Elme Communities (ELME) 10-K 3 Mar 14 2013 FY Annual report Financial data

Document_And_Entity_Informatio

Document And Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Feb. 26, 2014	Jun. 28, 2013
Document and Entity Information [Abstract]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Entity Registrant Name	'WASHINGTON REAL ESTATE INVESTMENT TRUST	'	'
Entity Central Index Key	'0000104894	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Entity Common Stock, Shares Outstanding	'	66,598,192	'
Entity Well-known Seasoned Issuer	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Public Float	'	'	$1,775,842,352

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets	'	'
Land	$426,575	$418,008
Income producing property	1,675,652	1,587,375
Real estate investment property, at cost	2,102,227	2,005,383
Accumulated depreciation and amortization	-565,342	-497,057
Net income producing property	1,536,885	1,508,326
Properties under development or held for future development	61,315	45,270
Total real estate held for investment, net	1,598,200	1,553,596
Investment in real estate sold or held for sale, net	79,901	364,999
Cash and cash equivalents	130,343	19,105
Restricted cash	9,189	13,423
Rents and other receivables, net of allowance for doubtful accounts of $6,783 and $10,443, respectively	48,756	46,904
Prepaid expenses and other assets	105,004	107,303
Other assets related to properties sold or held for sale	4,100	19,046
Total assets	1,975,493	2,124,376
Liabilities	'	'
Notes payable	846,703	906,190
Mortgage notes payable	294,671	319,025
Lines of credit	0	0
Accounts payable and other liabilities	51,742	50,094
Advance rents	13,529	12,925
Tenant security deposits	7,869	7,642
Other liabilities related to properties sold or held for sale	1,533	32,357
Total liabilities	1,216,047	1,328,233
Shareholders' equity	'	'
Preferred shares; $0.01 par value; 10,000 shares authorized; no shares issued or outstanding	0	0
Shares of beneficial interest; $0.01 par value; 100,000 shares authorized: 66,531 and 66,437 shares issued and outstanding at December 31, 2013 and 2012, respectively	665	664
Additional paid in capital	1,151,174	1,145,515
Distributions in excess of net income	-396,880	-354,122
Total shareholders’ equity	754,959	792,057
Noncontrolling interests in subsidiaries	4,487	4,086
Total equity	759,446	796,143
Total liabilities and shareholders’ equity	$1,975,493	$2,124,376

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, except Per Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Rents and other receivables, allowance for doubtful accounts	$6,783	$10,443
Preferred shares, par value	$0.01	$0.01
Preferred shares, shares authorized	10,000	10,000
Preferred shares, shares issued	0	0
Preferred shares, shares outstanding	0	0
Shares of beneficial interest, par value	$0.01	$0.01
Shares of beneficial interest, shares authorized	100,000	100,000
Shares of beneficial interest, shares issued	66,531	66,437
Shares of beneficial interest, shares outstanding	66,531	66,437

Consolidated_Statements_Of_Inc

Consolidated Statements Of Income (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue	'	'	'
Real estate rental revenue	$263,024	$254,794	$234,733
Expenses	'	'	'
Utilities	16,311	15,781	15,691
Real estate taxes	29,052	27,064	22,903
Repairs and maintenance	12,261	11,339	10,490
Property administration	10,155	9,248	8,430
Property management	8,255	8,503	7,272
Operating services and common area maintenance	13,469	12,358	11,804
Other real estate expenses	3,790	2,252	3,034
Depreciation and amortization	85,740	85,107	74,403
Acquisition costs	1,265	234	3,607
Real estate impairment	0	0	14,526
General and administrative	17,535	15,488	15,728
Total expenses	197,833	187,374	187,888
Real estate operating income	65,191	67,420	46,845
Other income (expense)	'	'	'
Interest expense	-63,573	-60,627	-61,402
Other income	926	975	1,144
Loss on extinguishment of debt	-2,737	0	-976
Total other income (expense)	-65,384	-59,652	-61,234
(Loss) income from continuing operations	-193	7,768	-14,389
Discontinued operations:	'	'	'
Income from operations of properties sold or held for sale	15,395	10,816	23,414
Gain on sale of real estate	22,144	5,124	97,491
Income tax expense	0	0	-1,138
Net income	37,346	23,708	105,378
Less: Net income attributable to noncontrolling interests in subsidiaries	0	0	-494
Net income attributable to the controlling interests	$37,346	$23,708	$104,884
Basic net (loss) income attributable to the controlling interests per share	'	'	'
Continuing operations - basic (in dollars per share)	$0	$0.11	($0.22)
Discontinued operations, including gain on sale of real estate (in dollars per share)	$0.55	$0.24	$1.80
Net income attributable to the controlling interests per share, basic	$0.55	$0.35	$1.58
Diluted net (loss) income attributable to the controlling interests per share	'	'	'
Continuing operations - diluted (in dollars per share)	$0	$0.11	($0.22)
Discontinued operations, including gain on sale of real estate (in dollars per share)	$0.55	$0.24	$1.80
Net income attributable to the controlling interests per share, diluted	$0.55	$0.35	$1.58
Weighted average shares outstanding – basic	66,580	66,239	65,982
Weighted average shares outstanding – diluted	66,580	66,376	65,982

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net income	$37,346	$23,708	$105,378
Change in fair value of interest rate hedge	0	0	1,469
Comprehensive income	37,346	23,708	106,847
Less: Net income attributable to noncontrolling interests in subsidiaries	0	0	-494
Comprehensive income attributable to the controlling interests	$37,346	$23,708	$106,353

Consolidated_Statements_Of_Sha

Consolidated Statements Of Shareholders' Equity (USD $)	Total	Total Shareholders' Equity [Member]	Shares Of Beneficial Interest At Par Value [Member]	Additional Paid In Capital [Member]	Distributions In Excess Of Net Income Attributable To The Controlling Interests [Member]	Accumulated Other Comprehensive Income [Member]	Noncontrolling Interests In Subsidiaries [Member]
In Thousands, except Share data, unless otherwise specified
Balance at Dec. 31, 2010	$860,858	$857,080	$659	$1,127,825	($269,935)	($1,469)	$3,778
Balance, shares at Dec. 31, 2010	'	'	65,870,000	'	'	'	'
Comprehensive income:	'	'	'	'	'	'	'
Net income attributable to the controlling interests	104,884	104,884	'	'	104,884	'	'
Net income attributable to noncontrolling interests	494	'	'	'	'	'	494
Change in fair value of interest rate hedge	1,469	1,469	'	'	'	1,469	'
Distributions to noncontrolling interests	-2,488	'	'	'	'	'	-2,488
Noncontrolling Interest, Increase from Sale of Parent Equity Interest	'	'	'	'	'	'	2,004
Dividends	-115,045	-115,045	'	'	-115,045	'	'
Shares issued under Dividend Reinvestment Program	5,043	5,043	2	5,041	'	'	'
Shares issued under Dividend Reinvestment Program, shares	'	'	170,000	'	'	'	'
Share options exercised	1,292	1,292	1	1,291	'	'	'
Share options exercised, shares	51,081	'	51,000	'	'	'	'
Share grants, net of share grant amorization and forfeitures	4,321	4,321	0	4,321	'	'	'
Share grants, net of share grant amortization and forfeitures, shares	'	'	174,000	'	'	'	'
Balance at Dec. 31, 2011	862,832	859,044	662	1,138,478	-280,096	0	3,788
Balance, shares at Dec. 31, 2011	'	'	66,265,000	'	'	'	'
Comprehensive income:	'	'	'	'	'	'	'
Net income attributable to the controlling interests	23,708	23,708	'	'	23,708	'	'
Net income attributable to noncontrolling interests	0	'	'	'	'	'	'
Change in fair value of interest rate hedge	0	'	'	'	'	'	'
Noncontrolling Interest, Increase from Sale of Parent Equity Interest	298	'	'	'	'	'	298
Dividends	-97,734	-97,734	'	'	-97,734	'	'
Shares issued under Dividend Reinvestment Program	1,316	1,316	1	1,315	'	'	'
Shares issued under Dividend Reinvestment Program, shares	'	'	55,000	'	'	'	'
Share options exercised	1,153	1,153	0	1,153	'	'	'
Share options exercised, shares	44,987	'	45,000	'	'	'	'
Share grants, net of share grant amorization and forfeitures	4,570	4,570	1	4,569	'	'	'
Share grants, net of share grant amortization and forfeitures, shares	'	'	72,000	'	'	'	'
Balance at Dec. 31, 2012	796,143	792,057	664	1,145,515	-354,122	0	4,086
Balance, shares at Dec. 31, 2012	'	'	66,437,000	'	'	'	'
Comprehensive income:	'	'	'	'	'	'	'
Net income attributable to the controlling interests	37,346	37,346	'	'	37,346	'	'
Net income attributable to noncontrolling interests	0	'	'	'	'	'	'
Change in fair value of interest rate hedge	0	'	'	'	'	'	'
Noncontrolling Interest, Increase from Sale of Parent Equity Interest	401	'	'	'	'	'	401
Dividends	-80,104	-80,104	'	'	-80,104	'	'
Shares issued under Dividend Reinvestment Program	'	'	'	0	'	'	'
Shares issued under Dividend Reinvestment Program, shares	'	'	0	'	'	'	'
Share options exercised, shares	0	'	'	'	'	'	'
Share grants, net of share grant amorization and forfeitures	5,660	5,660	1	5,659	'	'	'
Share grants, net of share grant amortization and forfeitures, shares	'	'	94,000	'	'	'	'
Balance at Dec. 31, 2013	$759,446	$754,959	$665	$1,151,174	($396,880)	$0	$4,487
Balance, shares at Dec. 31, 2013	'	'	66,531,000	'	'	'	'

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Cash flows from operating activities	'		'		'
Net income	$37,346		$23,708		$105,378
Adjustments to reconcile net income to net cash provided by operating activities:	'		'		'
Gain on sale of real estate	-22,144		-5,124		-97,491
Depreciation and amortization, including amounts in discontinued operations	97,901		103,934		100,528
Provision for losses on accounts receivable	3,772		3,847		4,005
Real estate impairment, including amounts in discontinued operations	0		2,097		15,125
Share-based compensation expense	6,246		5,856		5,597
Amortization of debt premiums, discounts and related financing costs	4,158		3,867		3,194
Loss on extinguishment of debt, net	2,737		0		0
Changes in other assets	-10,591		-8,458		-16,416
Changes in other liabilities	-6,107		1,721		-2,294
Net cash provided by operating activities	113,318		131,448		117,626
Cash flows from investing activities	'		'		'
Real estate acquisitions, net	-48,200	[1]	-52,142	[1]	-281,701	[1]
Capital improvements to real estate	-55,829		-51,180		-32,815
Development in progress	-15,826		-6,494		-25,929
Net cash received from sale of real estate	313,765		21,825		402,164
Payments for (Proceeds from) Deposits on Real Estate Acquisitions	-3,900		-250		0
Non-real estate capital improvements	-162		-555		-621
Net cash provided by (used in) investing activities	189,848		-88,796		61,098
Cash flows from financing activities	'		'		'
Line of credit borrowings (repayments), net	0		-99,000		-1,000
Dividends paid	-80,104		-97,734		-115,045
Net contributions from (distributions to) noncontrolling interests	401		298		-2,488
Proceeds from dividend reinvestment program	0		1,316		5,043
Borrowing under construction loan	7,297		0		0
Principal payments – mortgage notes payable, including penalties for early extinguishment	-58,679		-85,667		-32,331
Net proceeds from debt offering	0		298,314		0
Payment of financing costs	-843		-4,678		-3,905
Notes payable repayments, including penalties for early extinguishment	-60,000		-50,000		-96,521
Net proceeds from exercise of share options	0		1,153		1,292
Net cash (used in) financing activities	-191,928		-35,998		-244,955
Net increase (decrease) in cash and cash equivalents	111,238		6,654		-66,231
Cash and cash equivalents at beginning of year	19,105		12,451		78,682
Cash and cash equivalents at end of year	130,343		19,105		12,451
Supplemental disclosure of cash flow information:	'		'		'
Cash paid for interest, net of capitalized interest expense	62,744		58,282		63,916
Cash paid for income taxes	54		84		725
accured capital improvements and development costs	($328)		($2,128)		($2,404)
[1]	See note 3 to the consolidated financial statements for the supplemental disclosure of non-cash investing and financing activities, including the assumption of mortgage debt in conjunction with some of our real estate acquisitions.

Nature_Of_Business

Nature Of Business	12 Months Ended
	Dec. 31, 2013
Nature Of Business [Abstract]	'
Nature Of Business	'
	Washington Real Estate Investment Trust (“WRIT”), a Maryland real estate investment trust, is a self-administered, self-managed equity real estate investment trust, successor to a trust organized in 1960. Our business consists of the ownership and operation of income-producing real estate properties in the greater Washington Metro region. We own a diversified portfolio of office buildings, medical office buildings, multifamily buildings and retail centers.
	Federal Income Taxes
	We believe that we qualify as a real estate investment trust (“REIT”) under Sections 856-860 of the Internal Revenue Code and intend to continue to qualify as such. To maintain our status as a REIT, we are required to distribute 90% of our ordinary taxable income to our shareholders. When selling properties, we have the option of (a) reinvesting the sale proceeds of properties sold, allowing for a deferral of income taxes on the sale, (b) paying out capital gains to the shareholders with no tax to WRIT or (c) treating the capital gains as having been distributed to the shareholders, paying the tax on the gain deemed distributed and allocating the tax paid as a credit to the shareholders. During the three years ended December 31, 2013, we sold the following properties (in thousands):
	Disposition Date	Property	Type	Gain on Sale
	19-Mar-13	Atrium Building	Office	$	3,195
	Nov-13	Medical Office Portfolio Transactions I & II (1)	Medical Office / Office	18,949
			Total 2013	$	22,144
	31-Aug-12	1700 Research Boulevard	Office	$	3,724
	20-Dec-12	Plumtree Medical Center	Medical Office	1,400
			Total 2012	$	5,124
	5-Apr-11	Dulles Station, Phase I	Office	$	—
	October - November 2011	Industrial Portfolio (2)	Office/Industrial	97,491
			Total 2011	$	97,491
	(1) 2440 M Street, 15001 Shady Grove Road, 15505 Shady Grove Road, 19500 at Riverside Park (formerly Lansdowne Medical Office Building), 9707 Medical Center Drive, CentreMed I and II, 8301 Arlington Boulevard, Sterling Medical Office Building, Shady Grove Medical Village II, Alexandria Professional Center, Ashburn Farm Office Park I, Ashburn Farm Office Park II, Ashburn Farm Office Park III, Woodholme Medical Office Building, two office properties (6565 Arlington Boulevard and Woodholme Center) and undeveloped land at 4661 Kenmore Avenue. Subsequent to the end of 2013, we closed on Transaction III, consisting of Woodburn Medical Park I and II, and Transaction IV, consisting of Prosperity Medical Center I, II and III (see note 17).
	(2) The Industrial Portfolio consists of every property in our industrial segment and two office properties (the Crescent and Albemarle Point).
	We have identified a portion of the sold Medical Office Portfolio properties for tax deferred exchange under Section 1031 of the Internal Revenue Code. Section 1031 requires that we identify and close on the acquisition of replacement properties within limited time periods. We may not be able to identify and acquire appropriate replacement properties within the specified time periods. If we do not identify and acquire the replacement properties within the specified time periods, we would expect to recognize a taxable gain with respect to the sale of the Medical Office Portfolio. The amount of this taxable gain would depend upon the timing and size of the replacement property acquisitions and also our other results of operations, and it could be a material amount. If we recognize this taxable gain, we could be required to pay a significant portion of it as a special capital gain dividend to our shareholders or alternatively be subject to income taxes on the taxable gain.
	Generally, and subject to our ongoing qualification as a REIT, no provisions for income taxes are necessary except for taxes on undistributed REIT taxable income and taxes on the income generated by our taxable REIT subsidiaries (“TRS's”). Our TRS's are subject to corporate federal and state income tax on their taxable income at regular statutory rates, or as calculated under the alternative minimum tax, as appropriate. As of December 31, 2013, our TRS's had no net deferred tax assets and a net deferred tax liability of $0.6 million. As of December 31, 2012, our TRS's had no net deferred tax assets and a net deferred tax liability of $0.6 million. These are primarily related to temporary differences in the timing of the recognition of revenue, amortization and depreciation.
	During 2011, we settled on the sale of Dulles Station, Phase I, an office property held by one of our TRS's. After the application of available net operating loss carryforwards, we recognized $1.1 million in net federal and state income tax liabilities during 2011 in connection with the sale and operations of the entities.
	Also during 2011, we recognized a $14.5 million impairment charge at Dulles Station, Phase II, a development property held by one of our TRS's (see note 3). The impairment charge created a deferred tax asset of $5.7 million at this TRS, but we have determined that it is more likely than not that this deferred tax asset will not be realized. We have therefore recorded a valuation allowance for the full amount of the deferred tax asset related to the impairment charge at Dulles Station, Phase II.
	The following is a breakdown of the taxable percentage of our dividends for the years ended December 31, 2013, 2012 and 2011,(unaudited):
		2013			2012		2011
	Ordinary income	62	%		72	%	60	%
	Return of capital	38	%		26	%	17	%
	Qualified dividends	—	%		—	%	5	%
	Unrecaptured Section 1250 gain	—	%		2	%	13	%
	Capital gain	—	%		—	%	5	%

Accounting_Policies

Accounting Policies	12 Months Ended
	Dec. 31, 2013
Regulated Operations [Abstract]	'
Summary of Significant Accounting Policies	'
	Principles of Consolidation and Basis of Presentation
	The accompanying audited consolidated financial statements include the consolidated accounts of WRIT, our majority-owned subsidiaries and entities in which WRIT has a controlling interest, including where WRIT has been determined to be a primary beneficiary of a variable interest entity (“VIE”). See note 3 for additional information on the properties for which there is a noncontrolling interest. All intercompany balances and transactions have been eliminated in consolidation.
	We have prepared the accompanying audited consolidated financial statements pursuant to the rules and regulations of the Securities and Exchange Commission. In addition, in the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the results for the periods presented have been included.
	Use of Estimates in the Financial Statements
	The preparation of financial statements in conformity with Generally Accepted Accounting Principles ("GAAP") requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	Revenue Recognition
	We lease multifamily properties under operating leases with terms of generally one year or less. We lease commercial properties (our office, medical office and retail segments) under operating leases with average terms of three to five years. We recognize rental income and rental abatements from our multifamily and commercial leases when earned on a straight-line basis over the lease term. Recognition of rental income commences when control of the facility has been given to the tenant. We record a provision for losses on accounts receivable equal to the estimated uncollectible amounts. We base this estimate on our historical experience and a review of the current status of our receivables. We recognize percentage rents, which represent additional rents based on gross tenant sales, when tenants’ sales exceed specified thresholds.
	We recognize sales of real estate at closing only when sufficient down payments have been obtained, possession and other attributes of ownership have been transferred to the buyer and we have no significant continuing involvement.
	We recognize cost reimbursement income from pass-through expenses on an accrual basis over the periods in which the expenses were incurred. Pass-through expenses are comprised of real estate taxes, operating expenses and common area maintenance costs which are reimbursed by tenants in accordance with specific allowable costs per tenant lease agreements.
	Accounts Receivable and Allowance for Doubtful Accounts
	Accounts receivable primarily represents amounts accrued and unpaid from tenants in accordance with the terms of the respective leases, subject to our revenue recognition policy. We review receivables monthly and establish reserves when, in the opinion of management, collection of the receivable is doubtful. We establish reserves for tenants whose rent payment history or financial condition casts doubt upon the tenants’ ability to perform under their lease obligations. When we deem the collection of a receivable to be doubtful in the same quarter that we established the receivable, then we recognize the allowance for that receivable as an offset to real estate revenues. When we deem a receivable that was initially established in a prior quarter to be doubtful, then we recognize the allowance as an operating expense. In addition to rents due currently, accounts receivable include amounts representing minimal rental income accrued on a straight-line basis to be paid by tenants over the remaining term of their respective leases.
	Our accounts receivable balances include $6.2 million and $6.9 million of notes receivable as of December 31, 2013 and 2012, respectively. Included in theses balances is a note receivable we acquired with the 2445 M Street acquisition in 2008.
	Deferred Financing Costs
	We capitalize and amortize external costs associated with the issuance or assumption of mortgages, notes payable and fees associated with the lines of credit using the effective interest rate method or the straight-line method which approximates the effective interest rate method, over the estimated life of the related debt. We record the amortization of deferred financing costs as interest expense.
	Deferred Leasing Costs
	We capitalize and amortize costs associated with the successful negotiation of leases, both external commissions and internal direct costs, on a straight-line basis over the terms of the respective leases. We record the amortization of deferred leasing costs as amortization expense. If an applicable lease terminates prior to the expiration of its initial lease term, we write off the carrying amount of the costs to amortization expense.
	We capitalize and amortize against revenue leasing incentives associated with the successful negotiation of leases on a straight-line basis over the terms of the respective leases. We record the amortization of deferred leasing incentives as a reduction of revenue. If an applicable lease terminates prior to the expiration of its initial lease term, we write off the carrying amount of the costs as a reduction of revenue.
	Real Estate and Depreciation
	We depreciate buildings on a straight-line basis over estimated useful lives ranging from 28 to 50 years. We capitalize all capital improvements associated with replacements, improvements or major repairs to real property that extend its useful life and depreciate them using the straight-line method over their estimated useful lives ranging from 3 to 30 years. We also capitalize costs incurred in connection with our development projects, including capitalizing interest and other internal costs during periods in which qualifying expenditures have been made and activities necessary to get the development projects ready for their intended use are in progress. In addition, we capitalize tenant leasehold improvements when certain criteria are met, including when we supervise construction and will own the improvements. We depreciate all tenant improvements over the shorter of the useful life of the improvements or the term of the related tenant lease. Real estate depreciation expense from continuing operations was $63.4 million, $61.1 million, $55.1 million during the years ended December 31, 2013, 2012, 2011, respectively.
	We charge maintenance and repair costs that do not extend an asset’s life to expense as incurred.
	We capitalize interest costs incurred on borrowing obligations while qualifying assets are being readied for their intended use. We amortize capitalized interest over the useful life of the related underlying assets upon those assets being placed into service. Interest expense from continuing operations and interest capitalized to real estate assets related to development and major renovation activities for the three years ended December 31, 2013 were as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Total interest expense from continuing operations	$	64,809	$	62,315	$	62,140
	Capitalized interest	1,236		1,688		738
	Interest expense, net of capitalized interest	$	63,573	$	60,627	$	61,402
	We recognize impairment losses on long-lived assets used in operations and held for sale, development assets or land held for future development, if indicators of impairment are present and the net undiscounted cash flows estimated to be generated by those assets are less than the assets' carrying amount and estimated undiscounted cash flows associated with future development expenditures. If such carrying amount is in excess of the estimated cash flows from the operation and disposal of the property, we would recognize an impairment loss equivalent to an amount required to adjust the carrying amount to its estimated fair value, calculated in accordance with current GAAP fair value provisions (see note 3).
	We record acquired or assumed assets, including physical assets and in-place leases, and liabilities, based on their fair values. We determine the fair values of acquired buildings on an “as-if-vacant” basis considering a variety of factors, including the replacement cost of the property, estimated rental and absorption rates, estimated future cash flows and valuation assumptions consistent with current market conditions. We determine the fair value of land acquired based on comparisons to similar properties that have been recently marketed for sale or sold.
	The fair value of in-place leases consists of the following components – (a) the estimated cost to us to replace the leases, including foregone rents during the period of finding a new tenant and foregone recovery of tenant pass-throughs (referred to as “absorption cost”); (b) the estimated cost of tenant improvements, and other direct costs associated with obtaining a new tenant (referred to as “tenant origination cost”); (c) estimated leasing commissions associated with obtaining a new tenant (referred to as “leasing commissions”); (d) the above/at/below market cash flow of the leases, determined by comparing the projected cash flows of the leases in place, including consideration of renewal options, to projected cash flows of comparable market-rate leases (referred to as “net lease intangible”); and (e) the value, if any, of customer relationships, determined based on our evaluation of the specific characteristics of each tenant’s lease and our overall relationship with the tenant (referred to as “customer relationship value”). We have attributed no value to customer relationships as of December 31, 2013 and 2012.
	We discount the amounts used to calculate net lease intangibles using an interest rate which reflects the risks associated with the leases acquired. We include tenant origination costs in income producing property on our balance sheet and amortize the tenant origination costs as depreciation expense on a straight-line basis over the remaining life of the underlying leases. We classify leasing commissions and absorption costs as other assets and amortize leasing commissions and absorption costs as amortization expense on a straight-line basis over the remaining life of the underlying leases. We classify net lease intangible assets as other assets and amortize them on a straight-line basis as a decrease to real estate rental revenue over the remaining term of the underlying leases. We classify net lease intangible liabilities as other liabilities and amortize them on a straight-line basis as an increase to real estate rental revenue over the remaining term of the underlying leases. We classify below market net lease intangible liabilities as other liabilities and amortize them on a straight-line basis as an increase to real estate rental revenue over the remaining term of the underlying leases. If any of the fair value of below market lease intangibles includes fair value associated with a renewal option, such amounts are not amortized until the renewal option is executed, else the related value is expensed at that time. Should a tenant terminate its lease, we accelerate the amortization of the unamortized portion of the tenant origination cost, leasing commissions, absorption costs and net lease intangible associated with that lease, over its new, shorter term.
	Balances, net of accumulated depreciation or amortization, as appropriate, of the components of the fair value of in-place leases at December 31, 2013 and 2012 were as follows (in thousands):
		December 31,
		2013						2012
		Gross Carrying Value		Accumulated Amortization		Net		Gross Carrying Value		Accumulated Amortization		Net
	Tenant origination costs	$	47,697	$	29,653	$	18,044	$	48,172	$	23,719	$	24,453
	Leasing commissions/absorption costs	78,629		48,376		30,253		78,464		37,672		40,792
	Net lease intangible assets	12,495		7,008		5,487		12,430		5,350		7,080
	Net lease intangible liabilities	26,348		19,403		6,945		26,244		17,089		9,155
	Below-market ground lease intangible asset	12,080		1,145		10,935		12,080		956		11,124
	Amortization of these combined components from continuing operations for the three years ended December 31, 2013 was as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Amortization	$	17,290	$	19,573	$	13,704
	Amortization of these combined components from continuing operations over the next five years is projected to be as follows (in thousands):
	2014	$	14,675
	2015	11,886
	2016	8,957
	2017	5,830
	2018	3,333
	Discontinued Operations
	We classify properties as held for sale when they meet the necessary criteria, which include: (a) senior management commits to and actively embarks upon a plan to sell the assets, (b) the sale is expected to be completed within one year under terms usual and customary for such sales and (c) actions required to complete the plan indicate that it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. We generally consider that a property has met these criteria when a sale of the property has been approved by the Board of Trustees, or a committee with authorization from the Board, there are no known significant contingencies related to the sale and management believes it is probable that the sale will be completed within one year. Depreciation on these properties is discontinued at the time they are classified as held for sale, but operating revenues, operating expenses and interest expense continue to be recognized until the date of sale.
	Revenues and expenses of properties that are either sold or classified as held for sale are presented as discontinued operations for all periods presented in the consolidated statements of income. Interest on debt that can be identified as specifically attributed to these properties is included in discontinued operations. We do not have significant continuing involvement in the operations of any of our disposed properties.
	Segments
	We evaluate performance based upon operating income from the combined properties in each segment. Our reportable operating segments are consolidations of similar properties. GAAP requires that segment disclosures present the measure(s) used by the chief operating decision maker for purposes of assessing segments’ performance. Net operating income is a key measurement of our segment profit and loss. Net operating income is defined as segment real estate rental revenue less segment real estate expenses.
	Cash and Cash Equivalents
	Cash and cash equivalents include cash and commercial paper with original maturities of 90 days or less. WRIT maintains cash deposits with financial institutions that at times exceeds applicable insurance limits. WRIT reduces this risk by maintaining such deposits with high quality financial institutions that management believe are credit-worthy.
	Restricted Cash
	Restricted cash includes funds escrowed for tenant security deposits, real estate tax, insurance and mortgage escrows and escrow deposits required by lenders on certain of our properties to be used for future building renovations or tenant improvements.
	Earnings Per Common Share
	We determine “Basic earnings per share” using the two-class method as our unvested restricted share awards and units have non-forfeitable rights to dividends, and are therefore considered participating securities. We compute basic earnings per share by dividing net income attributable to the controlling interest less the allocation of undistributed earnings to unvested restricted share awards and units by the weighted-average number of common shares outstanding for the period.
	We also determine “Diluted earnings per share” under the two-class method with respect to the unvested restricted share awards. We further evaluate any other potentially dilutive securities at the end of the period and adjust the basic earnings per share calculation for the impact of those securities that are dilutive. Our dilutive earnings per share calculation includes the dilutive impact of employee stock options based on the treasury stock method and our performance share units under the contingently issuable method. The dilutive earnings per share calculation also considers our operating partnership units.
	Stock Based Compensation
	We currently maintain equity based compensation plans for trustees, officers and employees and previously maintained option plans for trustees, officers and employees.
We recognize compensation expense for service-based share awards ratably over the period from the service inception date through the vesting period based on the fair market value of the shares on the date of grant. We initially measure compensation expense for awards with performance conditions at fair value at the service inception date based on probability of payout, and we remeasure compensation expense at subsequent reporting dates until all of the award’s key terms and conditions are known and the grant date is established. We amortize awards with performance conditions over the performance period using the graded expense method. We measure compensation expense for awards with market conditions based on the grant date fair value, as determined using a Monte Carlo simulation, and we amortize the expense ratably over the requisite service period, regardless of whether the market conditions are achieved and the awards ultimately vest. Compensation expense for the trustee grants, which fully vest immediately, is fully recognized upon issuance based upon the fair market value of the shares on the date of grant.
Accounting for Uncertainty in Income Taxes
We can recognize a tax benefit only if it is “more likely than not” that a particular tax position will be sustained upon examination or audit. To the extent that the “more likely than not” standard has been satisfied, the benefit associated with a tax position is measured as the largest amount that is greater than 50% likely of being recognized upon settlement.
We are subject to U.S. federal income tax as well as income tax of the states of Maryland and Virginia, and the District of Columbia. However, as a REIT, we generally are not subject to income tax on our net income distributed as dividends to our shareholders.
Tax returns filed for 2009 through 2013 tax years are subject to examination by taxing authorities. We classify interest and penalties related to uncertain tax positions, if any, in our financial statements as a component of general and administrative expense.
Reclassifications
Certain prior year amounts have been reclassified from continuing operations to discontinued operations to conform to the current year presentation (see note 3). In addition, we reclassified $0.3 million of real estate deposits from operating activities to investing activities in the consolidated statement of cash flows for the year ended December 31, 2012.

Real_Estate_Investments

Real Estate Investments	12 Months Ended
	Dec. 31, 2013
Real Estate Investments, Net [Abstract]	'
Real Estate Investments	'
	Continuing Operations
	As of December 31, 2013 and 2012, our real estate investment portfolio, at cost, consists of properties as follows (in thousands):
		December 31,
		2013				2012
	Office	$	1,296,967			$	1,261,534
	Retail	415,899				411,948
	Multifamily	389,361				331,901
		$	2,102,227			$	2,005,383
	Our results of operations are dependent on the overall economic health of our markets, tenants and the specific segments in which we own properties. These segments include office, retail and multifamily. All segments are affected by external economic factors, such as inflation, consumer confidence, unemployment rates, etc. as well as changing tenant and consumer requirements.
	As of December 31, 2013, no single property or tenant accounted for more than 10% of total assets or total real estate rental revenue.
	We had properties under development or held for development as of December 31, 2013. In the office segment, we had a redevelopment project to renovate 7900 Westpark Drive and land held for development at Dulles Station, Phase II. In the multifamily segment, we had land under development at 650 North Glebe Road and held for development at 1225 First Street.
	The cost of our real estate portfolio under development or held for development as of December 31, 2013 and 2012 is as follows (in thousands):
		December 31,
		2013				2012
	Office	$	12,175			$	8,922
	Retail	495				587
	Multifamily	48,645				35,761
		$	61,315			$	45,270
	Acquisitions
	Our current strategy is focused on properties inside the Washington metro region’s Beltway, near major transportation nodes and in areas with strong employment drivers and superior growth demographics. We seek to upgrade our portfolio with acquisitions as opportunities arise. Properties and land for development acquired during the years ending December 31, 2013, 2012 and 2011 were as follows:
	Acquisition Date		Property		Type		Rentable			Contract
							Square  Feet			Purchase  Price
							(unaudited)			(In thousands)
	October 1, 2013		The Paramount (135 units)		Multifamily		N/A			$	48,200
					Total 2013					$	48,200
	June 21, 2012		Fairgate at Ballston		Office		142,000			$	52,250
					Total 2012		142,000			$	52,250
	January 11, 2011		1140 Connecticut Ave		Office		188,000			$	80,250
	March 30, 2011		1227 25th Street		Office		132,000			47,000
	June 15, 2011		650 North Glebe Road (1)		Mutifamily		N/A			11,800
	August 30, 2011		Olney Village Center		Retail		198,000			58,000
	September 13, 2011		Braddock Metro Center		Office		351,000			101,000
	September 15, 2011		John Marshall II		Office		223,000			73,500
	November 23, 2011		1225 First Street (1)		Mutifamily		N/A			13,850
					Total 2011		1,092,000			$	385,400
	(1) Land for development. 650 North Glebe Road is currently under development and development has been suspended at 1225 First Street.
	The results of operations from acquired operating properties are included in the consolidated statements of income as of their acquisition dates.
	The revenue and earnings of our acquisitions during their year of acquisition for the three years ended December 31, 2013 are as follows (in thousands):
		Year Ended December 31,
		2013				2012				2011
	Real estate rental revenue	$	907			$	3,358			$	20,944
	Net (loss) income	(105		)		325				484
	As discussed in note 2, we record the acquired physical assets (land, building and tenant improvements), in-place leases (absorption, tenant origination costs, leasing commissions, and net lease intangible assets/liabilities), and any other liabilities at their fair values.
	We have recorded the total purchase price of the above acquisitions as follows (in thousands):
		2013				2012				2011
	Land	$	8,568			$	17,750			$	90,896
	Buildings	37,930				26,893				219,613
	Tenant origination costs	32				3,100				15,667
	Leasing commissions/absorption costs	943				4,172				29,719
	Net lease intangible assets	102				508				6,805
	Net lease intangible liabilities	(117		)		(173		)		(2,454		)
	Fair value of assumed mortgage	—				—				(78,500		)
	Furniture, fixtures & equipment	742				—				—
	Total	$	48,200			$	52,250			$	281,746
	The weighted remaining average life for the 2013 acquisition components above, other than land and building, are 110 months for tenant origination costs, 22 months for leasing commissions/absorption costs, 81 months for net lease intangible assets and 88 months for net lease intangible liabilities.
	The difference in the contract purchase price of $52.3 million for the 2012 acquisition and the cash paid for the acquisition per the consolidated statements of cash flows of $52.1 million is primarily related to credits received at settlement totaling $0.1 million.
	The difference in the total contract price of $385.4 million for the 2011 acquisitions and the acquisition cost per the consolidated statements of cash flows of $281.7 million is primarily related to the two mortgage notes assumed for $76.7 million relating to John Marshall II and Olney Village Center, cash paid for the acquisition of land at 650 North Glebe Road for $11.8 million and at 1225 First Street for $13.9 million included in development, and credits received at settlement totaling $1.3 million.
	Noncontrolling Interests in Subsidiaries
	In August 2007, we acquired a 0.8 acre parcel of land located at 4661 Kenmore Avenue, Alexandria, Virginia for future medical office development. The acquisition was funded by issuing operating partnership units in an operating partnership, which is a consolidated subsidiary of WRIT. This resulted in a noncontrolling ownership interest in this property based upon defined company operating partnership units at the date of purchase. In November 2013, 4661 Kenmore Avenue was sold as part of the Medical Office Portfolio (see "Discontinued Operations").
	Variable Interest Entities
	In June 2011, we executed a joint venture operating agreement with a real estate development company to develop a mid-rise multifamily property at 650 North Glebe Road in Arlington, Virginia. We estimate the total cost of the project to be $49.9 million, and we secured third-party debt financing totaling $33.0 million (see note 4). WRIT is the 90% owner of the joint venture, and will have management and leasing responsibilities when the project is completed and stabilized (defined as 90% of the residential units leased). The real estate development company owns 10% of the joint venture and is responsible for the development and construction of the property. The joint venture currently expects to complete this development project during the fourth quarter of 2014.
	In November 2011, we executed a joint venture operating agreement with a real estate development company to develop a high-rise multifamily property at 1225 First Street (formerly 1219 First Street) in Alexandria, Virginia. We estimate the total cost of the project to be $95.3 million, with approximately 70% of the project financed with debt. WRIT is the 95% owner of the joint venture and will have management and leasing responsibilities when the project is completed and stabilized. The real estate development company owns 5% of the joint venture and is responsible for the development and construction of the property. In the first quarter of 2013, we decided to delay commencement of construction due to market conditions and concerns of oversupply. We continue to reassess this project on a periodic basis going forward.
	We have determined that the 650 North Glebe Road and 1225 First Street joint ventures are VIE's primarily based on the fact that the equity investment at risk is not sufficient to permit either entity to finance its activities without additional financial support. We expect that 70% of the total development costs will be financed through debt. We have also determined that WRIT is the primary beneficiary of each VIE due to the fact that WRIT is providing 90% to 95% of the equity contributions and will manage each property after stabilization.
We include the joint venture land acquisitions and related capitalized development costs on our consolidated balance sheets in properties under development or held for development, consistent with other development activity. As of December 31, 2013 and 2012, the land and capitalized development costs were as follows (in thousands):
	December 31,
	2013				2012
650 North Glebe Road	$	27,343			$	15,646
1225 First Street	20,788				19,807
As of December 31, 2013 and 2012, the accounts payable and accrued liabilities related to the joint ventures were as follows (in thousands):
	December 31,
	2013				2012
650 North Glebe Road	$	1,785			$	115
1225 First Street	39				1,676
Discontinued Operations
We dispose of assets that no longer meet our long-term strategy or return objectives and where market conditions for sale are favorable. The proceeds from the sales may be reinvested into other properties, used to fund development operations or to support other corporate needs, or distributed to our shareholders. Properties are considered held for sale when they meet specified criteria (see "Discontinued Operations" in note 2). Depreciation on these properties is discontinued at that time, but operating revenues, other operating expenses and interest continue to be recognized until the date of sale.
In September 2013, we entered into four separate purchase and sale agreements to effectuate the sale of our entire medical office segment (including land held for development at 4661 Kenmore Avenue) and two office buildings (Woodholme Center and 6565 Arlington Boulevard) for an aggregate purchase price of $500.8 million. The sale was structured as four transactions. Transactions I & II closed in November 2013. In January 2014, we closed on the remaining two transactions.
The impact of the sale on our medical office segment on revenues and net income is summarized as follows (in thousands, except per share data):
	December 31,
	2013				2012				2011
Real estate revenues	$	41,012			$	44,674			$	44,431
Net income	14,044				8,128				10,393
Basic net income per share	0.21				0.12				0.16
Diluted net income per share	0.21				0.12				0.16
During 2011, we sold our industrial segment, the impact of the disposal on revenues and net income for the three years ended December 31, 2013 were as follows (in thousands, except per share data):
	Year Ended December 31,
	2013				2012				2011
Real estate revenues	$	—			$	—			$	23,045
Net income	—				—				16,484
Basic net income per share	—				—				0.23
Diluted net income per share	—				—				0.23
We sold or classified as held for sale the following properties during the three years ended December 31, 2013:
Property		Type		Rentable			Contract				Gain on Sale
				Square Feet			Sales Price				(in thousands)
				(unaudited)			(in thousands)
Atrium Building		Office		79,000			$	15,750			$	3,195
Medical Office Portfolio Transactions I & II		Medical Office / Office		1,093,000			307,189				18,949
Medical Office Portfolio Transactions III & IV		Medical Office		427,000			193,561				N/A
		Total 2013		1,599,000			$	516,500			$	22,144
1700 Research Boulevard		Office		101,000			$	14,250			$	3,724
Plumtree Medical Center		Medical Office		33,000			8,750				1,400
		Total 2012		134,000			$	23,000			$	5,124
Industrial Portfolio		Industrial/Office		3,092,000			$	350,900			$	97,491
Dulles Station, Phase I		Office		180,000			58,800				—
		Total 2011		3,272,000			$	409,700			$	97,491
As of December 31, 2013 and 2012, investment in real estate for properties sold or held for sale were as follows (in thousands):
	December 31,
	2013				2012
Office	$	—			$	71,605
Medical office	125,967				406,874
Total	$	125,967			$	478,479
Less accumulated depreciation	(46,066		)		(113,480		)
Investment in real estate sold or held for sale, net	$	79,901			$	364,999
As of December 31, 2013 and 2012, liabilities related to properties sold or held for sale were as follows (in thousands):
	December 31,
	2013				2012
Mortgage notes payable	$	—			$	23,945
Other liabilities	1,533				8,412
Liabilities related to properties sold or held for sale	$	1,533			$	32,357
Income from operations of properties sold or held for sale for the three years ended December 31, 2013 was as follows (in thousands):
	December 31,
	2013				2012				2011
Revenues	$	45,791			$	54,344			$	80,948
Property expenses	(17,039		)		(18,273		)		(25,265		)
Real estate impairment	—				(2,097		)		(599		)
Depreciation and amortization	(12,161		)		(18,827		)		(26,125		)
Interest expense	(1,196		)		(4,331		)		(5,545		)
	$	15,395			$	10,816			$	23,414
Income from operations of properties sold or held for sale by property for the three years ended December 31, 2013 was as follows (in thousands):
			Year Ending December 31,
Property	Segment		2013				2012				2011
Dulles Station, Phase I	Office		$	—			$	—			$	(468	)
Industrial Portfolio	Industrial/Office		—				—				10,621
1700 Research Boulevard	Office		—				225				651
Plumtree Medical Center	Medical Office		—				197				67
Atrium Building	Office		185				1,063				1,052
Medical Office Portfolio	Medical/Office		15,210				9,331				11,491
			$	15,395			$	10,816			$	23,414
Real Estate Impairment
During the fourth quarter of 2012, we determined that the development of a medical office building at 4661 Kenmore Avenue in Alexandria, Virginia was no longer probable due to a change in corporate strategy. Due to this determination, we recognized in discontinued operations an impairment charge of $2.1 million during the fourth quarter of 2012 in order to reduce the carrying value of the land at 4661 Kenmore Avenue to its estimated fair value of $3.8 million. 4661 Kenmore Avenue was sold during 2013.
During the fourth quarter of 2011, we reviewed changes in market conditions, specifically higher vacancy and lower rental rates in the Washington metro region office market and other circumstances affecting the Herndon submarket, such as the increased uncertainty surrounding the timing of the completion of the second phase of the Dulles Metrorail project, and reassessed the likelihood that we would follow through on these development plans. Based upon the foregoing review and assessment, we determined that the development of the land at Dulles Station, Phase II was not probable under those market conditions. Due to this determination, we recognized in continuing operations a $14.5 million impairment charge during the fourth quarter of 2011 in order to reduce the carrying value of the land and garage at Dulles Station, Phase II to its fair value. In addition, we recognized in discontinued operations an impairment charge of $0.6 million at Dulles Station, Phase I, which was sold during 2011.
We used a combination of internal models and third-party valuation estimates to determine the fair values of 4661 Kenmore Avenue and Dulles Station, Phase II. These fair valuations incorporated both market and income approaches, including recent comparable land sales and return on cost of development metrics. The valuations are inherently subjective because there are few observable market transactions for similar land, and therefore we, through discussions with market participants, made certain significant assumptions with respect to appropriate comparable transactions to consider, cash flow estimates and discount rates. Our estimate of the fair value of the land was further corroborated by an independent third-party valuation specialist. These fair valuations fall into Level 3 in the fair value hierarchy due to its reliance on significant unobservable inputs.

Mortgage_Notes_Payable

Mortgage Notes Payable	12 Months Ended
	Dec. 31, 2013
Notes Payable, Noncurrent [Abstract]	'
Mortgage Notes Payable	'
	As of December 31, 2013 and 2012, we had outstanding mortgage notes payable, each collateralized by one or more buildings and related land from our portfolio, as follows (in thousands):
							December 31,
	Properties		Assumption/Issuance Date (1)		Effective Interest Rate (2)		2013		2012		Payoff Date/Maturity Date
	650 North Glebe Road (3), (4)		2/21/13		2.31	%	$	7,297	$	—	2/21/16
	John Marshall II		9/15/11		5.79	%	$	52,563	$	53,274	5/5/16
	Olney Village Center		8/30/11		4.94	%	20,743		22,343		10/1/23
	Kenmore Apartments		2/2/09		5.37	%	34,937		35,535		3/1/19
	2445 M Street (4)		12/2/08		7.25	%	98,102		96,848		1/6/17
	3801 Connecticut Avenue, Walker House and Bethesda Hill (5)		5/29/08		5.71	%	81,029		81,029		6/1/16
	Ashburn Farm Office Park (6)		6/1/07		5.56	%	—		2,313		11/21/13
	Ashburn Farm III Office Park (7)		6/1/07		5.69	%	—		2,024		11/21/13
	Woodholme Medical Office Center (8)		6/1/07		5.29	%	—		19,608		11/22/13
	West Gude Drive (9)		8/25/06		5.86	%	—		29,996		1/11/13
							$	294,671	$	342,970
	(1) Each of these mortgages was assumed with the acquisition of the collateralized properties, except for the mortgage notes secured by 3801 Connecticut Avenue, Walker House, Bethesda Hill, Kenmore Apartments, and the construction loan secured by the development project at 650 North Glebe Road, which were originally executed by WRIT. We record mortgages assumed in an acquisition at fair value, and balances presented include any recorded premiums or discounts.
	(2) Yield on the assumption/issuance date, including the effects of any premiums, discounts or fair value adjustments on the notes.
	(3) Interest rate on 650 North Glebe Road is variable, based on LIBOR plus 2.15%. The maturity date can be extended for up to two years, subject to fees and compliance with certain provisions in the loan agreement, until February 20, 2018.
	(4) Interest only is payable monthly until the maturity date upon which all unpaid principal and interest are payable in full.
	(5) Interest only is payable monthly until the maturity date, which can be extended for one year upon which the interest rate is reset on June 1, 2016. At maturity on June 1, 2017, all unpaid principal and interest are payable in full.
	(6) In November 2013, we extinguished the remaining $2.2 million of principal on the mortgage note secured by Ashburn Farm Office Park with extinguishment costs of $0.5 million.
	(7) In November 2013, we extinguished the remaining $1.9 million of principal on the mortgage note secured by Ashburn Farm III Office Park, with extinguishment costs of $0.4 million.
	(8) In November 2013, we extinguished the remaining $19.3 million of principal on the mortgage note secured by Woodholme Medical Office Center, with extinguishment costs of $1.8 million.
	(9) In January 2013, we extinguished without penalty the remaining $30.0 million of principal on the mortgage note secured by West Gude Drive.
	The mortgage notes secured by Ashburn Farm Office Park I and II and Woodholme Medical Office Building are included in "Other liabilities related to properties sold or held for sale" on our consolidated balance sheets as of December 31, 2012, as the properties were sold in 2013.
	Except as noted above, principal and interest are payable monthly until the maturity date, upon which all unpaid principal and interest are payable in full.
	Total carrying amount of the above mortgaged properties was $433.7 million and $510.0 million at December 31, 2013 and 2012, respectively.
	Scheduled principal payments subsequent to December 31, 2013 are as follows (in thousands):
	2014	$	2,840
	2015	3,017
	2016	141,688
	2017	104,369
	2018	2,661
	Thereafter	42,625
		297,200
	Net discounts/premiums	(2,529		)
	Total	$	294,671

Unsecured_Lines_Of_Credit_Paya

Unsecured Lines Of Credit Payable	12 Months Ended
	Dec. 31, 2013
Unsecured Debt [Abstract]	'
Unsecured Lines Of Credit Payable	'
	As of December 31, 2013, we maintained a $100.0 million unsecured line of credit maturing in June 2015 (“Credit Facility No. 1”) and a $400.0 million unsecured line of credit maturing in July 2016 (“Credit Facility No. 2”). Credit Facility No. 1 and No. 2 have accordion features that allow us to increase the facilities to $200.0 million and $600.0 million, respectively, subject to additional lender commitments. The amounts of these lines of credit unused and available at December 31, 2013 were as follows (in thousands):
		Credit Facility No. 1			Credit Facility No. 2
	Committed capacity	$	100,000		$	400,000
	Borrowings outstanding	—			—
	Letters of credit issued	—			—
	Unused and available	$	100,000		$	400,000
	We executed borrowings and repayments on the unsecured lines of credit during 2013 as follows (in thousands):
		Credit Facility No. 1			Credit Facility No. 2
	Balance at December 31, 2012	$	—		$	—
	Borrowings	100,000			60,000
	Repayments	(100,000		)	(60,000		)
	Balance at December 31, 2013	$	—		$	—
	We made borrowings to pay off the West Gude mortgage note and our 5.125% unsecured notes, fund the acquisition of The Paramount and for general corporate purposes. We made repayments during the year ended December 31, 2013 using proceeds from the sale of The Atrium Building, the sale of the Medical Office Portfolio transactions I & II, and cash from operations.
	Borrowings under Credit Facility No. 1 and No. 2 bear interest at LIBOR plus a spread based on the credit rating on our publicly issued debt. The interest rate spread is 120 basis points for each facility.
	All outstanding advances for Credit Facility No. 1 and No. 2 are due and payable upon maturity in June 2015 and July 2016, respectively. Credit Facility No. 1 and No. 2 may be extended for one year at our option. Interest only payments are due and payable generally on a monthly basis. For the three years ended December 31, 2013, we recognized interest expense (excluding facility fees) as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Credit Facility No. 1	$	281		$	470		$	355
	Credit Facility No. 2	586			783			2,735
	In addition, we pay a facility fee based on the credit rating of our publicly issued debt which as of December 31, 2013 equals 0.25%  per annum of the committed capacity of each facility, without regard to usage. Rates and fees may be adjusted up or down based on changes in our senior unsecured credit ratings. For the three years ended December 31, 2013, we incurred facility fees as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Credit Facility No. 1	$	253		$	175		$	114
	Credit Facility No. 2	1,014			887			658
	Credit Facility No. 1 and No. 2 contain certain financial and non-financial covenants, all of which we have met as of December 31, 2013 and 2012. Included in these covenants is the requirement to maintain a minimum level of net worth, as well as limits on our total liabilities, secured indebtedness and required debt service payments.
	Information related to revolving credit facilities for the three years ended December 31, 2013 as follows (in thousands, except percentage amounts):
		Year Ended December 31,
		2013			2012			2011
	Total revolving credit facilities at December 31	$	500,000		$	500,000		$	475,000
	Borrowings outstanding at December 31	—			—			99,000
	Weighted average daily borrowings during the year	61,548			108,589			160,090
	Maximum daily borrowings during the year	135,000			242,000			281,000
	Weighted average interest rate during the year	1.41		%	1.15		%	1.9		%
	Weighted average interest rate on borrowings outstanding at December 31	N/A			N/A			0.9		%

Notes_Payable

Notes Payable	12 Months Ended
	Dec. 31, 2013
Notes Payable [Abstract]	'
Notes Payable	'
	Our unsecured notes outstanding as of December 31, 2013 were as follows (in thousands):
		Coupon/Stated Rate		Effective Rate (1)		Principal Amount			Maturity Date (2)
	10 Year Unsecured Notes	5.25	%	5.339	%	$	100,000		1/15/14
	10 Year Unsecured Notes	5.35	%	5.359	%	50,000			5/1/15
	10 Year Unsecured Notes	5.35	%	5.49	%	100,000			5/1/15
	10 Year Unsecured Notes	4.95	%	5.053	%	250,000			10/1/20
	10 Year Unsecured Notes	3.95	%	4.018	%	300,000			10/15/22
	30 Year Unsecured Notes	7.25	%	7.36	%	50,000			2/25/28
	Total principal					850,000
	Net unamortized discount					(3,297		)
	Total					$	846,703
	(1) Yield on issuance date, including the effects of discounts on the notes.
	(2) No principal amounts are due prior to maturity.
	We extinguished the remaining $60.0 million of our 5.125% unsecured notes on their due date of March 15, 2013, using borrowings on our unsecured line of credit.
	After December 31, 2013, we extinguished the remaining $100.0 million of our 5.25% unsecured notes on its maturity date.
	The required principal payments excluding the effects of note discounts or premium for the remaining years subsequent to December 31, 2013 are as follows (in thousands):
	2014	$	100,000
	2015	150,000
	2016	—
	2017	—
	2018	—
	Thereafter	600,000
		$	850,000
	Interest on these notes is payable semi-annually. These notes contain certain financial and non-financial covenants, all of which we have met as of December 31, 2013. Included in these covenants is the requirement to maintain a minimum level of unencumbered assets, as well as limits on our total indebtedness, secured indebtedness and required debt service payments.
	The covenants under our line of credit agreements require us to insure our properties against loss or damage in amounts customarily maintained by similar businesses or as they may be required by applicable law. The covenants for the notes require us to keep all of our insurable properties insured against loss or damage at least equal to their then full insurable value. We have an insurance policy which has no terrorism exclusion, except for non-certified nuclear, chemical and biological acts of terrorism. Our financial condition and results of operations are subject to the risks associated with acts of terrorism and the potential for uninsured losses as the result of any such acts. Effective November 26, 2002, under this existing coverage, any losses caused by certified acts of terrorism would be partially reimbursed by the United States under a formula established by federal law. Under this formula the United States pays 85% of covered terrorism losses exceeding the statutorily established deductible paid by the insurance provider, and insurers pay 10% until aggregate insured losses from all insurers reach $100 billion in a calendar year. If the aggregate amount of insured losses under this program exceeds $100 billion during the applicable period for all insured and insurers combined, then each insurance provider will not be liable for payment of any amount which exceeds the aggregate amount of $100 billion. On December 26, 2007, the Terrorism Risk Insurance Program Reauthorization Act of 2007 was signed into law and extends the program through December 31, 2014.

Stock_Based_Compensation

Stock Based Compensation	12 Months Ended
	Dec. 31, 2013
Share-based Compensation [Abstract]	'
Stock Based Compensation	'
	WRIT maintains short-term and long-term incentive plans that allow for stock-based awards to officers and non-officer employees. Stock based awards are provided to officers and non-officer employees, as well as trustees, under the Washington Real Estate Investment Trust 2007 Omnibus Long-Term Incentive Plan which allows for awards in the form of restricted shares, restricted share units, options, and other awards up to an aggregate of 2,000,000 shares over the ten year period in which the plan will be in effect. Restricted share units are converted into shares of our stock upon full vesting through the issuance of new shares.
	WRIT's Compensation Committee conducted an extensive review of our executive compensation philosophy and a fundamental redesign of our short-term and long-term incentive plans for our officers, resulting in new short-term incentive (“STIP”) and new long-term incentive (“LTIP”) plans, which were approved by the Compensation Committee and Board of Trustees on February 17, 2011 effective as of January 1, 2011. In addition, the Compensation Committee approved a new long-term incentive plan for non-officer employees as of January 1, 2011, with minimal changes from the prior long-term incentive plan for non-officer employees.
	Short-Term Incentive Plan
	Under the STIP, officers earn awards, payable 50% in cash and 50% in restricted shares, based on a percentage of salary and the achievement of various performance conditions within a one-year performance period (except for 15% of such restricted share awards which will be exclusively service-based). With respect to the 50% of the STIP award payable in restricted shares, (i) the restricted shares subject to performance conditions will vest over a three-year period commencing on the January 1 following the end of the one-year performance period, and (ii) the restricted shares subject only to a service condition will vest over a three -year period commencing at the beginning of the one-year performance period.
	With respect to the 50% of the award payable in cash, the officer may elect to defer up to 80% of the cash portion pursuant to WRIT's deferred compensation plan for officers. If the officer makes such election, the cash will be converted to restricted share units and WRIT will match 25% of deferred amounts in restricted share units.
	For the service based awards, we recognize compensation expense based on the grant date fair value, ratably over a three-year period commencing with the start of the performance period. With respect to the restricted shares subject to performance conditions expected to be awarded under the STIP at the end of the one-year performance period, we recognize compensation expense based on the current fair market value of the probable award until the performance condition has been met, according to a graded vesting schedule over a four-year period commencing with the date the performance targets were established. Approximately 20% of the restricted shares subject to performance conditions awarded by the Compensation Committee at the end of the one-year performance period are based on subjective strategic acquisition and disposition goal criteria, for which we recognize compensation expense when the grant date occurs at the end of the one-year period through the three-year vesting period.
	Long-Term Incentive Plan
	Under the LTIP, officers earn awards, payable 50% in unrestricted shares and 50% in restricted shares, based on a percentage of salary and the achievement of various market and performance conditions during a defined three-year performance period (e.g., commencing on January 1, 2011 and concluding on December 31, 2013).
	LTIP performance is evaluated based on objective and subjective performance goals and weightings. Of the officers' total potential award, 40% is subject to market conditions based on absolute total shareholder return (“TSR”) and relative TSR. The remaining 60% of the award is based primarily on strategic plan fulfillment, evaluated and determined by the Compensation Committee in its discretion at the end of the three-year performance period.
	The unrestricted shares vest immediately at the end of the three-year performance period, and the restricted shares vest over a one year period commencing on the January 1 following the end of the three-year performance period.
	With respect to the 40% of the LTIP subject to market conditions, we recognize compensation expense ratably (over three years for the 50% unrestricted shares and over four years for the 50% restricted shares) based on the grant date fair value, as determined using a Monte Carlo simulation, and regardless of whether the market conditions are achieved and the awards ultimately vest. With respect to the 60% subjective portion of the LTIP, we recognized compensation expense for the 50% unrestricted shares on December 31, 2013 as the grant date occurred at the end of the three-year performance period. We will recognize compensation expense for the 50% restricted shares over the one-year vesting period commencing upon the grant date at the end of the three-year performance period.
	We use a binomial model which employs the Monte Carlo method as of the grant date to determine the fair value of the 40% of the LTIP subject to market conditions referenced above. The market condition performance measurement is the cumulative three-year total shareholder return on both an absolute basis (50% weighting) and relative to a defined population of 20 peer companies (50% weighting). The model evaluates the awards for changing total shareholder return over the term of the vesting, on an absolute basis and relative to a peer companies, and uses random simulations that are based on past stock characteristics as well as income growth and other factors for WRIT and each of the peer companies. The assumptions used to value the 40% of the LTIP subject to market conditions were an expected volatility of 58.1%, a risk-free interest rate of 1.2% and an expected life of 3 and 4 years.  We based the expected volatility upon the historical volatility of our daily closing share price. The price at the grant date, February 17, 2011, was $30.91. We based the risk-free interest rate used on U.S. treasury constant maturity bonds on the measurement date with a maturity equal to the market condition performance period. We based the expected term on the market condition performance period. The officers' total award opportunity under the LTIP stated as a percentage of base salary ranges from 65% to 150% at target level. The calculated grant date fair value as a percentage of base salary for the officers ranged from 79% to 185% for the 40% of the LTIP subject to market conditions.
	Non-officer employees earn restricted share awards under the LTIP based upon various percentages of their salaries and annual performance calculations. The restricted share awards vest ratably over three years from the grant date based upon continued employment. We recognize compensation expense for these awards according to a graded vesting schedule over four years from the date the performance target was established.
	Modification of Prior LTIP Awards
	In connection with the January 1, 2011 adoption of the STIP and the LTIP, the previous long-term incentive plan ("prior LTIP") for officers was amended such that awards subject to performance and market conditions through 2012 under the prior LTIP were converted when the new plans were adopted into 154,400 restricted share units as of February 17, 2011, of which 59,100 were previously granted and unvested as of December 31, 2010. Such restricted share units vested consistent with the periods in which they otherwise would have vested under the terms of the prior LTIP (i.e., either December 31, 2011 or December 31, 2012). We accounted for the amendment of these awards as a modification.
	Prior LTIP
	Other non-officer members of management earned restricted share units under the prior LTIP (before January 1, 2011) based on one-year performance targets that vest ratably over five years from the grant date based upon continued employment. We recognize compensation expense for these awards according to a graded vesting schedule over six years from the date the performance target was established.
	Officers earned restricted share units under the prior LTIP based on various percentages of their salaries that vest ratably over five years from the grant date based upon continued employment. We recognize compensation expense for these awards ratably over five years from the grant date.
	Trustee Awards
	We award share based compensation to our trustees on an annual basis in the form of restricted shares which vest immediately and are restricted from sale for the period of the trustees' service. The value of share-based compensation for each trustee was $55,000 for each of the years ended December 31, 2013, 2012 and 2011.
	Total Compensation Expense
	Total compensation expense recognized in the consolidated financial statements for the three years ended December 31, 2013 for all share based awards, was as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Stock-based compensation expense	$	6,246		$	5,856		$	5,597
	WRIT's prior chief executive officer ("Prior CEO") retired as of December 31, 2013. Under the terms of his separation agreement, all of the Prior CEO's unvested restricted shares and restricted share units under the STIP, LTIP, Prior LTIP and deferred compensation plans vested on December 31, 2013. The impact of this modification of the Prior CEO's awards was $1.0 million for the year ended December 31, 2013.
	Restricted Share Awards
	The activity for the three years ended December 31, 2013 related to our restricted share awards, excluding those subject to market conditions, was as follows:
		Year Ended December 31,
		2013					2012							2011
		Shares		Wtd Avg Grant Fair Value			Shares			Wtd Avg Grant Fair Value				Shares		Wtd Avg Grant Fair Value
	Vested at January 1	864,288		$	29.65		652,803			$	30.06			490,832		$	30.2
	Unvested at January 1	149,803		27.37			331,003			28.39				193,339		27.71
	Granted	141,609		26.3			36,884			26.4				303,168		29.48
	Vested during year	(158,657	)	26.66			(211,485	)		28.39				(161,971	)	29.8
	Forfeited	(2,940	)	27.8			(6,599	)		27.61				(3,533	)	28.1
	Unvested at December 31	129,815		27.06			149,803			27.37				331,003		28.39
	Vested at December 31	1,022,945		29.19			864,288			29.65				652,803		30.06
	The total fair value of share grants vested for the years ended December 31, 2013, 2012 and 2011 was $3.8 million, $5.6 million and $4.9 million, respectively.
	As of December 31, 2013, the total compensation cost related to non-vested share awards not yet recognized was $1.8 million, which we expect to recognize over a weighted average period of 21 months.
	Restricted and Unrestricted Shares with Market Conditions
	Stock based awards with market conditions under the LTIP were granted in February 2011 with fair market values, as determined using a Monte Carlo simulation, as follows (in thousands):
		Grant Date Fair Value
		Restricted			Unrestricted
	Relative TSR	$	1,066		$	1,066
	Absolute TSR	365			365
	The unamortized value of these awards with market conditions as of December 31, 2013 and 2012 was as follows (in thousands):
		December 31,
		2013						2012
		Restricted			Unrestricted			Restricted				Unrestricted
	Relative TSR	$	162		$	—		$	501			$	338
	Absolute TSR	55			—			172				116
	Options
	The previous option plans provided for the grant of qualified and non-qualified options. The last option awards to officers were in 2002, to non-officer key employees in 2003 and to trustees in 2004. Options granted under the plans were granted with exercise prices equal to the market price on the date of grant, vested 50% after year one and 50% after year two and expire ten years following the date of grant. Options granted to trustees were granted with exercise prices equal to the market price on the date of grant and were fully vested on the grant date. We accounted for option awards in accordance with ASC 718, and we have recognized no compensation cost for stock options.
	The previously issued and currently outstanding and exercisable stock options for the three years ended December 31, 2013 was as follows:
		Year Ended December 31,
		2013					2012							2011
		Shares		Wtd Avg			Shares			Wtd Avg				Shares		Wtd Avg
				Ex Price						Ex Price						Ex Price
	Outstanding at January 1	38,119		$	30.48		89,106			$	27.69			145,950		$	26.74
	Granted	—		—			—			—				—		—
	Exercised	—		—			(44,987	)		25.61				(51,081	)	25.29
	Expired/Forfeited	(28,119	)	29.55			(6,000	)		25.61				(5,763	)	24.85
Outstanding at December 31	10,000		33.09			38,119			30.48				89,106		27.69
Exercisable at December 31	10,000		33.09			38,119			30.48				89,106		27.69
The options outstanding at December 31, 2013 are all exercisable, have an exercise price of $33.09 and have a remaining contractual life of 1.0 years. The outstanding exercisable options at December 31, 2013 had no aggregate intrinsic value. The aggregate intrinsic value of options exercised was $0.1 million and $0.3 million in the years ended December 31, 2012 and 2011, respectively. There were no options forfeited in the years ended December 31, 2013, 2012 and 2011.

Other_Benefit_Plans

Other Benefit Plans	12 Months Ended
	Dec. 31, 2013
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]	'
Other Benefit Plans	'
	We have a Retirement Savings Plan (the “401(k) Plan”), which permits all eligible employees to defer a portion of their compensation in accordance with the Internal Revenue Code. Under the 401(k) Plan, we may make discretionary contributions on behalf of eligible employees. For the three years ended December 31, 2013, we made contributions to the 401(k) plan as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	401(k) plan contributions	$	428	$	467	$	529
	We have adopted non-qualified deferred compensation plans for the officers and members of the Board of Trustees. The plans allow for a deferral of a percentage of annual cash compensation and trustee fees. The plans are unfunded and payments are to be made out of the general assets of WRIT. The deferred compensation liability at December 31, 2013 and 2012 was as follows (in thousands):
		December 31,
		2013		2012
	Deferred compensation liability	$	1,437	$	1,314
	We established a Supplemental Executive Retirement Plan (“SERP”) effective July 1, 2002 for the benefit of a former CEO. Under this plan, upon the former CEO's termination of employment from WRIT for any reason other than death, permanent and total disability, or discharge for cause, he is entitled to receive an annual benefit equal to his accrued benefit times his vested interest. We accounted for this plan in accordance with ASC 715-30, whereby we accrued benefit cost in an amount that resulted in an accrued balance at the end of the former CEO's employment in June 2007 which was not less than the present value of the estimated benefit payments to be made. At December 31, 2013 and 2012, the accrued benefit liability was $1.3 million and $1.4 million, respectively. For the three years ended December 31, 2013, we recognized current service cost as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Former CEO SERP current service cost	$	99	$	106	$	113
	We currently have an investment in corporate owned life insurance intended to meet the SERP benefit liability since the former CEO's retirement. Benefit payments to the prior CEO began in 2008.
	In November 2005, the Board of Trustees approved the establishment of a SERP for the benefit of the officers, other than the former CEO. This is a defined contribution plan under which, upon a participant's termination of employment from WRIT for any reason other than death, discharge for cause or total and permanent disability, the participant will be entitled to receive a benefit equal to the participant's accrued benefit times the participant's vested interest. We account for this plan in accordance with ASC 710-10 and ASC 320-10, whereby the investments are reported at fair value, and unrealized holding gains and losses are included in earnings. At December 31, 2013 and 2012, the accrued benefit liability was $3.3 million and $2.3 million, respectively. For the three years ended December 31, 2013, we recognized current service cost as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Officer SERP current service cost	$	325	$	342	$	334

Fair_Value_Disclosures

Fair Value Disclosures	12 Months Ended
	Dec. 31, 2013
Fair Value Disclosures [Abstract]	'
Fair Value Disclosures	'
	Assets and Liabilities Measured at Fair Value
	For assets and liabilities measured at fair value on a recurring basis, quantitative disclosures about the fair value measurements are required to be disclosed separately for each major category of assets and liabilities, as follows:
	Level 1: Quoted prices in active markets for identical assets
	Level 2: Significant other observable inputs
	Level 3: Significant unobservable inputs
	The only assets or liabilities we had at December 31, 2013 and 2012 that are recorded at fair value on a recurring basis are the assets held in the SERP. We base the valuations related to these items on assumptions derived from significant other observable inputs and accordingly these valuations fall into Level 2 in the fair value hierarchy. The fair values of these assets at December 31, 2013 and 2012 were as follows (in thousands):
		December 31, 2013								December 31, 2012
		Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs		Significant Unobservable Inputs		Fair Value		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
						(Level 2)		(Level 3)				(Level 1)		(Level 2)		(Level 3)
	Assets:
	SERP	$	3,290	$	—	$	3,290	$	—	$	2,421	$	—	$	2,421	$	—
	Financial Assets and Liabilities Not Measured at Fair Value
	The following disclosures of estimated fair value were determined by management using available market information and established valuation methodologies, including discounted cash flow. Many of these estimates involve significant judgment. The estimated fair value disclosed may not necessarily be indicative of the amounts we could realize on disposition of the financial instruments. The use of different market assumptions or estimation methodologies could have an effect on the estimated fair value amounts. In addition, fair value estimates are made at a point in time and thus, estimates of fair value subsequent to December 31, 2013 may differ significantly from the amounts presented.
	Below is a summary of significant methodologies used in estimating fair values and a schedule of fair values at December 31, 2013.
	Cash and Cash Equivalents and Restricted Cash
	Cash and cash equivalents and restricted cash include cash and commercial paper with original maturities of less than 90 days, which are valued at the carrying value, which approximates fair value due to the short maturity of these instruments (Level 1 inputs).
	Notes Receivable
	We acquired a note receivable ("2445 M Street note") in 2008 with the purchase of 2445 M Street. We estimate the fair value of the 2445 M Street note based on a discounted cash flow methodology using market discount rates (Level 3 inputs).
	Debt
	Mortgage notes payable consist of instruments in which certain of our real estate assets are used for collateral. We estimate the fair value of the mortgage notes payable by discounting the contractual cash flows at a rate equal to the relevant treasury rates (with respect to the timing of each cash flow) plus credit spreads estimated through independent comparisons to real estate assets or loans with similar characteristics. Lines of credit payable consist of bank facilities which we use for various purposes including working capital, acquisition funding or capital improvements. The lines of credit advances are priced at a specified rate plus a spread. We estimate the market value based on a comparison of the spreads of the advances to market given the adjustable base rate. We estimate the fair value of the notes payable by discounting the contractual cash flows at a rate equal to the relevant treasury rates (with respect to the timing of each cash flow) plus credit spreads derived using the relevant securities’ market prices. We classify these fair value measurements as Level 3 as we use significant unobservable inputs and management judgment due to the absence of quoted market prices.
	As of December 31, 2013 and 2012, the carrying values and estimated fair values of our financial instruments were as follows (in thousands):
		December 31,
		2013				2012
		Carrying		Fair Value		Carrying		Fair Value
		Value				Value
	Cash and cash equivalents(1)	$	130,343	$	130,343	$	19,324	$	19,324
	Restricted cash(1)	9,189		9,189		14,582		14,582
	2445 M Street note receivable	6,070		6,803		6,617		6,654
	Mortgage notes payable (1)	294,671		313,476		342,970		374,591
	Notes payable	846,703		856,171		906,190		968,040
	(1) Includes amounts that have been reclassified to "Other asset related to properties sold or held for sale" or "Other liabilities related to properties sold or held for sale" on the consolidated balance sheets (see note 3).

Earnings_Per_Common_Share

Earnings Per Common Share	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Earnings per Common Share	'
	We determine “Basic earnings per share” using the two-class method as our unvested restricted share awards and units have non-forfeitable rights to dividends, and are therefore considered participating securities. We compute basic earnings per share by dividing net income attributable to the controlling interest less the allocation of undistributed earnings to unvested restricted share awards and units by the weighted-average number of common shares outstanding for the period.
	We also determine “Diluted earnings per share” under the two-class method with respect to the unvested restricted share awards. We further evaluate any other potentially dilutive securities at the end of the period and adjust the basic earnings per share calculation for the impact of those securities that are dilutive. Our dilutive earnings per share calculation includes the dilutive impact of employee stock options based on the treasury stock method and our performance share units under the contingently issuable method. The dilutive earnings per share calculation also considers our operating partnership units. We have a loss from continuing operations for the years ended December 31, 2013 and 2011, and therefore diluted earnings per share is calculated in the same manner as basic earnings per share for these years.
	The computation of basic and diluted earnings per share for the three years ended December 31, 2013 was as follows (in thousands; except per share data):
		Year Ended December 31,
		2013			2012			2011
	Numerator:
	(Loss) income from continuing operations	$	(193	)	$	7,768		$	(14,389	)
	Allocation of undistributed earnings to unvested restricted share awards and units to continuing operations	—			(191		)	—
	Adjusted (loss) income from continuing operations attributable to the controlling interests	(193		)	7,577			(14,389		)
	Income from discontinued operations, including gain on sale of real estate, net of taxes	37,539			15,940			119,767
	Net income attributable to noncontrolling interests	—			—			(494		)
	Allocation of undistributed earnings to unvested restricted share awards and units to discontinued operations	(415		)	(391		)	(712		)
	Adjusted income from discontinued operations attributable to the controlling interests	37,124			15,549			118,561
	Adjusted net income attributable to the controlling interests	$	36,931		$	23,126		$	104,172
	Denominator:
	Weighted average shares outstanding – basic	66,580			66,239			65,982
	Effect of dilutive securities:
	Employee stock options and restricted share awards	—			137			—
	Weighted average shares outstanding – diluted	66,580			66,376			65,982
	Earnings per common share, basic:
	Continuing operations	$	—		$	0.11		$	(0.22	)
	Discontinued operations	0.55			0.24			1.8
		$	0.55		$	0.35		$	1.58
	Earnings per common share, diluted:
	Continuing operations	$	—		$	0.11		$	(0.22	)
	Discontinued operations	0.55			0.24			1.8
		$	0.55		$	0.35		$	1.58

Rentals_Under_Operating_Leases

Rentals Under Operating Leases	12 Months Ended
	Dec. 31, 2013
Rentals Under Operating Leases [Abstract]	'
Rentals Under Operating Leases	'
	As of December 31, 2013, non-cancelable commercial operating leases provide for minimum rental income from continuing operations were as follows (in thousands):
	2014	$	177,776
	2015	155,154
	2016	131,374
	2017	111,883
	2018	91,966
	Thereafter	259,546
		$	927,699
	Apartment leases are not included as the terms are generally for one year. Most of these commercial leases increase in future years based on agreed-upon percentages or in some instances, changes in the Consumer Price Index.
	Percentage rents from retail centers, based on a percentage of tenants’ gross sales, for the three years ended December 31, 2013 were as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Percentage rents	$	123	$	150	$	193
	Real estate tax, operating expense and common area maintenance reimbursement income from continuing operations for the three years ended December 31, 2013 was as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Reimbursement income	$	26,822	$	25,528	$	21,877

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Development Commitments
	At December 31, 2013, we had no committed contracts outstanding with third parties in connection with our development and redevelopment projects at 1225 First Street, 650 North Glebe Road and 7900 Westpark Drive.
	Litigation
	We are involved from time to time in various legal proceedings, lawsuits, examinations by various tax authorities and claims that have arisen in the ordinary course of business. Management believes that the resolution of any such current matters will not have a material adverse effect on our financial condition or results of operations.
	Other
	At December 31, 2013, we had no letters of credit issued under our line of credit facility.

Segment_Information

Segment Information	12 Months Ended
	Dec. 31, 2013
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'
Segment Information	'
	We have four reportable segments: office, medical office, retail, and multifamily. Office buildings provide office space for various types of businesses and professions. Retail centers are typically neighborhood grocery store or drug store anchored retail centers. Multifamily properties provide rental housing for families throughout the Washington metropolitan area. Medical office buildings provide offices and facilities for a variety of medical services. We have executed purchase and sale agreements to effectuate the sale of our medical office segment, and have classified this segment as discontinued operations (see note 3).
	Real estate rental revenue as a percentage of the total for each of the reportable operating segments in continuing operations for the three years ended December 31, 2013 was as follows:
		Year Ended December 31,
		2013		2012			2011
	Office	58	%	58	%		57	%
	Retail	21	%	21	%		21	%
	Multifamily	21	%	21	%		22	%
	The percentage of total income producing real estate assets, at cost, for each of the reportable operating segments in continuing operations as of December 31, 2013 and 2012 was as follows:
		December 31,
		2013		2012
	Office	62	%	63	%
	Retail	20	%	20	%
	Multifamily	18	%	17	%
	The accounting policies of each of the segments are the same as those described in note 2.
	The following tables present revenues, net operating income, capital expenditures and total assets for the three years ended December 31, 2013 from these segments, and reconciles net operating income of reportable segments to net income attributable to the controlling interests as reported (in thousands):
		Year Ended December 31, 2013
		Office			Medical				Retail		Multifamily		Corporate			Consolidated
					Office								and Other
	Real estate rental revenue	$	152,339		$	—			$	56,189	$	54,496	$	—		$	263,024
	Real estate expenses	57,293			—				13,768		22,232		—			93,293
	Net operating income	$	95,046		$	—			$	42,421	$	32,264	$	—		$	169,731
	Depreciation and amortization															(85,740		)
	General and administrative															(17,535		)
	Acquisition costs															(1,265		)
	Interest expense															(63,573		)
	Other income															926
	Gain (loss) on extinguishment of debt															(2,737		)
	Discontinued operations:
	Income from properties sold or held for sale															15,395
	Gain on sale of real estate															22,144
	Net income															37,346
	Less: Net income attributable to noncontrolling interests															—
	Net income attributable to the controlling interests															$	37,346
	Capital expenditures	$	37,777		$	3,695			$	4,204	$	10,153	$	162		$	55,991
	Total assets	$	1,073,302		$	84,001			$	344,207	$	309,117	$	164,866		$	1,975,493
		Year Ended December 31, 2012
		Office			Medical				Retail		Multifamily			Corporate			Consolidated
					Office									and Other
	Real estate rental revenue	$	147,401		$	—			$	54,506	$	52,887		$	—		$	254,794
	Real estate expenses	53,376			—				12,702		20,467			—			86,545
	Net operating income	$	94,025		$	—			$	41,804	$	32,420		$	—		$	168,249
	Depreciation and amortization																(85,107		)
	General and administrative																(15,488		)
	Acquisition costs																(234		)
	Interest expense																(60,627		)
	Other income																975
	Discontinued operations:
	Income from properties sold or held for sale																10,816
	Gain on sale of real estate																5,124
	Net income																23,708
	Less: Net income attributable to noncontrolling interests																—
	Net income attributable to the controlling interests																$	23,708
	Capital expenditures	$	35,330		$	7,004			$	2,977	$	5,869		$	555		$	51,735
	Total assets	$	1,140,046		$	327,573			$	355,585	$	249,503		$	51,669		$	2,124,376
		Year Ended December 31, 2011
		Office			Medical				Retail		Multifamily		Industrial/Flex			Corporate				Consolidated
					Office											and Other
	Real estate rental revenue	$	133,333		$	—			$	50,421	$	50,979	$	—		$	—			$	234,733
	Real estate expenses	45,634			—				14,273		19,717		—			—				79,624
	Net operating income	$	87,699		$	—			$	36,148	$	31,262	$	—		$	—			$	155,109
	Depreciation and amortization																			(74,403		)
	General and administrative																			(15,728		)
	Real estate impairment																			(14,526		)
Acquisition costs																			(3,607		)
Interest expense																			(61,402		)
Other income																			1,144
Loss on extinguishment of debt																			(976		)
Discontinued operations:
Income from properties sold or held for sale																			23,414
Gain on sale of real estate																			97,491
Income tax expense																			(1,138		)
Net income																			105,378
Less: Net income attributable to noncontrolling interests																			(494		)
Net income attributable to the controlling interests																			$	104,884
Capital expenditures	$	21,065		$	5,654			$	2,922	$	2,823	$	351		$	621			$	33,436
Total assets	$	1,118,074		$	347,735			$	365,164	$	247,170	$	—		$	42,615			$	2,120,758

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Selected Quarterly Financial Data	'
	Unaudited financial data by quarter for each of the three months in the years ended December 31, 2013 and 2012 were as follows (in thousands, except for per share data):
		Quarter(1)(2)
		First		Second		Third		Fourth
	2013
	Real estate rental revenue	$	64,560	$	65,915	$	65,828	$	66,721
	Income (loss) from continuing operations	$	857	$	1,538	$	1,709	$	(4,297	)
	Effect of disposal of medical office segment on net income	$	2,821	$	3,439	$	3,820	$	3,964
	Net income	$	7,335	$	5,263	$	5,840	$	18,908
	Net income attributable to the controlling interests	$	7,335	$	5,263	$	5,840	$	18,908
	Income (loss) from continuing operations per share
	Basic	$	0.01	$	0.02	$	0.03	$	(0.06	)
	Diluted	$	0.01	$	0.02	$	0.03	$	(0.06	)
	Net income per share
	Basic	$	0.11	$	0.08	$	0.09	$	0.28
	Diluted	$	0.11	$	0.08	$	0.09	$	0.28
	2012
	Real estate rental revenue	$	62,590	$	63,073	$	64,471	$	64,660
	Income from continuing operations	$	1,852	$	2,928	$	2,604	$	384
	Effect of disposal of medical office segment on net income	$	2,623	$	2,370	$	2,462	$	673
	Net income	$	5,181	$	6,008	$	9,561	$	2,958		(3)
	Net income attributable to the controlling interests	$	5,181	$	6,008	$	9,561	$	2,958
	Income from continuing operations per share
	Basic	$	0.03	$	0.04	$	0.04	$	0.01
	Diluted	$	0.03	$	0.04	$	0.04	$	0.01
	Net income per share
	Basic	$	0.08	$	0.09	$	0.14	$	0.04
	Diluted	$	0.08	$	0.09	$	0.14	$	0.04
	(1)	With regard to per share calculations, the sum of the quarterly results may not equal full year results due to rounding.
	(2)	The prior quarter results have been restated to conform to the current quarter presentation. Specifically, results related to properties sold or held for sale have been reclassified into discontinued operations.

Shareholders_Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2013
Stockholders' Equity Note [Abstract]	'
Shareholders' Equity	'
	We are party to a sales agency financing agreement with BNY Mellon Capital Markets, LLC relating to the issuance and sale of up to $250.0 million of our common shares from time to time over a period of no more than 36 months from June 2012. Sales of our common shares are made at market prices prevailing at the time of sale. Net proceeds for the sale of common shares under this program are used for general corporate purposes. As of December 31, 2013, we have not issued any common shares under this sales agency financing agreement.
	We have a dividend reinvestment program, whereby shareholders may use their dividends and optional cash payments to purchase common shares. The common shares sold under this program may either be common shares issued by us or common shares purchased in the open market. Net proceeds under this program are used for general corporate purposes.
	We executed issuances under this program for the three years ended December 31, 2013 as follows (in thousands, except for weighted average issue price):
		Year Ended December 31,
		2013		2012		2011
	Common shares issued	—		55		170
	Weighted average issue price	$	—	$	29.67	$	29.97
	Net proceeds	$	—	$	1,315	$	5,041

Deferred_Costs_Notes

Deferred Costs (Notes)	12 Months Ended
	Dec. 31, 2013
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]	'
Deferred Cost Disclosure	'
	As of December 31, 2013 and 2012 deferred costs were included in prepaid expenses and other assets as follows (in thousands):
		December 31,
		2013						2012
		Gross Carrying		Accumulated		Net		Gross Carrying		Accumulated		Net
		Value		Amortization				Value		Amortization
	Deferred financing costs	$	17,842	$	8,950	$	8,892	$	18,761	$	8,162	$	10,599
	Deferred leasing costs	39,642		14,788		24,854		31,872		13,756		18,116
	Deferred leasing incentives	7,143		2,417		4,726		5,847		1,448		4,399
	NOTE 16: DEFERRED COSTS
	As of December 31, 2013 and 2012 deferred costs were included in prepaid expenses and other assets as follows (in thousands):
		December 31,
		2013						2012
		Gross Carrying		Accumulated		Net		Gross Carrying		Accumulated		Net
		Value		Amortization				Value		Amortization
	Deferred financing costs	$	17,842	$	8,950	$	8,892	$	18,761	$	8,162	$	10,599
	Deferred leasing costs	39,642		14,788		24,854		31,872		13,756		18,116
	Deferred leasing incentives	7,143		2,417		4,726		5,847		1,448		4,399
	Amortization and write-offs of deferred financing, leasing and leasing incentives costs from continuing operations for the three years ended December 31, 2013 were as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Deferred financing costs amortization	$	2,550	$	2,411	$	2,194
	Deferred leasing costs amortization	4,279		3,635		3,827
	Deferred leasing incentives amortization	980		675		556

Subsequent_Events_Notes

Subsequent Events (Notes)	12 Months Ended
	Dec. 31, 2013
Subsequent Events [Abstract]	'
Subsequent Events	'
	NOTE 17: SUBSEQUENT EVENTS
	On January 21, 2014, we closed on Transaction III (for the sale of Woodburn Medical Park I and II) and Transaction IV (for the sale of Prosperity Medical Center I and II and III) of the Medical Office Portfolio sale for an aggregate sales price of $193.6 million (see note 3).
	On February 21, 2014, we closed on the purchase of Yale West, a 216-unit residential building in Washington, DC, for $73.0 million. We assumed a $48.2 million mortgage and funded the remainder of the purchase price through proceeds from the Medical Office Portfolio sale.

Schedule_II_Notes

Schedule II (Notes)	12 Months Ended
	Dec. 31, 2013
Valuation and Qualifying Accounts [Abstract]	'
Schedule II	'
	SCHEDULE II
	VALUATION AND QUALIFYING ACCOUNTS
	FOR THE YEARS ENDED DECEMBER 31, 2013, 2012 AND 2011
	(IN THOUSANDS)
		Balance at Beginning of Year		Additions Charged to Expenses		Net Deductions (Recoveries)			Balance at End of Year
	Allowance for doubtful accounts
	2013	$	10,443	$	3,531	$	(7,191	)	$	6,783
	2012	$	8,049	$	3,811	$	(1,417	)	$	10,443
	2011	$	6,210	$	3,687	$	(1,848	)	$	8,049
	Valuation allowance for deferred tax assets
	2013	$	5,773	$	—	$	(32	)	$	5,741
	2012	$	5,651	$	122	$	—		$	5,773
	2011	$	—	$	5,651	$	—		$	5,651

Schedule_III

Schedule III	12 Months Ended
	Dec. 31, 2013
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]	'
Schedule III	'
	SCHEDULE III
					Initial Cost (b)									Net Improvements (Retirement) since Acquisition				Gross Amounts at Which Carried at December 31, 2013												Accumulated Depreciation at December 31, 2013
	Properties		Location		Land					Buildings and Improvements								Land				Buildings and Improvements				Total (c)							Year of Construction		Date of Acquisition		Net		Units		Depreciation Life (d)
																																					Rentable
																																					Square
																																					Feet (e)
	Multifamily Properties
	3801 Connecticut Avenue (a)		Washington, DC		$	420,000				$	2,678,000			$	9,715,000			$	420,000			$	12,393,000			$	12,813,000			$	8,905,000		1951		Jan-63		179,000		307		30 years
	Roosevelt Towers		Virginia		$	336,000				$	1,996,000			$	10,995,000			$	336,000			$	12,991,000			$	13,327,000			$	7,719,000		1964		May-65		170,000		191		40 years
	Country Club Towers		Virginia		$	299,000				$	2,562,000			$	15,088,000			$	299,000			$	17,650,000			$	17,949,000			$	10,252,000		1965		Jul-69		159,000		227		35 years
	Park Adams		Virginia		$	287,000				$	1,654,000			$	9,808,000			$	287,000			$	11,462,000			$	11,749,000			$	7,856,000		1959		Jan-69		173,000		200		35 years
	Munson Hill Towers		Virginia		$	322,000				$	3,337,000			$	15,359,000			$	322,000			$	18,696,000			$	19,018,000			$	13,331,000		1963		Jan-70		258,000		279		33 years
	The Ashby at McLean		Virginia		$	4,356,000				$	17,102,000			$	16,156,000			$	4,356,000			$	33,258,000			$	37,614,000			$	19,402,000		1982		Aug-96		274,000		256		30 years
	Walker House Apartments (a)		Maryland		$	2,851,000				$	7,946,000			$	6,827,000			$	2,851,000			$	14,773,000			$	17,624,000			$	9,101,000		1971		Mar-96		157,000		212		30 years
	Bethesda Hill Apartments (a)		Maryland		$	3,900,000				$	13,412,000			$	12,116,000			$	3,900,000			$	25,528,000			$	29,428,000			$	14,758,000		1986		Nov-97		225,000		195		30 years
	Bennett Park		Virginia		$	2,861,000				$	917,000			$	79,425,000			$	4,774,000			$	78,429,000			$	83,203,000			$	23,117,000		2007		Feb-01		214,000		224		28 years
	The Clayborne		Virginia		$	269,000				$	—			$	30,527,000			$	699,000			$	30,097,000			$	30,796,000			$	10,245,000		2008		Jun-03		60,000		74		26 years
	The Kenmore (a)		Washington, DC		$	28,222,000				$	33,955,000			$	6,776,000			$	28,222,000			$	40,731,000			$	68,953,000			$	7,219,000		1948		Sep-08		268,000		374		30 years
	650 N. Glebe Rd (g)		Virginia		$	12,787,000				$	—			$	14,556,000			$	27,343,000			$	—			$	27,343,000			$	—		N/A		Jun-11		—		—		N/A
	1225 First Street (g)		Virginia		$	14,046,000				$	—			$	6,742,000			$	20,788,000			$	—			$	20,788,000			$	—		N/A		Nov-11		—		—		N/A
	The Paramount		Virginia		8,568,000			3,871,600		38,716,000				119,000				8,568,000				38,835,000				47,403,000				366,000			1984		Oct-13		141,000		135		30 years
					$	79,524,000				$	124,275,000			$	234,209,000			$	103,165,000			$	334,843,000			$	438,008,000			$	132,271,000						2,278,000		2,674
	Office Buildings
	1901 Pennsylvania Avenue		Washington, DC		$	892,000				$	3,481,000			$	15,955,000			$	892,000			$	19,436,000			$	20,328,000			$	14,068,000		1960		May-77		101,000				28 years
	51 Monroe Street		Maryland		$	840,000				$	10,869,000			$	26,553,000			$	840,000			$	37,422,000			$	38,262,000			$	26,144,000		1975		Aug-79		222,000				41 years
	515 King Street		Virginia		$	4,102,000				$	3,931,000			$	5,494,000			$	4,102,000			$	9,425,000			$	13,527,000			$	4,989,000		1966		Jul-92		75,000				50 years
	6110 Executive Boulevard		Maryland		$	4,621,000				$	11,926,000			$	15,144,000			$	4,621,000			$	27,070,000			$	31,691,000			$	16,490,000		1971		Jan-95		203,000				30 years
	1220 19th Street		Washington, DC		$	7,803,000				$	11,366,000			$	10,612,000			$	7,803,000			$	21,978,000			$	29,781,000			$	11,233,000		1976		Nov-95		104,000				30 years
	1600 Wilson Boulevard		Virginia		$	6,661,000				$	16,742,000			$	20,384,000			$	6,661,000			$	37,126,000			$	43,787,000			$	16,668,000		1973		Oct-97		168,000				30 years
	7900 Westpark Drive (f)		Virginia		$	12,049,000				$	71,825,000			$	40,805,000			$	12,049,000			$	112,630,000			$	124,679,000			$	60,969,000		1972		Nov-97		530,000				30 years
	600 Jefferson Plaza		Maryland		$	2,296,000				$	12,188,000			$	6,199,000			$	2,296,000			$	18,387,000			$	20,683,000			$	8,988,000		1985		May-99		113,000				30 years
	Wayne Plaza		Maryland		$	1,564,000				$	6,243,000			$	8,431,000			$	1,564,000			$	14,674,000			$	16,238,000			$	7,281,000		1970		May-00		96,000				30 years
	Courthouse Square		Virginia		$	—				$	17,096,000			$	7,441,000			$	—			$	24,537,000			$	24,537,000			$	10,899,000		1979		Oct-00		115,000				30 years
	One Central Plaza		Maryland		$	5,480,000				$	39,107,000			$	16,750,000			$	5,480,000			$	55,857,000			$	61,337,000			$	26,059,000		1974		Apr-01		267,000				30 years
	1776 G Street		Washington, DC		$	31,500,000				$	54,327,000			$	4,865,000			$	31,500,000			$	59,192,000			$	90,692,000			$	23,247,000		1979		Aug-03		263,000				30 years
	Dulles Station II (f)		Virginia		$	15,001,000				$	494,000			$	(3,425,000	)		$	4,130,000			$	7,940,000			$	12,070,000			$	291,000		n/a		Dec-05		—				n/a
	West Gude		Maryland		$	11,580,000				$	43,240,000			$	10,876,000			$	11,580,000			$	54,116,000			$	65,696,000			$	15,195,000		1984		Aug-06		277,000				30 years
	Monument II		Virginia		$	10,244,000				$	65,205,000			$	4,733,000			$	10,244,000			$	69,938,000			$	80,182,000			$	17,810,000		2000		Mar-07		207,000				30 years
	2000 M Street		Washington, DC		$	—				$	61,101,000			$	20,866,000			$	—			$	81,967,000			$	81,967,000			$	17,061,000		1971		Dec-07		230,000				30 years
	2445 M Street (a)		Washington, DC		$	46,887,000				$	106,743,000			$	3,060,000			$	46,887,000			$	109,803,000			$	156,690,000			$	22,179,000		1986		Dec-08		290,000				30 years
	925 Corporate Drive		Virginia		$	4,518,000				$	24,801,000			$	428,000			$	4,518,000			$	25,229,000			$	29,747,000			$	5,100,000		2007		Jun-10		134,000				30 years
	1000 Corporate Drive		Virginia		$	4,897,000				$	25,376,000			$	(129,000	)		$	4,897,000			$	25,247,000			$	30,144,000			$	5,217,000		2009		Jun-10		136,000				30 years
	1140 Connecticut Avenue		Washington, DC		$	25,226,000				$	50,495,000			$	8,124,000			$	25,226,000			$	58,619,000			$	83,845,000			$	7,425,000		1966		Jan-11		184,000				30 years
	1227 25th Street		Washington, DC		$	17,505,000				$	21,319,000			$	2,339,000			$	17,505,000			$	23,658,000			$	41,163,000			$	3,158,000		1988		Mar-11		132,000				30 years
	Braddock Metro Center		Virginia		$	18,817,000				$	71,250,000			$	5,564,000			$	18,817,000			$	76,814,000			$	95,631,000			$	8,542,000		1985		Sep-11		345,000				30 years
					Initial Cost (b)									Net Improvements (Retirement) since Acquisition				Gross Amounts at Which Carried at December 31, 2013												Accumulated Depreciation at December 31, 2013
	Properties		Location		Land					Buildings and Improvements								Land				Buildings and Improvements				Total (c)							Year of Construction		Date of Acquisition		Net		Units		Depreciation Life (d)
																																					Rentable
																																					Square
																																					Feet (e)
	John Marshall II (a)		Virginia		$	13,490,000				$	53,024,000			$	173,000			$	13,490,000			$	53,197,000			$	66,687,000			$	5,071,000		1996		Sep-11		223,000				30 years
	Fairgate at Ballston		Virginia		$	17,750,000				$	29,885,000			$	2,137,000			$	17,750,000			$	32,022,000			$	49,772,000			$	2,524,000		1988		Jun-12		142,000				30 years
					$	263,723,000				$	812,034,000			$	233,379,000			$	252,852,000			$	1,056,284,000			$	1,309,136,000			$	336,608,000						4,557,000
	Medical Office
	Woodburn Medical Park I		Virginia		$	2,563,000			$	12,460,000			$	4,393,000			$	2,563,000			$	16,853,000			$	19,416,000			$	8,620,000		1984		Nov-98		77,000				30 years
	Woodburn Medical Park II		Virginia		$	2,632,000			$	17,574,000			$	4,366,000			$	2,632,000			$	21,940,000			$	24,572,000			$	10,901,000		1988		Nov-98		97,000				30 years
	Prosperity Medical Center I		Virginia		$	2,071,000			$	26,317,000			$	1,335,000			$	2,071,000			$	27,652,000			$	29,723,000			$	9,733,000		2000		Oct-03		91,000				30 years
	Prosperity Medical Center II		Virginia		$	1,598,000			$	25,850,000			$	1,521,000			$	1,598,000			$	27,371,000			$	28,969,000			$	9,474,000		2001		Oct-03		87,000				30 years
	Prosperity Medical Center III		Virginia		$	2,819,000			$	19,680,000			$	788,000			$	2,819,000			$	20,468,000			$	23,287,000			$	7,338,000		2002		Oct-03		75,000				30 years
					$	11,683,000			$	101,881,000			$	12,403,000			$	11,683,000			$	114,284,000			$	125,967,000			$	46,066,000						427,000
	Retail Centers
	Takoma Park		Maryland		$	415,000			$	1,084,000			$	238,000			$	415,000			$	1,322,000			$	1,737,000			$	1,184,000		1962		Jul-63		51,000				50 years
	Westminster		Maryland		$	519,000			$	1,775,000			$	9,171,000			$	519,000			$	10,946,000			$	11,465,000			$	6,534,000		1969		Sep-72		150,000				37 years
Concord Centre		Virginia		$	413,000			$	850,000			$	3,511,000			$	413,000			$	4,361,000			$	4,774,000			$	2,966,000		1960		Dec-73		76,000				33 years
Wheaton Park		Maryland		$	796,000			$	857,000			$	4,455,000			$	796,000			$	5,312,000			$	6,108,000			$	3,364,000		1967		Sep-77		74,000				50 years
Bradlee Shopping Center		Virginia		$	4,152,000			$	5,383,000			$	8,261,000			$	4,152,000			$	13,644,000			$	17,796,000			$	9,639,000		1955		Dec-84		168,000				40 years
Chevy Chase Metro Plaza		Washington, DC		$	1,549,000			$	4,304,000			$	5,366,000			$	1,549,000			$	9,670,000			$	11,219,000			$	6,012,000		1975		Sep-85		49,000				50 years
Montgomery Village Center		Maryland		$	11,625,000			$	9,105,000			$	3,252,000			$	11,625,000			$	12,357,000			$	23,982,000			$	5,502,000		1969		Dec-92		197,000				50 years
Shoppes of Foxchase		Virginia		$	5,838,000			$	2,979,000			$	13,245,000			$	5,838,000			$	16,224,000			$	22,062,000			$	5,419,000		1960		Jun-94		134,000				50 years
Frederick County Square		Maryland		$	6,561,000			$	6,830,000			$	4,105,000			$	6,561,000			$	10,935,000			$	17,496,000			$	6,381,000		1973		Aug-95		227,000				30 years
800 S. Washington Street		Virginia		$	2,904,000			$	5,489,000			$	5,999,000			$	2,904,000			$	11,488,000			$	14,392,000			$	4,106,000		1951		Jun-98		47,000				30 years
Centre at Hagerstown .		Maryland		$	13,029,000			$	25,415,000			$	2,306,000			$	13,029,000			$	27,721,000			$	40,750,000			$	10,836,000		2000		Jun-02		332,000				30 years
Frederick Crossing		Maryland		$	12,759,000			$	35,477,000			$	2,206,000			$	12,759,000			$	37,683,000			$	50,442,000			$	11,701,000		1999		Mar-05		295,000				30 years
Randolph Shopping Center		Maryland		$	4,928,000			$	13,025,000			$	727,000			$	4,928,000			$	13,752,000			$	18,680,000			$	3,848,000		1972		May-06		82,000				30 years
Montrose Shopping Center		Maryland		$	11,612,000			$	22,410,000			$	2,545,000			$	11,612,000			$	24,955,000			$	36,567,000			$	6,934,000		1970		May-06		145,000				30 years
Gateway Overlook		Maryland		$	28,816,000			$	52,249,000			$	1,240,000			$	29,394,000			$	52,911,000			$	82,305,000			$	8,328,000		2007		Dec-10		223,000				30 years
Olney Village Center (a)		Maryland		$	15,842,000			$	39,133,000			$	1,648,000			$	15,842,000			$	40,781,000			$	56,623,000			$	3,709,000		1979		Aug-11		199,000				30 years
				$	121,758,000			$	226,365,000			$	68,275,000			$	122,336,000			$	294,062,000			$	416,398,000			$	96,463,000						2,449,000
Total				$	476,688,000			1,264,555,000			$	548,266,000			$	490,036,000			$	1,799,473,000			$	2,289,509,000			$	611,408,000						9,711,000			2,674
a) At December 31, 2013, our properties were encumbered by non-recourse mortgage amounts as follows: $35.4 million on 3801 Connecticut Avenue, $16.5 million on Walker House, $29.1 million on Bethesda Hill, $34.9 million on The Kenmore, $98.1 million on 2445 M Street, $52.6 million on John Marshall II, and $20.7 million on Olney Village Center.
b) The purchase cost of real estate investments has been divided between land and buildings and improvements on the basis of management’s determination of the fair values.
c) At December 31, 2013, total land, buildings and improvements are carried at $1,939.3 million for federal income tax purposes.
d) The useful life shown is for the main structure. Buildings and improvements are depreciated over various useful lives ranging from 3 to 50 years.
e) Residential properties are presented in gross square feet.
f) As of December 31, 2013, WRIT had under development an office project with 360,000 square feet of office space and a parking garage to be developed in Herndon, VA (Dulles Station, Phase II). The total land value not yet placed in service of the development project at December 31, 2013 was $3.6 million. $0.5 million of Dulles Station, Phase II land was placed into service upon the completion of a portion of the parking garage structure. Additionally, WRIT had investments in various smaller development or redevelopment projects, including 7900 Westpark Drive. The total value of this redevelopment not yet placed in service is $3.3 million at December 31, 2013.
g) As of December 31, 2013, WRIT had under development via joint venture arrangements, a mid-rise multifamily property in Arlington, Virginia (650 North Glebe) and a high-rise multifamily property in Alexandria, Virginia (1225 First Street). The value not yet placed into service of these development projects via joint venture arrangements at December 31, 2013 was $48.1 million. 650 North Glebe was encumbered by a construction loan with a $7.3 million balance at December 31, 2013.
The following is a reconciliation of real estate assets and accumulated depreciation for the three years ended December 31, 2013 (in thousands):
	Year Ended December 31,
	2013				2012				2011
Real estate assets
Balance, beginning of period	$	2,529,131			$	2,449,872			$	2,443,127
Additions:
Property acquisitions (1)	47,444				47,772				352,658
Improvements (1)	71,127				59,664				36,386
Deductions:
Impairment write-down	—				(2,097		)		(16,416		)
Write-off of disposed assets	(2,017		)		(1,450		)		(1,648		)
Property sales	(356,176		)		(24,630		)		(364,235		)
Balance, end of period	$	2,289,509			$	2,529,131			$	2,449,872
Accumulated depreciation
Balance, beginning of period	$	610,536			$	535,732			$	538,786
Additions:
Depreciation	80,510				84,949				84,167
Deductions:
Impairment write-down	—				—				(1,291		)
Write-off of disposed assets	(1,404		)		(1,124		)		(1,648		)
Property sales	(78,234		)		(9,021		)		(84,282		)
Balance, end of period	$	611,408			$	610,536			$	535,732
(1) Includes non-cash accruals for capital items and assumed mortgages.

Accounting_Policies_Policy

Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Consolidation, Policy [Policy Text Block]	'
	Principles of Consolidation and Basis of Presentation
	The accompanying audited consolidated financial statements include the consolidated accounts of WRIT, our majority-owned subsidiaries and entities in which WRIT has a controlling interest, including where WRIT has been determined to be a primary beneficiary of a variable interest entity (“VIE”). See note 3 for additional information on the properties for which there is a noncontrolling interest. All intercompany balances and transactions have been eliminated in consolidation.
	We have prepared the accompanying audited consolidated financial statements pursuant to the rules and regulations of the Securities and Exchange Commission. In addition, in the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the results for the periods presented have been included.
Use of Estimates in the Financial Statements, Policy	'
	Use of Estimates in the Financial Statements
	The preparation of financial statements in conformity with Generally Accepted Accounting Principles ("GAAP") requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Revenue Recognition, Policy	'
	Revenue Recognition
	We lease multifamily properties under operating leases with terms of generally one year or less. We lease commercial properties (our office, medical office and retail segments) under operating leases with average terms of three to five years. We recognize rental income and rental abatements from our multifamily and commercial leases when earned on a straight-line basis over the lease term. Recognition of rental income commences when control of the facility has been given to the tenant. We record a provision for losses on accounts receivable equal to the estimated uncollectible amounts. We base this estimate on our historical experience and a review of the current status of our receivables. We recognize percentage rents, which represent additional rents based on gross tenant sales, when tenants’ sales exceed specified thresholds.
	We recognize sales of real estate at closing only when sufficient down payments have been obtained, possession and other attributes of ownership have been transferred to the buyer and we have no significant continuing involvement.
	We recognize cost reimbursement income from pass-through expenses on an accrual basis over the periods in which the expenses were incurred. Pass-through expenses are comprised of real estate taxes, operating expenses and common area maintenance costs which are reimbursed by tenants in accordance with specific allowable costs per tenant lease agreements.
Accounts Receivable and Allowance for Doubtful Accounts, Policy	'
	Accounts Receivable and Allowance for Doubtful Accounts
	Accounts receivable primarily represents amounts accrued and unpaid from tenants in accordance with the terms of the respective leases, subject to our revenue recognition policy. We review receivables monthly and establish reserves when, in the opinion of management, collection of the receivable is doubtful. We establish reserves for tenants whose rent payment history or financial condition casts doubt upon the tenants’ ability to perform under their lease obligations. When we deem the collection of a receivable to be doubtful in the same quarter that we established the receivable, then we recognize the allowance for that receivable as an offset to real estate revenues. When we deem a receivable that was initially established in a prior quarter to be doubtful, then we recognize the allowance as an operating expense. In addition to rents due currently, accounts receivable include amounts representing minimal rental income accrued on a straight-line basis to be paid by tenants over the remaining term of their respective leases.
	Our accounts receivable balances include $6.2 million and $6.9 million of notes receivable as of December 31, 2013 and 2012, respectively. Included in theses balances is a note receivable we acquired with the 2445 M Street acquisition in 2008.
Deferred Financing Costs, Policy	'
	Deferred Financing Costs
	We capitalize and amortize external costs associated with the issuance or assumption of mortgages, notes payable and fees associated with the lines of credit using the effective interest rate method or the straight-line method which approximates the effective interest rate method, over the estimated life of the related debt. We record the amortization of deferred financing costs as interest expense.
Deferred Leasing Costs, Policy	'
	Deferred Leasing Costs
	We capitalize and amortize costs associated with the successful negotiation of leases, both external commissions and internal direct costs, on a straight-line basis over the terms of the respective leases. We record the amortization of deferred leasing costs as amortization expense. If an applicable lease terminates prior to the expiration of its initial lease term, we write off the carrying amount of the costs to amortization expense.
	We capitalize and amortize against revenue leasing incentives associated with the successful negotiation of leases on a straight-line basis over the terms of the respective leases. We record the amortization of deferred leasing incentives as a reduction of revenue. If an applicable lease terminates prior to the expiration of its initial lease term, we write off the carrying amount of the costs as a reduction of revenue.
Real Estate and Depreciation, Policy	'
	Real Estate and Depreciation
	We depreciate buildings on a straight-line basis over estimated useful lives ranging from 28 to 50 years. We capitalize all capital improvements associated with replacements, improvements or major repairs to real property that extend its useful life and depreciate them using the straight-line method over their estimated useful lives ranging from 3 to 30 years. We also capitalize costs incurred in connection with our development projects, including capitalizing interest and other internal costs during periods in which qualifying expenditures have been made and activities necessary to get the development projects ready for their intended use are in progress. In addition, we capitalize tenant leasehold improvements when certain criteria are met, including when we supervise construction and will own the improvements. We depreciate all tenant improvements over the shorter of the useful life of the improvements or the term of the related tenant lease. Real estate depreciation expense from continuing operations was $63.4 million, $61.1 million, $55.1 million during the years ended December 31, 2013, 2012, 2011, respectively.
	We charge maintenance and repair costs that do not extend an asset’s life to expense as incurred.
	We capitalize interest costs incurred on borrowing obligations while qualifying assets are being readied for their intended use. We amortize capitalized interest over the useful life of the related underlying assets upon those assets being placed into service. Interest expense from continuing operations and interest capitalized to real estate assets related to development and major renovation activities for the three years ended December 31, 2013 were as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Total interest expense from continuing operations	$	64,809	$	62,315	$	62,140
	Capitalized interest	1,236		1,688		738
	Interest expense, net of capitalized interest	$	63,573	$	60,627	$	61,402
	We recognize impairment losses on long-lived assets used in operations and held for sale, development assets or land held for future development, if indicators of impairment are present and the net undiscounted cash flows estimated to be generated by those assets are less than the assets' carrying amount and estimated undiscounted cash flows associated with future development expenditures. If such carrying amount is in excess of the estimated cash flows from the operation and disposal of the property, we would recognize an impairment loss equivalent to an amount required to adjust the carrying amount to its estimated fair value, calculated in accordance with current GAAP fair value provisions (see note 3).
	We record acquired or assumed assets, including physical assets and in-place leases, and liabilities, based on their fair values. We determine the fair values of acquired buildings on an “as-if-vacant” basis considering a variety of factors, including the replacement cost of the property, estimated rental and absorption rates, estimated future cash flows and valuation assumptions consistent with current market conditions. We determine the fair value of land acquired based on comparisons to similar properties that have been recently marketed for sale or sold.
	The fair value of in-place leases consists of the following components – (a) the estimated cost to us to replace the leases, including foregone rents during the period of finding a new tenant and foregone recovery of tenant pass-throughs (referred to as “absorption cost”); (b) the estimated cost of tenant improvements, and other direct costs associated with obtaining a new tenant (referred to as “tenant origination cost”); (c) estimated leasing commissions associated with obtaining a new tenant (referred to as “leasing commissions”); (d) the above/at/below market cash flow of the leases, determined by comparing the projected cash flows of the leases in place, including consideration of renewal options, to projected cash flows of comparable market-rate leases (referred to as “net lease intangible”); and (e) the value, if any, of customer relationships, determined based on our evaluation of the specific characteristics of each tenant’s lease and our overall relationship with the tenant (referred to as “customer relationship value”). We have attributed no value to customer relationships as of December 31, 2013 and 2012.
	We discount the amounts used to calculate net lease intangibles using an interest rate which reflects the risks associated with the leases acquired. We include tenant origination costs in income producing property on our balance sheet and amortize the tenant origination costs as depreciation expense on a straight-line basis over the remaining life of the underlying leases. We classify leasing commissions and absorption costs as other assets and amortize leasing commissions and absorption costs as amortization expense on a straight-line basis over the remaining life of the underlying leases. We classify net lease intangible assets as other assets and amortize them on a straight-line basis as a decrease to real estate rental revenue over the remaining term of the underlying leases. We classify net lease intangible liabilities as other liabilities and amortize them on a straight-line basis as an increase to real estate rental revenue over the remaining term of the underlying leases. We classify below market net lease intangible liabilities as other liabilities and amortize them on a straight-line basis as an increase to real estate rental revenue over the remaining term of the underlying leases. If any of the fair value of below market lease intangibles includes fair value associated with a renewal option, such amounts are not amortized until the renewal option is executed, else the related value is expensed at that time. Should a tenant terminate its lease, we accelerate the amortization of the unamortized portion of the tenant origination cost, leasing commissions, absorption costs and net lease intangible associated with that lease, over its new, shorter term.
Discontinued Operations, Policy	'
	Discontinued Operations
	We classify properties as held for sale when they meet the necessary criteria, which include: (a) senior management commits to and actively embarks upon a plan to sell the assets, (b) the sale is expected to be completed within one year under terms usual and customary for such sales and (c) actions required to complete the plan indicate that it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. We generally consider that a property has met these criteria when a sale of the property has been approved by the Board of Trustees, or a committee with authorization from the Board, there are no known significant contingencies related to the sale and management believes it is probable that the sale will be completed within one year. Depreciation on these properties is discontinued at the time they are classified as held for sale, but operating revenues, operating expenses and interest expense continue to be recognized until the date of sale.
	Revenues and expenses of properties that are either sold or classified as held for sale are presented as discontinued operations for all periods presented in the consolidated statements of income. Interest on debt that can be identified as specifically attributed to these properties is included in discontinued operations. We do not have significant continuing involvement in the operations of any of our disposed properties.
Segment Reporting, Policy	'
	Segments
	We evaluate performance based upon operating income from the combined properties in each segment. Our reportable operating segments are consolidations of similar properties. GAAP requires that segment disclosures present the measure(s) used by the chief operating decision maker for purposes of assessing segments’ performance. Net operating income is a key measurement of our segment profit and loss. Net operating income is defined as segment real estate rental revenue less segment real estate expenses.
Cash and Cash Equivalents, Policy	'
	Cash and Cash Equivalents
	Cash and cash equivalents include cash and commercial paper with original maturities of 90 days or less. WRIT maintains cash deposits with financial institutions that at times exceeds applicable insurance limits. WRIT reduces this risk by maintaining such deposits with high quality financial institutions that management believe are credit-worthy.
Restricted Cash, Policy	'
	Restricted Cash
	Restricted cash includes funds escrowed for tenant security deposits, real estate tax, insurance and mortgage escrows and escrow deposits required by lenders on certain of our properties to be used for future building renovations or tenant improvements.
Earnings Per Share, Policy	'
	Earnings Per Common Share
	We determine “Basic earnings per share” using the two-class method as our unvested restricted share awards and units have non-forfeitable rights to dividends, and are therefore considered participating securities. We compute basic earnings per share by dividing net income attributable to the controlling interest less the allocation of undistributed earnings to unvested restricted share awards and units by the weighted-average number of common shares outstanding for the period.
	We also determine “Diluted earnings per share” under the two-class method with respect to the unvested restricted share awards. We further evaluate any other potentially dilutive securities at the end of the period and adjust the basic earnings per share calculation for the impact of those securities that are dilutive. Our dilutive earnings per share calculation includes the dilutive impact of employee stock options based on the treasury stock method and our performance share units under the contingently issuable method. The dilutive earnings per share calculation also considers our operating partnership units.
Stock based Compensation, Policy	'
	Stock Based Compensation
	We currently maintain equity based compensation plans for trustees, officers and employees and previously maintained option plans for trustees, officers and employees.
	We recognize compensation expense for service-based share awards ratably over the period from the service inception date through the vesting period based on the fair market value of the shares on the date of grant. We initially measure compensation expense for awards with performance conditions at fair value at the service inception date based on probability of payout, and we remeasure compensation expense at subsequent reporting dates until all of the award’s key terms and conditions are known and the grant date is established. We amortize awards with performance conditions over the performance period using the graded expense method. We measure compensation expense for awards with market conditions based on the grant date fair value, as determined using a Monte Carlo simulation, and we amortize the expense ratably over the requisite service period, regardless of whether the market conditions are achieved and the awards ultimately vest. Compensation expense for the trustee grants, which fully vest immediately, is fully recognized upon issuance based upon the fair market value of the shares on the date of grant.
Accounting for Uncertainty in Income Taxes, Policy	'
	Accounting for Uncertainty in Income Taxes
	We can recognize a tax benefit only if it is “more likely than not” that a particular tax position will be sustained upon examination or audit. To the extent that the “more likely than not” standard has been satisfied, the benefit associated with a tax position is measured as the largest amount that is greater than 50% likely of being recognized upon settlement.
	We are subject to U.S. federal income tax as well as income tax of the states of Maryland and Virginia, and the District of Columbia. However, as a REIT, we generally are not subject to income tax on our net income distributed as dividends to our shareholders.
	Tax returns filed for 2009 through 2013 tax years are subject to examination by taxing authorities. We classify interest and penalties related to uncertain tax positions, if any, in our financial statements as a component of general and administrative expense.
Comparability of Prior Year Financial Data, Policy	'
	Reclassifications
	Certain prior year amounts have been reclassified from continuing operations to discontinued operations to conform to the current year presentation (see note 3). In addition, we reclassified $0.3 million of real estate deposits from operating activities to investing activities in the consolidated statement of cash flows for the year ended December 31, 2012.

Nature_of_Business_Tables

Nature of Business (Tables)	12 Months Ended
	Dec. 31, 2013
Nature Of Business [Abstract]	'
Taxable Percentage of Dividends Paid	'
	taxable percentage of our dividends for the years ended December 31, 2013, 2012 and 2011,(unaudited):
		2013		2012		2011
	Ordinary income	62	%	72	%	60	%
	Return of capital	38	%	26	%	17	%
	Qualified dividends	—	%	—	%	5	%
	Unrecaptured Section 1250 gain	—	%	2	%	13	%
	Capital gain	—	%	—	%	5	%

Accounting_Policies_Tables

Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Capitalized Interest Expense	'
	Interest expense from continuing operations and interest capitalized to real estate assets related to development and major renovation activities for the three years ended December 31, 2013 were as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Total interest expense from continuing operations	$	64,809	$	62,315	$	62,140
	Capitalized interest	1,236		1,688		738
	Interest expense, net of capitalized interest	$	63,573	$	60,627	$	61,402
Components of Fair Value of In-Place Leases [Table Text Block]	'
	Balances, net of accumulated depreciation or amortization, as appropriate, of the components of the fair value of in-place leases at December 31, 2013 and 2012 were as follows (in thousands):
		December 31,
		2013						2012
		Gross Carrying Value		Accumulated Amortization		Net		Gross Carrying Value		Accumulated Amortization		Net
	Tenant origination costs	$	47,697	$	29,653	$	18,044	$	48,172	$	23,719	$	24,453
	Leasing commissions/absorption costs	78,629		48,376		30,253		78,464		37,672		40,792
	Net lease intangible assets	12,495		7,008		5,487		12,430		5,350		7,080
	Net lease intangible liabilities	26,348		19,403		6,945		26,244		17,089		9,155
	Below-market ground lease intangible asset	12,080		1,145		10,935		12,080		956		11,124
Components of Fair Value of In-Place Leases Amortization [Table Text Block]	'
	Amortization of these combined components from continuing operations for the three years ended December 31, 2013 was as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Amortization	$	17,290	$	19,573	$	13,704
Components of Fair Value of In-Place Leases - Future Amortization [Table Text Block]	'
	Amortization of these combined components from continuing operations over the next five years is projected to be as follows (in thousands):
	2014	$	14,675
	2015	11,886
	2016	8,957
	2017	5,830
	2018	3,333

Real_Estate_Investments_Tables

Real Estate Investments (Tables)	12 Months Ended
	Dec. 31, 2013
Real Estate Investments, Net [Abstract]	'
Investment	'
	As of December 31, 2013 and 2012, our real estate investment portfolio, at cost, consists of properties as follows (in thousands):
		December 31,
		2013				2012
	Office	$	1,296,967			$	1,261,534
	Retail	415,899				411,948
	Multifamily	389,361				331,901
		$	2,102,227			$	2,005,383
Real Estate Portfolio in Development	'
	The cost of our real estate portfolio under development or held for development as of December 31, 2013 and 2012 is as follows (in thousands):
		December 31,
		2013				2012
	Office	$	12,175			$	8,922
	Retail	495				587
	Multifamily	48,645				35,761
		$	61,315			$	45,270
Acquisition Of Properties and Land For Development	'
	Our current strategy is focused on properties inside the Washington metro region’s Beltway, near major transportation nodes and in areas with strong employment drivers and superior growth demographics. We seek to upgrade our portfolio with acquisitions as opportunities arise. Properties and land for development acquired during the years ending December 31, 2013, 2012 and 2011 were as follows:
	Acquisition Date		Property		Type		Rentable			Contract
							Square  Feet			Purchase  Price
							(unaudited)			(In thousands)
	October 1, 2013		The Paramount (135 units)		Multifamily		N/A			$	48,200
					Total 2013					$	48,200
	June 21, 2012		Fairgate at Ballston		Office		142,000			$	52,250
					Total 2012		142,000			$	52,250
	January 11, 2011		1140 Connecticut Ave		Office		188,000			$	80,250
	March 30, 2011		1227 25th Street		Office		132,000			47,000
	June 15, 2011		650 North Glebe Road (1)		Mutifamily		N/A			11,800
	August 30, 2011		Olney Village Center		Retail		198,000			58,000
	September 13, 2011		Braddock Metro Center		Office		351,000			101,000
	September 15, 2011		John Marshall II		Office		223,000			73,500
	November 23, 2011		1225 First Street (1)		Mutifamily		N/A			13,850
					Total 2011		1,092,000			$	385,400
	(1) Land for development
Revenue and Earnings from Acquisitions	'
	The revenue and earnings of our acquisitions during their year of acquisition for the three years ended December 31, 2013 are as follows (in thousands):
		Year Ended December 31,
		2013				2012				2011
	Real estate rental revenue	$	907			$	3,358			$	20,944
	Net (loss) income	(105		)		325				484
Total Purchase Price Of Acquisitions	'
	We have recorded the total purchase price of the above acquisitions as follows (in thousands):
		2013				2012				2011
	Land	$	8,568			$	17,750			$	90,896
	Buildings	37,930				26,893				219,613
	Tenant origination costs	32				3,100				15,667
	Leasing commissions/absorption costs	943				4,172				29,719
	Net lease intangible assets	102				508				6,805
	Net lease intangible liabilities	(117		)		(173		)		(2,454		)
	Fair value of assumed mortgage	—				—				(78,500		)
	Furniture, fixtures & equipment	742				—				—
	Total	$	48,200			$	52,250			$	281,746
Land and Capitalized Development Costs	'
	We include the joint venture land acquisitions and related capitalized development costs on our consolidated balance sheets in properties under development or held for development, consistent with other development activity. As of December 31, 2013 and 2012, the land and capitalized development costs were as follows (in thousands):
		December 31,
		2013				2012
	650 North Glebe Road	$	27,343			$	15,646
	1225 First Street	20,788				19,807
Schedule Of Accounts Payable and Accrued Liabilities Of Joint Ventures	'
	As of December 31, 2013 and 2012, the accounts payable and accrued liabilities related to the joint ventures were as follows (in thousands):
		December 31,
		2013				2012
	650 North Glebe Road	$	1,785			$	115
	1225 First Street	39				1,676
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures	'
	The impact of the sale on our medical office segment on revenues and net income is summarized as follows (in thousands, except per share data):
		December 31,
		2013				2012				2011
	Real estate revenues	$	41,012			$	44,674			$	44,431
	Net income	14,044				8,128				10,393
	Basic net income per share	0.21				0.12				0.16
	Diluted net income per share	0.21				0.12				0.16
	During 2011, we sold our industrial segment, the impact of the disposal on revenues and net income for the three years ended December 31, 2013 were as follows (in thousands, except per share data):
		Year Ended December 31,
		2013				2012				2011
	Real estate revenues	$	—			$	—			$	23,045
	Net income	—				—				16,484
	Basic net income per share	—				—				0.23
	Diluted net income per share	—				—				0.23
Schedule of Dispositions	'
	During the three years ended December 31, 2013, we sold the following properties (in thousands):
	Disposition Date	Property	Type	Gain on Sale
	19-Mar-13	Atrium Building	Office	$	3,195
	Nov-13	Medical Office Portfolio Transactions I & II (1)	Medical Office / Office	18,949
			Total 2013	$	22,144
	31-Aug-12	1700 Research Boulevard	Office	$	3,724
	20-Dec-12	Plumtree Medical Center	Medical Office	1,400
			Total 2012	$	5,124
	5-Apr-11	Dulles Station, Phase I	Office	$	—
	October - November 2011	Industrial Portfolio (2)	Office/Industrial	97,491
			Total 2011	$	97,491
	(1) 2440 M Street, 15001 Shady Grove Road, 15505 Shady Grove Road, 19500 at Riverside Park (formerly Lansdowne Medical Office Building), 9707 Medical Center Drive, CentreMed I and II, 8301 Arlington Boulevard, Sterling Medical Office Building, Shady Grove Medical Village II, Alexandria Professional Center, Ashburn Farm Office Park I, Ashburn Farm Office Park II, Ashburn Farm Office Park III, Woodholme Medical Office Building, two office properties (6565 Arlington Boulevard and Woodholme Center) and undeveloped land at 4661 Kenmore Avenue. Subsequent to the end of 2013, we closed on Transaction III, consisting of Woodburn Medical Park I and II, and Transaction IV, consisting of Prosperity Medical Center I, II and III (see note 17).
	(2) The Industrial Portfolio consists of every property in our industrial segment and two office properties (the Crescent and Albemarle Point).
	We sold or classified as held for sale the following properties during the three years ended December 31, 2013:
	Property		Type		Rentable			Contract				Gain on Sale
					Square Feet			Sales Price				(in thousands)
					(unaudited)			(in thousands)
	Atrium Building		Office		79,000			$	15,750			$	3,195
	Medical Office Portfolio Transactions I & II		Medical Office / Office		1,093,000			307,189				18,949
	Medical Office Portfolio Transactions III & IV		Medical Office		427,000			193,561				N/A
			Total 2013		1,599,000			$	516,500			$	22,144
	1700 Research Boulevard		Office		101,000			$	14,250			$	3,724
	Plumtree Medical Center		Medical Office		33,000			8,750				1,400
			Total 2012		134,000			$	23,000			$	5,124
	Industrial Portfolio		Industrial/Office		3,092,000			$	350,900			$	97,491
	Dulles Station, Phase I		Office		180,000			58,800				—
			Total 2011		3,272,000			$	409,700			$	97,491
Disclosure of Long Lived Assets Held-for-sale	'
	As of December 31, 2013 and 2012, investment in real estate for properties sold or held for sale were as follows (in thousands):
		December 31,
		2013				2012
	Office	$	—			$	71,605
	Medical office	125,967				406,874
	Total	$	125,967			$	478,479
	Less accumulated depreciation	(46,066		)		(113,480		)
	Investment in real estate sold or held for sale, net	$	79,901			$	364,999
	As of December 31, 2013 and 2012, liabilities related to properties sold or held for sale were as follows (in thousands):
		December 31,
		2013				2012
	Mortgage notes payable	$	—			$	23,945
	Other liabilities	1,533				8,412
	Liabilities related to properties sold or held for sale	$	1,533			$	32,357
Operating Results of Properties Classified as Discontinued Operations	'
	Income from operations of properties sold or held for sale for the three years ended December 31, 2013 was as follows (in thousands):
		December 31,
		2013				2012				2011
	Revenues	$	45,791			$	54,344			$	80,948
	Property expenses	(17,039		)		(18,273		)		(25,265		)
	Real estate impairment	—				(2,097		)		(599		)
	Depreciation and amortization	(12,161		)		(18,827		)		(26,125		)
	Interest expense	(1,196		)		(4,331		)		(5,545		)
		$	15,395			$	10,816			$	23,414
Operating Income (Loss) By Property Classified As Discontinued Operations	'
	Income from operations of properties sold or held for sale by property for the three years ended December 31, 2013 was as follows (in thousands):
				Year Ending December 31,
	Property	Segment		2013				2012				2011
	Dulles Station, Phase I	Office		$	—			$	—			$	(468	)
	Industrial Portfolio	Industrial/Office		—				—				10,621
	1700 Research Boulevard	Office		—				225				651
	Plumtree Medical Center	Medical Office		—				197				67
	Atrium Building	Office		185				1,063				1,052
	Medical Office Portfolio	Medical/Office		15,210				9,331				11,491
				$	15,395			$	10,816			$	23,414

Mortgage_Notes_Payable_Tables

Mortgage Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2013
Notes Payable, Noncurrent [Abstract]	'
Schedule of Debt	'
	As of December 31, 2013 and 2012, we had outstanding mortgage notes payable, each collateralized by one or more buildings and related land from our portfolio, as follows (in thousands):
							December 31,
	Properties		Assumption/Issuance Date (1)		Effective Interest Rate (2)		2013		2012		Payoff Date/Maturity Date
	650 North Glebe Road (3), (4)		2/21/13		2.31	%	$	7,297	$	—	2/21/16
	John Marshall II		9/15/11		5.79	%	$	52,563	$	53,274	5/5/16
	Olney Village Center		8/30/11		4.94	%	20,743		22,343		10/1/23
	Kenmore Apartments		2/2/09		5.37	%	34,937		35,535		3/1/19
	2445 M Street (4)		12/2/08		7.25	%	98,102		96,848		1/6/17
	3801 Connecticut Avenue, Walker House and Bethesda Hill (5)		5/29/08		5.71	%	81,029		81,029		6/1/16
	Ashburn Farm Office Park (6)		6/1/07		5.56	%	—		2,313		11/21/13
	Ashburn Farm III Office Park (7)		6/1/07		5.69	%	—		2,024		11/21/13
	Woodholme Medical Office Center (8)		6/1/07		5.29	%	—		19,608		11/22/13
	West Gude Drive (9)		8/25/06		5.86	%	—		29,996		1/11/13
							$	294,671	$	342,970
	(1) Each of these mortgages was assumed with the acquisition of the collateralized properties, except for the mortgage notes secured by 3801 Connecticut Avenue, Walker House, Bethesda Hill, Kenmore Apartments, and the construction loan secured by the development project at 650 North Glebe Road, which were originally executed by WRIT. We record mortgages assumed in an acquisition at fair value, and balances presented include any recorded premiums or discounts.
	(2) Yield on the assumption/issuance date, including the effects of any premiums, discounts or fair value adjustments on the notes.
	(3) Interest rate on 650 North Glebe Road is variable, based on LIBOR plus 2.15%. The maturity date can be extended for up to two years, subject to fees and compliance with certain provisions in the loan agreement, until February 20, 2018.
	(4) Interest only is payable monthly until the maturity date upon which all unpaid principal and interest are payable in full.
	(5) Interest only is payable monthly until the maturity date, which can be extended for one year upon which the interest rate is reset on June 1, 2016. At maturity on June 1, 2017, all unpaid principal and interest are payable in full.
	(6) In November 2013, we extinguished the remaining $2.2 million of principal on the mortgage note secured by Ashburn Farm Office Park with extinguishment costs of $0.5 million.
	(7) In November 2013, we extinguished the remaining $1.9 million of principal on the mortgage note secured by Ashburn Farm III Office Park, with extinguishment costs of $0.4 million.
	(8) In November 2013, we extinguished the remaining $19.3 million of principal on the mortgage note secured by Woodholme Medical Office Center, with extinguishment costs of $1.8 million.
	(9) In January 2013, we extinguished without penalty the remaining $30.0 million of principal on the mortgage note secured by West Gude Drive.
	The mortgage notes secured by Ashburn Farm Office Park I and II and Woodholme Medical Office Building are included in "Other liabilities related to properties sold or held for sale" on our consolidated balance sheets as of December 31, 2012, as the properties were sold in 2013.
Schedule of Maturities of Long-term Debt	'
	Scheduled principal payments subsequent to December 31, 2013 are as follows (in thousands):
	2014	$	2,840
	2015	3,017
	2016	141,688
	2017	104,369
	2018	2,661
	Thereafter	42,625
		297,200
	Net discounts/premiums	(2,529		)
	Total	$	294,671
	The required principal payments excluding the effects of note discounts or premium for the remaining years subsequent to December 31, 2013 are as follows (in thousands):
	2014	$	100,000
	2015	150,000
	2016	—
	2017	—
	2018	—
	Thereafter	600,000
		$	850,000

Unsecured_Lines_Of_Credit_Paya1

Unsecured Lines Of Credit Payable (Tables)	12 Months Ended
	Dec. 31, 2013
Unsecured Debt [Abstract]	'
Lines Of Credit Unused And Available	'
	The amounts of these lines of credit unused and available at December 31, 2013 were as follows (in thousands):
		Credit Facility No. 1			Credit Facility No. 2
	Committed capacity	$	100,000		$	400,000
	Borrowings outstanding	—			—
	Letters of credit issued	—			—
	Unused and available	$	100,000		$	400,000
Repayments And Borrowings On Unsecured Lines Of Credit	'
	We executed borrowings and repayments on the unsecured lines of credit during 2013 as follows (in thousands):
		Credit Facility No. 1			Credit Facility No. 2
	Balance at December 31, 2012	$	—		$	—
	Borrowings	100,000			60,000
	Repayments	(100,000		)	(60,000		)
	Balance at December 31, 2013	$	—		$	—
Interest Expense, Line of Credit Facilities	'
	For the three years ended December 31, 2013, we recognized interest expense (excluding facility fees) as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Credit Facility No. 1	$	281		$	470		$	355
	Credit Facility No. 2	586			783			2,735
Facility Fees, Line of Credit	'
	For the three years ended December 31, 2013, we incurred facility fees as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Credit Facility No. 1	$	253		$	175		$	114
	Credit Facility No. 2	1,014			887			658
Schedule of Revolving Credit Facilities Covenant Compliance	'
	Information related to revolving credit facilities for the three years ended December 31, 2013 as follows (in thousands, except percentage amounts):
		Year Ended December 31,
		2013			2012			2011
	Total revolving credit facilities at December 31	$	500,000		$	500,000		$	475,000
	Borrowings outstanding at December 31	—			—			99,000
	Weighted average daily borrowings during the year	61,548			108,589			160,090
	Maximum daily borrowings during the year	135,000			242,000			281,000
	Weighted average interest rate during the year	1.41		%	1.15		%	1.9		%
	Weighted average interest rate on borrowings outstanding at December 31	N/A			N/A			0.9		%

Notes_Payable_Tables

Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2013
Notes Payable [Abstract]	'
Schedule of Long-term Debt Instruments	'
	Our unsecured notes outstanding as of December 31, 2013 were as follows (in thousands):
		Coupon/Stated Rate			Effective Rate (1)		Principal Amount			Maturity Date (2)
	10 Year Unsecured Notes	5.25	%		5.339	%	$	100,000		1/15/14
	10 Year Unsecured Notes	5.35	%		5.359	%	50,000			5/1/15
	10 Year Unsecured Notes	5.35	%		5.49	%	100,000			5/1/15
	10 Year Unsecured Notes	4.95	%		5.053	%	250,000			10/1/20
	10 Year Unsecured Notes	3.95	%		4.018	%	300,000			10/15/22
	30 Year Unsecured Notes	7.25	%		7.36	%	50,000			2/25/28
	Total principal						850,000
	Net unamortized discount						(3,297		)
	Total						$	846,703
	(1) Yield on issuance date, including the effects of discounts on the notes.
	(2) No principal amounts are due prior to maturity.
Schedule of Maturities of Long-term Debt	'
	Scheduled principal payments subsequent to December 31, 2013 are as follows (in thousands):
	2014	$	2,840
	2015	3,017
	2016	141,688
	2017	104,369
	2018	2,661
	Thereafter	42,625
		297,200
	Net discounts/premiums	(2,529		)
	Total	$	294,671
	The required principal payments excluding the effects of note discounts or premium for the remaining years subsequent to December 31, 2013 are as follows (in thousands):
	2014	$	100,000
	2015	150,000
	2016	—
	2017	—
	2018	—
	Thereafter	600,000
		$	850,000

Stock_Based_Compensation_Table

Stock Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2013
Share-based Compensation [Abstract]	'
Schedule Of Stock-Based Compensation Expense	'
	Total compensation expense recognized in the consolidated financial statements for the three years ended December 31, 2013 for all share based awards, was as follows (in thousands):
		Year Ended December 31,
		2013			2012			2011
	Stock-based compensation expense	$	6,246		$	5,856		$	5,597
Schedule of Restricted Share Awards [Table Text Block]	'
	Restricted Share Awards
	The activity for the three years ended December 31, 2013 related to our restricted share awards, excluding those subject to market conditions, was as follows:
		Year Ended December 31,
		2013					2012							2011
		Shares		Wtd Avg Grant Fair Value			Shares			Wtd Avg Grant Fair Value				Shares		Wtd Avg Grant Fair Value
	Vested at January 1	864,288		$	29.65		652,803			$	30.06			490,832		$	30.2
	Unvested at January 1	149,803		27.37			331,003			28.39				193,339		27.71
	Granted	141,609		26.3			36,884			26.4				303,168		29.48
	Vested during year	(158,657	)	26.66			(211,485	)		28.39				(161,971	)	29.8
	Forfeited	(2,940	)	27.8			(6,599	)		27.61				(3,533	)	28.1
	Unvested at December 31	129,815		27.06			149,803			27.37				331,003		28.39
	Vested at December 31	1,022,945		29.19			864,288			29.65				652,803		30.06
Fair Value of Share Grants Vested	'
	The total fair value of share grants vested for the years ended December 31, 2013, 2012 and 2011 was $3.8 million, $5.6 million and $4.9 million, respectively.
Performance Share Units with Market Conditions [Table Text Block]	'
	Stock based awards with market conditions under the LTIP were granted in February 2011 with fair market values, as determined using a Monte Carlo simulation, as follows (in thousands):
		Grant Date Fair Value
		Restricted			Unrestricted
	Relative TSR	$	1,066		$	1,066
	Absolute TSR	365			365
Schedule Of Unamortized Value Of Awards With Market Conditions [Table Text Block]	'
	The unamortized value of these awards with market conditions as of December 31, 2013 and 2012 was as follows (in thousands):
		December 31,
		2013						2012
		Restricted			Unrestricted			Restricted				Unrestricted
	Relative TSR	$	162		$	—		$	501			$	338
	Absolute TSR	55			—			172				116
Schedule of Share-based Compensation, Stock Options, Activity	'
	The previously issued and currently outstanding and exercisable stock options for the three years ended December 31, 2013 was as follows:
		Year Ended December 31,
		2013					2012							2011
		Shares		Wtd Avg			Shares			Wtd Avg				Shares		Wtd Avg
				Ex Price						Ex Price						Ex Price
	Outstanding at January 1	38,119		$	30.48		89,106			$	27.69			145,950		$	26.74
	Granted	—		—			—			—				—		—
	Exercised	—		—			(44,987	)		25.61				(51,081	)	25.29
	Expired/Forfeited	(28,119	)	29.55			(6,000	)		25.61				(5,763	)	24.85
	Outstanding at December 31	10,000		33.09			38,119			30.48				89,106		27.69
	Exercisable at December 31	10,000		33.09			38,119			30.48				89,106		27.69

Other_Benefit_Plans_Tables

Other Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2013
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]	'
Schedule of 401 (k) Employer Contributions	'
	For the three years ended December 31, 2013, we made contributions to the 401(k) plan as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	401(k) plan contributions	$	428	$	467	$	529
Schedule of Deferred Compensation Liability	'
	The deferred compensation liability at December 31, 2013 and 2012 was as follows (in thousands):
		December 31,
		2013		2012
	Deferred compensation liability	$	1,437	$	1,314
Schedule of Current Service Cost, Prior Executive	'
	For the three years ended December 31, 2013, we recognized current service cost as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Former CEO SERP current service cost	$	99	$	106	$	113
Schedule of Current Service Cost, Current Officers	'
	For the three years ended December 31, 2013, we recognized current service cost as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Officer SERP current service cost	$	325	$	342	$	334

Fair_Value_Disclosures_Tables

Fair Value Disclosures (Tables)	12 Months Ended
	Dec. 31, 2013
Fair Value Disclosures [Abstract]	'
Financial Assets And Liabilities Measured At Fair Value	'
	The fair values of these assets at December 31, 2013 and 2012 were as follows (in thousands):
		December 31, 2013								December 31, 2012
		Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs		Significant Unobservable Inputs		Fair Value		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
						(Level 2)		(Level 3)				(Level 1)		(Level 2)		(Level 3)
	Assets:
	SERP	$	3,290	$	—	$	3,290	$	—	$	2,421	$	—	$	2,421	$	—
Financial Assets And Liabilities Not Measured At Fair Value	'
	As of December 31, 2013 and 2012, the carrying values and estimated fair values of our financial instruments were as follows (in thousands):
		December 31,
		2013				2012
		Carrying		Fair Value		Carrying		Fair Value
		Value				Value
	Cash and cash equivalents(1)	$	130,343	$	130,343	$	19,324	$	19,324
	Restricted cash(1)	9,189		9,189		14,582		14,582
	2445 M Street note receivable	6,070		6,803		6,617		6,654
	Mortgage notes payable (1)	294,671		313,476		342,970		374,591
	Notes payable	846,703		856,171		906,190		968,040

Earnings_Per_Common_Share_Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Computation Of Basic And Diluted Earnings Per Share	'
	The computation of basic and diluted earnings per share for the three years ended December 31, 2013 was as follows (in thousands; except per share data):
		Year Ended December 31,
		2013			2012			2011
	Numerator:
	(Loss) income from continuing operations	$	(193	)	$	7,768		$	(14,389	)
	Allocation of undistributed earnings to unvested restricted share awards and units to continuing operations	—			(191		)	—
	Adjusted (loss) income from continuing operations attributable to the controlling interests	(193		)	7,577			(14,389		)
	Income from discontinued operations, including gain on sale of real estate, net of taxes	37,539			15,940			119,767
	Net income attributable to noncontrolling interests	—			—			(494		)
	Allocation of undistributed earnings to unvested restricted share awards and units to discontinued operations	(415		)	(391		)	(712		)
	Adjusted income from discontinued operations attributable to the controlling interests	37,124			15,549			118,561
	Adjusted net income attributable to the controlling interests	$	36,931		$	23,126		$	104,172
	Denominator:
	Weighted average shares outstanding – basic	66,580			66,239			65,982
	Effect of dilutive securities:
	Employee stock options and restricted share awards	—			137			—
	Weighted average shares outstanding – diluted	66,580			66,376			65,982
	Earnings per common share, basic:
	Continuing operations	$	—		$	0.11		$	(0.22	)
	Discontinued operations	0.55			0.24			1.8
		$	0.55		$	0.35		$	1.58
	Earnings per common share, diluted:
	Continuing operations	$	—		$	0.11		$	(0.22	)
	Discontinued operations	0.55			0.24			1.8
		$	0.55		$	0.35		$	1.58

Rentals_Under_Operating_Leases1

Rentals Under Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2013
Rentals Under Operating Leases [Abstract]	'
Schedule of Future Minimum Rental Payments for Operating Leases	'
	non-cancelable commercial operating leases provide for minimum rental income from continuing operations were as follows (in thousands):
	2014	$	177,776
	2015	155,154
	2016	131,374
	2017	111,883
	2018	91,966
	Thereafter	259,546
		$	927,699
Percentage Rents From Retail Centers	'
	Percentage rents from retail centers, based on a percentage of tenants’ gross sales, for the three years ended December 31, 2013 were as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Percentage rents	$	123	$	150	$	193
Reimbursement Income	'
	Real estate tax, operating expense and common area maintenance reimbursement income from continuing operations for the three years ended December 31, 2013 was as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Reimbursement income	$	26,822	$	25,528	$	21,877

Segment_Information_Tables

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2013
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'
Real Estate Rental Revenue, Percent	'
	Real estate rental revenue as a percentage of the total for each of the reportable operating segments in continuing operations for the three years ended December 31, 2013 was as follows:
		Year Ended December 31,
		2013		2012			2011
	Office	58	%	58	%		57	%
	Retail	21	%	21	%		21	%
	Multifamily	21	%	21	%		22	%
Percentage of Real Estate Assets by Segment	'
	The percentage of total income producing real estate assets, at cost, for each of the reportable operating segments in continuing operations as of December 31, 2013 and 2012 was as follows:
		December 31,
		2013		2012
	Office	62	%	63	%
	Retail	20	%	20	%
	Multifamily	18	%	17	%
Reconciliation Of Net Operating Income Of Reportable Segments	'
	The following tables present revenues, net operating income, capital expenditures and total assets for the three years ended December 31, 2013 from these segments, and reconciles net operating income of reportable segments to net income attributable to the controlling interests as reported (in thousands):
		Year Ended December 31, 2013
		Office			Medical				Retail		Multifamily		Corporate			Consolidated
					Office								and Other
	Real estate rental revenue	$	152,339		$	—			$	56,189	$	54,496	$	—		$	263,024
	Real estate expenses	57,293			—				13,768		22,232		—			93,293
	Net operating income	$	95,046		$	—			$	42,421	$	32,264	$	—		$	169,731
	Depreciation and amortization															(85,740		)
	General and administrative															(17,535		)
	Acquisition costs															(1,265		)
	Interest expense															(63,573		)
	Other income															926
	Gain (loss) on extinguishment of debt															(2,737		)
	Discontinued operations:
	Income from properties sold or held for sale															15,395
	Gain on sale of real estate															22,144
	Net income															37,346
	Less: Net income attributable to noncontrolling interests															—
	Net income attributable to the controlling interests															$	37,346
	Capital expenditures	$	37,777		$	3,695			$	4,204	$	10,153	$	162		$	55,991
	Total assets	$	1,073,302		$	84,001			$	344,207	$	309,117	$	164,866		$	1,975,493
		Year Ended December 31, 2012
		Office			Medical				Retail		Multifamily			Corporate			Consolidated
					Office									and Other
	Real estate rental revenue	$	147,401		$	—			$	54,506	$	52,887		$	—		$	254,794
	Real estate expenses	53,376			—				12,702		20,467			—			86,545
	Net operating income	$	94,025		$	—			$	41,804	$	32,420		$	—		$	168,249
	Depreciation and amortization																(85,107		)
	General and administrative																(15,488		)
	Acquisition costs																(234		)
	Interest expense																(60,627		)
	Other income																975
	Discontinued operations:
	Income from properties sold or held for sale																10,816
	Gain on sale of real estate																5,124
	Net income																23,708
	Less: Net income attributable to noncontrolling interests																—
	Net income attributable to the controlling interests																$	23,708
	Capital expenditures	$	35,330		$	7,004			$	2,977	$	5,869		$	555		$	51,735
	Total assets	$	1,140,046		$	327,573			$	355,585	$	249,503		$	51,669		$	2,124,376
		Year Ended December 31, 2011
		Office			Medical				Retail		Multifamily		Industrial/Flex			Corporate				Consolidated
					Office											and Other
	Real estate rental revenue	$	133,333		$	—			$	50,421	$	50,979	$	—		$	—			$	234,733
	Real estate expenses	45,634			—				14,273		19,717		—			—				79,624
	Net operating income	$	87,699		$	—			$	36,148	$	31,262	$	—		$	—			$	155,109
	Depreciation and amortization																			(74,403		)
	General and administrative																			(15,728		)
	Real estate impairment																			(14,526		)
	Acquisition costs																			(3,607		)
	Interest expense																			(61,402		)
	Other income																			1,144
	Loss on extinguishment of debt																			(976		)
	Discontinued operations:
	Income from properties sold or held for sale																			23,414
	Gain on sale of real estate																			97,491
	Income tax expense																			(1,138		)
	Net income																			105,378
	Less: Net income attributable to noncontrolling interests																			(494		)
	Net income attributable to the controlling interests																			$	104,884
	Capital expenditures	$	21,065		$	5,654			$	2,922	$	2,823	$	351		$	621			$	33,436
	Total assets	$	1,118,074		$	347,735			$	365,164	$	247,170	$	—		$	42,615			$	2,120,758

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Schedule of Quarterly Financial Information	'
	financial data by quarter for each of the three months in the years ended December 31, 2013 and 2012 were as follows (in thousands, except for per share data):
		Quarter(1)(2)
		First		Second		Third		Fourth
	2013
	Real estate rental revenue	$	64,560	$	65,915	$	65,828	$	66,721
	Income (loss) from continuing operations	$	857	$	1,538	$	1,709	$	(4,297	)
	Effect of disposal of medical office segment on net income	$	2,821	$	3,439	$	3,820	$	3,964
	Net income	$	7,335	$	5,263	$	5,840	$	18,908
	Net income attributable to the controlling interests	$	7,335	$	5,263	$	5,840	$	18,908
	Income (loss) from continuing operations per share
	Basic	$	0.01	$	0.02	$	0.03	$	(0.06	)
	Diluted	$	0.01	$	0.02	$	0.03	$	(0.06	)
	Net income per share
	Basic	$	0.11	$	0.08	$	0.09	$	0.28
	Diluted	$	0.11	$	0.08	$	0.09	$	0.28
	2012
	Real estate rental revenue	$	62,590	$	63,073	$	64,471	$	64,660
	Income from continuing operations	$	1,852	$	2,928	$	2,604	$	384
	Effect of disposal of medical office segment on net income	$	2,623	$	2,370	$	2,462	$	673
	Net income	$	5,181	$	6,008	$	9,561	$	2,958		(3)
	Net income attributable to the controlling interests	$	5,181	$	6,008	$	9,561	$	2,958
	Income from continuing operations per share
	Basic	$	0.03	$	0.04	$	0.04	$	0.01
	Diluted	$	0.03	$	0.04	$	0.04	$	0.01
	Net income per share
	Basic	$	0.08	$	0.09	$	0.14	$	0.04
	Diluted	$	0.08	$	0.09	$	0.14	$	0.04
	(1)	With regard to per share calculations, the sum of the quarterly results may not equal full year results due to rounding.
	(2)	The prior quarter results have been restated to conform to the current quarter presentation. Specifically, results related to properties sold or held for sale have been reclassified into discontinued operations.
	(3)	The three months ended December 31, 2012 includes the impact of real estate impairment of $2.1 million.

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2013
Stockholders' Equity Note [Abstract]	'
Common Stock Offering Program	'
Dividend Reinvestment Program	'
	We executed issuances under this program for the three years ended December 31, 2013 as follows (in thousands, except for weighted average issue price):
		Year Ended December 31,
		2013		2012		2011
	Common shares issued	—		55		170
	Weighted average issue price	$	—	$	29.67	$	29.97
	Net proceeds	$	—	$	1,315	$	5,041

Deferred_Costs_Tables

Deferred Costs (Tables)	12 Months Ended
	Dec. 31, 2013
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]	'
Schedule of Deferred Cost	'
	As of December 31, 2013 and 2012 deferred costs were included in prepaid expenses and other assets as follows (in thousands):
		December 31,
		2013						2012
		Gross Carrying		Accumulated		Net		Gross Carrying		Accumulated		Net
		Value		Amortization				Value		Amortization
	Deferred financing costs	$	17,842	$	8,950	$	8,892	$	18,761	$	8,162	$	10,599
	Deferred leasing costs	39,642		14,788		24,854		31,872		13,756		18,116
	Deferred leasing incentives	7,143		2,417		4,726		5,847		1,448		4,399
	NOTE 16: DEFERRED COSTS
	As of December 31, 2013 and 2012 deferred costs were included in prepaid expenses and other assets as follows (in thousands):
		December 31,
		2013						2012
		Gross Carrying		Accumulated		Net		Gross Carrying		Accumulated		Net
		Value		Amortization				Value		Amortization
	Deferred financing costs	$	17,842	$	8,950	$	8,892	$	18,761	$	8,162	$	10,599
	Deferred leasing costs	39,642		14,788		24,854		31,872		13,756		18,116
	Deferred leasing incentives	7,143		2,417		4,726		5,847		1,448		4,399
	Amortization and write-offs of deferred financing, leasing and leasing incentives costs from continuing operations for the three years ended December 31, 2013 were as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Deferred financing costs amortization	$	2,550	$	2,411	$	2,194
	Deferred leasing costs amortization	4,279		3,635		3,827
	Deferred leasing incentives amortization	980		675		556
Schedule of Amortization and Write-Offs of Deferred Financing, Leasing, and Leasing Incentive Costs	'
	Amortization and write-offs of deferred financing, leasing and leasing incentives costs from continuing operations for the three years ended December 31, 2013 were as follows (in thousands):
		Year Ended December 31,
		2013		2012		2011
	Deferred financing costs amortization	$	2,550	$	2,411	$	2,194
	Deferred leasing costs amortization	4,279		3,635		3,827
	Deferred leasing incentives amortization	980		675		556

Nature_Of_Business_Details

Nature Of Business (Details) (USD $)

3 Months Ended

12 Months Ended

0 Months Ended

2 Months Ended

0 Months Ended

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Aug. 31, 2012

Dec. 20, 2012

Apr. 05, 2011

Nov. 02, 2011

Dec. 31, 2013

Dec. 31, 2012

Mar. 19, 2013

Aug. 05, 2011

Research Boulevard 1700 [Member]

Plumtree Medical Center [Member]

Dulles Station, Phase I [Member]

Industrial Portfolio [Member]

Taxable Reit Subsidiary [Member]

Taxable Reit Subsidiary [Member]

Office Building [Member]

Office Building [Member]

Atrium Building [Member]

Industrial Portfolio [Member]

properties

Nature of Business [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of Distribution of Ordinary Taxable Income

'

'

90.00%

'

'

'

'

'

'

'

'

'

'

Gain on sale of properties

'

'

$22,144,000

$5,124,000

$97,491,000

$3,724,000

$1,400,000

$0

$97,491,000

[1]

'

'

$3,195,000

'

Number of real estate properties

'

'

'

'

'

'

'

'

'

'

'

'

2

Federal and state income tax liabilities recognized

'

'

0

0

1,138,000

'

'

'

'

'

'

'

'

Real estate impairment

2,097,000

14,526,000

0

0

14,526,000

'

'

'

'

'

'

'

'

Deferred Tax Assets

'

'

5,700,000

'

'

'

'

'

'

'

'

'

'

Deferred Tax Assets, Net

'

'

'

'

'

'

'

'

'

0

0

'

'

Deferred Tax Liabilities

'

'

'

'

'

'

'

'

'

$600,000

$600,000

'

'

Ordinary income

'

'

62.00%

72.00%

60.00%

'

'

'

'

'

'

'

'

Return of capital

'

'

38.00%

26.00%

17.00%

'

'

'

'

'

'

'

'

Qualified dividends

'

'

0.00%

0.00%

5.00%

'

'

'

'

'

'

'

'

Unrecaptured Section 1250 gain

'

'

0.00%

2.00%

13.00%

'

'

'

'

'

'

'

'

Capital gain

'

'

0.00%

0.00%

5.00%

'

'

'

'

'

'

'

'

[1]

The Industrial Portfolio consists of every property in our industrial segment and two office properties (the Crescent and Albemarle Point).

Nature_Of_Business_Schedule_of

Nature Of Business Schedule of Dispositions (Details) (USD $)	12 Months Ended			0 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Nov. 22, 2013
				Medical Office And Office Building [Member]
				Medical Office Porfolio [Member]
schedule of dispositions [Line Items]	'	'	'	'
Gain (Loss) on Sale of Properties	$22,144	$5,124	$97,491	$18,949	[1]
[1]	2440 M Street, 15001 Shady Grove Road, 15505 Shady Grove Road, 19500 at Riverside Park (formerly Lansdowne Medical Office Building), 9707 Medical Center Drive, CentreMed I and II, 8301 Arlington Boulevard, Sterling Medical Office Building, Shady Grove Medical Village II, Alexandria Professional Center, Ashburn Farm Office Park I, Ashburn Farm Office Park II, Ashburn Farm Office Park III, Woodholme Medical Office Building, two office properties (6565 Arlington Boulevard and Woodholme Center) and undeveloped land at 4661 Kenmore Avenue. Subsequent to the end of 2013, we closed on Transaction III, consisting of Woodburn Medical Park I and II, and Transaction IV, consisting of Prosperity Medical Center I, II and III (see note 17).

Accounting_Policies_Revenue_Re

Accounting Policies - Revenue Recognition and Accounts Receivable and Allowance (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Accounting Policies [Abstract]	'	'
Notes receivable, net	$6.20	$6.90

Accounting_Policies_Real_Estat

Accounting Policies - Real Estate and Depreciation (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]	'	'	'
Operating Lease Term, Average, Minimum	'3 years	'	'
Real estate depreciation	$63,400,000	$61,100,000	$55,100,000
Total interest expense from continuing operations	64,809,000	62,315,000	62,140,000
Capitalized interest	1,236,000	1,688,000	738,000
Interest expense, net of capitalized interest	$63,573,000	$60,627,000	$61,402,000
Operating Lease Term, Average, Maximum	'5 years	'	'
Minimum [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Useful Life	'3 years	'	'
Minimum [Member] | Building [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Useful Life	'28 years	'	'
Minimum [Member] | Building and Building Improvements [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Useful Life	'3 years	'	'
Maximum [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Useful Life	'50 years	'	'
Maximum [Member] | Building [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Useful Life	'50 years	'	'
Maximum [Member] | Building and Building Improvements [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Useful Life	'30 years	'	'

Accounting_Policies_Fair_value

Accounting Policies Fair value of in place leases (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Tenant Origination Costs Member	'	'
Acquired Finite-Lived Intangible Assets [Line Items]	'	'
Finite-lived Intangible Liabilities, Net Lease, Gross	$47,697	$48,172
Finite-lived Intangible Liabilities, Net Lease, Accumulated Amortization	29,653	23,719
Finite-lived Intangible Liabilities, Net Lease, Net	18,044	24,453
Leasing Commissions Absorption Costs Member	'	'
Acquired Finite-Lived Intangible Assets [Line Items]	'	'
Finite-lived Intangible Liabilities, Net Lease, Gross	78,629	78,464
Finite-lived Intangible Liabilities, Net Lease, Accumulated Amortization	48,376	37,672
Finite-lived Intangible Liabilities, Net Lease, Net	30,253	40,792
Net Lease Intangible Assets Member	'	'
Acquired Finite-Lived Intangible Assets [Line Items]	'	'
Finite-lived Intangible Liabilities, Net Lease, Gross	12,495	12,430
Finite-lived Intangible Liabilities, Net Lease, Accumulated Amortization	7,008	5,350
Finite-lived Intangible Liabilities, Net Lease, Net	5,487	7,080
Net Lease Intangible Liabilities Member	'	'
Acquired Finite-Lived Intangible Assets [Line Items]	'	'
Finite-lived Intangible Liabilities, Net Lease, Gross	26,348	26,244
Finite-lived Intangible Liabilities, Net Lease, Accumulated Amortization	19,403	17,089
Finite-lived Intangible Liabilities, Net Lease, Net	6,945	9,155
Leases, Acquired-in-Place, Below-Market Ground Lease [Member]	'	'
Acquired Finite-Lived Intangible Assets [Line Items]	'	'
Finite-lived Intangible Liabilities, Net Lease, Gross	12,080	12,080
Finite-lived Intangible Liabilities, Net Lease, Accumulated Amortization	1,145	956
Finite-lived Intangible Liabilities, Net Lease, Net	$10,935	$11,124

Accounting_Policies_amortizati

Accounting Policies amortization of leased assets (Details) (Leases, Acquired-in-Place [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Leases, Acquired-in-Place [Member]	'	'	'
Acquired Indefinite-lived Intangible Assets [Line Items]	'	'	'
Amortization of Leased Asset	$17,290	$19,573	$13,704

Accounting_Policies_Acquired_f

Accounting Policies Acquired finite-lived intangible assets (Details) (Leases, Acquired-in-Place [Member], USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Leases, Acquired-in-Place [Member]	'
Impaired Intangible Assets [Line Item]	'
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$14,675
Finite-Lived Intangible Assets, Amortization Expense, Year Two	11,886
Finite-Lived Intangible Assets, Amortization Expense, Year Three	8,957
Finite-Lived Intangible Assets, Amortization Expense, Year Four	5,830
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$3,333

Accounting_Policies_Reclassfic

Accounting Policies Reclassfications (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012
Accounting Policies [Abstract]	'
Payments for (Proceeds from) Deposits on Real Estate Acquisitions	($250)

Real_Estate_Investments_Contin

Real Estate Investments - Continuing Operations (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Real Estate Properties [Line Items]	'	'	'
Real estate investment property, at cost	$2,102,227	$2,005,383	$385,400
Properties under development or held for future development	61,315	45,270	'
Office [Member]	'	'	'
Real Estate Properties [Line Items]	'	'	'
Properties under development or held for future development	12,175	8,922	'
Retail [Member]	'	'	'
Real Estate Properties [Line Items]	'	'	'
Properties under development or held for future development	495	587	'
Multifamily [Member]	'	'	'
Real Estate Properties [Line Items]	'	'	'
Properties under development or held for future development	48,645	35,761	'
Office [Member]	'	'	'
Real Estate Properties [Line Items]	'	'	'
Real estate investment property, at cost	1,296,967	1,261,534	'
Retail [Member]	'	'	'
Real Estate Properties [Line Items]	'	'	'
Real estate investment property, at cost	415,899	411,948	'
Multifamily [Member]	'	'	'
Real Estate Properties [Line Items]	'	'	'
Real estate investment property, at cost	$389,361	$331,901	'

Real_Estate_Investments_Acquis

Real Estate Investments - Acquistions (Details) (USD $)

3 Months Ended

12 Months Ended

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2011

Mar. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

note

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Real Estate, Type of Property, Multifamily

'

'

'

'

'

'

'

'

'Multifamily

'

'

Contract Purchase Price

$2,102,227,000

'

'

'

$2,005,383,000

'

'

'

$2,102,227,000

$2,005,383,000

$385,400,000

Real estate rental revenue

66,721,000

65,828,000

65,915,000

[1],[2]

64,560,000

[1],[2]

64,660,000

[1],[2]

64,471,000

[1],[2]

63,073,000

[1],[2]

62,590,000

[1],[2]

263,024,000

254,794,000

234,733,000

Land

'

'

'

'

'

'

'

'

8,568,000

17,750,000

90,896,000

Buildings

'

'

'

'

'

'

'

'

37,930,000

26,893,000

219,613,000

Tenant origination costs

32,000

'

'

'

3,100,000

'

'

'

32,000

3,100,000

15,667,000

Leasing commissions/absorption costs

943,000

'

'

'

4,172,000

'

'

'

943,000

4,172,000

29,719,000

Net lease intangible assets

102,000

'

'

'

508,000

'

'

'

102,000

508,000

6,805,000

Net lease intangible liabilities

-117,000

'

'

'

-173,000

'

'

'

-117,000

-173,000

-2,454,000

Fair value of assumed mortgage

0

'

'

'

0

'

'

'

0

0

-78,500,000

Furniture, fixtures & equipment

742,000

'

'

'

0

'

'

'

742,000

0

0

Total property purchase price

'

'

'

'

'

'

'

'

48,200,000

52,250,000

281,746,000

Payments to Acquire Real Estate

'

'

'

'

'

'

'

'

48,200,000

[3]

52,142,000

[3]

281,701,000

[3]

Number of Mortgage Notes Assumed

'

'

'

'

'

'

'

'

'

'

2

Notes Assumed

'

'

'

'

'

'

'

'

'

'

76,700,000

Credits received at settlement

'

'

'

'

'

'

'

'

'

100,000

1,300,000

The Paramount [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

1-Oct-13

[4]

'

'

Fairgate at Ballston [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

1-Jun-12

'

'

1140 Connecticut Avenue [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

1-Jan-11

'

'

1227 25th Street [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

1-Mar-11

'

'

Six Fifty North Glebe Road [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

1-Jun-11

[5]

'

'

Cash paid for acquisitions

'

'

'

'

'

'

'

'

'

'

11,800,000

Olney Village Center Member

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

1-Aug-11

[4]

'

'

Braddock Place Member

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

1-Sep-11

'

'

John Marshall II Member

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

1-Sep-11

'

'

1225 First Street [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Cash paid for acquisitions

'

'

'

'

'

'

'

'

'

'

13,900,000

Property Acquired [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Rentable Square Feet

'

'

'

'

'

'

'

'

'

142,000

1,092,000

Contract Purchase Price

48,200,000

'

'

'

52,250,000

'

'

'

48,200,000

52,250,000

385,400,000

Real estate rental revenue

'

'

'

'

'

'

'

'

907,000

3,358,000

20,944,000

Net (loss) income

'

'

'

'

'

'

'

'

-105,000

325,000

484,000

Property Acquired [Member] | The Paramount [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

1-Oct-13

'

'

Contract Purchase Price

48,200,000

'

'

'

'

'

'

'

48,200,000

'

'

Property Acquired [Member] | Fairgate at Ballston [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

'

21-Jun-12

'

Real Estate, Type of Property, Office

'

'

'

'

'

'

'

'

'

'Office

'

Rentable Square Feet

'

'

'

'

'

'

'

'

'

142,000

'

Contract Purchase Price

'

'

'

'

52,250,000

'

'

'

'

52,250,000

'

Property Acquired [Member] | 1140 Connecticut Avenue [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

'

'

11-Jan-11

Real Estate, Type of Property, Office

'

'

'

'

'

'

'

'

'

'

'Office

Rentable Square Feet

'

'

'

'

'

'

'

'

'

'

188,000

Contract Purchase Price

'

'

'

'

'

'

'

'

'

'

80,250,000

Property Acquired [Member] | 1227 25th Street [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

'

'

30-Mar-11

Real Estate, Type of Property, Office

'

'

'

'

'

'

'

'

'

'

'Office

Rentable Square Feet

'

'

'

'

'

'

'

'

'

'

132,000

Contract Purchase Price

'

'

'

'

'

'

'

'

'

'

47,000,000

Property Acquired [Member] | Six Fifty North Glebe Road [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

'

'

15-Jun-11

[6]

Real Estate, Type of Property, Multifamily

'

'

'

'

'

'

'

'

'

'

'Mutifamily

[6]

Contract Purchase Price

'

'

'

'

'

'

'

'

'

'

11,800,000

[6]

Property Acquired [Member] | Olney Village Center Member

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

'

'

30-Aug-11

Real Estate, Type of Property, Retail

'

'

'

'

'

'

'

'

'

'

'Retail

Rentable Square Feet

'

'

'

'

'

'

'

'

'

'

198,000

Contract Purchase Price

'

'

'

'

'

'

'

'

'

'

58,000,000

Property Acquired [Member] | Braddock Place Member

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

'

'

13-Sep-11

Real Estate, Type of Property, Office

'

'

'

'

'

'

'

'

'

'

'Office

Rentable Square Feet

'

'

'

'

'

'

'

'

'

'

351,000

Contract Purchase Price

'

'

'

'

'

'

'

'

'

'

101,000,000

Property Acquired [Member] | John Marshall II Member

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

'

'

15-Sep-11

Real Estate, Type of Property, Office

'

'

'

'

'

'

'

'

'

'

'Office

Rentable Square Feet

'

'

'

'

'

'

'

'

'

'

223,000

Contract Purchase Price

'

'

'

'

'

'

'

'

'

'

73,500,000

Property Acquired [Member] | 1225 First Street [Member]

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Acquisition Date

'

'

'

'

'

'

'

'

'

'

23-Nov-11

[6]

Real Estate, Type of Property, Multifamily

'

'

'

'

'

'

'

'

'

'

'Mutifamily

[6]

Contract Purchase Price

'

'

'

'

'

'

'

'

'

'

$13,850,000

[6]

Tenant Origination Costs Member

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Weighted remaining average life, in months

'

'

'

'

'

'

'

'

'110 months

'

'

Leasing Commissions Absorption Costs Member

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Weighted remaining average life, in months

'

'

'

'

'

'

'

'

'22 months

'

'

Net Lease Intangible Assets Member

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Weighted remaining average life, in months

'

'

'

'

'

'

'

'

'81 months

'

'

Net Lease Intangible Liabilities Member

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Weighted remaining average life, in months

'

'

'

'

'

'

'

'

'88 months

'

'

[1]

With regard to per share calculations, the sum of the quarterly results may not equal full year results due to rounding.

[2]

The prior quarter results have been restated to conform to the current quarter presentation. Specifically, results related to properties sold or held for sale have been reclassified into discontinued operations.

[3]

See note 3 to the consolidated financial statements for the supplemental disclosure of non-cash investing and financing activities, including the assumption of mortgage debt in conjunction with some of our real estate acquisitions.

[4]

At December 31, 2013, our properties were encumbered by non-recourse mortgage amounts as follows: $35.4 million on 3801 Connecticut Avenue, $16.5 million on Walker House, $29.1 million on Bethesda Hill, $34.9 million on The Kenmore, $98.1 million on 2445 M Street, $52.6 million on John Marshall II, and $20.7 million on Olney Village Center.

[5]

As of December 31, 2013, WRIT had under development via joint venture arrangements, a mid-rise multifamily property in Arlington, Virginia (650 North Glebe) and a high-rise multifamily property in Alexandria, Virginia (1225 First Street). The value not yet placed into service of these development projects via joint venture arrangements at December 31, 2013 was $48.1 million. 650 North Glebe was encumbered by a construction loan with a $7.3 million balance at December 31, 2013.

[6]

Land for development. 650 North Glebe Road is currently under development and development has been suspended at 1225 First Street.

Real_Estate_Investments_Noncon

Real Estate Investments - Noncontrolling Interests in Subsidiaries and VIEs (Details) (USD $)

12 Months Ended

6 Months Ended

1 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Aug. 31, 2007

Jun. 30, 2011

Dec. 31, 2013

Feb. 21, 2013

Dec. 31, 2012

Nov. 30, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

4661 Kenmore Avenue [Member]

Six Fifty North Glebe Road [Member]

Six Fifty North Glebe Road [Member]

Six Fifty North Glebe Road [Member]

Six Fifty North Glebe Road [Member]

1225 First Street [Member]

1225 First Street [Member]

1225 First Street [Member]

Minimum [Member]

Maximum [Member]

acre

Real Estate Properties [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Land, Acres Held

'

'

'

0.8

'

'

'

'

'

'

'

'

'

Gain on sale of properties

$22,144,000

$5,124,000

$97,491,000

'

'

'

'

'

'

'

'

'

'

Estimated development costs

'

'

'

'

49,900,000

'

'

'

95,300,000

'

'

'

'

Percentage of capital contribution through debt

70.00%

'

'

'

'

'

'

'

70.00%

'

'

'

'

Ownership percentage

'

'

'

'

90.00%

'

'

'

95.00%

'

'

90.00%

95.00%

Percentage Of residential property to be leased to achieve project stabilization stage

'

'

'

'

90.00%

'

'

'

'

'

'

'

'

Ownership percentage by noncontrolling owners

'

'

'

'

10.00%

'

'

'

5.00%

'

'

'

'

Land and capitalized development costs

'

'

'

'

'

27,343,000

'

15,646,000

'

20,788,000

19,807,000

'

'

Accounts payable and accrued liabilities

51,742,000

50,094,000

'

'

'

1,785,000

'

115,000

'

39,000

1,676,000

'

'

Construction loan agreement

'

'

'

'

'

'

$33,000,000

'

'

'

'

'

'

Real_Estate_Investments_Discon

Real Estate Investments - Discontinued Operations (Details) (USD $)

3 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

2 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

0 Months Ended

0 Months Ended

1 Months Ended

0 Months Ended

0 Months Ended

2 Months Ended

In Thousands, except Per Share data, unless otherwise specified

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Aug. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 20, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Nov. 02, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Apr. 05, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Sep. 30, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Nov. 22, 2013

Dec. 31, 2013

Dec. 31, 2012

Aug. 31, 2012

Apr. 05, 2011

Sep. 30, 2013

Mar. 19, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 20, 2012

Nov. 02, 2011

Sep. 02, 2011

Jan. 21, 2014

sqft

sqft

sqft

sqft

sqft

Atrium Building [Member]

Atrium Building [Member]

Atrium Building [Member]

Medical Office Porfolio [Member]

Medical Office Porfolio [Member]

Medical Office Porfolio [Member]

Research Boulevard 1700 [Member]

Research Boulevard 1700 [Member]

Research Boulevard 1700 [Member]

Research Boulevard 1700 [Member]

Plumtree Medical Center [Member]

Plumtree Medical Center [Member]

Plumtree Medical Center [Member]

Plumtree Medical Center [Member]

Industrial Portfolio [Member]

Industrial Portfolio [Member]

Industrial Portfolio [Member]

Industrial Portfolio [Member]

Dulles Station, Phase I [Member]

Dulles Station, Phase I [Member]

Dulles Station, Phase I [Member]

Dulles Station, Phase I [Member]

Medical Office Porfolio [Member]

Medical Office Porfolio [Member]

Medical Office Porfolio [Member]

Medical Office Porfolio [Member]

Industrial Segment Member

Industrial Segment Member

Industrial Segment Member

Discontinued Properties Member

Discontinued Properties Member

Discontinued Properties Member

Medical Office And Office Building [Member]

Office [Member]

Office [Member]

Office [Member]

Office [Member]

Office [Member]

Office Building [Member]

Medical Office Building [Member]

Medical Office Building [Member]

Medical Office Building [Member]

Industrial and Office [Member]

Industrial and Office [Member]

Subsequent Event [Member]

agreements

Medical Office Porfolio [Member]

1700 Research Boulevard [Member]

Dulles Station, Phase I [Member]

Medical Office Porfolio [Member]

Atrium Building [Member]

Plumtree Medical Center [Member]

Industrial Portfolio [Member]

Industrial Portfolio [Member]

Medical Office Building [Member]

sqft

sqft

sqft

buildings

sqft

sqft

sqft

Medical Office Porfolio [Member]

sqft

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Mortgage Notes Payable on Assets Held for Sale

$23,945

'

$0

$23,945

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Purchase and Sale Agreements

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Buildings Sold

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

Real Estate Held-for-sale

364,999

'

79,901

364,999

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Real Estate Held-for-sale, Gross

478,479

'

125,967

478,479

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

71,605

'

'

'

'

125,967

406,874

'

'

'

'

Rentable Square Feet

134,000

3,272,000

1,599,000

134,000

3,272,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,093,000

'

'

101,000

180,000

'

79,000

'

'

33,000

'

3,092,000

427,000

Sale Price

23,000

409,700

516,500

23,000

409,700

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

500,800

'

'

'

'

'

'

'

'

'

307,189

'

'

14,250

58,800

'

15,750

'

'

8,750

'

350,900

193,561

Gain on sale of properties

'

'

22,144

5,124

97,491

'

'

'

'

'

'

3,724

'

'

'

1,400

'

'

'

97,491

[1]

'

'

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

18,949

[2]

'

'

3,724

0

'

3,195

'

'

1,400

97,491

'

'

Real estate revenues

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

41,012

44,674

44,431

0

0

23,045

45,791

54,344

80,948

'

'

'

'

'

'

'

'

'

'

'

'

'

Net income

'

'

37,539

15,940

119,767

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

14,044

8,128

10,393

0

0

16,484

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Discontinued operations (in dollars per share)

'

'

$0.55

$0.24

$1.80

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0.21

$0.12

$0.16

$0

$0

$0.23

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Discontinued operations (in dollars per share)

'

'

$0.55

$0.24

$1.80

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0.21

$0.12

$0.16

$0

$0

$0.23

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Property expenses

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-17,039

-18,273

-25,265

'

'

'

'

'

'

'

'

'

'

'

'

'

Real estate impairment

-2,097

-14,526

0

0

-14,526

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

-2,097

-599

'

'

'

'

'

'

'

'

'

'

'

'

'

Depreciation and amortization

'

'

-97,901

-103,934

-100,528

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-12,161

-18,827

-26,125

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,196

-4,331

-5,545

'

'

'

'

'

'

'

'

'

'

'

'

'

Income from operations of properties sold or held for sale

'

'

15,395

10,816

23,414

185

197

67

15,210

9,331

11,491

'

0

225

651

'

0

1,063

1,052

'

0

0

10,621

'

0

0

-468

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Liabilities Of Assets Held For Sale

8,412

'

1,533

8,412

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other liabilities related to properties sold or held for sale

32,357

'

1,533

32,357

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Real Estate Held for Sale, Accumulated Depreciation

($113,480)

'

($46,066)

($113,480)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

The Industrial Portfolio consists of every property in our industrial segment and two office properties (the Crescent and Albemarle Point).

[2]

2440 M Street, 15001 Shady Grove Road, 15505 Shady Grove Road, 19500 at Riverside Park (formerly Lansdowne Medical Office Building), 9707 Medical Center Drive, CentreMed I and II, 8301 Arlington Boulevard, Sterling Medical Office Building, Shady Grove Medical Village II, Alexandria Professional Center, Ashburn Farm Office Park I, Ashburn Farm Office Park II, Ashburn Farm Office Park III, Woodholme Medical Office Building, two office properties (6565 Arlington Boulevard and Woodholme Center) and undeveloped land at 4661 Kenmore Avenue. Subsequent to the end of 2013, we closed on Transaction III, consisting of Woodburn Medical Park I and II, and Transaction IV, consisting of Prosperity Medical Center I, II and III (see note 17).

Real_Estate_Investments_Real_E

Real Estate Investments - Real Estate Impairment (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Real Estate Properties [Line Items]	'	'	'	'	'
Impairment of Real Estate	$2,097	$14,526	$0	$0	$14,526
Real Estate Investment Property, Net	1,553,596	'	1,598,200	1,553,596	'
Real estate impairment, including amounts in discontinued operations	'	599	0	2,097	15,125
4661 Kenmore Avenue [Member]	'	'	'	'	'
Real Estate Properties [Line Items]	'	'	'	'	'
Real Estate Investment Property, Net	'	'	$3,800	'	'

Mortgage_Notes_Payable_Details

Mortgage Notes Payable (Details) (USD $)

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Nov. 21, 2013

Dec. 31, 2013

Dec. 31, 2012

Nov. 21, 2013

Dec. 31, 2013

Dec. 31, 2012

Nov. 22, 2013

Dec. 31, 2013

Dec. 31, 2012

Jan. 11, 2013

Dec. 31, 2013

Dec. 31, 2012

buildings

650 N Glebe [Member]

650 N Glebe [Member]

John Marshall II Member

John Marshall II Member

Olney Village Center Member

Olney Village Center Member

Kenmore Apartments [Member]

Kenmore Apartments [Member]

2445 M Street [Member]

2445 M Street [Member]

3801 Connecticut, Walker House, Bethesda Hill [Member]

3801 Connecticut, Walker House, Bethesda Hill [Member]

Ashburn Farm Office 5.56% [Member]

Ashburn Farm Office 5.56% [Member]

Ashburn Farm Office 5.56% [Member]

Ashburn Farm Office 5.69% [Member]

Ashburn Farm Office 5.69% [Member]

Ashburn Farm Office 5.69% [Member]

Woodholme Medical Center [Member]

Woodholme Medical Center [Member]

Woodholme Medical Center [Member]

West Gude [Member]

West Gude [Member]

West Gude [Member]

Mortgage Loans on Real Estate [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Collateral for mortgage notes payable

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Description of Variable Rate Basis

'

'

'

'0.0215

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Mortgage note, fair value interest rate

'

'

'

2.31%

[1],[2],[3]

'

5.79%

[1]

'

4.94%

[1]

'

5.37%

[1]

'

7.25%

[1],[3]

'

5.71%

[1],[4]

'

'

5.56%

[1],[5]

'

'

5.69%

[1],[6]

'

'

5.29%

[1],[7]

'

'

5.86%

[1],[8]

'

Land Available for Development

$3,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Mortgage notes payable

294,671,000

342,970,000

'

7,297,000

0

[2],[3]

52,563,000

53,274,000

20,743,000

22,343,000

34,937,000

35,535,000

98,102,000

[3]

96,848,000

[3]

81,029,000

[4]

81,029,000

[4]

'

0

[5]

2,313,000

[5]

'

0

[6]

2,024,000

[6]

'

0

[7]

19,608,000

[7]

'

0

[8]

29,996,000

[8]

Debt Instrument, Maturity Date

'

'

'

21-Feb-16

[2],[3]

'

5-May-16

'

1-Oct-23

'

1-Mar-19

'

6-Jan-17

[3]

'

1-Jun-16

[4]

'

'

21-Nov-13

[5]

'

'

21-Nov-13

[6]

'

'

22-Nov-13

[7]

'

'

11-Jan-13

[8]

'

Debt Instrument, Issuance Date

'

'

'

21-Feb-13

[2],[3],[9]

'

15-Sep-11

[9]

'

30-Aug-11

[9]

'

2-Feb-09

[9]

'

2-Dec-08

[3],[9]

'

29-May-08

[4],[9]

'

'

1-Jun-07

[5],[9]

'

'

1-Jun-07

[6],[9]

'

'

1-Jun-07

[7],[9]

'

'

25-Aug-06

[8],[9]

'

Extension term

'

'

'

'2 years

'

'

'

'

'

'

'

'

'

'1 year

'

'

'

'

'

'

'

'

'

'

'

'

'

Principal payments – mortgage notes payable

58,679,000

85,667,000

32,331,000

'

'

'

'

'

'

'

'

'

'

'

'

2,200,000

'

'

1,900,000

'

'

19,300,000

'

'

30,000,000

'

'

Payments of Debt Extinguishment Costs

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

500,000

'

'

400,000

'

'

1,800,000

'

'

'

'

'

Carrying Amount, Mortgaged Properties

$433,700,000

$510,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

Yield on the assumption/issuance date, including the effects of any premiums, discounts or fair value adjustments on the notes.

[2]

Interest rate on 650 North Glebe Road is variable, based on LIBOR plus 2.15%. The maturity date can be extended for up to two years, subject to fees and compliance with certain provisions in the loan agreement, until February 20, 2018.

[3]

Interest only is payable monthly until the maturity date upon which all unpaid principal and interest are payable in full.

[4]

Interest only is payable monthly until the maturity date, which can be extended for one year upon which the interest rate is reset on June 1, 2016. At maturity on June 1, 2017, all unpaid principal and interest are payable in full.

[5]

n November 2013, we extinguished the remaining $2.2 million of principal on the mortgage note secured by Ashburn Farm Office Park with extinguishment costs of $0.5 million.

[6]

n November 2013, we extinguished the remaining $1.9 million of principal on the mortgage note secured by Ashburn Farm III Office Park, with extinguishment costs of $0.4 million.

[7]

n November 2013, we extinguished the remaining $19.3 million of principal on the mortgage note secured by Woodholme Medical Office Center, with extinguishment costs of $1.8 million.

[8]

n January 2013, we extinguished without penalty the remaining $30.0 million of principal on the mortgage note secured by West Gude Drive.

[9]

Each of these mortgages was assumed with the acquisition of the collateralized properties, except for the mortgage notes secured by 3801 Connecticut Avenue, Walker House, Bethesda Hill, Kenmore Apartments, and the construction loan secured by the development project at 650 North Glebe Road, which were originally executed by WRIT. We record mortgages assumed in an acquisition at fair value, and balances presented include any recorded premiums or discounts.

Mortgage_Notes_Payable_Schedul

Mortgage Notes Payable - Scheduled Principal Payments (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Notes Payable, Noncurrent [Abstract]	'	'
2014	$2,840	'
2015	3,017	'
2016	141,688	'
2017	104,369	'
2018	2,661	'
Thereafter	42,625	'
Total Debt	297,200	'
Net discounts, premiums	-2,529	'
Secured Debt	$294,671	$319,025

Unsecured_Lines_Of_Credit_Paya2

Unsecured Lines Of Credit Payable - Repayments and Borrowings on Unsecured Lines of Credit (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Line of Credit Facility, Amount Outstanding [Roll Forward]	'	'	'
Balance at December 31, 2011	$0	$99,000,000	'
Balance at December 31, 2012	0	0	99,000,000
Interest expense, net of capitalized interest	63,573,000	60,627,000	61,402,000
Total revolving credit facilities at December 31	500,000,000	500,000,000	475,000,000
Balance at December 31, 2011	0	0	99,000,000
Weighted average daily borrowings during the year	61,548,000	108,589,000	160,090,000
Maximum daily borrowings during the year	135,000,000	242,000,000	281,000,000
Weighted average interest rate during the year	1.41%	1.15%	1.90%
Weighted average interest rate at period end	'	'	0.90%
Credit Facility No. 1 [Member]	'	'	'
Line of Credit Facility, Amount Outstanding [Roll Forward]	'	'	'
Balance at December 31, 2011	0	'	'
Borrowings	100,000,000	'	'
Repayments	-100,000,000	'	'
Balance at December 31, 2012	0	0	'
Interest expense, net of capitalized interest	281,000	470,000	355,000
Facility fees	253,000	175,000	114,000
Total revolving credit facilities at December 31	100,000,000	'	'
Balance at December 31, 2011	0	0	'
Credit Facility No. 2 [Member]	'	'	'
Line of Credit Facility, Amount Outstanding [Roll Forward]	'	'	'
Balance at December 31, 2011	0	'	'
Borrowings	60,000,000	'	'
Repayments	-60,000,000	'	'
Balance at December 31, 2012	0	0	'
Interest expense, net of capitalized interest	586,000	783,000	2,735,000
Facility fees	1,014,000	887,000	658,000
Total revolving credit facilities at December 31	400,000,000	'	'
Balance at December 31, 2011	$0	$0	'

Unsecured_Lines_Of_Credit_Paya3

Unsecured Lines Of Credit Payable - Narrative (Details) (USD $)

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Mar. 15, 2013

Dec. 31, 2013

Credit Facility No. 1 [Member]

Credit Facility No. 1 [Member]

Credit Facility No. 1 [Member]

Credit Facility No. 2 [Member]

Credit Facility No. 2 [Member]

Credit Facility No. 2 [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

London Interbank Offered Rate (LIBOR) [Member]

Maximum [Member]

London Interbank Offered Rate (LIBOR) [Member]

Maximum [Member]

10 Year Unsecured Notes 5.125% [Member]

10 Year Unsecured Notes 3.950 % [Member]

Line of Credit Facility [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Committed capacity

$500,000,000

$500,000,000

$475,000,000

$100,000,000

'

$200,000,000

$400,000,000

'

$600,000,000

'

'

Debt Instrument, Maturity Date

'

'

'

'

'

'

'

'

'

'

15-Oct-22

[1]

Stated interest rate

'

'

'

'

'

'

'

'

'

5.13%

[2]

3.95%

Expiration date

'

'

'

30-Jun-15

'

'

31-Jul-16

'

'

'

'

Spread on variable rate

'

'

'

'

1.20%

'

'

1.20%

'

'

'

Extension term

'1 year

'

'

'

'

'

'

'

'

'

'

Facility fee

0.25%

'

'

'

'

'

'

'

'

'

'

[1]

No principal amounts are due prior to maturity.

[2]

Yield on issuance date, including the effects of discounts on the notes.

Unsecured_Lines_Of_Credit_Paya4

Unsecured Lines Of Credit Payable - Lines Of Credit Unused and Available (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Line of Credit Facility [Line Items]	'	'	'
Committed capacity	$500,000,000	$500,000,000	$475,000,000
Borrowings outstanding	0	0	99,000,000
Credit Facility No. 1 [Member]	'	'	'
Line of Credit Facility [Line Items]	'	'	'
Committed capacity	100,000,000	'	'
Borrowings outstanding	0	0	'
Letters of credit issued	0	'	'
Unused and available	100,000,000	'	'
Credit Facility No. 2 [Member]	'	'	'
Line of Credit Facility [Line Items]	'	'	'
Committed capacity	400,000,000	'	'
Borrowings outstanding	0	0	'
Letters of credit issued	0	'	'
Unused and available	$400,000,000	'	'

Notes_Payable_Details

Notes Payable (Details) (USD $)

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Mar. 15, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

In Thousands, unless otherwise specified

Unsecured Debt [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

Subsequent Event [Member]

10 Year Unsecured Notes 5.125% [Member]

10 Year Unsecured Notes 5.34% [Member]

10 Year Unsecured Notes 5.359% [Member]

10 Year Unsecured Notes 5.49% [Member]

10 Year Unsecured Notes 5.053% [Member]

10 Year Unsecured Notes 3.950 % [Member]

20 Year Unsecured Notes [Member]

Unsecured Debt [Member]

10 Year Unsecured Notes 5.34% [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Coupon stated rate

'

'

'

5.13%

[1]

5.25%

5.35%

5.35%

4.95%

3.95%

7.25%

'

Effective rate

'

'

'

'

'

5.36%

[1]

5.49%

[1]

5.05%

[1]

4.02%

[1]

7.36%

[1]

5.34%

[1]

Total principal

$297,200

'

$850,000

'

'

'

'

'

'

'

'

Net unamortized discount

'

'

-3,297

'

'

'

'

'

'

'

'

Notes Payable

$846,703

$906,190

$846,703

$60,000

'

$50,000

$100,000

$250,000

$300,000

$50,000

$100,000

Debt Instrument, Maturity Date

'

'

'

'

15-Jan-14

[2]

1-May-15

[2]

1-May-15

[2]

1-Oct-20

[2]

15-Oct-22

[2]

25-Feb-28

[2]

'

[1]

Yield on issuance date, including the effects of discounts on the notes.

[2]

No principal amounts are due prior to maturity.

Notes_Payable_Maturities_of_No

Notes Payable - Maturities of Notes Payable (Details) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Long-term Debt of Registrant, Maturities, Repayments of Principal, Fiscal Year Maturity [Abstract]	'
2014	$2,840
2015	3,017
2016	141,688
2017	104,369
2018	2,661
Thereafter	42,625
Total principal	297,200
Unsecured Debt [Member]	'
Long-term Debt of Registrant, Maturities, Repayments of Principal, Fiscal Year Maturity [Abstract]	'
2014	100,000
2015	150,000
2016	0
2017	0
2018	0
Thereafter	600,000
Total principal	$850,000

Notes_Payable_Line_of_Credit_C

Notes Payable - Line of Credit Covenants (Details) (USD $)	12 Months Ended
In Billions, unless otherwise specified	Dec. 31, 2013
Notes Payable [Abstract]	'
U.S. Covered Terrorism Losses, Percent	0.85
Insurance Provider, Covered Terrorism Losses, Percent	0.1
Aggregate Insured Terrorism Losses	$100

Stock_Based_Compensation_Narra

Stock Based Compensation - Narrative (Details) (USD $)

12 Months Ended

0 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Feb. 17, 2011

Feb. 17, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Prior LTIP [Member]

Prior LTIP [Member]

Washington Real Estate Investment Trust 2007 Omnibus Long Term Incentive Plan [Member]

New STIP [Member]

New STIP [Member]

New STIP [Member]

New LTIP [Member]

New LTIP [Member]

New LTIP [Member]

New LTIP [Member]

New LTIP [Member]

Unrestricted Share Awards [Member]

Cash [Member]

Restricted Share Units [Member]

Restricted Share Units [Member]

Restricted Share Units [Member]

Restricted Share Units [Member]

Management [Member]

Chief Executive Officer [Member]

Officer [Member]

Performance-Based Awards [Member]

Service-Based Awards [Member]

Minimum [Member]

Maximum [Member]

Unrestricted Share Units [Member]

Restricted Share Units [Member]

New LTIP [Member]

New STIP [Member]

New STIP [Member]

New STIP [Member]

New LTIP [Member]

New LTIP [Member]

Restricted Share Units [Member]

Restricted Share Units [Member]

Performance-Based Awards [Member]

Performance-Based Awards [Member]

Service-Based Awards [Member]

Performance-Based Awards [Member]

Prior LTIP [Member]

Prior LTIP [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1,000,000

'

Number of shares authorized

'

'

'

'

'

'

2,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Plan in effect, period

'

'

'

'

'

'

'10 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage payable In unrestricted shares

'

'

'

'

'

'

'

'

'

'

'

'

'

'

50.00%

'

50.00%

'

'

'

'

'

'

'

Percentage payable in restricted shares

'

'

'

'

'

'

'

'

'

'

'

65.00%

150.00%

50.00%

50.00%

'

'

50.00%

'

'

'

'

'

'

Percentage of awards earned

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15.00%

'

'

'

'

'

Award vesting period

'

'

'

'

'

'

'

'4 years

'3 years

'3 years

'3 years

'

'

'

'

'

'

'

'

'1 year

'

'5 years

'

'5 years

Percentage officer may elect to defer

'

'

'

'

'

'

'

80.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of employer contribution, restricted units

'

'

'

'

'

'

'

25.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total compensation cost not yet recognized, period for recognition

'

'

'

'

'

'

'

'

'

'3 years

'4 years

'

'

'

'

'3 years

'

'

'

'

'4 years

'6 years

'

'5 years

Percentage of restricted shares subject to performance conditions

'

'

'

'

'

'

'

20.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Performance period

'

'

'

'

'

'

'

'1 year

'

'

'3 years

'

'

'

'

'

'

'

'

'1 year

'

'1 year

'

'

Percentage of potential award dependent upon market condition

'

'

'

'

'

'

'

'

'

'

40.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of potential award based upon strategic plan fulfillment

'

'

'

'

'

'

'

'

'

'

60.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighting for performance measurement based on cumulative 3-Year total shareholder return

'

'

'

'

'

'

'

'

'

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighting for performance measurement based on 20 peer comapnies

'

'

'

'

'

'

'

'

'

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair value assumptions, expected volatility rate

58.10%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair value assumptions, risk free interest rate

1.20%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair value assumptions, expected term

'

'

'

'

'

'

'

'

'

'

'

'3 years

'4 years

'

'

'

'

'

'

'

'

'

'

'

Closing share price, date of grant

'

'

'

$30.91

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Grant date fair value as a percentage of base salary

'

'

'

'

'

'

'

'

'

'

'

79.00%

185.00%

'

'

'

'

'

'

'

'

'

'

'

Number of restricted shares subsequent to adoption of new share-based compensation plan

'

'

'

'

154,400

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other than options, nonvested, number,

'

'

'

'

'

59,100

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Trustee share-based compensation

55,000

55,000

55,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock-based compensation expense

$6,246,000

$5,856,000

$5,597,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock_Based_Compensation_Restr

Stock Based Compensation - Restricted Share Awards (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]	'	'	'
Fair value of restricted share units vested	$3.80	$5.60	$4.90
Restricted Share Awards [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Other Than Options, Vested, Beginning	864,288	652,803	490,832
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]	'	'	'
Other Than Options, Nonvested, Number, Beginning	149,803	331,003	193,339
Other Than Options, Granted	141,609	36,884	303,168
Other Than Options, Vested During Year	-158,657	-211,485	-161,971
Other Than Options, Forfeited	-2,940	-6,599	-3,533
Other Than Options, Nonvested, Number, Beginning	129,815	149,803	331,003
Other Than Options, Vested, Ending	1,022,945	864,288	652,803
Other Than Options, Vested, Weighted Average Grant Date Fair Value, Beginning	$29.65	$30.06	$30.20
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]	'	'	'
Other Than Options, Nonvested, Weighted Average Grant Date Fair Value	$27.37	$28.39	$27.71
Other Than Options, Granted, Weighted Average Grant Date Fair Value	$26.30	$26.40	$29.48
Other Than Options, Vested During Year, Weighted Average Grant Date Fair Value	$26.66	$28.39	$29.80
Other Than Options, Forfeited, Weighted Average Grant Date Fair Value	$27.80	$27.61	$28.10
Other Than Options, Nonvested, Weighted Average Grant Date Fair Value	$27.06	$27.37	$28.39
Other Than Options, Vested, Weighted Average Grant Date Fair Value, Ending	$29.19	$29.65	$30.06
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$1.80	'	'
Total compensation cost not yet recognized, period for recognition	'21 months	'	'

Stock_Based_Compensation_Restr1

Stock Based Compensation - Restricted and Unrestricted Shares with Market Conditions (Details) (USD $)	1 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Feb. 28, 2011	Dec. 31, 2013	Dec. 31, 2012
Relative TSR [Member] | Restricted Share Awards [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Restricted and Unrestricted Share Awards, Grant Date Fair Value	$1,066	'	'
Unamortized Value Of Restricted and Unrestricted Shares	'	162	501
Relative TSR [Member] | Unrestricted Share Awards [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Restricted and Unrestricted Share Awards, Grant Date Fair Value	1,066	'	'
Unamortized Value Of Restricted and Unrestricted Shares	'	0	338
Absolute TSR [Member] | Restricted Share Awards [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Restricted and Unrestricted Share Awards, Grant Date Fair Value	365	'	'
Unamortized Value Of Restricted and Unrestricted Shares	'	55	172
Absolute TSR [Member] | Unrestricted Share Awards [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Restricted and Unrestricted Share Awards, Grant Date Fair Value	365	'	'
Unamortized Value Of Restricted and Unrestricted Shares	'	$0	$116

Stock_Based_Compensation_Optio

Stock Based Compensation - Options (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock Options, Vesting Percentage, After Year One	50.00%	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]	'	'	'	'
Options outstanding, beginning	38,119	89,106	145,950	'
Stock Options, granted	0	0	0	'
Options exercised	0	-44,987	-51,081	'
Stock Options, expired/forfeited	-28,119	-6,000	-5,763	'
Options outstanding, ending	10,000	38,119	89,106	'
Stock Options, exercisable	10,000	38,119	89,106	'
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]	'	'	'	'
Weighted average exercise price, beginning	$33.09	$30.48	$27.69	$26.74
Stock Options, granted, weighted average exercise price	$0	$0	$0	'
Stock Options, exercised, weighted average exercise price	$0	$25.61	$25.29	'
Stock Options, expired/forfeited, weighted average exercise price	$29.55	$25.61	$24.85	'
Weighted average exercise price, ending	$33.09	$30.48	$27.69	$26.74
Stock Options, weighted average exercise price	$33.09	$30.48	$27.69	'
Aggregate intrinsic value of outstanding exercisable shares	$0	'	'	'
Aggregate intrinsic value of options exercised	'	$100,000	$300,000	'
Options forfeited	0	0	0	'
Stock Options [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock Options, Expiration in Years	'10 years	'	'	'
Employee Stock Option [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]	'	'	'	'
Weighted average exercise price, beginning	$33.09	'	'	'
Weighted average exercise price, ending	$33.09	'	'	'
Weighted average remaining contractual term, options outstanding (years)	'1 year 0 months 0 days	'	'	'

Other_Benefit_Plans_Details

Other Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]	'	'	'
401I(k) plan contributions by employer	$428,000	$467,000	$529,000
Deferred Compensation Liability	1,437,000	1,314,000	'
Accrued benefit liability, prior CEO	1,300,000	1,400,000	'
Prior CEO SERP current service cost	99,000	106,000	113,000
Officer SERP current service cost	325,000	342,000	334,000
Officer [Member]	'	'	'
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]	'	'	'
Accrued benefit liability	$3,300,000	$2,300,000	'

Fair_Value_Disclosures_Financi

Fair Value Disclosures (Financial Assets And Liabilities Measured At Fair Value) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Assets: SERP	$3,290	$2,421
Cash and Cash Equivalents and Restricted Cash Maturity Period	'90 days	'
Level 1 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Assets: SERP	0	0
Level 2 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Assets: SERP	3,290	2,421
Level 3 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Assets: SERP	$0	$0

Fair_Value_Disclosures_Financi1

Fair Value Disclosures (Financial Assets And Liabilities Not Measured At Fair Value) (Details) (USD $)	Dec. 31, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Notes receivable, net	$6,200		$6,900
Carrying (Reported) Amount, Fair Value Disclosure [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Cash and cash equivalents(1)	130,343	[1]	19,324	[1]
Restricted cash(1)	9,189	[1]	14,582	[1]
Mortgage notes payable (1)	294,671	[1]	342,970	[1]
Notes payable	846,703		906,190
Estimate of Fair Value, Fair Value Disclosure [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Cash and cash equivalents(1)	130,343	[1]	19,324	[1]
Restricted cash(1)	9,189	[1]	14,582	[1]
Mortgage notes payable (1)	313,476	[1]	374,591	[1]
Notes payable	856,171		968,040
Estimate of Fair Value, Fair Value Disclosure [Member] | 2445 M Street Note Receivable [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
2445 M Street note receivable	6,803		6,654
2445 M Street [Member]	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Notes receivable, net	$6,070		$6,617
[1]	Includes amounts that have been reclassified to "Other asset related to properties sold or held for sale" or "Other liabilities related to properties sold or held for sale" on the consolidated balance sheets (see note 3).

Earnings_Per_Common_Share_Comp

Earnings Per Common Share - Computation Of Basic And Diluted Earnings Per Share (Details) (USD $)

3 Months Ended

12 Months Ended

In Thousands, except Per Share data, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2011

Mar. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Earnings Per Share [Abstract]

'

'

'

'

'

'

'

'

'

'

'

(Loss) income from continuing operations

($4,297)

$1,709

$1,538

[1],[2]

$857

[1],[2]

$384

[1],[2],[3]

$2,604

[1],[2]

$2,928

[1],[2]

$1,852

[1],[2]

($193)

$7,768

($14,389)

Allocation of undistributed earnings to unvested restricted share awards and units to continuing operations

'

'

'

'

'

'

'

'

0

-191

0

Adjusted (loss) income from continuing operations attributable to the controlling interests

'

'

'

'

'

'

'

'

-193

7,577

-14,389

Income from discontinued operations, including gain on sale of real estate, net of taxes

'

'

'

'

'

'

'

'

37,539

15,940

119,767

Net income attributable to noncontrolling interests

'

'

'

'

'

'

'

'

0

0

-494

Allocation of undistributed earnings to unvested restricted share awards and units to discontinued operations

'

'

'

'

'

'

'

'

-415

-391

-712

Adjusted income from discontinued operations attributable to the controlling interests

'

'

'

'

'

'

'

'

37,124

15,549

118,561

Adjusted net income attributable to the controlling interests

'

'

'

'

'

'

'

'

$36,931

$23,126

$104,172

Weighted average shares outstanding – basic

'

'

'

'

'

'

'

'

66,580

66,239

65,982

Employee stock options and restricted share awards

'

'

'

'

'

'

'

'

0

137

0

Weighted average shares outstanding - diluted

'

'

'

'

'

'

'

'

66,580

66,376

65,982

Continuing operations - basic (in dollars per share)

($0.06)

[1]

$0.03

[1]

$0.02

[1],[2]

$0.01

[1],[2]

$0.01

[1],[2]

$0.04

[1],[2]

$0.04

[1],[2]

$0.03

[1],[2]

$0

$0.11

($0.22)

Discontinued operations (in dollars per share)

'

'

'

'

'

'

'

'

$0.55

$0.24

$1.80

Basic earnings: Adjusted net income attributable to the controlling interests - Per Share Amount

$0.28

[1]

$0.09

[1]

$0.08

[1],[2]

$0.11

[1],[2]

$0.04

[1],[2]

$0.14

[1],[2]

$0.09

[1],[2]

$0.08

[1],[2]

$0.55

$0.35

$1.58

Continuing operations - diluted (in dollars per share)

($0.06)

[1]

$0.03

[1]

$0.02

[1],[2]

$0.01

[1],[2]

$0.01

[1],[2]

$0.04

[1],[2]

$0.04

[1],[2]

$0.03

[1],[2]

$0

$0.11

($0.22)

Discontinued operations (in dollars per share)

'

'

'

'

'

'

'

'

$0.55

$0.24

$1.80

Net income per share, Diluted

$0.28

[1]

$0.09

[1]

$0.08

[1],[2]

$0.11

[1],[2]

$0.04

[1],[2]

$0.14

[1],[2]

$0.09

[1],[2]

$0.08

[1],[2]

$0.55

$0.35

$1.58

[1]

With regard to per share calculations, the sum of the quarterly results may not equal full year results due to rounding.

[2]

The prior quarter results have been restated to conform to the current quarter presentation. Specifically, results related to properties sold or held for sale have been reclassified into discontinued operations.

[3]

The three months ended December 31, 2012 includes the impact of real estate impairment of $2.1 million.

Rentals_Under_Operating_Leases2

Rentals Under Operating Leases (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Rentals Under Operating Leases [Abstract]	'	'	'
2013	$177,776	'	'
2014	155,154	'	'
2015	131,374	'	'
2016	111,883	'	'
2017	91,966	'	'
Thereafter	259,546	'	'
Operating Leases, Future Minimum Payments Receivable	927,699	'	'
Percentage Rents	123	150	193
Reimbursement income	$26,822	$25,528	$21,877

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2013
	Contracts
Loss Contingencies [Line Items]	'
Development Contracts with Third Parties, Number	0
West Gude Drive [Member]	'
Loss Contingencies [Line Items]	'
Letters of Credit Outstanding, Amount	0

Segment_Information_Details

Segment Information (Details) (USD $)

3 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Dec. 31, 2011

Jun. 30, 2011

Mar. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

segment

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Number of Reportable Segments

'

'

'

'

'

'

'

'

'

4

'

'

Real estate rental revenue

$66,721

$65,828

$65,915

[1],[2]

$64,560

[1],[2]

$64,660

[1],[2]

$64,471

[1],[2]

'

$63,073

[1],[2]

$62,590

[1],[2]

$263,024

$254,794

$234,733

Real estate expenses

'

'

'

'

'

'

'

'

'

93,293

86,545

79,624

Net operating income

'

'

'

'

'

'

'

'

'

169,731

168,249

155,109

Depreciation and amortization

'

'

'

'

'

'

'

'

'

-85,740

-85,107

-74,403

General and administrative

'

'

'

'

'

'

'

'

'

-17,535

-15,488

-15,728

Real estate impairment

'

'

'

'

-2,097

'

-14,526

'

'

0

0

-14,526

Acquisition costs

'

'

'

'

'

'

'

'

'

-1,265

-234

-3,607

Interest expense

'

'

'

'

'

'

'

'

'

-63,573

-60,627

-61,402

Other income

'

'

'

'

'

'

'

'

'

926

975

1,144

Loss on extinguishment of debt, net

'

'

'

'

'

'

'

'

'

-2,737

0

-976

Income from properties sold or held for sale

'

'

'

'

'

'

'

'

'

15,395

10,816

23,414

Gain on sale of real estate

'

'

'

'

'

'

'

'

'

22,144

5,124

97,491

Income tax benefit (expense)

'

'

'

'

'

'

'

'

'

0

0

-1,138

Net income

18,908

[1],[3]

5,840

5,263

[1],[2]

7,335

[1],[2]

2,958

[1],[2],[3]

9,561

[1],[2]

'

6,008

[1],[2]

5,181

[1],[2]

37,346

23,708

105,378

Less: Net income attributable to noncontrolling interests in subsidiaries

'

'

'

'

'

'

'

'

'

0

0

-494

Net income attributable to the controlling interests

18,908

[1]

5,840

5,263

[1],[2]

7,335

[1],[2]

2,958

[1],[2]

9,561

[1],[2]

'

6,008

[1],[2]

5,181

[1],[2]

37,346

23,708

104,884

capital expenditures

'

'

'

'

'

'

'

'

'

55,991

51,735

33,436

Total assets

1,975,493

'

'

'

2,124,376

'

2,120,758

'

'

1,975,493

2,124,376

2,120,758

Office [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Real estate rental revenue as a percentage of total

'

'

'

'

'

'

'

'

'

0.58

0.58

0.57

Percentage of total income producing real estate assets

'

'

'

'

'

'

'

'

'

0.62

0.63

'

Real estate rental revenue

'

'

'

'

'

'

'

'

'

152,339

147,401

133,333

Real estate expenses

'

'

'

'

'

'

'

'

'

57,293

53,376

45,634

Net operating income

'

'

'

'

'

'

'

'

'

95,046

94,025

87,699

capital expenditures

'

'

'

'

'

'

'

'

'

37,777

35,330

21,065

Total assets

1,073,302

'

'

'

249,503

'

1,118,074

'

'

1,073,302

249,503

1,118,074

Medical Office [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Real estate rental revenue

'

'

'

'

'

'

'

'

'

0

0

0

Real estate expenses

'

'

'

'

'

'

'

'

'

0

0

0

Net operating income

'

'

'

'

'

'

'

'

'

0

0

0

capital expenditures

'

'

'

'

'

'

'

'

'

3,695

7,004

5,654

Total assets

84,001

'

'

'

1,140,046

'

347,735

'

'

84,001

1,140,046

347,735

Retail [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Real estate rental revenue as a percentage of total

'

'

'

'

'

'

'

'

'

0.21

0.21

0.21

Percentage of total income producing real estate assets

'

'

'

'

'

'

'

'

'

0.2

0.2

'

Real estate rental revenue

'

'

'

'

'

'

'

'

'

56,189

54,506

50,421

Real estate expenses

'

'

'

'

'

'

'

'

'

13,768

12,702

14,273

Net operating income

'

'

'

'

'

'

'

'

'

42,421

41,804

36,148

capital expenditures

'

'

'

'

'

'

'

'

'

4,204

2,977

2,922

Total assets

344,207

'

'

'

327,573

'

365,164

'

'

344,207

327,573

365,164

Multifamily [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Real estate rental revenue as a percentage of total

'

'

'

'

'

'

'

'

'

0.21

0.21

0.22

Percentage of total income producing real estate assets

'

'

'

'

'

'

'

'

'

0.18

0.17

'

Real estate rental revenue

'

'

'

'

'

'

'

'

'

54,496

52,887

50,979

Real estate expenses

'

'

'

'

'

'

'

'

'

22,232

20,467

19,717

Net operating income

'

'

'

'

'

'

'

'

'

32,264

32,420

31,262

capital expenditures

'

'

'

'

'

'

'

'

'

10,153

5,869

2,823

Total assets

309,117

'

'

'

355,585

'

247,170

'

'

309,117

355,585

247,170

Industrial/Flex [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Real estate rental revenue

'

'

'

'

'

'

'

'

'

'

'

0

Real estate expenses

'

'

'

'

'

'

'

'

'

'

'

0

Net operating income

'

'

'

'

'

'

'

'

'

'

'

0

capital expenditures

'

'

'

'

'

'

'

'

'

'

'

351

Total assets

'

'

'

'

'

'

0

'

'

'

'

0

Corporate And Other [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Real estate rental revenue

'

'

'

'

'

'

'

'

'

0

0

0

Real estate expenses

'

'

'

'

'

'

'

'

'

0

0

0

Net operating income

'

'

'

'

'

'

'

'

'

0

0

0

capital expenditures

'

'

'

'

'

'

'

'

'

162

555

621

Total assets

$164,866

'

'

'

$51,669

'

$42,615

'

'

$164,866

$51,669

$42,615

[1]

With regard to per share calculations, the sum of the quarterly results may not equal full year results due to rounding.

[2]

The prior quarter results have been restated to conform to the current quarter presentation. Specifically, results related to properties sold or held for sale have been reclassified into discontinued operations.

[3]

The three months ended December 31, 2012 includes the impact of real estate impairment of $2.1 million.

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (Unaudited) (Details) (USD $)

3 Months Ended

12 Months Ended

In Thousands, except Per Share data, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Dec. 31, 2011

Jun. 30, 2011

Mar. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Real estate rental revenue

$66,721

$65,828

$65,915

[1],[2]

$64,560

[1],[2]

$64,660

[1],[2]

$64,471

[1],[2]

'

$63,073

[1],[2]

$62,590

[1],[2]

$263,024

$254,794

$234,733

Income (loss) from continuing operations

-4,297

1,709

1,538

[1],[2]

857

[1],[2]

384

[1],[2],[3]

2,604

[1],[2]

'

2,928

[1],[2]

1,852

[1],[2]

-193

7,768

-14,389

Effect of disposal of medical office segment on net income

3,964

3,820

3,439

2,821

673

2,462

'

2,370

2,623

'

'

'

Net income

18,908

[1],[3]

5,840

5,263

[1],[2]

7,335

[1],[2]

2,958

[1],[2],[3]

9,561

[1],[2]

'

6,008

[1],[2]

5,181

[1],[2]

37,346

23,708

105,378

Net income attributable to the controlling interests

18,908

[1]

5,840

5,263

[1],[2]

7,335

[1],[2]

2,958

[1],[2]

9,561

[1],[2]

'

6,008

[1],[2]

5,181

[1],[2]

37,346

23,708

104,884

Continuing operations - basic (in dollars per share)

($0.06)

[1]

$0.03

[1]

$0.02

[1],[2]

$0.01

[1],[2]

$0.01

[1],[2]

$0.04

[1],[2]

'

$0.04

[1],[2]

$0.03

[1],[2]

$0

$0.11

($0.22)

Continuing operations - diluted (in dollars per share)

($0.06)

[1]

$0.03

[1]

$0.02

[1],[2]

$0.01

[1],[2]

$0.01

[1],[2]

$0.04

[1],[2]

'

$0.04

[1],[2]

$0.03

[1],[2]

$0

$0.11

($0.22)

Net income per share, Basic

$0.28

[1]

$0.09

[1]

$0.08

[1],[2]

$0.11

[1],[2]

$0.04

[1],[2]

$0.14

[1],[2]

'

$0.09

[1],[2]

$0.08

[1],[2]

$0.55

$0.35

$1.58

Net income per share, Diluted

$0.28

[1]

$0.09

[1]

$0.08

[1],[2]

$0.11

[1],[2]

$0.04

[1],[2]

$0.14

[1],[2]

'

$0.09

[1],[2]

$0.08

[1],[2]

$0.55

$0.35

$1.58

Real estate impairment

'

'

'

'

2,097

'

14,526

'

'

0

0

14,526

Dulles Station II [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Condensed Financial Statements, Captions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Real estate impairment

'

'

'

'

$2,100

'

'

'

'

'

'

'

[1]

With regard to per share calculations, the sum of the quarterly results may not equal full year results due to rounding.

[2]

The prior quarter results have been restated to conform to the current quarter presentation. Specifically, results related to properties sold or held for sale have been reclassified into discontinued operations.

[3]

The three months ended December 31, 2012 includes the impact of real estate impairment of $2.1 million.

Shareholders_Equity_Details

Shareholders' Equity (Details) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended
Share data in Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
				At The Market Offering Program [Member]	Common Stock [Member]	Common Stock [Member]	Common Stock [Member]	Additional Paid In Capital [Member]	Additional Paid In Capital [Member]	Additional Paid In Capital [Member]
Financing Agreements [Line Items]	'	'	'	'	'	'	'	'	'	'
Issuance and sale of stock, term	'	'	'	'36 months	'	'	'	'	'	'
Common stock reserved for future issuance	$250,000,000	'	'	'	'	'	'	'	'	'
Common shares issued	66,531	66,437	'	'	'	'	'	'	'	'
Shares issued under Dividend Reinvestment Program, shares	'	'	'	'	0	55	170	'	'	'
Weighted average issue price, dividend reinvestment program	$0	$29.67	$29.97	'	'	'	'	'	'	'
Net proceeds, dividend reinvestment program	0	1,316,000	5,043,000	'	'	'	'	'	'	'
Stock Issued During Period, Value, Dividend Reinvestment Plan	'	$1,316,000	$5,043,000	'	'	$1,000	$2,000	$0	$1,315,000	$5,041,000

Deferred_Costs_Schedule_of_Pre

Deferred Costs Schedule of Prepaid Expenses and Other Assets (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]	'	'
Deferred Finance Costs, Gross	$17,842	$18,761
Accumulated Amortization, Deferred Finance Costs	8,950	8,162
Deferred Finance Costs, Net	8,892	10,599
Deferred Costs, Leasing, Gross	39,642	31,872
Deferred Costs, Leasing, Accumulated Amortization	14,788	13,756
Deferred Costs, Leasing, Net	24,854	18,116
Deferred Leasing Incentives, Gross	7,143	5,847
Accumulated Amortization, Deferred Leasing Incentives	2,417	1,448
Deferred Leasing Incentives, Net	$4,726	$4,399

Deferred_Costs_Schedule_of_Amo

Deferred Costs Schedule of Amortization and Write-Offs of Deferred Financing, Leasing, and Leasing Incentive Costs (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]	'	'	'
Amortization of Financing Costs	$2,550	$2,411	$2,194
Amortization of Deferred Leasing Fees	4,279	3,635	3,827
Deferred leasing incentives amortization	$980	$675	$556

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Feb. 21, 2014	Jan. 21, 2014
	units			Yale West [Member]	Medical Office Building [Member]
				Subsequent Event [Member]	Medical Office Porfolio [Member]
				units	Subsequent Event [Member]
Subsequent Event [Line Items]	'	'	'	'	'
Sale Price	$516,500,000	$23,000,000	$409,700,000	'	$193,561,000
Units	2,674	'	'	216	'
Value of Assets Acquired	'	'	'	73,000,000	'
Value of Liabilities Assumed	'	'	'	$48,200,000	'

Schedule_II_Details

Schedule II (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Allowance for doubtful accounts	'	'	'
Movement in Valuation Allowances and Reserves [Roll Forward]	'	'	'
Balance at Beginning of Year	$10,443	$8,049	$6,210
Additions Charged to Expenses	3,531	3,811	3,687
Net Deductions (Recoveries)	-7,191	-1,417	-1,848
Balance at End of Year	6,783	10,443	8,049
Valuation allowance for deferred tax assets	'	'	'
Movement in Valuation Allowances and Reserves [Roll Forward]	'	'	'
Balance at Beginning of Year	5,773	5,651	0
Additions Charged to Expenses	0	122	5,651
Net Deductions (Recoveries)	-32	0	0
Balance at End of Year	$5,741	$5,773	$5,651

Schedule_III_Details

Schedule III (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
	units		sqft		sqft
	sqft
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Initial Cost, Land	$476,688,000	[1]	'		'
Initial Cost, Buildings and Improvements	1,264,555,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	548,266,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	490,036,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	1,799,473,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	2,289,509,000	[2]	2,529,131,000		2,449,872,000
Accumulated Depreciation at December 31, 2011	611,408,000		610,536,000		535,732,000
Net Rentable Square Feet	9,711,000	[3]	'		'
Units	2,674		'		'
Secured Debt	294,671,000		319,025,000		'
Mortgage notes payable	294,671,000		342,970,000		'
Real estate, federal income tax basis	1,939,300,000		'		'
Area of land	1,599,000		134,000		3,272,000
Land Available for Development	3,600,000		'		'
Development in Process	61,315,000		45,270,000		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, beginning of period	2,529,131,000		2,449,872,000		2,443,127,000
Property acquisitions	47,444,000	[4]	47,772,000	[4]	352,658,000	[4]
Improvements	71,127,000	[4]	59,664,000	[4]	36,386,000	[4]
Impairment write-down	0		-2,097,000		-16,416,000
Write-off of disposed assets	-2,017,000		-1,450,000		-1,648,000
Property sales	-356,176,000		-24,630,000		-364,235,000
Balance, end of period	2,289,509,000	[2]	2,529,131,000		2,449,872,000
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, beginning of period	610,536,000		535,732,000		538,786,000
Depreciation	80,510,000		84,949,000		84,167,000
Impairment write-down	0		0		-1,291,000
Write-off of disposed assets	-1,404,000		-1,124,000		-1,648,000
Property sales	-78,234,000		-9,021,000		-84,282,000
Balance, end of period	611,408,000		610,536,000		535,732,000
Multifamily Properties [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Initial Cost, Land	79,524,000	[1]	'		'
Initial Cost, Buildings and Improvements	124,275,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	234,209,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	103,165,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	334,843,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	438,008,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	132,271,000		'		'
Net Rentable Square Feet	2,278,000	[3]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	438,008,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	132,271,000		'		'
3801 Connecticut [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Washington, DC	[5]	'		'
Initial Cost, Land	420,000	[1],[5]	'		'
Initial Cost, Buildings and Improvements	2,678,000	[1],[5]	'		'
Net Improvements (Retirement) since Acquisition	9,715,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	420,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	12,393,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	12,813,000	[2],[5]	'		'
Accumulated Depreciation at December 31, 2011	8,905,000	[5]	'		'
Year of Construction	1-Jan-51	[5]	'		'
Date of Acquisition	1-Jan-63	[5]	'		'
Net Rentable Square Feet	179,000	[3]	'		'
Units	307		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	12,813,000	[2],[5]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	8,905,000	[5]	'		'
Roosevelt Towers [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	336,000	[1]	'		'
Initial Cost, Buildings and Improvements	1,996,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	10,995,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	336,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	12,991,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	13,327,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	7,719,000		'		'
Year of Construction	1-Jan-64		'		'
Date of Acquisition	1-May-65		'		'
Net Rentable Square Feet	170,000	[3]	'		'
Units	191		'		'
Depreciation Life	'40 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	13,327,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	7,719,000		'		'
Country Club Towers [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	299,000	[1]	'		'
Initial Cost, Buildings and Improvements	2,562,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	15,088,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	299,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	17,650,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	17,949,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	10,252,000		'		'
Year of Construction	1-Jan-65		'		'
Date of Acquisition	1-Jul-69		'		'
Net Rentable Square Feet	159,000	[3]	'		'
Units	227		'		'
Depreciation Life	'35 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	17,949,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	10,252,000		'		'
Park Adams [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	287,000	[1]	'		'
Initial Cost, Buildings and Improvements	1,654,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	9,808,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	287,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	11,462,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	11,749,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	7,856,000		'		'
Year of Construction	1-Jan-59		'		'
Date of Acquisition	1-Jan-69		'		'
Net Rentable Square Feet	173,000	[3]	'		'
Units	200		'		'
Depreciation Life	'35 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	11,749,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	7,856,000		'		'
Munson Hill Towers [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	322,000	[1]	'		'
Initial Cost, Buildings and Improvements	3,337,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	15,359,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	322,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	18,696,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	19,018,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	13,331,000		'		'
Year of Construction	1-Jan-63		'		'
Date of Acquisition	1-Jan-70		'		'
Net Rentable Square Feet	258,000	[3]	'		'
Units	279		'		'
Depreciation Life	'33 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	19,018,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	13,331,000		'		'
The Ashby at McLean [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	4,356,000	[1]	'		'
Initial Cost, Buildings and Improvements	17,102,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	16,156,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	4,356,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	33,258,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	37,614,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	19,402,000		'		'
Year of Construction	1-Jan-82		'		'
Date of Acquisition	1-Aug-96		'		'
Net Rentable Square Feet	274,000	[3]	'		'
Units	256		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	37,614,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	19,402,000		'		'
Walker House Apartments [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland	[5]	'		'
Initial Cost, Land	2,851,000	[1],[5]	'		'
Initial Cost, Buildings and Improvements	7,946,000	[1],[5]	'		'
Net Improvements (Retirement) since Acquisition	6,827,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	2,851,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	14,773,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	17,624,000	[2],[5]	'		'
Accumulated Depreciation at December 31, 2011	9,101,000	[5]	'		'
Year of Construction	1-Jan-71	[5]	'		'
Date of Acquisition	1-Mar-96	[5]	'		'
Net Rentable Square Feet	157,000	[3]	'		'
Units	212		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	17,624,000	[2],[5]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	9,101,000	[5]	'		'
Bethesda Hill Apartments [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland	[5]	'		'
Initial Cost, Land	3,900,000	[1],[5]	'		'
Initial Cost, Buildings and Improvements	13,412,000	[1],[5]	'		'
Net Improvements (Retirement) since Acquisition	12,116,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	3,900,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	25,528,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	29,428,000	[2],[5]	'		'
Accumulated Depreciation at December 31, 2011	14,758,000	[5]	'		'
Year of Construction	1-Jan-86	[5]	'		'
Date of Acquisition	1-Nov-97	[5]	'		'
Net Rentable Square Feet	225,000	[3],[5]	'		'
Units	195		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	29,428,000	[2],[5]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	14,758,000	[5]	'		'
Bennett Park [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	2,861,000	[1]	'		'
Initial Cost, Buildings and Improvements	917,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	79,425,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	4,774,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	78,429,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	83,203,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	23,117,000		'		'
Year of Construction	1-Jan-07		'		'
Date of Acquisition	1-Feb-01		'		'
Net Rentable Square Feet	214,000	[3]	'		'
Units	224		'		'
Depreciation Life	'28 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	83,203,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	23,117,000		'		'
The Clayborne [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	269,000	[1]	'		'
Initial Cost, Buildings and Improvements	0	[1]	'		'
Net Improvements (Retirement) since Acquisition	30,527,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	699,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	30,097,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	30,796,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	10,245,000		'		'
Year of Construction	1-Jan-08		'		'
Date of Acquisition	1-Jun-03		'		'
Net Rentable Square Feet	60,000	[3]	'		'
Units	74		'		'
Depreciation Life	'26 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	30,796,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	10,245,000		'		'
The Kenmore [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Washington, DC	[5]	'		'
Initial Cost, Land	28,222,000	[1],[5]	'		'
Initial Cost, Buildings and Improvements	33,955,000	[1],[5]	'		'
Net Improvements (Retirement) since Acquisition	6,776,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	28,222,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	40,731,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	68,953,000	[2],[5]	'		'
Accumulated Depreciation at December 31, 2011	7,219,000	[5]	'		'
Year of Construction	1-Jan-48	[5]	'		'
Date of Acquisition	1-Sep-08	[5]	'		'
Net Rentable Square Feet	268,000	[3]	'		'
Units	374		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	68,953,000	[2],[5]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	7,219,000	[5]	'		'
The Paramount [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	8,568,000	[1]	'		'
Initial Cost, Buildings and Improvements	38,716,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	119,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	8,568,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	38,835,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	47,403,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	366,000		'		'
Year of Construction	1-Jan-84		'		'
Date of Acquisition	1-Oct-13	[5]	'		'
Net Rentable Square Feet	141,000	[3]	'		'
Units	135		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	47,403,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	366,000		'		'
North Glebe, 650 and 1219 First Street [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Land Available for Development	48,100,000		'		'
Six Fifty North Glebe Road [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia	[7]	'		'
Initial Cost, Land	12,787,000	[1],[7]	'		'
Initial Cost, Buildings and Improvements	0	[1],[7]	'		'
Net Improvements (Retirement) since Acquisition	14,556,000	[7]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	27,343,000	[7]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	0	[7]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	27,343,000	[2],[7]	'		'
Accumulated Depreciation at December 31, 2011	0	[7]	'		'
Date of Acquisition	1-Jun-11	[7]	'		'
Net Rentable Square Feet	0		'		'
Units	0		'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	27,343,000	[2],[7]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	0	[7]	'		'
1219 First Street [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia	[7]	'		'
Initial Cost, Land	14,046,000	[1],[7]	'		'
Initial Cost, Buildings and Improvements	0	[1],[7]	'		'
Net Improvements (Retirement) since Acquisition	6,742,000	[7]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	20,788,000	[7]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	0	[7]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	20,788,000	[2],[7]	'		'
Accumulated Depreciation at December 31, 2011	0	[7]	'		'
Date of Acquisition	1-Nov-11	[7]	'		'
Net Rentable Square Feet	0		'		'
Units	0		'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	20,788,000	[2],[7]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	0	[7]	'		'
Office Buildings [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Initial Cost, Land	263,723,000	[1]	'		'
Initial Cost, Buildings and Improvements	812,034,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	233,379,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	252,852,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	1,056,284,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	1,309,136,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	336,608,000		'		'
Net Rentable Square Feet	4,557,000	[3]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	1,309,136,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	336,608,000		'		'
1901 Pennsylvania Avenue [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Washington, DC		'		'
Initial Cost, Land	892,000	[1]	'		'
Initial Cost, Buildings and Improvements	3,481,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	15,955,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	892,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	19,436,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	20,328,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	14,068,000		'		'
Year of Construction	1-Jan-60		'		'
Date of Acquisition	1-May-77		'		'
Net Rentable Square Feet	101,000		'		'
Depreciation Life	'28 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	20,328,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	14,068,000		'		'
51 Monroe Street [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	840,000	[1]	'		'
Initial Cost, Buildings and Improvements	10,869,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	26,553,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	840,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	37,422,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	38,262,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	26,144,000		'		'
Year of Construction	1-Jan-75		'		'
Date of Acquisition	1-Aug-79		'		'
Net Rentable Square Feet	222,000		'		'
Depreciation Life	'41 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	38,262,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	26,144,000		'		'
515 King Street [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	4,102,000	[1]	'		'
Initial Cost, Buildings and Improvements	3,931,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	5,494,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	4,102,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	9,425,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	13,527,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	4,989,000		'		'
Year of Construction	1-Jan-66		'		'
Date of Acquisition	1-Jul-92		'		'
Net Rentable Square Feet	75,000		'		'
Depreciation Life	'50 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	13,527,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	4,989,000		'		'
6110 Executive Boulevard [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	4,621,000	[1]	'		'
Initial Cost, Buildings and Improvements	11,926,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	15,144,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	4,621,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	27,070,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	31,691,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	16,490,000		'		'
Year of Construction	1-Jan-71		'		'
Date of Acquisition	1-Jan-95		'		'
Net Rentable Square Feet	203,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	31,691,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	16,490,000		'		'
1220 19th Street [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Washington, DC		'		'
Initial Cost, Land	7,803,000	[1]	'		'
Initial Cost, Buildings and Improvements	11,366,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	10,612,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	7,803,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	21,978,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	29,781,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	11,233,000		'		'
Year of Construction	1-Jan-76		'		'
Date of Acquisition	1-Nov-95		'		'
Net Rentable Square Feet	104,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	29,781,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	11,233,000		'		'
1600 Wilson Boulevard [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	6,661,000	[1]	'		'
Initial Cost, Buildings and Improvements	16,742,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	20,384,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	6,661,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	37,126,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	43,787,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	16,668,000		'		'
Year of Construction	1-Jan-73		'		'
Date of Acquisition	1-Oct-97		'		'
Net Rentable Square Feet	168,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	43,787,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	16,668,000		'		'
7900 Westpark Drive [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia	[8]	'		'
Initial Cost, Land	12,049,000	[1],[8]	'		'
Initial Cost, Buildings and Improvements	71,825,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	40,805,000	[8]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	12,049,000	[8]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	112,630,000	[8]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	124,679,000	[2],[8]	'		'
Accumulated Depreciation at December 31, 2011	60,969,000	[8]	'		'
Year of Construction	1-Jan-72		'		'
Date of Acquisition	1-Nov-97		'		'
Net Rentable Square Feet	530,000		'		'
Depreciation Life	'30 years	[6]	'		'
Development in Process	3,300,000		'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	124,679,000	[2],[8]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	60,969,000	[8]	'		'
600 Jefferson Plaza [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	2,296,000	[1]	'		'
Initial Cost, Buildings and Improvements	12,188,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	6,199,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	2,296,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	18,387,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	20,683,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	8,988,000		'		'
Year of Construction	1-Jan-85		'		'
Date of Acquisition	1-May-99		'		'
Net Rentable Square Feet	113,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	20,683,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	8,988,000		'		'
Wayne Plaza [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	1,564,000	[1]	'		'
Initial Cost, Buildings and Improvements	6,243,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	8,431,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	1,564,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	14,674,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	16,238,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	7,281,000		'		'
Year of Construction	1-Jan-70		'		'
Date of Acquisition	1-May-00		'		'
Net Rentable Square Feet	96,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	16,238,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	7,281,000		'		'
Courthouse Square [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	0	[1]	'		'
Initial Cost, Buildings and Improvements	17,096,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	7,441,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	0		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	24,537,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	24,537,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	10,899,000		'		'
Year of Construction	1-Jan-79		'		'
Date of Acquisition	1-Oct-00		'		'
Net Rentable Square Feet	115,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	24,537,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	10,899,000		'		'
One Central Plaza [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	5,480,000	[1]	'		'
Initial Cost, Buildings and Improvements	39,107,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	16,750,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	5,480,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	55,857,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	61,337,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	26,059,000		'		'
Year of Construction	1-Jan-74		'		'
Date of Acquisition	1-Apr-01		'		'
Net Rentable Square Feet	267,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	61,337,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	26,059,000		'		'
1776 G Street [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Washington, DC		'		'
Initial Cost, Land	31,500,000	[1]	'		'
Initial Cost, Buildings and Improvements	54,327,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	4,865,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	31,500,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	59,192,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	90,692,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	23,247,000		'		'
Year of Construction	1-Jan-79		'		'
Date of Acquisition	1-Aug-03		'		'
Net Rentable Square Feet	263,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	90,692,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	23,247,000		'		'
Dulles Station II [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia	[8]	'		'
Initial Cost, Land	15,001,000	[1],[8]	'		'
Initial Cost, Buildings and Improvements	494,000	[1],[8]	'		'
Net Improvements (Retirement) since Acquisition	-3,425,000	[8]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	4,130,000	[8]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	7,940,000	[8]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	12,070,000	[2],[8]	'		'
Accumulated Depreciation at December 31, 2011	291,000	[8]	'		'
Date of Acquisition	1-Dec-05	[8]	'		'
Net Rentable Square Feet	0		'		'
Area of land	360,000		'		'
Land Placed In Service	500,000		'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	12,070,000	[2],[8]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	291,000	[8]	'		'
West Gude Drive [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	11,580,000	[1]	'		'
Initial Cost, Buildings and Improvements	43,240,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	10,876,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	11,580,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	54,116,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	65,696,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	15,195,000		'		'
Year of Construction	1-Jan-84		'		'
Date of Acquisition	1-Aug-06		'		'
Net Rentable Square Feet	277,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	65,696,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	15,195,000		'		'
Monument II [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	10,244,000	[1]	'		'
Initial Cost, Buildings and Improvements	65,205,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	4,733,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	10,244,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	69,938,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	80,182,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	17,810,000		'		'
Year of Construction	1-Jan-00		'		'
Date of Acquisition	1-Mar-07		'		'
Net Rentable Square Feet	207,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	80,182,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	17,810,000		'		'
2000 M Street [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Washington, DC		'		'
Initial Cost, Land	0	[1]	'		'
Initial Cost, Buildings and Improvements	61,101,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	20,866,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	0		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	81,967,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	81,967,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	17,061,000		'		'
Year of Construction	1-Jan-71		'		'
Date of Acquisition	1-Dec-07		'		'
Net Rentable Square Feet	230,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	81,967,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	17,061,000		'		'
M Street 2445 [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Washington, DC	[5]	'		'
Initial Cost, Land	46,887,000	[1],[5]	'		'
Initial Cost, Buildings and Improvements	106,743,000	[1],[5]	'		'
Net Improvements (Retirement) since Acquisition	3,060,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	46,887,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	109,803,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	156,690,000	[2],[5]	'		'
Accumulated Depreciation at December 31, 2011	22,179,000	[5]	'		'
Year of Construction	1-Jan-86		'		'
Date of Acquisition	1-Dec-08		'		'
Net Rentable Square Feet	290,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	156,690,000	[2],[5]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	22,179,000	[5]	'		'
Quantico Building E [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	4,518,000	[1]	'		'
Initial Cost, Buildings and Improvements	24,801,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	428,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	4,518,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	25,229,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	29,747,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	5,100,000		'		'
Year of Construction	1-Jan-07		'		'
Date of Acquisition	1-Jun-10		'		'
Net Rentable Square Feet	134,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	29,747,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	5,100,000		'		'
Quantico Building G [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	4,897,000	[1]	'		'
Initial Cost, Buildings and Improvements	25,376,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	-129,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	4,897,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	25,247,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	30,144,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	5,217,000		'		'
Year of Construction	1-Jan-09		'		'
Date of Acquisition	1-Jun-10		'		'
Net Rentable Square Feet	136,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	30,144,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	5,217,000		'		'
1140 Connecticut Avenue [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Washington, DC		'		'
Initial Cost, Land	25,226,000	[1]	'		'
Initial Cost, Buildings and Improvements	50,495,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	8,124,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	25,226,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	58,619,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	83,845,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	7,425,000		'		'
Year of Construction	1-Jan-66		'		'
Date of Acquisition	1-Jan-11		'		'
Net Rentable Square Feet	184,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	83,845,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	7,425,000		'		'
1227 25th Street [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Washington, DC		'		'
Initial Cost, Land	17,505,000	[1]	'		'
Initial Cost, Buildings and Improvements	21,319,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	2,339,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	17,505,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	23,658,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	41,163,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	3,158,000		'		'
Year of Construction	1-Jan-88		'		'
Date of Acquisition	1-Mar-11		'		'
Net Rentable Square Feet	132,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	41,163,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	3,158,000		'		'
Braddock Place Member	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	18,817,000	[1]	'		'
Initial Cost, Buildings and Improvements	71,250,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	5,564,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	18,817,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	76,814,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	95,631,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	8,542,000		'		'
Year of Construction	1-Jan-85		'		'
Date of Acquisition	1-Sep-11		'		'
Net Rentable Square Feet	345,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	95,631,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	8,542,000		'		'
John Marshall II Member	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia	[5]	'		'
Initial Cost, Land	13,490,000	[1],[5]	'		'
Initial Cost, Buildings and Improvements	53,024,000	[1],[5]	'		'
Net Improvements (Retirement) since Acquisition	173,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	13,490,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	53,197,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	66,687,000	[2],[5]	'		'
Accumulated Depreciation at December 31, 2011	5,071,000	[5]	'		'
Year of Construction	1-Jan-96		'		'
Date of Acquisition	1-Sep-11		'		'
Net Rentable Square Feet	223,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	66,687,000	[2],[5]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	5,071,000	[5]	'		'
Fairgate at Ballston [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	17,750,000	[1]	'		'
Initial Cost, Buildings and Improvements	29,885,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	2,137,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	17,750,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	32,022,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	49,772,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	2,524,000		'		'
Year of Construction	1-Jan-88		'		'
Date of Acquisition	1-Jun-12		'		'
Net Rentable Square Feet	142,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	49,772,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	2,524,000		'		'
Medical Office [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Initial Cost, Land	11,683,000	[1]	'		'
Initial Cost, Buildings and Improvements	101,881,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	12,403,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	11,683,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	114,284,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	125,967,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	46,066,000		'		'
Net Rentable Square Feet	427,000		'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	125,967,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	46,066,000		'		'
Woodburn Medical Park I [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	2,563,000	[1]	'		'
Initial Cost, Buildings and Improvements	12,460,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	4,393,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	2,563,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	16,853,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	19,416,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	8,620,000		'		'
Year of Construction	1-Jan-84		'		'
Date of Acquisition	1-Nov-98		'		'
Net Rentable Square Feet	77,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	19,416,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	8,620,000		'		'
Woodburn Medical Park II [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	2,632,000	[1]	'		'
Initial Cost, Buildings and Improvements	17,574,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	4,366,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	2,632,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	21,940,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	24,572,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	10,901,000		'		'
Year of Construction	1-Jan-88		'		'
Date of Acquisition	1-Nov-98		'		'
Net Rentable Square Feet	97,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	24,572,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	10,901,000		'		'
8501 Arlington Boulevard [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	2,071,000	[1]	'		'
Initial Cost, Buildings and Improvements	26,317,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	1,335,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	2,071,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	27,652,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	29,723,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	9,733,000		'		'
Year of Construction	1-Jan-00		'		'
Date of Acquisition	1-Oct-03		'		'
Net Rentable Square Feet	91,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	29,723,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	9,733,000		'		'
8503 Arlington Boulevard [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	1,598,000	[1]	'		'
Initial Cost, Buildings and Improvements	25,850,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	1,521,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	1,598,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	27,371,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	28,969,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	9,474,000		'		'
Year of Construction	1-Jan-01		'		'
Date of Acquisition	1-Oct-03		'		'
Net Rentable Square Feet	87,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	28,969,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	9,474,000		'		'
8505 Arlington Boulevard [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	2,819,000	[1]	'		'
Initial Cost, Buildings and Improvements	19,680,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	788,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	2,819,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	20,468,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	23,287,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	7,338,000		'		'
Year of Construction	1-Jan-02		'		'
Date of Acquisition	1-Oct-03		'		'
Net Rentable Square Feet	75,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	23,287,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	7,338,000		'		'
Retail Centers [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Initial Cost, Land	121,758,000	[1]	'		'
Initial Cost, Buildings and Improvements	226,365,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	68,275,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	122,336,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	294,062,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	416,398,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	96,463,000		'		'
Net Rentable Square Feet	2,449,000		'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	416,398,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	96,463,000		'		'
Takoma Park [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	415,000	[1]	'		'
Initial Cost, Buildings and Improvements	1,084,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	238,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	415,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	1,322,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	1,737,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	1,184,000		'		'
Year of Construction	1-Jan-62		'		'
Date of Acquisition	1-Jul-63		'		'
Net Rentable Square Feet	51,000		'		'
Depreciation Life	'50 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	1,737,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	1,184,000		'		'
Westminster [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	519,000	[1]	'		'
Initial Cost, Buildings and Improvements	1,775,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	9,171,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	519,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	10,946,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	11,465,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	6,534,000		'		'
Year of Construction	1-Jan-69		'		'
Date of Acquisition	1-Sep-72		'		'
Net Rentable Square Feet	150,000		'		'
Depreciation Life	'37 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	11,465,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	6,534,000		'		'
Concord Centre [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	413,000	[1]	'		'
Initial Cost, Buildings and Improvements	850,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	3,511,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	413,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	4,361,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	4,774,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	2,966,000		'		'
Year of Construction	1-Jan-60		'		'
Date of Acquisition	1-Dec-73		'		'
Net Rentable Square Feet	76,000		'		'
Depreciation Life	'33 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	4,774,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	2,966,000		'		'
Wheaton Park [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	796,000	[1]	'		'
Initial Cost, Buildings and Improvements	857,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	4,455,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	796,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	5,312,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	6,108,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	3,364,000		'		'
Year of Construction	1-Jan-67		'		'
Date of Acquisition	1-Sep-77		'		'
Net Rentable Square Feet	74,000		'		'
Depreciation Life	'50 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	6,108,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	3,364,000		'		'
Bradlee [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	4,152,000	[1]	'		'
Initial Cost, Buildings and Improvements	5,383,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	8,261,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	4,152,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	13,644,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	17,796,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	9,639,000		'		'
Year of Construction	1-Jan-55		'		'
Date of Acquisition	1-Dec-84		'		'
Net Rentable Square Feet	168,000		'		'
Depreciation Life	'40 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	17,796,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	9,639,000		'		'
Chevy Chase Metro Plaza [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Washington, DC		'		'
Initial Cost, Land	1,549,000	[1]	'		'
Initial Cost, Buildings and Improvements	4,304,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	5,366,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	1,549,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	9,670,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	11,219,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	6,012,000		'		'
Year of Construction	1-Jan-75		'		'
Date of Acquisition	1-Sep-85		'		'
Net Rentable Square Feet	49,000		'		'
Depreciation Life	'50 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	11,219,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	6,012,000		'		'
Montgomery Village Center [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	11,625,000	[1]	'		'
Initial Cost, Buildings and Improvements	9,105,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	3,252,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	11,625,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	12,357,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	23,982,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	5,502,000		'		'
Year of Construction	1-Jan-69		'		'
Date of Acquisition	1-Dec-92		'		'
Net Rentable Square Feet	197,000		'		'
Depreciation Life	'50 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	23,982,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	5,502,000		'		'
Shoppes of Foxchase [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	5,838,000	[1]	'		'
Initial Cost, Buildings and Improvements	2,979,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	13,245,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	5,838,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	16,224,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	22,062,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	5,419,000		'		'
Year of Construction	1-Jan-60		'		'
Date of Acquisition	1-Jun-94		'		'
Net Rentable Square Feet	134,000		'		'
Depreciation Life	'50 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	22,062,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	5,419,000		'		'
Frederick County Square [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	6,561,000	[1]	'		'
Initial Cost, Buildings and Improvements	6,830,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	4,105,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	6,561,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	10,935,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	17,496,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	6,381,000		'		'
Year of Construction	1-Jan-73		'		'
Date of Acquisition	1-Aug-95		'		'
Net Rentable Square Feet	227,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	17,496,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	6,381,000		'		'
800 S. Washington Street [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Virginia		'		'
Initial Cost, Land	2,904,000	[1]	'		'
Initial Cost, Buildings and Improvements	5,489,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	5,999,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	2,904,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	11,488,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	14,392,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	4,106,000		'		'
Year of Construction	1-Jan-51		'		'
Date of Acquisition	1-Jun-98		'		'
Net Rentable Square Feet	47,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	14,392,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	4,106,000		'		'
Centre at Hagerstown . [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	13,029,000	[1]	'		'
Initial Cost, Buildings and Improvements	25,415,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	2,306,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	13,029,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	27,721,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	40,750,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	10,836,000		'		'
Year of Construction	1-Jan-00		'		'
Date of Acquisition	1-Jun-02		'		'
Net Rentable Square Feet	332,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	40,750,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	10,836,000		'		'
Frederick Crossing [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	12,759,000	[1]	'		'
Initial Cost, Buildings and Improvements	35,477,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	2,206,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	12,759,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	37,683,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	50,442,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	11,701,000		'		'
Year of Construction	1-Jan-99		'		'
Date of Acquisition	1-Mar-05		'		'
Net Rentable Square Feet	295,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	50,442,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	11,701,000		'		'
Randolph Shopping Center [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	4,928,000	[1]	'		'
Initial Cost, Buildings and Improvements	13,025,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	727,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	4,928,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	13,752,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	18,680,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	3,848,000		'		'
Year of Construction	1-Jan-72		'		'
Date of Acquisition	1-May-06		'		'
Net Rentable Square Feet	82,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	18,680,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	3,848,000		'		'
Montrose Shopping Center [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	11,612,000	[1]	'		'
Initial Cost, Buildings and Improvements	22,410,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	2,545,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	11,612,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	24,955,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	36,567,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	6,934,000		'		'
Year of Construction	1-Jan-70		'		'
Date of Acquisition	1-May-06		'		'
Net Rentable Square Feet	145,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	36,567,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	6,934,000		'		'
Gateway Overlook [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland		'		'
Initial Cost, Land	28,816,000	[1]	'		'
Initial Cost, Buildings and Improvements	52,249,000	[1]	'		'
Net Improvements (Retirement) since Acquisition	1,240,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Land	29,394,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	52,911,000		'		'
Gross Amounts at Which Carried at December 31, 2011, Total	82,305,000	[2]	'		'
Accumulated Depreciation at December 31, 2011	8,328,000		'		'
Year of Construction	1-Jan-07		'		'
Date of Acquisition	1-Dec-10		'		'
Net Rentable Square Feet	223,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	82,305,000	[2]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	8,328,000		'		'
Olney Village Center Member	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Location	'Maryland	[5]	'		'
Initial Cost, Land	15,842,000	[1],[5]	'		'
Initial Cost, Buildings and Improvements	39,133,000	[1],[5]	'		'
Net Improvements (Retirement) since Acquisition	1,648,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Land	15,842,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Buildings and Improvements	40,781,000	[5]	'		'
Gross Amounts at Which Carried at December 31, 2011, Total	56,623,000	[2],[5]	'		'
Accumulated Depreciation at December 31, 2011	3,709,000	[5]	'		'
Year of Construction	1-Jan-79	[5]	'		'
Date of Acquisition	1-Aug-11	[5]	'		'
Net Rentable Square Feet	199,000		'		'
Depreciation Life	'30 years	[6]	'		'
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]	'		'		'
Balance, end of period	56,623,000	[2],[5]	'		'
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]	'		'		'
Balance, end of period	3,709,000	[5]	'		'
650 N Glebe [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Mortgage notes payable	7,297,000		0	[10],[9]	'
3801 Connecticut [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Secured Debt	35,400,000		'		'
Kenmore Apartments [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Mortgage notes payable	34,937,000		35,535,000		'
Walker House Apartments [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Secured Debt	16,500,000		'		'
Olney Village Center Member	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Mortgage notes payable	20,743,000		22,343,000		'
Bethesda Hill Apartments [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Secured Debt	29,100,000		'		'
John Marshall II Member	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Mortgage notes payable	52,563,000		53,274,000		'
M Street 2445 [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Mortgage notes payable	$98,102,000	[10]	$96,848,000	[10]	'
Minimum [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Useful Life	'3 years		'		'
Maximum [Member]	'		'		'
Real Estate and Accumulated Depreciation [Line Items]	'		'		'
Useful Life	'50 years		'		'
[1]	The purchase cost of real estate investments has been divided between land and buildings and improvements on the basis of management’s determination of the fair values.
[2]	At December 31, 2013, total land, buildings and improvements are carried at $1,939.3 million for federal income tax purposes.
[3]	Residential properties are presented in gross square feet.
[4]	Includes non-cash accruals for capital items and assumed mortgages.
[5]	At December 31, 2013, our properties were encumbered by non-recourse mortgage amounts as follows: $35.4 million on 3801 Connecticut Avenue, $16.5 million on Walker House, $29.1 million on Bethesda Hill, $34.9 million on The Kenmore, $98.1 million on 2445 M Street, $52.6 million on John Marshall II, and $20.7 million on Olney Village Center.
[6]	The useful life shown is for the main structure. Buildings and improvements are depreciated over various useful lives ranging from 3 to 50 years.
[7]	As of December 31, 2013, WRIT had under development via joint venture arrangements, a mid-rise multifamily property in Arlington, Virginia (650 North Glebe) and a high-rise multifamily property in Alexandria, Virginia (1225 First Street). The value not yet placed into service of these development projects via joint venture arrangements at December 31, 2013 was $48.1 million. 650 North Glebe was encumbered by a construction loan with a $7.3 million balance at December 31, 2013.
[8]	As of December 31, 2013, WRIT had under development an office project with 360,000 square feet of office space and a parking garage to be developed in Herndon, VA (Dulles Station, Phase II). The total land value not yet placed in service of the development project at December 31, 2013 was $3.6 million. $0.5 million of Dulles Station, Phase II land was placed into service upon the completion of a portion of the parking garage structure. Additionally, WRIT had investments in various smaller development or redevelopment projects, including 7900 Westpark Drive. The total value of this redevelopment not yet placed in service is $3.3 million at December 31, 2013.
[9]	Interest rate on 650 North Glebe Road is variable, based on LIBOR plus 2.15%. The maturity date can be extended for up to two years, subject to fees and compliance with certain provisions in the loan agreement, until February 20, 2018.
[10]	Interest only is payable monthly until the maturity date upon which all unpaid principal and interest are payable in full.