amount at which carried at close of period, Land	506
Gross amount at which carried at close of period, Buildings and Improvements	12,717
Gross amount at which carried at close of period, Total	13,223
Accumulated Depreciation and Amortization	4,238
Idylwood Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	4,308
Initial cost to company, Buildings and Improvements	10,026
Cost Capitalized Subsequent to Acquisition	2,779
Gross amount at which carried at close of period, Land	4,308
Gross amount at which carried at close of period, Buildings and Improvements	12,805
Gross amount at which carried at close of period, Total	17,113
Accumulated Depreciation and Amortization	9,716
Kings Court
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	0
Initial cost to company, Buildings and Improvements	10,714
Cost Capitalized Subsequent to Acquisition	866
Gross amount at which carried at close of period, Land	0
Gross amount at which carried at close of period, Buildings and Improvements	11,580
Gross amount at which carried at close of period, Total	11,580
Accumulated Depreciation and Amortization	9,545
Lancaster
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances
Initial cost to company, Land	0
Initial cost to company, Buildings and Improvements	2,103
Cost Capitalized Subsequent to Acquisition	6,116
Gross amount at which carried at close of period, Land	432
Gross amount at which carried at close of period, Buildings and Improvements	7,787
Gross amount at which carried at close of period, Total	8,219
Accumulated Depreciation and Amortization	6,008
Langhorne Square
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	720
Initial cost to company, Buildings and Improvements	2,974
Cost Capitalized Subsequent to Acquisition	18,992
Gross amount at which carried at close of period, Land	720
Gross amount at which carried at close of period, Buildings and Improvements	21,966
Gross amount at which carried at close of period, Total	22,686
Accumulated Depreciation and Amortization	16,661
Laurel
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	7,458
Initial cost to company, Buildings and Improvements	22,525
Cost Capitalized Subsequent to Acquisition	28,273
Gross amount at which carried at close of period, Land	7,462
Gross amount at which carried at close of period, Buildings and Improvements	50,794
Gross amount at which carried at close of period, Total	58,256
Accumulated Depreciation and Amortization	40,417
Lawrence Park
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	6,150
Initial cost to company, Buildings and Improvements	8,491
Cost Capitalized Subsequent to Acquisition	19,621
Gross amount at which carried at close of period, Land	6,161
Gross amount at which carried at close of period, Buildings and Improvements	28,101
Gross amount at which carried at close of period, Total	34,262
Accumulated Depreciation and Amortization	23,385
Leesburg Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	8,184
Initial cost to company, Buildings and Improvements	10,722
Cost Capitalized Subsequent to Acquisition	18,165
Gross amount at which carried at close of period, Land	8,184
Gross amount at which carried at close of period, Buildings and Improvements	28,887
Gross amount at which carried at close of period, Total	37,071
Accumulated Depreciation and Amortization	16,067
Linden Square
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	79,382
Initial cost to company, Buildings and Improvements	19,247
Cost Capitalized Subsequent to Acquisition	51,735
Gross amount at which carried at close of period, Land	79,346
Gross amount at which carried at close of period, Buildings and Improvements	71,018
Gross amount at which carried at close of period, Total	150,364
Accumulated Depreciation and Amortization	26,947
Melville Mall
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	35,622
Initial cost to company, Buildings and Improvements	32,882
Cost Capitalized Subsequent to Acquisition	31,450
Gross amount at which carried at close of period, Land	35,622
Gross amount at which carried at close of period, Buildings and Improvements	64,332
Gross amount at which carried at close of period, Total	99,954
Accumulated Depreciation and Amortization	17,028
Mercer Mall
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances
Initial cost to company, Land	5,917
Initial cost to company, Buildings and Improvements	18,358
Cost Capitalized Subsequent to Acquisition	48,524
Gross amount at which carried at close of period, Land	5,917
Gross amount at which carried at close of period, Buildings and Improvements	66,882
Gross amount at which carried at close of period, Total	72,799
Accumulated Depreciation and Amortization	33,340
Montrose Crossing
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	67,492
Initial cost to company, Land	48,624
Initial cost to company, Buildings and Improvements	91,819
Cost Capitalized Subsequent to Acquisition	22,110
Gross amount at which carried at close of period, Land	48,624
Gross amount at which carried at close of period, Buildings and Improvements	113,929
Gross amount at which carried at close of period, Total	162,553
Accumulated Depreciation and Amortization	32,948
Mount Vernon/South Valley/7770 Richmond Hwy,
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	10,068
Initial cost to company, Buildings and Improvements	33,501
Cost Capitalized Subsequent to Acquisition	42,942
Gross amount at which carried at close of period, Land	10,150
Gross amount at which carried at close of period, Buildings and Improvements	76,361
Gross amount at which carried at close of period, Total	86,511
Accumulated Depreciation and Amortization	39,734
North Dartmouth
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	9,366
Initial cost to company, Buildings and Improvements	0
Cost Capitalized Subsequent to Acquisition	3
Gross amount at which carried at close of period, Land	9,366
Gross amount at which carried at close of period, Buildings and Improvements	3
Gross amount at which carried at close of period, Total	9,369
Accumulated Depreciation and Amortization	1
Northeast
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	938
Initial cost to company, Buildings and Improvements	8,779
Cost Capitalized Subsequent to Acquisition	22,027
Gross amount at which carried at close of period, Land	939
Gross amount at which carried at close of period, Buildings and Improvements	30,805
Gross amount at which carried at close of period, Total	31,744
Accumulated Depreciation and Amortization	19,120
Old Keene Mill
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	638
Initial cost to company, Buildings and Improvements	998
Cost Capitalized Subsequent to Acquisition	11,093
Gross amount at which carried at close of period, Land	638
Gross amount at which carried at close of period, Buildings and Improvements	12,091
Gross amount at which carried at close of period, Total	12,729
Accumulated Depreciation and Amortization	6,017
Old Town Center
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	3,420
Initial cost to company, Buildings and Improvements	2,765
Cost Capitalized Subsequent to Acquisition	29,348
Gross amount at which carried at close of period, Land	3,420
Gross amount at which carried at close of period, Buildings and Improvements	32,113
Gross amount at which carried at close of period, Total	35,533
Accumulated Depreciation and Amortization	22,722
Olivo at Mission Hills
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	15,048
Initial cost to company, Buildings and Improvements	46,732
Cost Capitalized Subsequent to Acquisition	17,869
Gross amount at which carried at close of period, Land	15,048
Gross amount at which carried at close of period, Buildings and Improvements	64,601
Gross amount at which carried at close of period, Total	79,649
Accumulated Depreciation and Amortization	3,016
Pan Am Shopping Center
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	8,694
Initial cost to company, Buildings and Improvements	12,929
Cost Capitalized Subsequent to Acquisition	8,314
Gross amount at which carried at close of period, Land	8,695
Gross amount at which carried at close of period, Buildings and Improvements	21,242
Gross amount at which carried at close of period, Total	29,937
Accumulated Depreciation and Amortization	16,292
Pentagon Row
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	0
Initial cost to company, Buildings and Improvements	2,955
Cost Capitalized Subsequent to Acquisition	103,383
Gross amount at which carried at close of period, Land	0
Gross amount at which carried at close of period, Buildings and Improvements	106,338
Gross amount at which carried at close of period, Total	106,338
Accumulated Depreciation and Amortization	52,509
Perring Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	2,800
Initial cost to company, Buildings and Improvements	6,461
Cost Capitalized Subsequent to Acquisition	22,943
Gross amount at which carried at close of period, Land	2,800
Gross amount at which carried at close of period, Buildings and Improvements	29,404
Gross amount at which carried at close of period, Total	32,204
Accumulated Depreciation and Amortization	24,834
Pike & Rose
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	31,471
Initial cost to company, Buildings and Improvements	10,335
Cost Capitalized Subsequent to Acquisition	579,682
Gross amount at which carried at close of period, Land	27,929
Gross amount at which carried at close of period, Buildings and Improvements	593,559
Gross amount at which carried at close of period, Total	621,488
Accumulated Depreciation and Amortization	50,600
Pike 7
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	14,970
Initial cost to company, Buildings and Improvements	22,799
Cost Capitalized Subsequent to Acquisition	11,569
Gross amount at which carried at close of period, Land	14,914
Gross amount at which carried at close of period, Buildings and Improvements	34,424
Gross amount at which carried at close of period, Total	49,338
Accumulated Depreciation and Amortization	18,736
Plaza Del Mercado
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	10,305
Initial cost to company, Buildings and Improvements	21,553
Cost Capitalized Subsequent to Acquisition	14,859
Gross amount at which carried at close of period, Land	10,305
Gross amount at which carried at close of period, Buildings and Improvements	36,412
Gross amount at which carried at close of period, Total	46,717
Accumulated Depreciation and Amortization	5,571
Plaza Del Sol
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	8,308
Initial cost to company, Land	5,605
Initial cost to company, Buildings and Improvements	12,331
Cost Capitalized Subsequent to Acquisition	0
Gross amount at which carried at close of period, Land	5,605
Gross amount at which carried at close of period, Buildings and Improvements	12,331
Gross amount at which carried at close of period, Total	17,936
Accumulated Depreciation and Amortization	1,185
Plaza El Segundo/The Point
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	124,336
Initial cost to company, Land	62,127
Initial cost to company, Buildings and Improvements	153,556
Cost Capitalized Subsequent to Acquisition	77,079
Gross amount at which carried at close of period, Land	64,788
Gross amount at which carried at close of period, Buildings and Improvements	227,974
Gross amount at which carried at close of period, Total	292,762
Accumulated Depreciation and Amortization	54,745
Queen Anne Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	3,319
Initial cost to company, Buildings and Improvements	8,457
Cost Capitalized Subsequent to Acquisition	6,166
Gross amount at which carried at close of period, Land	3,319
Gross amount at which carried at close of period, Buildings and Improvements	14,623
Gross amount at which carried at close of period, Total	17,942
Accumulated Depreciation and Amortization	10,580
Quince Orchard Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	3,197
Initial cost to company, Buildings and Improvements	7,949
Cost Capitalized Subsequent to Acquisition	30,386
Gross amount at which carried at close of period, Land	2,928
Gross amount at which carried at close of period, Buildings and Improvements	38,604
Gross amount at which carried at close of period, Total	41,532
Accumulated Depreciation and Amortization	22,770
Riverpoint Center
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	15,422
Initial cost to company, Buildings and Improvements	104,572
Cost Capitalized Subsequent to Acquisition	1,930
Gross amount at which carried at close of period, Land	15,422
Gross amount at which carried at close of period, Buildings and Improvements	106,502
Gross amount at which carried at close of period, Total	121,924
Accumulated Depreciation and Amortization	9,487
Rockville Town Square
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances
Initial cost to company, Land	0
Initial cost to company, Buildings and Improvements	8,092
Cost Capitalized Subsequent to Acquisition	39,639
Gross amount at which carried at close of period, Land	0
Gross amount at which carried at close of period, Buildings and Improvements	47,731
Gross amount at which carried at close of period, Total	47,731
Accumulated Depreciation and Amortization	20,001
Rollingwood Apts.
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances
Initial cost to company, Land	552
Initial cost to company, Buildings and Improvements	2,246
Cost Capitalized Subsequent to Acquisition	8,575
Gross amount at which carried at close of period, Land	774
Gross amount at which carried at close of period, Buildings and Improvements	10,599
Gross amount at which carried at close of period, Total	11,373
Accumulated Depreciation and Amortization	9,940
Sam's Park and Shop
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	4,840
Initial cost to company, Buildings and Improvements	6,319
Cost Capitalized Subsequent to Acquisition	3,022
Gross amount at which carried at close of period, Land	4,840
Gross amount at which carried at close of period, Buildings and Improvements	9,341
Gross amount at which carried at close of period, Total	14,181
Accumulated Depreciation and Amortization	5,912
San Antonio Center
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	26,400
Initial cost to company, Buildings and Improvements	18,462
Cost Capitalized Subsequent to Acquisition	1,141
Gross amount at which carried at close of period, Land	26,400
Gross amount at which carried at close of period, Buildings and Improvements	19,603
Gross amount at which carried at close of period, Total	46,003
Accumulated Depreciation and Amortization	3,752
Santana Row
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	66,682
Initial cost to company, Buildings and Improvements	7,502
Cost Capitalized Subsequent to Acquisition	976,080
Gross amount at which carried at close of period, Land	53,217
Gross amount at which carried at close of period, Buildings and Improvements	997,047
Gross amount at which carried at close of period, Total	1,050,264
Accumulated Depreciation and Amortization	221,350
Saugus
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	4,383
Initial cost to company, Buildings and Improvements	8,291
Cost Capitalized Subsequent to Acquisition	4,501
Gross amount at which carried at close of period, Land	4,383
Gross amount at which carried at close of period, Buildings and Improvements	12,792
Gross amount at which carried at close of period, Total	17,175
Accumulated Depreciation and Amortization	7,557
Sylmar Towne Center
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	16,854
Initial cost to company, Land	18,522
Initial cost to company, Buildings and Improvements	24,636
Cost Capitalized Subsequent to Acquisition	679
Gross amount at which carried at close of period, Land	18,522
Gross amount at which carried at close of period, Buildings and Improvements	25,315
Gross amount at which carried at close of period, Total	43,837
Accumulated Depreciation and Amortization	2,205
The Avenue at White Marsh
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	52,597
Initial cost to company, Land	20,682
Initial cost to company, Buildings and Improvements	72,432
Cost Capitalized Subsequent to Acquisition	29,311
Gross amount at which carried at close of period, Land	20,685
Gross amount at which carried at close of period, Buildings and Improvements	101,740
Gross amount at which carried at close of period, Total	122,425
Accumulated Depreciation and Amortization	38,923
The Grove at Shrewsbury
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	42,874
Initial cost to company, Land	18,016
Initial cost to company, Buildings and Improvements	103,115
Cost Capitalized Subsequent to Acquisition	5,419
Gross amount at which carried at close of period, Land	18,021
Gross amount at which carried at close of period, Buildings and Improvements	108,529
Gross amount at which carried at close of period, Total	126,550
Accumulated Depreciation and Amortization	20,825
The Shoppes At Nottingham Square
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	4,441
Initial cost to company, Buildings and Improvements	12,849
Cost Capitalized Subsequent to Acquisition	735
Gross amount at which carried at close of period, Land	4,441
Gross amount at which carried at close of period, Buildings and Improvements	13,584
Gross amount at which carried at close of period, Total	18,025
Accumulated Depreciation and Amortization	5,889
The Shops at Sunset Place
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	62,426
Initial cost to company, Land	64,499
Initial cost to company, Buildings and Improvements	50,853
Cost Capitalized Subsequent to Acquisition	8,944
Gross amount at which carried at close of period, Land	64,499
Gross amount at which carried at close of period, Buildings and Improvements	59,797
Gross amount at which carried at close of period, Total	124,296
Accumulated Depreciation and Amortization	10,136
Third Street Promenade
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	22,645
Initial cost to company, Buildings and Improvements	12,709
Cost Capitalized Subsequent to Acquisition	45,863
Gross amount at which carried at close of period, Land	25,125
Gross amount at which carried at close of period, Buildings and Improvements	56,092
Gross amount at which carried at close of period, Total	81,217
Accumulated Depreciation and Amortization	36,201
Tower
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	7,170
Initial cost to company, Buildings and Improvements	10,518
Cost Capitalized Subsequent to Acquisition	4,797
Gross amount at which carried at close of period, Land	7,280
Gross amount at which carried at close of period, Buildings and Improvements	15,205
Gross amount at which carried at close of period, Total	22,485
Accumulated Depreciation and Amortization	9,921
Tower Shops
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	29,940
Initial cost to company, Buildings and Improvements	43,390
Cost Capitalized Subsequent to Acquisition	24,855
Gross amount at which carried at close of period, Land	29,962
Gross amount at which carried at close of period, Buildings and Improvements	68,223
Gross amount at which carried at close of period, Total	98,185
Accumulated Depreciation and Amortization	21,085
Town Center of New Britain
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	1,282
Initial cost to company, Buildings and Improvements	12,285
Cost Capitalized Subsequent to Acquisition	2,888
Gross amount at which carried at close of period, Land	1,535
Gross amount at which carried at close of period, Buildings and Improvements	14,920
Gross amount at which carried at close of period, Total	16,455
Accumulated Depreciation and Amortization	5,931
Townson Residential
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	2,328
Initial cost to company, Buildings and Improvements	0
Cost Capitalized Subsequent to Acquisition	20,042
Gross amount at which carried at close of period, Land	2,328
Gross amount at which carried at close of period, Buildings and Improvements	20,042
Gross amount at which carried at close of period, Total	22,370
Accumulated Depreciation and Amortization	1,454
Troy
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	3,126
Initial cost to company, Buildings and Improvements	5,193
Cost Capitalized Subsequent to Acquisition	32,655
Gross amount at which carried at close of period, Land	5,865
Gross amount at which carried at close of period, Buildings and Improvements	35,109
Gross amount at which carried at close of period, Total	40,974
Accumulated Depreciation and Amortization	23,135
Tyson's Station
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	388
Initial cost to company, Buildings and Improvements	453
Cost Capitalized Subsequent to Acquisition	4,170
Gross amount at which carried at close of period, Land	493
Gross amount at which carried at close of period, Buildings and Improvements	4,518
Gross amount at which carried at close of period, Total	5,011
Accumulated Depreciation and Amortization	3,939
Village at Shirlington
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances
Initial cost to company, Land	9,761
Initial cost to company, Buildings and Improvements	14,808
Cost Capitalized Subsequent to Acquisition	38,771
Gross amount at which carried at close of period, Land	4,234
Gross amount at which carried at close of period, Buildings and Improvements	59,106
Gross amount at which carried at close of period, Total	63,340
Accumulated Depreciation and Amortization	30,187
Westgate Center
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	6,319
Initial cost to company, Buildings and Improvements	107,284
Cost Capitalized Subsequent to Acquisition	43,870
Gross amount at which carried at close of period, Land	6,319
Gross amount at which carried at close of period, Buildings and Improvements	151,154
Gross amount at which carried at close of period, Total	157,473
Accumulated Depreciation and Amortization	61,106
White Marsh Plaza
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	3,478
Initial cost to company, Buildings and Improvements	21,413
Cost Capitalized Subsequent to Acquisition	1,028
Gross amount at which carried at close of period, Land	3,478
Gross amount at which carried at close of period, Buildings and Improvements	22,441
Gross amount at which carried at close of period, Total	25,919
Accumulated Depreciation and Amortization	9,736
White Marsh Other
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	29,725
Initial cost to company, Buildings and Improvements	1,843
Cost Capitalized Subsequent to Acquisition	146
Gross amount at which carried at close of period, Land	29,754
Gross amount at which carried at close of period, Buildings and Improvements	1,960
Gross amount at which carried at close of period, Total	31,714
Accumulated Depreciation and Amortization	913
Wildwood
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	9,111
Initial cost to company, Buildings and Improvements	1,061
Cost Capitalized Subsequent to Acquisition	15,905
Gross amount at which carried at close of period, Land	9,111
Gross amount at which carried at close of period, Buildings and Improvements	16,966
Gross amount at which carried at close of period, Total	26,077
Accumulated Depreciation and Amortization	9,208
Willow Grove
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	1,499
Initial cost to company, Buildings and Improvements	6,643
Cost Capitalized Subsequent to Acquisition	22,061
Gross amount at which carried at close of period, Land	1,499
Gross amount at which carried at close of period, Buildings and Improvements	28,704
Gross amount at which carried at close of period, Total	30,203
Accumulated Depreciation and Amortization	27,812
Willow Lawn
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	3,192
Initial cost to company, Buildings and Improvements	7,723
Cost Capitalized Subsequent to Acquisition	91,838
Gross amount at which carried at close of period, Land	7,790
Gross amount at which carried at close of period, Buildings and Improvements	94,963
Gross amount at which carried at close of period, Total	102,753
Accumulated Depreciation and Amortization	62,087
Wynnewood
Real Estate and Accumulated Depreciation [Line Items]
Initial cost to company, Land	8,055
Initial cost to company, Buildings and Improvements	13,759
Cost Capitalized Subsequent to Acquisition	21,272
Gross amount at which carried at close of period, Land	8,055
Gross amount at which carried at close of period, Buildings and Improvements	35,031
Gross amount at which carried at close of period, Total	43,086
Accumulated Depreciation and Amortization	$ 25,668

Schedule III Part II - Summar_2

Schedule III Part II - Summary of Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements [Abstract]
Balance at beginning of year	$ 7,819,472	$ 7,635,061	$ 6,759,073
Acquisitions	309,921	14,940	555,476
Improvements	441,703	407,225	492,541
Deduction during period—dispositions and retirements of property	(201,105)	(237,754)	(172,029)
Balance at end of year	8,298,132	7,819,472	7,635,061
Aggregate cost basis for Federal tax purposes	7,400,000
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Balance at beginning of year	2,059,143	1,876,544	1,729,234
Additions during period—depreciation and amortization expense	215,382	215,969	193,340
Deductions during period—dispositions and retirements of property	(40,939)	(33,370)	(46,030)
Balance at end of year	2,215,413	$ 2,059,143	$ 1,876,544
Accounting Standards Update 2016-02
January 1, 2019 adoption of new accounting standard - See Note 2	(71,859)
January 1, 2019 adoption of new accounting standard - See Note 2	$ (18,173)

Schedule IV - Mortgage Loans _2

Schedule IV - Mortgage Loans on Real Estate (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2017	Dec. 31, 2019		Dec. 31, 2018
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Prior Liens					$ 0
Face Amount of Mortgages					30,429
Carrying Amount of Mortgages		$ 30,429	[1]	$ 30,429	30,429	[1]	$ 30,429
Principal Amount of Loans Subject to delinquent Principal or Interest					0
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate, Other Disclosure [Abstract]
Aggregate tax basis for Federal tax purposes					30,400		$ 30,400
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Balance at beginning of year		30,429		29,904
Issuance of loans				525
Balance at end of year		30,429	[1]	$ 30,429
Mortgage On Retail Buildings in Philadelphia, PA, Loan One
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Prior Liens					0
Face Amount of Mortgages					21,179
Carrying Amount of Mortgages	[2]	21,179			21,179
Principal Amount of Loans Subject to delinquent Principal or Interest					0
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Balance at end of year	[2]	$ 21,179
Mortgage On Retail Buildings in Philadelphia, PA, Loan One | Maximum
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Face Amount of Mortgages					25,000
Mortgage On Retail Buildings in Philadelphia, PA, Loan Two
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate		10.00%
Prior Liens					0
Face Amount of Mortgages					9,250
Carrying Amount of Mortgages		$ 9,250			9,250
Principal Amount of Loans Subject to delinquent Principal or Interest					$ 0
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Balance at end of year		$ 9,250
Interest Rate One | Mortgage On Retail Buildings in Philadelphia, PA, Loan One
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate		8.00%
Interest Rate Two | Mortgage On Retail Buildings in Philadelphia, PA, Loan One
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate		10.00%
[1]	For Federal tax purposes, the aggregate tax basis is approximately $30.4 million as of December 31, 2019 .
[2]	This mortgage is available for up to $25.0 million .