First Potomac Realty Trust (FPO) 10-Q 30 Oct 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 28, 2015
Document And Entity Information [Abstract]
Entity Registrant Name	FIRST POTOMAC REALTY TRUST
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Entity Central Index Key	1,254,595
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		57,824,938

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015		Dec. 31, 2014
Assets:
Rental property, net	$ 1,276,960	[1]	$ 1,288,873	[2]
Assets held-for-sale	12,011		59,717
Cash and cash equivalents	12,875		13,323
Escrows and reserves	1,699		2,986
Accounts and other receivables, net of allowance for doubtful accounts of $1,171 and $1,207, respectively	8,882		10,587
Accrued straight-line rents, net of allowance for doubtful accounts of $141 and $104, respectively	40,725		34,226
Notes receivable, net	34,000		63,679
Investment in affiliates	48,490		47,482
Deferred costs, net	45,707		43,991
Prepaid expenses and other assets	8,021		7,712
Intangible assets, net	37,154		45,884
Total assets	1,526,524	[3],[4]	1,618,460
Liabilities:
Mortgage and Construction loans	313,217		305,139
Unsecured term loan	300,000		300,000
Unsecured revolving credit facility	155,000		205,000
Liabilities held-for-sale	227		4,562
Accounts payable and other liabilities	39,026		41,113
Accrued interest	1,594		1,720
Rents received in advance	6,286		7,971
Tenant security deposits	5,822		5,891
Deferred market rent, net	2,360		2,827
Total liabilities	823,532		874,223
Noncontrolling interests in the Operating Partnership	30,663		33,332
Equity:
Common shares, $0.001 par value, 150,000 shares authorized; 57,835 and 58,815 shares issued and outstanding, respectively	58		59
Additional paid-in capital	906,274		913,282
Accumulated other comprehensive loss	(4,283)		(3,268)
Dividends in excess of accumulated earnings	(390,520)		(360,066)
Total equity	672,329		710,905
Total liabilities, noncontrolling interests and equity	1,526,524		1,618,460
Series A Preferred Shares
Equity:
Series A Preferred Shares, $25 per share liquidation preference, 6,400 shares issued and outstanding	$ 160,000		$ 160,000
[1]	Excludes rental property totaling $11.5 million at September 30, 2015 related to Newington Business Park Center, which was classified as held-for-sale at September 30, 2015.
[2]	Excludes rental property totaling $57.7 million at December 31, 2014 related to the sale of the Richmond Portfolio, which was classified as held-for-sale at December 31, 2014 and was sold on March 19, 2015.
[3]	Corporate assets not allocated to any of our reportable segments totaled $45,358 and $85,238 at September 30, 2015 and 2014, respectively.
[4]	Total assets include our investment in properties that are owned through joint ventures that are not consolidated within our condensed consolidated financial statements. For more information on our unconsolidated investments, including location within our reportable segments, see note 6, Investment in Affiliates.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts, accounts and other receivables	$ 1,171	$ 1,207
Allowance for doubtful accounts, accrued straight-line rents	$ 141	$ 104
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	50,000,000	50,000,000
Series A Preferred Shares liquidation preference	$ 25	$ 25
Series A Preferred Shares, shares issued	6,400,000	6,400,000
Series A Preferred Shares, shares outstanding	6,400,000	6,400,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	57,835,000	58,815,000
Common stock, shares outstanding	57,835,000	58,815,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014
Revenues:
Rental	$ 34,828	$ 31,915	$ 104,051		$ 93,967
Tenant reimbursements and other	8,026	8,140	25,690		24,758
Total revenues	42,854	40,055	129,741		118,725
Operating expenses:
Property operating	10,901	10,564	34,676		32,825
Real estate taxes and insurance	4,815	4,059	14,668		12,431
General and administrative	4,605	4,955	15,110		15,370
Acquisition costs	0	1,488	0		2,667
Depreciation and amortization	16,758	15,217	49,909		44,357
Impairment of rental property	0	0	0		3,956
Total operating expenses	37,079	36,283	114,363		111,606
Operating income	5,775	3,772	15,378		7,119
Other expenses (income)
Interest expense	6,589	6,116	20,222		17,884
Interest and other income	(995)	(1,684)	(5,797)		(5,112)
Equity in earnings of affiliates	(432)	(412)	(1,235)		(385)
Gain on sale of rental property	(3,384)	0	(3,384)		(21,230)
Total other expenses (income)	1,778	4,020	9,806		(8,843)
Income from continuing operations	3,997	(248)	5,572		15,962
Discontinued operations:
Income (loss) from operations	0	297	(975)		(359)
Loss on debt extinguishment	0	0	(489)		0
Gain on sale of rental property	0	0	857		1,338
Income (loss) from discontinued operations	0	297	(607)	[1]	979	[1]
Net income	3,997	49	4,965		16,941
Less: Net (income) loss attributable to noncontrolling interests	(38)	131	189		(327)
Net income attributable to First Potomac Realty Trust	3,959	180	5,154		16,614
Less: Dividends on preferred shares	(3,100)	(3,100)	(9,300)		(9,300)
Net income (loss) attributable to common shareholders	$ 859	$ (2,920)	$ (4,146)		$ 7,314
Basic and diluted earnings per common share:
Income (loss) from continuing operations (in dollars per share)	$ 0.01	$ (0.05)	$ (0.06)		$ 0.10
Income (loss) from discontinued operations (in dollars per share)	0	0	(0.01)		0.02
Net income (loss) (in dollars per share)	$ 0.01	$ (0.05)	$ (0.07)		$ 0.12
Weighted average common shares outstanding:
Basic (in shares)	57,961	58,167	58,155		58,137
Diluted (in shares)	58,045	58,167	58,155		58,209
[1]	Includes the operating results from the Richmond Portfolio, Patrick Center, West Park, Girard Business Center and Gateway Center. For information, see note 7(b), Dispositions - Discontinued Operations.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 3,997	$ 49	$ 4,965	$ 16,941
Unrealized gain on derivative instruments	171	1,910	560	1,231
Unrealized loss on derivative instruments	(903)	0	(1,620)	(125)
Total comprehensive income	3,265	1,959	3,905	18,047
Net (income) loss attributable to noncontrolling interests	(38)	131	189	(327)
Net loss (gain) from derivative instruments attributable to noncontrolling interests	31	(82)	45	(47)
Comprehensive income attributable to First Potomac Realty Trust	$ 3,258	$ 2,008	$ 4,139	$ 17,673

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities:
Net income	$ 4,965	$ 16,941
Discontinued operations:
Gain on sale of rental property	(857)	(1,338)
Depreciation and amortization	1,222	2,853
Depreciation and amortization	50,387	45,157
Stock based compensation	2,337	2,817
Bad debt expense	525	918
Amortization of deferred market rent	132	(43)
Amortization of financing costs and discounts	1,048	1,073
Equity in earnings of affiliates	(1,235)	(385)
Distributions from investments in affiliates	632	1,229
Gain on sale of rental property	(3,384)	(21,230)
Impairment of rental property	0	3,956
Changes in assets and liabilities:
Escrows and reserves	1,111	3,809
Accounts and other receivables	1,151	583
Accrued straight-line rents	(6,781)	(4,893)
Prepaid expenses and other assets	(868)	(736)
Tenant security deposits	(613)	868
Accounts payable and accrued expenses	1,114	431
Accrued interest	(125)	79
Rents received in advance	(1,952)	931
Deferred costs	(6,069)	(7,606)
Total adjustments	37,775	28,473
Net cash provided by operating activities	42,740	45,414
Cash flows from investing activities:
Investment in note receivable	0	(9,000)
Proceeds from sale of rental property	71,899	85,284
Principal payments from note receivable	29,720	129
Change in escrow and reserve accounts	176	0
Additions to rental property and furniture, fixtures and equipment	(36,832)	(25,464)
Additions to construction in progress	(13,014)	(9,295)
Acquisition of rental property and associated intangible assets	0	(150,731)
Contributions to investment in affiliates	405	1,653
Distributions from investment in affiliates	0	1,951
Net cash provided by (used in) investing activities	51,544	(108,779)
Cash flows from financing activities:
Financing costs	(2,236)	(496)
Issuance of debt	180,956	209,794
Repayments of debt	(226,155)	(106,127)
Dividends to common shareholders	(26,425)	(26,391)
Dividends to preferred shareholders	(9,300)	(9,300)
Contributions from consolidated joint venture partners	0	161
Distributions to consolidated joint venture partners	(96)	0
Distributions to noncontrolling interests	(1,181)	(1,183)
Repurchases of common shares	(10,180)	0
Operating partnership unit redemptions	(134)	0
Proceeds from stock option exercises	19	160
Net cash (used in) provided by financing activities	(94,732)	66,618
Net (decrease) increase in cash and cash equivalents	(448)	3,253
Cash and cash equivalents, beginning of period	13,323	8,740
Cash and cash equivalents, end of period	12,875	11,993
Cash paid for interest, net	19,078	16,606
Non-cash investing and financing activities:
Debt assumed in connection with the acquisition of rental property	0	37,269
Value of common shares retired to settle employee income tax obligations	454	383
Issuance of common Operating Partnership units in connection with the acquisition of rental property	(1,123)	350
Changes in accruals:	0	40
Changes in accruals:
Additions to rental property and furniture, fixtures and equipment	(2,034)	(290)
Additions to development and redevelopment	$ 640	$ (782)

Consolidated Statements of Cas7

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Capitalized interest on indebtedness paid in cash	$ 1,300	$ 2,800
Surrendered common shares to satisfy statutory minimum federal income tax obligations	454	383
Change in redemption value, noncontrolling interest	$ 3,600	3,700
Operating Partnership units issued for acquisition	0
Furniture and Fixtures [Member]
Accrued capital expenditure	$ 7,300	8,200
Development and Redevelopment [Member]
Accrued capital expenditure	$ 2,000	$ 800
840 First Street, NE [Member]
Operating Partnership units issued for acquisition		3,125
Operating Partnership units fair valued		$ 40

Description of Business

Description of Business	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Description of Business	Description of Business First Potomac Realty Trust (the “Company”) is a leader in the ownership, management, development and redevelopment of office and business park properties in the greater Washington, D.C. region. The Company strategically focuses on acquiring and redeveloping properties that it believes can benefit from its intensive property management, leasing expertise, market knowledge and established relationships, and seeks to reposition these properties to increase their profitability and value. The Company’s portfolio primarily contains a mix of single-tenant and multi-tenant office properties and business parks. Office properties are single-story and multi-story buildings that are primarily for office use; and business parks contain buildings with office features combined with some industrial property space. The Company separates its properties into four distinct reporting segments, which it refers to as the Washington, D.C., Maryland, Northern Virginia and Southern Virginia reporting segments. References in these unaudited condensed consolidated financial statements to “we,” “our,” “us,” the “Company” or “First Potomac,” refer to the Company and its subsidiaries, on a consolidated basis, unless the context indicates otherwise. We conduct our business through our Operating Partnership. We are the sole general partner of, and, as of September 30, 2015 , owned 100% of the preferred interest and 95.7% of the common interest in the Operating Partnership. The remaining common interests in the Operating Partnership, which are presented as noncontrolling interests in the Operating Partnership in the accompanying unaudited condensed consolidated financial statements, are limited partnership interests, some of which are owned by two of our executive officers and one of our trustees, each of whom contributed certain properties and other assets to us upon our formation, and the remainder of which are owned by other unrelated parties. At September 30, 2015 , we wholly owned or had a controlling interest in properties totaling 7.8 million square feet and had a noncontrolling ownership interest in properties totaling an additional 0.9 million square feet through five unconsolidated joint ventures. We also owned land that can support 1.3 million square feet of additional development. Our consolidated properties were 89.9% occupied by 491 tenants at September 30, 2015 . We did not include square footage that was in development or redevelopment, which totaled 0.2 million square feet at September 30, 2015 , in our occupancy calculation. We derive substantially all of our revenue from leases of space within our properties. As of September 30, 2015 , our largest tenant was the U.S. Government, which accounted for 13.5% of our total annualized cash basis rent, and the U.S. Government combined with government contractors accounted for 25.7% of our total annualized cash basis rent as of September 30, 2015 . We operate so as to qualify as a real estate investment trust (“REIT”) for federal income tax purposes.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies (a) Principles of Consolidation Our unaudited condensed consolidated financial statements include our accounts and the accounts of our Operating Partnership and the subsidiaries in which we or our Operating Partnership has a controlling interest, which includes First Potomac Management LLC, a wholly-owned subsidiary that manages the majority of our properties. All intercompany balances and transactions have been eliminated in consolidation. We have condensed or omitted certain information and note disclosures normally included in financial statements presented in accordance with U.S. generally accepted accounting principles (“GAAP”) in the accompanying unaudited condensed consolidated financial statements. We believe the disclosures made are adequate to prevent the information presented from being misleading. However, the unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in our annual report on Form 10-K for the year ended December 31, 2014 and as updated from time to time in our other filings with the SEC. In our opinion, the accompanying unaudited condensed consolidated financial statements reflect all adjustments, consisting of normal recurring adjustments and accruals necessary to present fairly our financial position as of September 30, 2015 , the results of our operations and our comprehensive income for the three and nine months ended September 30, 2015 and 2014 and our cash flows for the nine months ended September 30, 2015 and 2014 . Interim results are not necessarily indicative of full-year performance due, in part, to the timing of transactions and the impact of acquisitions and dispositions throughout the year, as well as the seasonality of certain operating expenses such as utilities expense and snow and ice removal costs. (b) Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires our management team to make a number of estimates and assumptions relating to the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the unaudited condensed consolidated financial statements and the reported amounts of revenues and expenses during the period. Estimates include the amount of accounts receivable that may be uncollectible, recoverability of notes receivable, future cash flows, discount and capitalization rate assumptions used to fair value acquired properties and to test impairment of certain long-lived assets and goodwill, derivative valuations, market lease rates, lease-up periods, leasing and tenant improvement costs used to fair value intangible assets acquired and probability weighted cash flow analysis used to fair value contingent liabilities. Actual results could differ from those estimates. (c) Rental Property Rental property is initially recorded at fair value, when acquired in a business combination, or initial cost when constructed or acquired in an asset purchase. Improvements and replacements are capitalized at cost when they extend the useful life, increase capacity or improve the efficiency of the asset. Repairs and maintenance are charged to expense when incurred. Depreciation and amortization are recorded on a straight-line basis over the estimated useful lives of the assets. The estimated useful lives of our assets, by class, are as follows: Buildings 39 years Building improvements 5 to 20 years Furniture, fixtures and equipment 5 to 15 years Lease related intangible assets The term of the related lease Tenant improvements Shorter of the useful life of the asset or the term of the related lease We regularly review market conditions for possible impairment of a property’s carrying value. When circumstances such as adverse market conditions, changes in management’s intended holding period or potential sale to a third party indicate a possible impairment of the carrying value of a property, an impairment analysis is performed. We assess potential impairments based on an estimate of the future undiscounted cash flows (excluding interest charges) expected to result from the property’s use and eventual disposition. This estimate is based on projections of future revenues, expenses, capital improvement costs to maintain the operating capacity, expected holding periods and capitalization rates. These cash flows consider factors such as expected market trends and leasing prospects, as well as the effects of leasing demand, competition and other factors. If impairment exists due to the inability to recover the carrying value of a real estate investment based on forecasted undiscounted cash flows, an impairment loss is recorded to the extent that the carrying value exceeds the estimated fair value of the property. Further, we will record an impairment loss if we expect to dispose of a property in the near term, at a price below carrying value. In such an event, we will classify the property as held-for-sale and record an impairment loss based on the difference between a property’s carrying value and its projected sales price less any estimated costs to sell. We will classify a building as held-for-sale in accordance with GAAP in the period in which we have made the decision to dispose of the building, our Board of Trustees or a designated delegate has approved the sale, there is a high likelihood a binding agreement to purchase the property will be signed under which the buyer will be required to commit a significant amount of nonrefundable cash and no significant financing contingencies exist that could cause the transaction not to be completed in a timely manner. We will cease recording depreciation on a building once it has been classified as held-for-sale. In the second quarter of 2014, we prospectively adopted Accounting Standards Update No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity (“ASU 2014-08”), which impacts the presentation of operations and gains or losses from disposed properties and properties classified as held-for-sale. ASU 2014-08 states that a disposal of a component of an entity or a group of components of an entity is required to be reported in discontinued operations only if the disposal represents a strategic shift that has, or will have, a major effect on an entity’s operations or financial results. The operations of all properties that were sold prior to the adoption of ASU 2014-08, two properties (West Park and Patrick Center) that were classified as held-for-sale in previously issued financial statements prior to our adoption of ASU 2014-08 and were subsequently sold, as well as our Richmond, Virginia portfolio, which included Chesterfield Business Center, Hanover Business Center, Park Central, Virginia Technology Center and a three-acre parcel of undeveloped land (the “Richmond Portfolio”), are reflected within discontinued operations in our consolidated statements of operations for all periods presented. If the building does not qualify as a discontinued operation under ASU 2014-08, we will classify the building's operating results, together with any impairment charges and any gains or losses on the sale of the building, in continuing operations for all periods presented in our consolidated statements of operations. We will classify the assets and liabilities related to the building as held-for-sale in our consolidated balance sheet for the period the held-for-sale criteria were met. If the building does qualify as a discontinued operation under ASU 2014-08, we will classify the building's operating results, together with any impairment charges and any gains or losses on the sale of the building, in discontinued operations in our consolidated statements of operations for all periods presented and classify the assets and liabilities related to the building as held-for-sale in our consolidated balance sheets for the periods presented. Interest expense is reclassified to discontinued operations only to the extent the disposed or held-for-sale property is secured by specific mortgage debt and the mortgage debt will not be assigned to another property owned by us after the disposition. We recognize the fair value, if sufficient information exists to reasonably estimate the fair value, of any liability for conditional asset retirement obligations when assumed or incurred, which is generally upon acquisition, construction, development or redevelopment and/or through the normal operation of the asset. We capitalize interest costs incurred on qualifying expenditures for real estate assets under development or redevelopment, which include our investments in assets owned through unconsolidated joint ventures that are under development or redevelopment, while being readied for their intended use in accordance with accounting requirements regarding capitalization of interest. We will capitalize interest when qualifying expenditures for the asset have been made, activities necessary to get the asset ready for its intended use are in progress and interest costs are being incurred. Capitalized interest also includes interest associated with expenditures incurred to acquire developable land while development activities are in progress. We also capitalize direct compensation costs of our construction personnel who manage the development and redevelopment projects, but only to the extent the employee’s time can be allocated to a project. Any portion of construction management costs not directly attributable to a specific project are recognized as general and administrative expense in the period incurred. We do not capitalize any other general and administrative costs such as office supplies, office rent expense or an overhead allocation to our development or redevelopment projects. Capitalized compensation costs were immaterial for the nine months ended September 30, 2015 and 2014 . Capitalization of interest ends when the asset is substantially complete and ready for its intended use, but no later than one year from completion of major construction activity, if the property is not occupied. We place redevelopment and development assets into service at this time and commence depreciation upon the substantial completion of tenant improvements and the recognition of revenue. Capitalized interest is depreciated over the useful life of the underlying assets, commencing when those assets are placed into service. (d) Notes Receivable We provide loans to the owners of real estate properties, which can be collateralized by interest in the real estate property. We record these loans as “Notes receivable, net” in our consolidated balance sheets. The loans are recorded net of any discount or issuance costs, which are amortized over the life of the respective note receivable using the effective interest method. We record interest earned from notes receivable and amortization of any discount costs or issuance costs within “Interest and other income” in our consolidated statements of operations. We will establish a provision for anticipated credit losses associated with our notes receivable when we anticipate that we may be unable to collect any contractually due amounts. This determination is based upon such factors as delinquencies, loss experience, collateral quality and current economic or borrower conditions. Our collectability of our notes receivable may be adversely impacted by the financial stability of the Washington, D.C. region and the ability of the underlying assets to keep current tenants or attract new tenants. Estimated losses are recorded as a charge to earnings to establish an allowance for credit losses that we estimate to be adequate based on these factors. Based on the review of the above criteria, we did not record an allowance for credit losses for our notes receivable during the nine months ended September 30, 2015 and 2014 . (e) Application of New Accounting Standards In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers and will replace most existing revenue recognition guidance when it becomes effective. In July 2015, the FASB deferred by one year the mandatory effective date of ASU 2014-09 from January 1, 2017 to January 1, 2018. Early adoption is permitted, but not prior to the original effective date of January 1, 2017. ASU 2014-09 permits the use of either the retrospective or cumulative effect transition method. We have not yet selected a transition method and are evaluating the impact that ASU 2014-09 will have on our consolidated financial statements or related disclosures. In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern (“ASU 2014-15”), which requires an entity to evaluate whether conditions or events, in the aggregate, raise substantial doubt about the entity's ability to continue as a going concern for one year from the date the financial statements are issued or are available to be issued. The guidance will become effective for annual periods ending after December 15, 2016. The adoption of ASU 2014-15 is not expected to have an impact on our consolidated financial statements or related disclosures. In January 2015, the FASB issued Accounting Standards Update No. 2015-01, Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items ("ASU 2015-01"), which eliminates the concept of extraordinary items from GAAP and the requirement that an entity separately report extraordinary items in the income statement. ASU 2015-01 also requires that entities continue to evaluate whether items are unusual in nature or infrequent in occurrence for presentation and disclosure purposes. ASU 2015-01 applies to all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted and the guidance may be applied prospectively or retrospectively to all prior periods presented in the consolidated financial statements. The adoption of ASU 2015-01 is not expected to have a material impact on our consolidated financial statements or related disclosures. In February 2015, the FASB issued Accounting Standards Update No. 2015-02, Amendments to the Consolidation Analysis (“ASU 2015-02”), which makes certain changes to both the variable interest model and the voting model, including changes to the identification of variable interests (fees paid to a decision maker or service provider), the variable interest entity characteristics for a limited partnership or similar entity and the primary beneficiary determination. ASU 2015-02 is effective January 1, 2016. The adoption of ASU 2015-02 is not expected to have a material impact on our consolidated financial statements or related disclosures. In April 2015, the FASB issued Accounting Standards Update No. 2015-03, Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”), which requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying value of the debt liability. ASU 2015-03 is effective for periods beginning after December 15, 2015 with early adoption permitted and will be applied on a retrospective basis. The guidance will be effective on January 1, 2016 and is not expected to have a material impact on our consolidated financial statements or related disclosures. (f) Reclassifications Certain prior year amounts have been reclassified to conform to the current year presentation as a result of reclassifying the operating results of several properties as discontinued operations. For more information, see note 7 , Dispositions.

Earnings Per Common Share

Earnings Per Common Share	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share Basic earnings or loss per common share (“EPS”) is calculated by dividing net income or loss attributable to common shareholders by the weighted average common shares outstanding for the periods presented. Diluted EPS is computed after adjusting the basic EPS computation for the effect of dilutive common equivalent shares outstanding during the periods presented, which include stock options, non-vested shares and preferred shares. We apply the two-class method for determining EPS as our outstanding unvested shares with non-forfeitable dividend rights are considered participating securities. Our excess of distributions over earnings related to participating securities is shown as a reduction in total earnings attributable to common shareholders in our computation of EPS. The following table sets forth the computation of our basic and diluted earnings per common share (amounts in thousands, except per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Numerator for basic and diluted earnings per common share: Income (loss) from continuing operations $ 3,997 $ (248 ) $ 5,572 $ 15,962 Income (loss) from discontinued operations — 297 (607 ) 979 Net income 3,997 49 4,965 16,941 Less: Net (income) loss from continuing operations attributable to noncontrolling interests (38 ) 144 163 (285 ) Less: Net (income) loss from discontinued operations attributable to noncontrolling interests — (13 ) 26 (42 ) Net income attributable to First Potomac Realty Trust 3,959 180 5,154 16,614 Less: Dividends on preferred shares (3,100 ) (3,100 ) (9,300 ) (9,300 ) Net income (loss) attributable to common shareholders 859 (2,920 ) (4,146 ) 7,314 Less: Allocation to participating securities (69 ) (80 ) (211 ) (235 ) Net income (loss) attributable to common shareholders $ 790 $ (3,000 ) $ (4,357 ) $ 7,079 Denominator for basic and diluted earnings per common share: Weighted average common shares outstanding: Basic 57,961 58,167 58,155 58,137 Diluted 58,045 58,167 58,155 58,209 Basic and diluted earnings per common share: Income (loss) from continuing operations $ 0.01 $ (0.05 ) $ (0.06 ) $ 0.10 (Loss) income from discontinued operations — — (0.01 ) 0.02 Net income (loss) $ 0.01 $ (0.05 ) $ (0.07 ) $ 0.12 In accordance with GAAP regarding earnings per common share, we did not include the following potential weighted average common shares in our calculation of diluted earnings per common share as they are anti-dilutive for the periods presented (amounts in thousands): Three Months Ended Nine Months Ended 2015 2014 2015 2014 Stock option awards 987 1,103 1,037 1,143 Non-vested share awards 307 433 374 401 Series A Preferred Shares (1) 14,627 12,356 14,190 12,438 15,921 13,892 15,601 13,982 (1) Our Series A Preferred Shares are only convertible into our common shares upon certain changes in control of our Company. The dilutive shares are calculated as the daily average of the face value of the Series A Preferred Shares divided by the outstanding common share price.

Rental Property

Rental Property	9 Months Ended
	Sep. 30, 2015
Real Estate [Abstract]
Rental Property	Rental Property Rental property represents buildings and related improvements, net of accumulated depreciation, and developable land that are wholly owned or owned by an entity in which we have a controlling interest. All of our rental properties are located within the greater Washington, D.C. region. Rental property consists of the following (dollars in thousands): September 30, 2015 (1) December 31, 2014 (2) Land and land improvements $ 319,569 $ 325,214 Buildings and building improvements 931,749 949,683 Construction in progress 83,778 69,181 Tenant improvements 179,728 159,867 Furniture, fixtures and equipment 431 427 1,515,255 1,504,372 Less: accumulated depreciation (238,295 ) (215,499 ) $ 1,276,960 $ 1,288,873 (1) Excludes rental property totaling $11.5 million at September 30, 2015 related to Newington Business Park Center, which was classified as held-for-sale at September 30, 2015. (2) Excludes rental property totaling $57.7 million at December 31, 2014 related to the sale of the Richmond Portfolio, which was classified as held-for-sale at December 31, 2014 and was sold on March 19, 2015 . Development and Redevelopment Activity We will place completed development and redevelopment assets in service upon the earlier of one year after major construction activity is deemed to be substantially complete or upon occupancy. We construct office buildings and/or business parks on a build-to-suit basis or with the intent to lease upon completion of construction. We own developable land that can accommodate 1.3 million square feet of additional building space, of which, 0.7 million is located in the Washington, D.C. reporting segment, 0.1 million in the Maryland reporting segment, 0.4 million in the Northern Virginia reporting segment and 0.1 million in the Southern Virginia reporting segment. During the third quarter of 2014, we signed a lease for 167,000 square feet at a to-be-constructed building in our Northern Virginia reporting segment on vacant land that we have in our portfolio. We currently expect to complete construction of the new building in early 2016 and expect to complete the construction of the tenant improvements in the second half of 2016. However, we can provide no assurance regarding the timing of the project. At September 30, 2015, our total investment in the development project, excluding tenant improvement and leasing commission costs, was $18.7 million , which included the original cost basis of the applicable portion of the vacant land of $5.2 million . The majority of the costs incurred as of September 30, 2015 in excess of the original cost basis of the land relate to design and permit fees, site preparation costs, foundation work and completion of the superstructure. On August 4, 2011, we formed a joint venture, in which we have a 97% interest, with an affiliate of Perseus Realty, LLC to acquire Storey Park in our Washington, D.C. reporting segment. At the time, the site was leased to Greyhound Lines, Inc. (“Greyhound”), which subsequently relocated its operations. Greyhound’s lease expired on August 31, 2013 , at which time the property was placed into development with the anticipation of developing a mixed-use project on the 1.6 acre site, which can accommodate up to 712,000 square feet. At September 30, 2015, our total investment in the development project was $57.2 million , which included the original cost basis of the property of $43.3 million . The majority of the costs in excess of the original cost basis relate to architectural fees and site preparation costs, as well as capitalized interest and taxes. We are currently exploring our options related to this property; however, until a definitive plan for the property has been reached and we begin significant development activities, we cannot determine the total cost of the project or the anticipated completion date. While we continue pre-development work on Storey Park, we engaged a sales broker to strategically monetize our majority interest in Storey Park, which could result in a sale of all or a portion of our interest in Storey Park; however, we can provide no assurances regarding the timing or pricing of such transaction, or that a sale will occur at all. On December 28, 2010, we acquired 440 First Street, NW, a vacant eight-story office building in our Washington, D.C. reporting segment. In October 2013, we substantially completed the redevelopment of the 139,000 square foot property. During the fourth quarter of 2014, all vacant space at the property was placed in service. At September 30, 2015, the property was 67.4% leased and 51.2% occupied. At September 30, 2015, our total investment in the redevelopment project was $55.5 million , which included the original cost basis of the property of $23.6 million . During the third quarter of 2015, we did no t place in-service any significant completed development or redevelopment space. At September 30, 2015, we had no completed development or redevelopment space that have yet to be placed in service.

Notes Receivable

Notes Receivable	9 Months Ended
	Sep. 30, 2015
Receivables [Abstract]
Notes Receivable	Notes Receivable Below is a summary of our notes receivable for our outstanding mezzanine loans (dollars in thousands): Balance at September 30, 2015 Property Face Amount Unamortized Balance Interest Rate 950 F Street, NW $ 34,000 $ — $ 34,000 9.75 % Balance at December 31, 2014 Property Face Amount Unamortized Balance Interest Rate 950 F Street, NW $ 34,000 $ — $ 34,000 9.75 % America’s Square 29,720 (41 ) 29,679 9.00 % $ 63,720 $ (41 ) $ 63,679 On February 24, 2015, the owners of America’s Square, a 461,000 square foot office complex located in Washington, D.C., prepaid a mezzanine loan that had an outstanding balance of $29.7 million . We provided the owners of America’s Square a $30.0 million loan in April 2011, which was secured by a portion of the owner’s interest in the property. The loan had a fixed-interest rate of 9.0% and was scheduled to mature on May 1, 2016 . We received a yield maintenance payment of $2.4 million with the repayment of the loan. The proceeds from the loan repayment, including the yield maintenance payment, were used to pay down a portion of the outstanding balance of our unsecured revolving credit facility. In December 2010, we provided a $25.0 million mezzanine loan to the owners of 950 F Street, NW, a ten-story, 287,000 square-foot office/retail building located in Washington, D.C. that is secured by a portion of the owners’ interest in the property. The loan requires monthly interest-only payments with a constant interest rate over the life of the loan. On January 10, 2014, we amended the loan to increase the outstanding balance to $34.0 million and reduce the fixed interest rate from 12.5% to 9.75% . The amended mezzanine loan matures on April 1, 2017 and is repayable in full on or after December 21, 2015. The $9.0 million increase in the loan was provided by a draw under our unsecured revolving credit facility. We recorded interest income related to our notes receivable of $0.8 million and $2.9 million for the three and nine months ended September 30, 2015, respectively, and $1.5 million and $4.5 million for the three and nine months ended September 30, 2014, respectively, which is included within “Interest and other income” in our consolidated statements of operations. We recorded no income from the amortization of origination fees for the three months ended September 30, 2015 and $5 thousand for the nine months ended September 30, 2015. We recorded $7 thousand and $25 thousand of income from the amortization of origination fees for the three and nine months ended September 30, 2014, respectively. During the first quarter of 2014, we wrote-off $0.1 million of unamortized fees related to the original 950 F Street, NW mezzanine loan. We recorded income from the yield maintenance payment of $2.4 million during the first quarter of 2015. The yield maintenance payment and the amortization and write-off of unamortized fees are recorded within “Interest and other income” in our consolidated statements of operations.

Investment in Affiliates

Investment in Affiliates	9 Months Ended
	Sep. 30, 2015
Equity Method Investments and Joint Ventures [Abstract]
Investment in Affiliates	Investment in Affiliates We own an interest in several joint ventures that own properties. We do not control the activities that are most significant to the joint ventures. As a result, the assets, the liabilities and the operating results of these noncontrolled joint ventures are not consolidated within our unaudited condensed consolidated financial statements. Our investments in these joint ventures are recorded as “Investment in affiliates” in our consolidated balance sheets. Our investment in affiliates consisted of the following (dollars in thousands): Reporting Segment Ownership September 30, 2015 December 31, 2014 Prosperity Metro Plaza Northern Virginia 51 % $ 24,980 $ 24,651 1750 H Street, NW Washington, D.C. 50 % 15,444 14,834 Aviation Business Park Maryland 50 % 5,879 5,748 RiversPark I and II (1) Maryland 25 % 2,187 2,249 $ 48,490 $ 47,482 (1) RiversPark I and RiversPark II are owned through two separate joint ventures. On November 12, 2014, our 51% owned unconsolidated joint venture repaid a $48.3 million mortgage loan that encumbered Prosperity Metro Plaza, a two-building, 327,000 square-foot office building located in Merrifield, Virginia. Simultaneously with the repayment, the joint venture entered into a new $50.0 million mortgage loan that has a fixed-interest rate of 3.91% . The new loan requires interest only payments through December 2024 , at which time the loan requires principal and interest payments through its maturity date. The loan has a maturity date of December 1, 2029 and is repayable in full without penalty on or after June 1, 2029 . On September 26, 2014, our two 25% owned unconsolidated joint ventures amended a $28.0 million mortgage loan that encumbers RiversPark I and II, a six-building, 308,000 square-foot business park located in Columbia, Maryland. The amended mortgage loan reduced the variable interest rate spread by 60 basis points and reduced the amount of outstanding principal recourse to us from 25% to 10% . The amended loan matures on September 26, 2017 and is repayable in full without penalty at any time during the term of the loan. On July 10, 2014, an unconsolidated joint venture, in which we have a 50% ownership interest, repaid a $27.9 million mortgage loan that encumbered 1750 H Street, NW, a ten-story, 113,000 square-foot office building located in Washington, D.C. Simultaneously with the repayment, the joint venture entered into a new $32.0 million mortgage loan that has a fixed interest rate of 3.92% , a maturity date of August 1, 2024 , and is repayable in full without penalty on or after August 1, 2021 . The new loan requires monthly interest-only payments with a constant interest rate over the life of the loan. The net assets of our unconsolidated joint ventures consisted of the following (dollars in thousands): September 30, 2015 December 31, 2014 Assets: Rental property, net $ 194,442 $ 193,533 Cash and cash equivalents 5,510 4,567 Other assets 15,162 16,748 Total assets 215,114 214,848 Liabilities: Mortgage loans (1) 110,000 110,000 Other liabilities 5,413 7,256 Total liabilities 115,413 117,256 Net assets $ 99,701 $ 97,592 (1) Of the total mortgage debt that encumbers our unconsolidated properties, $2.8 million is recourse to us. We believe the fair value of the potential liability to us under this guaranty is inconsequential as the likelihood of our need to perform under the debt agreement is remote. Our share of earnings or losses related to our unconsolidated joint ventures is recorded in our consolidated statements of operations as “Equity in (earnings) losses of affiliates.” The following table summarizes the results of operations of our unconsolidated joint ventures, which, due to our varying ownership interests in the joint ventures and the varying operations of the joint ventures, may not be reflective of the amounts recorded in our consolidated statements of operations (dollars in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Total revenues $ 5,975 $ 5,713 $ 18,205 $ 17,245 Total operating expenses (1,866 ) (1,818 ) (5,778 ) (5,738 ) Net operating income 4,109 3,895 12,427 11,507 Depreciation and amortization (2,254 ) (2,256 ) (6,790 ) (7,323 ) Other expense, net (980 ) (890 ) (2,928 ) (2,978 ) Net income $ 875 $ 749 $ 2,709 $ 1,206 We earn various fees from several of our joint ventures, which include management fees, leasing commissions and construction management fees. We recognize fees only to the extent of the third party ownership interest in our unconsolidated joint ventures. We recognized fees from our unconsolidated joint ventures of $0.2 million and $0.5 million for the three and nine months ended September 30, 2015, respectively, as well as for the three and nine months ended September 30, 2014, respectively, which are reflected within “Tenant reimbursements and other revenues” in our consolidated statements of operations.

Dispositions

Dispositions	9 Months Ended
	Sep. 30, 2015
Discontinued Operations and Disposal Groups [Abstract]
Dispositions	Dispositions During the second quarter of 2014, we prospectively adopted ASU 2014-08, which states that a component of an entity or a group of components of an entity is required to be reported in discontinued operations only if the disposal represents a strategic shift that has, or will have, a major effect on an entity’s operations and financial results. All other disposed properties will have their operating results reflected within continuing operations on our consolidated statements of operations for all periods presented. We have had, and will have, no continuing involvement with any of our disposed properties subsequent to their disposal. The operations of the disposed properties were not subject to any income based taxes. Other than the properties discussed below in this Note 7, Dispositions , we did not dispose of or enter into any agreements to sell any other properties during the nine months ended September 30, 2015 and 2014 . (a) Disposed or Held-for-Sale Properties within Continuing Operations The following table is a summary of property dispositions or held-for-sale properties whose operating results are included in continuing operations in our consolidated statements of operations for the periods presented (dollars in thousands): Property Reporting Disposition Date Property Type Square Feet Net Sale Proceeds Newington Business Park Center (1) Northern Virginia TBD Business Park 255,600 $ N/A Rumsey Center Maryland 7/28/2015 Business Park 135,015 14,956 Owings Mills Business Park Maryland 10/16/2014 Business Park 180,475 12,417 Corporate Campus at Ashburn Center Northern Virginia 6/26/2014 Business Park 194,184 39,910 (1) Newington Business Park Center was classified as held-for-sale at September 30, 2015. The sale is expected to be completed in the fourth quarter of 2015 or in early 2016; however, we can provide no assurances regarding the timing or pricing of the sale, or that such sale will occur at all. In October 2015, we entered into a non-binding contract to sell Newington Business Park Center, a seven-building, 255,600 square foot business park, which is located in our Northern Virginia reporting segment. The sale is expected to be completed in the fourth quarter of 2015; however, we can provide no assurances regarding the timing or pricing of the sale, or that such sale will occur at all. As of September 30, 2015, Newington Business Park Center met our held-for-sale criteria and, therefore, the assets of the buildings were classified within “Assets held-for-sale” and the liabilities of the buildings, which totaled $0.2 million , were classified within “Liabilities held-for-sale” on our consolidated balance sheet at September 30, 2015. The majority of the assets classified within assets held-for-sale as of September 30, 2015 consisted of $3.1 million in land and land improvements, $13.7 million in buildings and building improvements, $0.8 million in tenant improvements and $6.1 million of accumulated depreciation. The remaining $0.5 million classified within assets held-for-sale consisted of accrued straight-line rents, net of allowance for doubtful accounts, deferred costs, net of accumulated amortization, and prepaid expenses and other assets. On July 28, 2015 , we sold Rumsey Center, a four-building, single-story business park, which is located in our Maryland reporting segment, totaling 135,000 square feet, for net proceeds of $15.0 million and reported a gain on sale of $3.4 million . We used the net proceeds from the sale of Rumsey Center to fund repurchases of our common shares and to repay a portion of the outstanding balance under our unsecured revolving credit facility. The operating results of Newington Business Park Center and Rumsey Center are reflected in continuing operations in our consolidated statements of operations for the three and nine months ended September 30, 2015 and 2014. The operating results of Corporate Campus at Ashburn Center and Owings Mills Business Park are reflected in continuing operations in our consolidated statements of operations for the three and nine months ended September 30, 2014. The following table summarizes the aggregate results of operations for the four properties that are included in continuing operations for the periods presented (dollars in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Revenues $ 890 $ 1,279 $ 3,422 $ 6,356 Property operating expenses (299 ) (529 ) (1,222 ) (2,289 ) Depreciation and amortization (98 ) (530 ) (714 ) (2,132 ) Interest expense (24 ) (111 ) (244 ) (334 ) Impairment of rental property — — — (3,956 ) Income (loss) from operations of disposed property 469 109 1,242 (2,355 ) Gain on sale of rental property 3,384 — 3,384 21,230 Net income from continuing operations of disposed property $ 3,853 $ 109 $ 4,626 $ 18,875 (b) Discontinued Operations The following table is a summary of property dispositions whose operating results are reflected as discontinued operations in our consolidated statements of operations for the periods presented (dollars in thousands): Reporting Segment Disposition Date Property Type Square Feet Net Sale Proceeds Richmond Portfolio Southern Virginia 3/19/2015 Business Park 827,900 $ 53,768 Patrick Center Maryland 4/16/2014 Office 66,269 10,888 West Park Maryland 4/2/2014 Office 28,333 2,871 Girard Business Center and Gateway Center Maryland 1/29/2014 Business Park and Office 341,973 31,616 The Richmond Portfolio was sold subsequent to our adoption of ASU 2014-08 and resulted in a strategic shift away from the Richmond, Virginia area. As a result, we reflected the operating results of the Richmond Portfolio as discontinued operations in our consolidated statements of operations for the periods presented. All properties sold prior to our adoption of ASU 2014-08 or classified as held-for-sale in previously issued consolidated financial statements prior to our adoption of ASU 2014-08 are classified within discontinued operations. The following table summarizes the results of operations of properties included in discontinued operations (dollars in thousands): Three Months Ended Nine Months Ended 2015 2014 2015 2014 Revenues $ — $ 1,949 $ 877 $ 5,705 Income (loss) from operations, before taxes (1) — 297 (975 ) (359 ) Loss on debt extinguishment — — (489 ) — Gain on sale of rental property — — 857 1,338 (1) During the first quarter of 2015, we accelerated $2.0 million of unamortized straight-line rents, deferred rent abatements and leasing commissions related to the sale of the Richmond Portfolio in March 2015. During the first quarter of 2014, we accelerated $1.5 million of unamortized straight-line rents, deferred rent abatements and leasing commissions related to the sale of both Girard Business Center and Gateway Center in January 2014.

Debt

Debt	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Debt	Debt Our borrowings consisted of the following (dollars in thousands): September 30, December 31, 2014 (1) Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030 (2) $ 313,217 $ 308,637 Unsecured term loan, effective interest rates ranging from LIBOR plus 1.65% to LIBOR plus 2.05%, with staggered maturity dates ranging from October 2018 to October 2020 (2) 300,000 300,000 Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017 (2) 155,000 205,000 $ 768,217 $ 813,637 (1) The balance at December 31, 2014, includes five mortgage loans that were repaid with the sale of the Richmond Portfolio on March 19, 2015. At December 31, 2014, the mortgage loans had an aggregate principal balance of $3.5 million and were classified within “Liabilities held-for-sale” on our consolidated balance sheet for December 31, 2014. (2) At September 30, 2015, LIBOR was 0.19% . All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR. (a) Mortgage and Construction Loans The following table provides a summary of our mortgage and construction loans at September 30, 2015 and December 31, 2014 (dollars in thousands): Encumbered Property Contractual Effective Maturity September 30, December 31, 2014 Jackson National Life Loan (1) 5.19% 5.19% August 2015 $ — $ 64,943 440 First Street, NW (2) LIBOR + 2.50% LIBOR + 2.50% May 2016 32,217 32,216 Storey Park (2) LIBOR + 2.50% LIBOR + 2.50% October 2016 22,000 22,000 Gateway Centre Manassas Building I 7.35% 5.88% November 2016 269 432 Hillside I and II 5.75% 4.62% December 2016 12,644 12,949 Redland Corporate Center Buildings II & III 4.20% 4.64% November 2017 64,866 65,816 Northern Virginia Development Project (2) LIBOR + 1.85% LIBOR + 1.85% September 2019 9,176 — 840 First Street, NE 5.72% 6.01% July 2020 36,054 36,539 Battlefield Corporate Center 4.26% 4.40% November 2020 3,568 3,692 1211 Connecticut Avenue, NW 4.22% 4.47% July 2022 29,257 29,691 1401 K Street, NW 4.80% 4.93% June 2023 36,386 36,861 11 Dupont Circle, NW (3) 4.05% 4.22% September 2030 66,780 — 4.54% (4) 313,217 305,139 Unamortized fair value adjustments (221 ) (370 ) Principal balance 312,996 304,769 Debt Classified within “Liabilities-Held-for-Sale” Richmond Portfolio (5) Hanover Business Center Building D 8.88% 6.63% August 2015 — 104 Chesterfield Business Center Buildings C,D,G and H 8.50% 6.63% September 2015 — 302 Hanover Business Center Building C 7.88% 6.63% December 2017 — 505 Chesterfield Business Center Buildings A,B,E and F 7.45% 6.63% June 2021 — 1,674 Airpark Business Center 7.45% 6.63% June 2021 — 913 — 3,498 Total unamortized fair value adjustments — (73 ) Principal balance — 3,425 Total principal balance $ 312,996 $ 308,194 (1) On July 21, 2015, we prepaid, without penalty, the $64.2 million outstanding balance on our Jackson National Life Loan, which was scheduled to mature in August 2015 and was secured by the following properties: Plaza 500, Van Buren Office Park, Greenbrier Technology Center II, Norfolk Business Center, Snowden Center and Rumsey Center, which was subsequently sold on July 28, 2015 . (2) At September 30, 2015, LIBOR was 0.19% . (3) On August 7, 2015, we entered into a $66.8 million mortgage loan, which encumbers our 11 Dupont Circle, NW property. The new loan, which is interest only until September 1, 2025, has a fixed interest rate of 4.05% , matures on September 1, 2030 and is prepayable in full, without penalty, on or after August 8, 2025. (4) Weighted average interest rate on total mortgage and construction debt. (5) The mortgage loans and unamortized fair value adjustments that encumbered properties within the Richmond Portfolio were classified within “Liabilities held-for-sale” on our consolidated balance sheet at December 31, 2014. The loans were prepaid upon the sale of the Richmond Portfolio on March 19, 2015. On July 21, 2015, we prepaid, without penalty, the $64.2 million outstanding balance on our Jackson National Life Loan, which was scheduled to mature in August 2015 and was secured by the following properties: Plaza 500, Van Buren Office Park, Greenbrier Technology Center II, Norfolk Business Center, Snowden Center and Rumsey Center, which was sold on July 28, 2015. The loan was initially prepaid with a draw from our unsecured revolving credit facility. The draw from our unsecured revolving credit facility was subsequently paid down when we entered into a $66.8 million mortgage loan, which encumbers our 11 Dupont Circle, NW property, on August 7, 2015. The new loan, which is interest only until September 1, 2025, has a fixed interest rate of 4.05% , matures on September 1, 2030 and is prepayable in full, without penalty, on or after August 8, 2025. Land Loan On October 16, 2014, our 97% owned consolidated joint venture that owns Storey Park repaid a $22.0 million loan that encumbered the Storey Park land and was subject to a 5.0% interest rate floor. Simultaneously with the repayment, the joint venture entered into a new $22.0 million land loan with a variable interest rate of LIBOR plus 2.50% . The new loan matures on October 16, 2016 , with a one -year extension at our option, and is repayable in full without penalty at any time during the term of the loan. Per the terms of the loan agreement, $6.0 million of the outstanding principal balance and all of the outstanding accrued interest is recourse to us. As of September 30, 2015, we were in compliance with all the financial covenants of the Storey Park land loan. Construction Loans On June 5, 2013, we entered into a construction loan (the “440 First Street Construction Loan”) that is collateralized by our 440 First Street, NW property, which underwent a major redevelopment that was substantially completed in October 2013. The loan has a borrowing capacity of up to $43.5 million , of which we initially borrowed $21.7 million in 2013 and borrowed an additional $10.5 million in 2014. The loan has a variable interest rate of LIBOR plus a spread of 2.5% and matures in May 2016 , with two one -year extension options at our discretion. We can repay all or a portion of the 440 First Street Construction Loan, without penalty, at any time during the term of the loan. At September 30, 2015, per the terms of the loan agreement, 50% of the outstanding principal balance and all of the outstanding accrued interest were recourse to us. The percentage of outstanding principal balance that is recourse to us can be reduced upon the property achieving certain operating thresholds. As of September 30, 2015 , we were in compliance with all of the financial covenants of the 440 First Street Construction Loan. On September 1, 2015, we entered into a construction loan (the “Northern Virginia Construction Loan”) that is collateralized by a to-be-constructed 167,000 square foot office building that is currently in development in Northern Virginia. We currently expect to complete construction of the new building in early 2016 and expect to complete the construction of the tenant improvements in the second half of 2016. The loan has a borrowing capacity of up to $43.7 million , of which we borrowed $9.2 million as of September 30, 2015. The loan has a variable interest rate of LIBOR plus a spread of 1.85% and matures on September 1, 2019 . We can repay all or a portion of the Northern Virginia Construction Loan, without penalty, at any time during the term of the loan. As of September 30, 2015 , we were in compliance with all of the financial covenants of the Northern Virginia Construction Loan. (b) Unsecured Term Loan The table below shows the outstanding balances and the interest rates of the three tranches of the $300.0 million unsecured term loan at September 30, 2015 (dollars in thousands): Maturity Date Amount Interest Rate (1) Tranche A October 2018 $ 100,000 LIBOR, plus 165 basis points Tranche B October 2019 100,000 LIBOR, plus 180 basis points Tranche C October 2020 100,000 LIBOR, plus 205 basis points $ 300,000 (1) At September 30, 2015, LIBOR was 0.19% . The interest rate spread is subject to change based on our maximum total indebtedness ratio. For more information, see note 8 (e) Debt – Financial Covenants . The term loan agreement contains various restrictive covenants substantially identical to those contained in our unsecured revolving credit facility, including with respect to liens, indebtedness, investments, distributions, mergers and asset sales. In addition, the agreement requires that we satisfy certain financial covenants that are also substantially identical to those contained in our unsecured revolving credit facility. The agreement also includes customary events of default, the occurrence of which, following any applicable cure period, would permit the lenders to, among other things, declare the principal, accrued interest and other obligations of our Company under the agreement to be immediately due and payable. As of September 30, 2015, we were in compliance with all the financial covenants of the unsecured term loan. (c) Unsecured Revolving Credit Facility During the third quarter of 2015, we borrowed $79.0 million under the unsecured revolving credit facility, $64.2 million of which was used to pay off the Jackson National Life Loan and the remainder was used for general corporate purposes, and repaid $76.0 million of the outstanding balance under the unsecured revolving credit facility with proceeds from a $66.8 million mortgage loan that encumbers 11 Dupont Circle, NW, a portion of the proceeds from the sale of Rumsey Center and available cash. For the three and nine months ended September 30, 2015, our weighted average borrowings under the unsecured revolving credit facility were $164.2 million and $168.9 million , respectively, with a weighted average interest rate of 1.9% for both the three and nine months ended September 30, 2015 compared with weighted average borrowings of $125.9 million and $112.0 million for the three and nine months ended September 30, 2014, respectively, with a weighted average interest rate of 1.7% for both periods in 2014. Our maximum outstanding borrowings were $217.0 million and $218.0 million for the three and nine months ended September 30, 2015, respectively, and $216.0 million for both the three and nine months ended September 30, 2014. At September 30, 2015, outstanding borrowings under the unsecured revolving credit facility were $155.0 million with a weighted average interest rate of 1.9% . At September 30, 2015, LIBOR was 0.19% and the applicable spread on our unsecured revolving credit facility was 170 basis points. The available capacity under the unsecured revolving credit facility was $142.0 million as of the date of this filing. We are required to pay an annual commitment fee of 0.25% based on the amount of unused capacity under the unsecured revolving credit facility. As of September 30, 2015, we were in compliance with all the financial covenants of the unsecured revolving credit facility. For more information, see note 8 (e) Debt – Financial Covenants . (d) Interest Rate Swap Agreements At September 30, 2015, we had eleven interest rate swap agreements outstanding that collectively fixed LIBOR, at a weighted average interest rate of 1.5% , on $300.0 million of our variable rate debt. See note 9 , Derivative Instruments , for more information about our interest rate swap agreements. (e) Financial Covenants Our outstanding corporate debt agreements contain specific financial covenants that may impact future financing decisions made by us or may be impacted by a decline in operations. These covenants relate to our allowable leverage, minimum tangible net worth, fixed charge coverage and other financial metrics. As of September 30, 2015, we were in compliance with the covenants of our unsecured term loan and unsecured revolving credit facility and any such financial covenants of our mortgage debt (including the 440 First Street Construction Loan, the Northern Virginia Construction Loan and the Storey Park land loan). Our continued ability to borrow under the unsecured revolving credit facility is subject to compliance with financial and operating covenants, and a failure to comply with any of these covenants could result in a default under the credit facility. These debt agreements also contain cross-default provisions that would be triggered if we were in default under other loans, including mortgage loans, in excess of certain amounts. In the event of a default, the lenders could accelerate the timing of payments under the debt obligations and we may be required to repay such debt with capital from other sources, which may not be available on attractive terms, or at all, which would have a material adverse effect on our liquidity, financial condition, results of operations and ability to make distributions to our shareholders. Our unsecured revolving credit facility and unsecured term loan are subject to interest rate spreads that float based on the quarterly measurement of our maximum consolidated total indebtedness to gross asset value ratio. Based on our leverage ratio at September 30, 2015, the applicable interest rate spreads on the unsecured revolving credit facility and the unsecured term loan will be unchanged.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments We are exposed to certain risks arising from business operations and economic factors. We use derivative financial instruments to manage exposures that arise from business activities in which our future exposure to interest rate fluctuations is unknown. The objective in the use of an interest rate derivative is to add stability to interest expenses and manage exposure to interest rate changes. We do not use derivatives for trading or speculative purposes and we intend to enter into derivative agreements only with counterparties that we believe have a strong credit rating to mitigate the risk of counterparty default or insolvency. No hedging activity can completely insulate us from the risks associated with changes in interest rates. Moreover, interest rate hedging could fail to protect us or adversely affect us because, among other things: • available interest rate hedging may not correspond directly with the interest rate risk for which we seek protection; • the duration of the hedge may not match the duration of the related liability; • the party owing money in the hedging transaction may default on its obligation to pay; and • the credit quality of the party owing money on the hedge may be downgraded to such an extent that it impairs our ability to sell or assign its side of the hedging transaction. We enter into interest rate swap agreements to hedge our exposure on our variable rate debt against fluctuations in prevailing interest rates. The interest rate swap agreements fix LIBOR to a specified interest rate; however, the swap agreements do not affect the contractual spreads associated with each variable debt instrument’s applicable interest rate. At September 30, 2015 , we had eleven interest rate swap agreements outstanding that collectively fixed LIBOR at a weighted average interest rate of 1.5% on $300.0 million of our variable rate debt. Our interest rate swap agreements are summarized below (dollars in thousands): Maturity Date Notional Amount Interest Rate Contractual Component Fixed LIBOR Interest Rate July 2016 $ 35,000 LIBOR 1.754 % July 2016 25,000 LIBOR 1.763 % July 2017 30,000 LIBOR 2.093 % July 2017 30,000 LIBOR 2.093 % July 2017 25,000 LIBOR 1.129 % July 2017 12,500 LIBOR 1.129 % July 2017 50,000 LIBOR 0.955 % July 2018 12,500 LIBOR 1.383 % July 2018 30,000 LIBOR 1.660 % July 2018 25,000 LIBOR 1.394 % July 2018 25,000 LIBOR 1.135 % Total/Weighted Average $ 300,000 1.505 % Our interest rate swap agreements are designated as cash flow hedges and we record the effective portion of any unrealized gains associated with the change in fair value of the swap agreements within “Accumulated other comprehensive loss” and “Prepaid expenses and other assets” and the effective portion of any unrealized losses within “Accumulated other comprehensive loss” and “Accounts payable and other liabilities” on our consolidated balance sheets. We record our proportionate share of any unrealized gains or losses on our cash flow hedges associated with our unconsolidated joint ventures within “Accumulated other comprehensive loss” and “Investment in affiliates” on our consolidated balance sheets. We record any gains or losses incurred as a result of each interest rate swap agreement’s fixed rate deviating from our respective loan’s contractual rate within “Interest expense” in our consolidated statements of operations. We did not have any material ineffectiveness associated with our cash flow hedges during the nine months ended September 30, 2015 and 2014. Amounts reported in accumulated other comprehensive loss related to derivatives will be reclassified to “Interest expense” on our consolidated statements of operations as interest payments are made on our variable-rate debt. We reclassified accumulated other comprehensive loss as an increase to interest expense of $1.0 million for both the three months ended September 30, 2015 and 2014, and $3.0 million and $3.1 million for the nine months ended September 30, 2015 and 2014, respectively. As of September 30, 2015 , we estimated that $4.3 million of our accumulated other comprehensive loss will be reclassified as an increase to interest expense over the following twelve months.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Our application of GAAP outlines a valuation framework and creates a fair value hierarchy, which distinguishes between assumptions based on market data (observable inputs) and a reporting entity’s own assumptions about market data (unobservable inputs). The required disclosures increase the consistency and comparability of fair value measurements and the related disclosures. Fair value is identified, under the standard, as the price that would be received to sell an asset or paid to transfer a liability between willing third parties at the measurement date (an exit price). In accordance with GAAP, certain assets and liabilities must be measured at fair value, and we provide the necessary disclosures that are required for items measured at fair value as outlined in the accounting requirements regarding fair value. Financial assets and liabilities, as well as those non-financial assets and liabilities requiring fair value measurement, are measured using inputs from three levels of the fair value hierarchy. The three levels are as follows: Level 1 - Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access at the measurement date. An active market is defined as a market in which transactions for the assets or liabilities occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2 - Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active (markets with few transactions), inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs derived principally from or corroborated by observable market data correlation or other means (market corroborated inputs). Level 3 - Unobservable inputs, only used to the extent that observable inputs are not available, reflect our assumptions about the pricing of an asset or liability. In accordance with accounting provisions and the fair value hierarchy described above, the following table shows the fair value of our consolidated assets and liabilities that are measured on a recurring basis as of September 30, 2015 and December 31, 2014 (dollars in thousands): Balance at Level 1 Level 2 Level 3 Recurring Measurements: Derivative instrument-swap liabilities $ 4,507 $ — $ 4,507 $ — Balance at Level 1 Level 2 Level 3 Recurring Measurements: Derivative instrument-swap assets $ 133 $ — $ 133 $ — Derivative instrument-swap liabilities 3,569 — 3,569 — We did not have any assets or liabilities that were measured on a non-recurring basis at September 30, 2015 and December 31, 2014. We did not re-measure or complete any transactions involving non-financial assets or non-financial liabilities that are measured at fair value on a recurring basis during the nine months ended September 30, 2015 and 2014. Also, no transfers into or out of fair value measurement levels for assets or liabilities that are measured on a recurring basis occurred during the nine months ended September 30, 2015 and 2014. Interest Rate Derivatives At September 30, 2015 , we had hedged $300.0 million of our variable rate debt through eleven interest rate swap agreements. See note 9, Derivative Instruments , for more information about our interest rate swap agreements. The interest rate derivatives are fair valued based on prevailing market yield curves on the measurement date and also incorporate credit valuation adjustments to appropriately reflect both our own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of our derivative contracts for the effect of nonperformance risk, we have considered the impact of netting any applicable credit enhancements, such as collateral postings, thresholds, mutual inputs and guarantees. We use a third party to assist in valuing our interest rate swap agreements. A daily “snapshot” of the market is taken to obtain close of business rates. The snapshot includes over 7,500 rates including LIBOR fixings, Eurodollar futures, swap rates, exchange rates, treasuries, etc. This market data is obtained via direct feeds from Bloomberg and Reuters and from Inter-Dealer Brokers. The selected rates are compared to their historical values. Any rate that has changed by more than normal mean and related standard deviation would be considered an outlier and flagged for further investigation. The rates are then compiled through a valuation process that generates daily valuations, which are used to value our interest rate swap agreements. Our interest rate swap derivatives are effective cash flow hedges and the effective portion of the change in fair value is recorded in the equity section of our consolidated balance sheets as “Accumulated other comprehensive loss.” Financial Instruments The carrying amounts of cash equivalents, accounts and other receivables, accounts payable and other liabilities, with the exception of any items listed above, approximate their fair values due to their short-term maturities. We determine the fair value of our notes receivable and debt instruments by discounting future contractual principal and interest payments using prevailing market rates for securities with similar terms and characteristics at the balance sheet date. We deem the fair value measurement of our debt instruments as a Level 2 measurement as we use quoted interest rates for similar debt instruments to value our debt instruments. We use quoted market interest rates for similar notes to value our notes receivable, which we consider a Level 2 measurement as we do not believe notes receivable trade in an active market. The carrying amount and estimated fair value of our notes receivable and debt instruments are as follows (amounts in thousands): September 30, 2015 December 31, 2014 Carrying Fair Carrying Fair Financial Assets: Notes receivable (1) $ 34,000 $ 34,000 $ 63,679 $ 63,720 Financial Liabilities: Mortgage debt (2) $ 313,217 $ 303,465 $ 308,637 $ 292,882 Unsecured term loan 300,000 303,163 300,000 300,000 Unsecured revolving credit facility 155,000 155,623 205,000 205,000 Total $ 768,217 $ 762,251 $ 813,637 $ 797,882 (1) The principal amount of our notes receivable was $34.0 million and $63.7 million at September 30, 2015 and December 31, 2014 , respectively. On February 24, 2015, the owners of America’s Square, a 461,000 square foot office complex located in Washington, D.C., prepaid a mezzanine loan, which had an outstanding $29.7 million balance of the $30.0 million mezzanine loan that we provided them in April 2011. (2) The balances at December 31, 2014, include five mortgage loans that were repaid with the sale of the Richmond Portfolio on March 19, 2015. At December 31, 2014, the mortgage loans had an aggregate principal balance of $3.5 million and were classified within “Liabilities held-for-sale” on our consolidated balance sheet for December 31, 2014.

Equity

Equity	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Equity	Equity In July 2015, our Board of Trustees authorized a share repurchase program that allows us to acquire up to five million of our common shares of beneficial interest from time to time through July 2016 in open market transactions at prevailing prices or in negotiated private transactions. We are not obligated to acquire any particular amount of common shares and the share repurchase program may be suspended by the Board of Trustees at any time. During the three months ended September 30, 2015, we repurchased 924,198 shares at a weighted-average share price of $10.99 for a total purchase price of $10.2 million , utilizing a portion of the proceeds from our sale of Rumsey Center. As of the date of this filing, we are authorized to repurchase an additional 4.1 million of our common shares through July 2016. On October 27, 2015 , we declared a dividend of $0.15 per common share, equating to an annualized dividend of $0.60 per common share. The dividend will be paid on November 16, 2015 to common shareholders of record as of November 9, 2015 . We also declared a dividend of $0.484375 per share on our Series A Preferred Shares. The dividend will be paid on November 16, 2015 to preferred shareholders of record as of November 9, 2015 . Dividends on all non-vested share awards are recorded as a reduction of shareholders’ equity. For each dividend paid by us on our common and preferred shares, the Operating Partnership distributes an equivalent distribution on our common and preferred Operating Partnership units, respectively. On July 28, 2015 , we declared a dividend of $0.15 per common share, equating to an annualized dividend of $0.60 per common share. The dividend was paid on August 17, 2015 to common shareholders of record as of August 10, 2015 . We also declared a dividend of $0.484375 per share on our Series A Preferred Shares. The dividend was paid on August 17, 2015 to preferred shareholders of record as of August 10, 2015 . Our unsecured revolving credit facility, unsecured term loan, the 440 First Street Construction Loan, the Northern Virginia Construction Loan and the Storey Park land loan contain certain restrictions that include, among other things, requirements to maintain specified coverage ratios and other financial covenants, which may limit our ability to make distributions to our common and preferred shareholders, except for distributions required to maintain our qualification as a REIT. Further, distributions with respect to our common shares are subject to our ability to first satisfy our obligations to pay distributions to the holders of our Series A Preferred Shares. As a result of the redemption feature of the Operating Partnership units, the noncontrolling interests associated with the Operating Partnership are recorded outside of permanent equity. Our equity and redeemable noncontrolling interests are as follows (dollars in thousands): First Potomac Realty Trust Non-redeemable noncontrolling interests Total Equity Redeemable noncontrolling interests Balance at December 31, 2014 $ 710,007 $ 898 $ 710,905 $ 33,332 Net income (loss) 5,154 (3 ) 5,151 (186 ) Changes in ownership, net 3,289 — 3,289 (1,257 ) Distributions to owners (35,725 ) (96 ) (35,821 ) (1,181 ) Other comprehensive loss (1,015 ) — (1,015 ) (45 ) Repurchase of common shares $ (10,180 ) $ — $ (10,180 ) $ — Balance at September 30, 2015 $ 671,530 $ 799 $ 672,329 $ 30,663 First Potomac Realty Trust Non-redeemable noncontrolling interests Total Equity Redeemable noncontrolling interests Balance at December 31, 2013 $ 738,510 $ 781 $ 739,291 $ 33,221 Net income 16,614 — 16,614 327 Changes in ownership, net 2,018 161 2,179 390 Distributions to owners (35,691 ) — (35,691 ) (1,183 ) Other comprehensive income 1,059 — 1,059 47 Balance at September 30, 2014 $ 722,510 $ 942 $ 723,452 $ 32,802 A summary of our accumulated other comprehensive loss is as follows (dollars in thousands): 2015 2014 Beginning balance at January 1, $ (3,268 ) $ (3,836 ) Net unrealized (loss) gain on derivative instruments (1,060 ) 1,106 Net loss (gain) attributable to noncontrolling interests 45 (47 ) Ending balance at September 30, $ (4,283 ) $ (2,777 )

Noncontrolling Interests

Noncontrolling Interests	9 Months Ended
	Sep. 30, 2015
Noncontrolling Interest [Abstract]
Noncontrolling Interests	Noncontrolling Interests (a) Noncontrolling Interests in the Operating Partnership Noncontrolling interests relate to the common interests in the Operating Partnership not owned by us. Interests in the Operating Partnership are owned by limited partners who contributed buildings and other assets to the Operating Partnership in exchange for common Operating Partnership units. Limited partners have the right to tender their units for redemption in exchange for, at our option, our common shares on a one-for-one basis or cash based on the fair value of our common shares at the date of redemption. Unitholders receive a distribution per unit equivalent to the dividend per common share. Differences between amounts paid to redeem noncontrolling interests and their carrying values are charged or credited to equity. As a result of the redemption feature of the Operating Partnership units, the noncontrolling interests are recorded outside of permanent equity. Noncontrolling interests are presented at the greater of their fair value or their cost basis, which is comprised of their fair value at issuance, subsequently adjusted for the noncontrolling interests’ share of net income or losses available to common shareholders, other comprehensive income or losses, distributions received or additional contributions. We account for issuances of common Operating Partnership units individually, which could result in some portion of our noncontrolling interests being carried at fair value with the remainder being carried at historical cost. Based on the closing price of our common shares at September 30, 2015 , the cost to acquire, through cash purchase or issuance of our common shares, all of the outstanding common Operating Partnership units not owned by us would be approximately $28.8 million . At September 30, 2015 and December 31, 2014, we recorded adjustments of $3.6 million and $4.7 million , respectively, to present certain common Operating Partnership units at the greater of their carrying value or redemption value. At September 30, 2015 , 2,619,069 of the total common Operating Partnership units, or 4.3% , were not owned by us. During the nine months ended September 30, 2015, 11,508 common Operating Partnership units were redeemed with available cash. There were no common Operating Partnership units redeemed for common shares during the nine months ended September 30, 2015 . During the first quarter of 2014, we issued 3,125 common Operating Partnership units to the seller of 840 First Street, NE to satisfy a contingent consideration obligation related to the acquisition of the property. (b) Noncontrolling Interests in a Consolidated Partnership When we are deemed to have a controlling interest in a partially-owned entity, we will consolidate all of the entity’s assets, liabilities and operating results within our condensed consolidated financial statements. The net assets contributed to the consolidated entity by the third party, if any, will be reflected within permanent equity in our consolidated balance sheets to the extent they are not mandatorily redeemable. The amount will be recorded based on the third party’s initial investment in the consolidated entity and will be adjusted to reflect the third party’s share of earnings or losses in the consolidated entity and any distributions received or additional contributions made by the third party. The earnings or losses from the entity attributable to the third party are recorded as a component of “Net loss (income) attributable to noncontrolling interests” in our consolidated statements of operations. On August 4, 2011, we formed a joint venture, in which we have a 97% interest, with an affiliate of Perseus Realty, LLC to acquire Storey Park in our Washington, D.C. reporting segment. At the time, the site was leased to Greyhound, which subsequently relocated its operations. Greyhound’s lease expired on August 31, 2013, at which time the property was placed into development with the anticipation of developing a mixed-use project on the 1.6 acre site, which can accommodate up to 712,000 square feet. At September 30, 2015 , our total investment in the development project was $57.2 million , which included the original cost basis of the property of $43.3 million . The majority of the costs in excess of the original cost basis relate to architectural fees and site preparation costs as well as capitalized interest and taxes. We are currently exploring our options related to this property; however, until a definitive plan for the property has been reached and we begin significant development activities, we cannot determine the total cost of the project or the anticipated completion date. While we continue pre-development work on Storey Park, we engaged a sales broker to strategically monetize our majority interest in Storey Park, which could result in a sale of all or a portion of our interest in Storey Park; however, we can provide no assurances regarding the timing or pricing of such transaction, or that a sale will occur at all.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Segment Information	Segment Information Our reportable segments consist of four distinct reporting and operational segments within the greater Washington, D.C. region in which we operate: Washington, D.C., Maryland, Northern Virginia and Southern Virginia. We evaluate the performance of our segments based on the operating results of the properties located within each segment, which excludes large non-recurring gains and losses, gains or losses from sale of rental property, interest expense, general and administrative costs, acquisition costs or any other indirect corporate expense to the segments. In addition, the segments do not have significant non-cash items other than straight-line and deferred market rent amortization reported in their operating results. There are no inter-segment sales or transfers recorded between segments. The results of continuing operations of our four reporting segments for the three and nine months ended September 30, 2015 and 2014 are as follows (dollars in thousands): Three Months Ended September 30, 2015 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Number of buildings (1) 6 34 49 19 108 Square feet (1) 915,692 1,884,741 3,020,293 2,021,667 7,842,393 Total revenues $ 11,337 $ 10,575 $ 13,715 $ 7,227 $ 42,854 Property operating expense (2,962 ) (2,467 ) (3,347 ) (2,125 ) (10,901 ) Real estate taxes and insurance (2,015 ) (893 ) (1,285 ) (622 ) (4,815 ) Total property operating income $ 6,360 $ 7,215 $ 9,083 $ 4,480 27,138 Depreciation and amortization expense (16,758 ) General and administrative (4,605 ) Other expenses (1,778 ) Net income $ 3,997 Capital expenditures (2) $ 2,440 $ 2,649 $ 11,309 $ 2,019 $ 18,521 Three Months Ended September 30, 2014 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Number of buildings (1)(3) 6 42 49 38 135 Square feet (1)(3) 815,093 2,179,366 3,020,975 2,852,212 8,867,646 Total revenues $ 8,489 $ 11,154 $ 13,309 $ 7,103 $ 40,055 Property operating expense (2,496 ) (2,540 ) (3,121 ) (2,407 ) (10,564 ) Real estate taxes and insurance (1,278 ) (956 ) (1,228 ) (597 ) (4,059 ) Total property operating income $ 4,715 $ 7,658 $ 8,960 $ 4,099 25,432 Depreciation and amortization expense (15,217 ) General and administrative (4,955 ) Acquisition costs (1,488 ) Other expenses (4,020 ) Discontinued operations (4) 297 Net income $ 49 Capital expenditures (2) $ 5,320 $ 1,875 $ 1,516 $ 2,001 $ 10,767 Nine Months Ended September 30, 2015 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Total revenues $ 33,522 $ 33,315 $ 41,529 $ 21,375 $ 129,741 Property operating expense (9,088 ) (9,129 ) (10,603 ) (5,856 ) (34,676 ) Real estate taxes and insurance (5,994 ) (2,681 ) (4,178 ) (1,815 ) (14,668 ) Total property operating income $ 18,440 $ 21,505 $ 26,748 $ 13,704 80,397 Depreciation and amortization expense (49,909 ) General and administrative (15,110 ) Other expenses (9,806 ) Discontinued operations (4) (607 ) Net income $ 4,965 Total assets (5)(6) $ 515,625 $ 344,676 $ 452,962 $ 167,903 $ 1,526,524 Capital expenditures (2) $ 9,859 $ 6,965 $ 27,190 $ 5,419 $ 49,846 Nine Months Ended September 30, 2014 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Total revenues $ 23,256 $ 34,025 $ 40,122 $ 21,322 $ 118,725 Property operating expense (6,889 ) (8,913 ) (10,203 ) (6,820 ) (32,825 ) Real estate taxes and insurance (3,579 ) (2,934 ) (4,217 ) (1,701 ) (12,431 ) Total property operating income $ 12,788 $ 22,178 $ 25,702 $ 12,801 73,469 Depreciation and amortization expense (44,357 ) General and administrative (15,370 ) Acquisition costs (2,667 ) Impairment of rental property (3,956 ) Other income 8,843 Discontinued operations (4) 979 Net income $ 16,941 Total assets (5)(6) $ 501,536 $ 375,399 $ 437,909 $ 228,655 $ 1,628,737 Capital expenditures (2) $ 16,702 $ 6,966 $ 3,876 $ 6,173 $ 34,410 (1) Excludes Storey Park from our Washington, D.C. reporting segment, which was placed in development in the third quarter of 2013. (2) Capital expenditures for corporate assets not allocated to any of our reportable segments totaled $104 and $55 for the three months ended September 30, 2015 and 2014, respectively, and $413 and $693 for the nine months ended September 30, 2015 and 2014, respectively. (3) Includes occupied space at 440 First Street, NW in our Washington, D.C. reporting segment, which was substantially completed in the third quarter of 2013. In October 2014, the property was placed in service. (4) Includes the operating results from the Richmond Portfolio, Patrick Center, West Park, Girard Business Center and Gateway Center. For information, see note 7 (b), Dispositions - Discontinued Operations . (5) Total assets include our investment in properties that are owned through joint ventures that are not consolidated within our condensed consolidated financial statements. For more information on our unconsolidated investments, including location within our reportable segments, see note 6 , Investment in Affiliates . (6) Corporate assets not allocated to any of our reportable segments totaled $45,358 and $85,238 at September 30, 2015 and 2014, respectively.

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation Our unaudited condensed consolidated financial statements include our accounts and the accounts of our Operating Partnership and the subsidiaries in which we or our Operating Partnership has a controlling interest, which includes First Potomac Management LLC, a wholly-owned subsidiary that manages the majority of our properties. All intercompany balances and transactions have been eliminated in consolidation. We have condensed or omitted certain information and note disclosures normally included in financial statements presented in accordance with U.S. generally accepted accounting principles (“GAAP”) in the accompanying unaudited condensed consolidated financial statements. We believe the disclosures made are adequate to prevent the information presented from being misleading. However, the unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in our annual report on Form 10-K for the year ended December 31, 2014 and as updated from time to time in our other filings with the SEC. In our opinion, the accompanying unaudited condensed consolidated financial statements reflect all adjustments, consisting of normal recurring adjustments and accruals necessary to present fairly our financial position as of September 30, 2015 , the results of our operations and our comprehensive income for the three and nine months ended September 30, 2015 and 2014 and our cash flows for the nine months ended September 30, 2015 and 2014 . Interim results are not necessarily indicative of full-year performance due, in part, to the timing of transactions and the impact of acquisitions and dispositions throughout the year, as well as the seasonality of certain operating expenses such as utilities expense and snow and ice removal costs.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires our management team to make a number of estimates and assumptions relating to the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the unaudited condensed consolidated financial statements and the reported amounts of revenues and expenses during the period. Estimates include the amount of accounts receivable that may be uncollectible, recoverability of notes receivable, future cash flows, discount and capitalization rate assumptions used to fair value acquired properties and to test impairment of certain long-lived assets and goodwill, derivative valuations, market lease rates, lease-up periods, leasing and tenant improvement costs used to fair value intangible assets acquired and probability weighted cash flow analysis used to fair value contingent liabilities. Actual results could differ from those estimates.
Rental Property	Rental Property Rental property is initially recorded at fair value, when acquired in a business combination, or initial cost when constructed or acquired in an asset purchase. Improvements and replacements are capitalized at cost when they extend the useful life, increase capacity or improve the efficiency of the asset. Repairs and maintenance are charged to expense when incurred. Depreciation and amortization are recorded on a straight-line basis over the estimated useful lives of the assets. The estimated useful lives of our assets, by class, are as follows: Buildings 39 years Building improvements 5 to 20 years Furniture, fixtures and equipment 5 to 15 years Lease related intangible assets The term of the related lease Tenant improvements Shorter of the useful life of the asset or the term of the related lease We regularly review market conditions for possible impairment of a property’s carrying value. When circumstances such as adverse market conditions, changes in management’s intended holding period or potential sale to a third party indicate a possible impairment of the carrying value of a property, an impairment analysis is performed. We assess potential impairments based on an estimate of the future undiscounted cash flows (excluding interest charges) expected to result from the property’s use and eventual disposition. This estimate is based on projections of future revenues, expenses, capital improvement costs to maintain the operating capacity, expected holding periods and capitalization rates. These cash flows consider factors such as expected market trends and leasing prospects, as well as the effects of leasing demand, competition and other factors. If impairment exists due to the inability to recover the carrying value of a real estate investment based on forecasted undiscounted cash flows, an impairment loss is recorded to the extent that the carrying value exceeds the estimated fair value of the property. Further, we will record an impairment loss if we expect to dispose of a property in the near term, at a price below carrying value. In such an event, we will classify the property as held-for-sale and record an impairment loss based on the difference between a property’s carrying value and its projected sales price less any estimated costs to sell. We will classify a building as held-for-sale in accordance with GAAP in the period in which we have made the decision to dispose of the building, our Board of Trustees or a designated delegate has approved the sale, there is a high likelihood a binding agreement to purchase the property will be signed under which the buyer will be required to commit a significant amount of nonrefundable cash and no significant financing contingencies exist that could cause the transaction not to be completed in a timely manner. We will cease recording depreciation on a building once it has been classified as held-for-sale. In the second quarter of 2014, we prospectively adopted Accounting Standards Update No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity (“ASU 2014-08”), which impacts the presentation of operations and gains or losses from disposed properties and properties classified as held-for-sale. ASU 2014-08 states that a disposal of a component of an entity or a group of components of an entity is required to be reported in discontinued operations only if the disposal represents a strategic shift that has, or will have, a major effect on an entity’s operations or financial results. The operations of all properties that were sold prior to the adoption of ASU 2014-08, two properties (West Park and Patrick Center) that were classified as held-for-sale in previously issued financial statements prior to our adoption of ASU 2014-08 and were subsequently sold, as well as our Richmond, Virginia portfolio, which included Chesterfield Business Center, Hanover Business Center, Park Central, Virginia Technology Center and a three-acre parcel of undeveloped land (the “Richmond Portfolio”), are reflected within discontinued operations in our consolidated statements of operations for all periods presented. If the building does not qualify as a discontinued operation under ASU 2014-08, we will classify the building's operating results, together with any impairment charges and any gains or losses on the sale of the building, in continuing operations for all periods presented in our consolidated statements of operations. We will classify the assets and liabilities related to the building as held-for-sale in our consolidated balance sheet for the period the held-for-sale criteria were met. If the building does qualify as a discontinued operation under ASU 2014-08, we will classify the building's operating results, together with any impairment charges and any gains or losses on the sale of the building, in discontinued operations in our consolidated statements of operations for all periods presented and classify the assets and liabilities related to the building as held-for-sale in our consolidated balance sheets for the periods presented. Interest expense is reclassified to discontinued operations only to the extent the disposed or held-for-sale property is secured by specific mortgage debt and the mortgage debt will not be assigned to another property owned by us after the disposition. We recognize the fair value, if sufficient information exists to reasonably estimate the fair value, of any liability for conditional asset retirement obligations when assumed or incurred, which is generally upon acquisition, construction, development or redevelopment and/or through the normal operation of the asset. We capitalize interest costs incurred on qualifying expenditures for real estate assets under development or redevelopment, which include our investments in assets owned through unconsolidated joint ventures that are under development or redevelopment, while being readied for their intended use in accordance with accounting requirements regarding capitalization of interest. We will capitalize interest when qualifying expenditures for the asset have been made, activities necessary to get the asset ready for its intended use are in progress and interest costs are being incurred. Capitalized interest also includes interest associated with expenditures incurred to acquire developable land while development activities are in progress. We also capitalize direct compensation costs of our construction personnel who manage the development and redevelopment projects, but only to the extent the employee’s time can be allocated to a project. Any portion of construction management costs not directly attributable to a specific project are recognized as general and administrative expense in the period incurred. We do not capitalize any other general and administrative costs such as office supplies, office rent expense or an overhead allocation to our development or redevelopment projects. Capitalized compensation costs were immaterial for the nine months ended September 30, 2015 and 2014 . Capitalization of interest ends when the asset is substantially complete and ready for its intended use, but no later than one year from completion of major construction activity, if the property is not occupied. We place redevelopment and development assets into service at this time and commence depreciation upon the substantial completion of tenant improvements and the recognition of revenue. Capitalized interest is depreciated over the useful life of the underlying assets, commencing when those assets are placed into service.
Notes Receivable	Notes Receivable We provide loans to the owners of real estate properties, which can be collateralized by interest in the real estate property. We record these loans as “Notes receivable, net” in our consolidated balance sheets. The loans are recorded net of any discount or issuance costs, which are amortized over the life of the respective note receivable using the effective interest method. We record interest earned from notes receivable and amortization of any discount costs or issuance costs within “Interest and other income” in our consolidated statements of operations. We will establish a provision for anticipated credit losses associated with our notes receivable when we anticipate that we may be unable to collect any contractually due amounts. This determination is based upon such factors as delinquencies, loss experience, collateral quality and current economic or borrower conditions. Our collectability of our notes receivable may be adversely impacted by the financial stability of the Washington, D.C. region and the ability of the underlying assets to keep current tenants or attract new tenants. Estimated losses are recorded as a charge to earnings to establish an allowance for credit losses that we estimate to be adequate based on these factors. Based on the review of the above criteria, we did not record an allowance for credit losses for our notes receivable during the nine months ended September 30, 2015 and 2014 .
Application of New Accounting Standards	Application of New Accounting Standards In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers and will replace most existing revenue recognition guidance when it becomes effective. In July 2015, the FASB deferred by one year the mandatory effective date of ASU 2014-09 from January 1, 2017 to January 1, 2018. Early adoption is permitted, but not prior to the original effective date of January 1, 2017. ASU 2014-09 permits the use of either the retrospective or cumulative effect transition method. We have not yet selected a transition method and are evaluating the impact that ASU 2014-09 will have on our consolidated financial statements or related disclosures. In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern (“ASU 2014-15”), which requires an entity to evaluate whether conditions or events, in the aggregate, raise substantial doubt about the entity's ability to continue as a going concern for one year from the date the financial statements are issued or are available to be issued. The guidance will become effective for annual periods ending after December 15, 2016. The adoption of ASU 2014-15 is not expected to have an impact on our consolidated financial statements or related disclosures. In January 2015, the FASB issued Accounting Standards Update No. 2015-01, Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items ("ASU 2015-01"), which eliminates the concept of extraordinary items from GAAP and the requirement that an entity separately report extraordinary items in the income statement. ASU 2015-01 also requires that entities continue to evaluate whether items are unusual in nature or infrequent in occurrence for presentation and disclosure purposes. ASU 2015-01 applies to all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted and the guidance may be applied prospectively or retrospectively to all prior periods presented in the consolidated financial statements. The adoption of ASU 2015-01 is not expected to have a material impact on our consolidated financial statements or related disclosures. In February 2015, the FASB issued Accounting Standards Update No. 2015-02, Amendments to the Consolidation Analysis (“ASU 2015-02”), which makes certain changes to both the variable interest model and the voting model, including changes to the identification of variable interests (fees paid to a decision maker or service provider), the variable interest entity characteristics for a limited partnership or similar entity and the primary beneficiary determination. ASU 2015-02 is effective January 1, 2016. The adoption of ASU 2015-02 is not expected to have a material impact on our consolidated financial statements or related disclosures. In April 2015, the FASB issued Accounting Standards Update No. 2015-03, Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”), which requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying value of the debt liability. ASU 2015-03 is effective for periods beginning after December 15, 2015 with early adoption permitted and will be applied on a retrospective basis. The guidance will be effective on January 1, 2016 and is not expected to have a material impact on our consolidated financial statements or related disclosures.
Reclassifications	Reclassifications Certain prior year amounts have been reclassified to conform to the current year presentation as a result of reclassifying the operating results of several properties as discontinued operations. For more information, see note 7 , Dispositions.

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Estimated Useful Life of Assets	The estimated useful lives of our assets, by class, are as follows: Buildings 39 years Building improvements 5 to 20 years Furniture, fixtures and equipment 5 to 15 years Lease related intangible assets The term of the related lease Tenant improvements Shorter of the useful life of the asset or the term of the related lease

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Computation of Company's Basic and Diluted Earnings Per Share	The following table sets forth the computation of our basic and diluted earnings per common share (amounts in thousands, except per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Numerator for basic and diluted earnings per common share: Income (loss) from continuing operations $ 3,997 $ (248 ) $ 5,572 $ 15,962 Income (loss) from discontinued operations — 297 (607 ) 979 Net income 3,997 49 4,965 16,941 Less: Net (income) loss from continuing operations attributable to noncontrolling interests (38 ) 144 163 (285 ) Less: Net (income) loss from discontinued operations attributable to noncontrolling interests — (13 ) 26 (42 ) Net income attributable to First Potomac Realty Trust 3,959 180 5,154 16,614 Less: Dividends on preferred shares (3,100 ) (3,100 ) (9,300 ) (9,300 ) Net income (loss) attributable to common shareholders 859 (2,920 ) (4,146 ) 7,314 Less: Allocation to participating securities (69 ) (80 ) (211 ) (235 ) Net income (loss) attributable to common shareholders $ 790 $ (3,000 ) $ (4,357 ) $ 7,079 Denominator for basic and diluted earnings per common share: Weighted average common shares outstanding: Basic 57,961 58,167 58,155 58,137 Diluted 58,045 58,167 58,155 58,209 Basic and diluted earnings per common share: Income (loss) from continuing operations $ 0.01 $ (0.05 ) $ (0.06 ) $ 0.10 (Loss) income from discontinued operations — — (0.01 ) 0.02 Net income (loss) $ 0.01 $ (0.05 ) $ (0.07 ) $ 0.12
Anti-Dilutive Shares Not Included in Calculation of Diluted Earnings Per Share	In accordance with GAAP regarding earnings per common share, we did not include the following potential weighted average common shares in our calculation of diluted earnings per common share as they are anti-dilutive for the periods presented (amounts in thousands): Three Months Ended Nine Months Ended 2015 2014 2015 2014 Stock option awards 987 1,103 1,037 1,143 Non-vested share awards 307 433 374 401 Series A Preferred Shares (1) 14,627 12,356 14,190 12,438 15,921 13,892 15,601 13,982 (1) Our Series A Preferred Shares are only convertible into our common shares upon certain changes in control of our Company. The dilutive shares are calculated as the daily average of the face value of the Series A Preferred Shares divided by the outstanding common share price.

Rental Property (Tables)

Rental Property (Tables)	9 Months Ended
	Sep. 30, 2015
Real Estate [Abstract]
Summary of Rental Property	Rental property consists of the following (dollars in thousands): September 30, 2015 (1) December 31, 2014 (2) Land and land improvements $ 319,569 $ 325,214 Buildings and building improvements 931,749 949,683 Construction in progress 83,778 69,181 Tenant improvements 179,728 159,867 Furniture, fixtures and equipment 431 427 1,515,255 1,504,372 Less: accumulated depreciation (238,295 ) (215,499 ) $ 1,276,960 $ 1,288,873 (1) Excludes rental property totaling $11.5 million at September 30, 2015 related to Newington Business Park Center, which was classified as held-for-sale at September 30, 2015. (2) Excludes rental property totaling $57.7 million at December 31, 2014 related to the sale of the Richmond Portfolio, which was classified as held-for-sale at December 31, 2014 and was sold on March 19, 2015 .

Notes Receivable (Tables)

Notes Receivable (Tables)	9 Months Ended
	Sep. 30, 2015
Receivables [Abstract]
Summary of Notes Receivable	Below is a summary of our notes receivable for our outstanding mezzanine loans (dollars in thousands): Balance at September 30, 2015 Property Face Amount Unamortized Balance Interest Rate 950 F Street, NW $ 34,000 $ — $ 34,000 9.75 % Balance at December 31, 2014 Property Face Amount Unamortized Balance Interest Rate 950 F Street, NW $ 34,000 $ — $ 34,000 9.75 % America’s Square 29,720 (41 ) 29,679 9.00 % $ 63,720 $ (41 ) $ 63,679

Investment in Affiliates (Table

Investment in Affiliates (Tables)	9 Months Ended
	Sep. 30, 2015
Equity Method Investments and Joint Ventures [Abstract]
Components of Investments in Affiliates	Our investment in affiliates consisted of the following (dollars in thousands): Reporting Segment Ownership September 30, 2015 December 31, 2014 Prosperity Metro Plaza Northern Virginia 51 % $ 24,980 $ 24,651 1750 H Street, NW Washington, D.C. 50 % 15,444 14,834 Aviation Business Park Maryland 50 % 5,879 5,748 RiversPark I and II (1) Maryland 25 % 2,187 2,249 $ 48,490 $ 47,482 (1) RiversPark I and RiversPark II are owned through two separate joint ventures.
Net Assets of Company's Unconsolidated Joint Ventures	The net assets of our unconsolidated joint ventures consisted of the following (dollars in thousands): September 30, 2015 December 31, 2014 Assets: Rental property, net $ 194,442 $ 193,533 Cash and cash equivalents 5,510 4,567 Other assets 15,162 16,748 Total assets 215,114 214,848 Liabilities: Mortgage loans (1) 110,000 110,000 Other liabilities 5,413 7,256 Total liabilities 115,413 117,256 Net assets $ 99,701 $ 97,592 (1) Of the total mortgage debt that encumbers our unconsolidated properties, $2.8 million is recourse to us. We believe the fair value of the potential liability to us under this guaranty is inconsequential as the likelihood of our need to perform under the debt agreement is remote.
Results of Operations of Company's Unconsolidated Joint Ventures	The following table summarizes the results of operations of our unconsolidated joint ventures, which, due to our varying ownership interests in the joint ventures and the varying operations of the joint ventures, may not be reflective of the amounts recorded in our consolidated statements of operations (dollars in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Total revenues $ 5,975 $ 5,713 $ 18,205 $ 17,245 Total operating expenses (1,866 ) (1,818 ) (5,778 ) (5,738 ) Net operating income 4,109 3,895 12,427 11,507 Depreciation and amortization (2,254 ) (2,256 ) (6,790 ) (7,323 ) Other expense, net (980 ) (890 ) (2,928 ) (2,978 ) Net income $ 875 $ 749 $ 2,709 $ 1,206

Dispositions (Tables)

Dispositions (Tables)	9 Months Ended
	Sep. 30, 2015
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations Square Feet Area [Table Text Block]	The following table is a summary of property dispositions or held-for-sale properties whose operating results are included in continuing operations in our consolidated statements of operations for the periods presented (dollars in thousands): Property Reporting Disposition Date Property Type Square Feet Net Sale Proceeds Newington Business Park Center (1) Northern Virginia TBD Business Park 255,600 $ N/A Rumsey Center Maryland 7/28/2015 Business Park 135,015 14,956 Owings Mills Business Park Maryland 10/16/2014 Business Park 180,475 12,417 Corporate Campus at Ashburn Center Northern Virginia 6/26/2014 Business Park 194,184 39,910 (1) Newington Business Park Center was classified as held-for-sale at September 30, 2015. The sale is expected to be completed in the fourth quarter of 2015 or in early 2016; however, we can provide no assurances regarding the timing or pricing of the sale, or that such sale will occur at all.
Schedule of Disposal Groups Including Not Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block]	The following table summarizes the aggregate results of operations for the four properties that are included in continuing operations for the periods presented (dollars in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Revenues $ 890 $ 1,279 $ 3,422 $ 6,356 Property operating expenses (299 ) (529 ) (1,222 ) (2,289 ) Depreciation and amortization (98 ) (530 ) (714 ) (2,132 ) Interest expense (24 ) (111 ) (244 ) (334 ) Impairment of rental property — — — (3,956 ) Income (loss) from operations of disposed property 469 109 1,242 (2,355 ) Gain on sale of rental property 3,384 — 3,384 21,230 Net income from continuing operations of disposed property $ 3,853 $ 109 $ 4,626 $ 18,875
Summary of Completed Property Dispositions	The following table is a summary of property dispositions whose operating results are reflected as discontinued operations in our consolidated statements of operations for the periods presented (dollars in thousands): Reporting Segment Disposition Date Property Type Square Feet Net Sale Proceeds Richmond Portfolio Southern Virginia 3/19/2015 Business Park 827,900 $ 53,768 Patrick Center Maryland 4/16/2014 Office 66,269 10,888 West Park Maryland 4/2/2014 Office 28,333 2,871 Girard Business Center and Gateway Center Maryland 1/29/2014 Business Park and Office 341,973 31,616
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures	The following table summarizes the results of operations of properties included in discontinued operations (dollars in thousands): Three Months Ended Nine Months Ended 2015 2014 2015 2014 Revenues $ — $ 1,949 $ 877 $ 5,705 Income (loss) from operations, before taxes (1) — 297 (975 ) (359 ) Loss on debt extinguishment — — (489 ) — Gain on sale of rental property — — 857 1,338 (1) During the first quarter of 2015, we accelerated $2.0 million of unamortized straight-line rents, deferred rent abatements and leasing commissions related to the sale of the Richmond Portfolio in March 2015. During the first quarter of 2014, we accelerated $1.5 million of unamortized straight-line rents, deferred rent abatements and leasing commissions related to the sale of both Girard Business Center and Gateway Center in January 2014.

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Schedule of Borrowings	Our borrowings consisted of the following (dollars in thousands): September 30, December 31, 2014 (1) Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030 (2) $ 313,217 $ 308,637 Unsecured term loan, effective interest rates ranging from LIBOR plus 1.65% to LIBOR plus 2.05%, with staggered maturity dates ranging from October 2018 to October 2020 (2) 300,000 300,000 Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017 (2) 155,000 205,000 $ 768,217 $ 813,637 (1) The balance at December 31, 2014, includes five mortgage loans that were repaid with the sale of the Richmond Portfolio on March 19, 2015. At December 31, 2014, the mortgage loans had an aggregate principal balance of $3.5 million and were classified within “Liabilities held-for-sale” on our consolidated balance sheet for December 31, 2014. (2) At September 30, 2015, LIBOR was 0.19% . All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR.
Summary of Company's Mortgage Debt	The following table provides a summary of our mortgage and construction loans at September 30, 2015 and December 31, 2014 (dollars in thousands): Encumbered Property Contractual Effective Maturity September 30, December 31, 2014 Jackson National Life Loan (1) 5.19% 5.19% August 2015 $ — $ 64,943 440 First Street, NW (2) LIBOR + 2.50% LIBOR + 2.50% May 2016 32,217 32,216 Storey Park (2) LIBOR + 2.50% LIBOR + 2.50% October 2016 22,000 22,000 Gateway Centre Manassas Building I 7.35% 5.88% November 2016 269 432 Hillside I and II 5.75% 4.62% December 2016 12,644 12,949 Redland Corporate Center Buildings II & III 4.20% 4.64% November 2017 64,866 65,816 Northern Virginia Development Project (2) LIBOR + 1.85% LIBOR + 1.85% September 2019 9,176 — 840 First Street, NE 5.72% 6.01% July 2020 36,054 36,539 Battlefield Corporate Center 4.26% 4.40% November 2020 3,568 3,692 1211 Connecticut Avenue, NW 4.22% 4.47% July 2022 29,257 29,691 1401 K Street, NW 4.80% 4.93% June 2023 36,386 36,861 11 Dupont Circle, NW (3) 4.05% 4.22% September 2030 66,780 — 4.54% (4) 313,217 305,139 Unamortized fair value adjustments (221 ) (370 ) Principal balance 312,996 304,769 Debt Classified within “Liabilities-Held-for-Sale” Richmond Portfolio (5) Hanover Business Center Building D 8.88% 6.63% August 2015 — 104 Chesterfield Business Center Buildings C,D,G and H 8.50% 6.63% September 2015 — 302 Hanover Business Center Building C 7.88% 6.63% December 2017 — 505 Chesterfield Business Center Buildings A,B,E and F 7.45% 6.63% June 2021 — 1,674 Airpark Business Center 7.45% 6.63% June 2021 — 913 — 3,498 Total unamortized fair value adjustments — (73 ) Principal balance — 3,425 Total principal balance $ 312,996 $ 308,194 (1) On July 21, 2015, we prepaid, without penalty, the $64.2 million outstanding balance on our Jackson National Life Loan, which was scheduled to mature in August 2015 and was secured by the following properties: Plaza 500, Van Buren Office Park, Greenbrier Technology Center II, Norfolk Business Center, Snowden Center and Rumsey Center, which was subsequently sold on July 28, 2015 . (2) At September 30, 2015, LIBOR was 0.19% . (3) On August 7, 2015, we entered into a $66.8 million mortgage loan, which encumbers our 11 Dupont Circle, NW property. The new loan, which is interest only until September 1, 2025, has a fixed interest rate of 4.05% , matures on September 1, 2030 and is prepayable in full, without penalty, on or after August 8, 2025. (4) Weighted average interest rate on total mortgage and construction debt. (5) The mortgage loans and unamortized fair value adjustments that encumbered properties within the Richmond Portfolio were classified within “Liabilities held-for-sale” on our consolidated balance sheet at December 31, 2014. The loans were prepaid upon the sale of the Richmond Portfolio on March 19, 2015.
Unsecured Term Loan	The table below shows the outstanding balances and the interest rates of the three tranches of the $300.0 million unsecured term loan at September 30, 2015 (dollars in thousands): Maturity Date Amount Interest Rate (1) Tranche A October 2018 $ 100,000 LIBOR, plus 165 basis points Tranche B October 2019 100,000 LIBOR, plus 180 basis points Tranche C October 2020 100,000 LIBOR, plus 205 basis points $ 300,000 (1) At September 30, 2015, LIBOR was 0.19% . The interest rate spread is subject to change based on our maximum total indebtedness ratio. For more information, see note 8 (e) Debt – Financial Covenants .

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Interest Rate Swap Agreements	Our interest rate swap agreements are summarized below (dollars in thousands): Maturity Date Notional Amount Interest Rate Contractual Component Fixed LIBOR Interest Rate July 2016 $ 35,000 LIBOR 1.754 % July 2016 25,000 LIBOR 1.763 % July 2017 30,000 LIBOR 2.093 % July 2017 30,000 LIBOR 2.093 % July 2017 25,000 LIBOR 1.129 % July 2017 12,500 LIBOR 1.129 % July 2017 50,000 LIBOR 0.955 % July 2018 12,500 LIBOR 1.383 % July 2018 30,000 LIBOR 1.660 % July 2018 25,000 LIBOR 1.394 % July 2018 25,000 LIBOR 1.135 % Total/Weighted Average $ 300,000 1.505 %

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities	In accordance with accounting provisions and the fair value hierarchy described above, the following table shows the fair value of our consolidated assets and liabilities that are measured on a recurring basis as of September 30, 2015 and December 31, 2014 (dollars in thousands): Balance at Level 1 Level 2 Level 3 Recurring Measurements: Derivative instrument-swap liabilities $ 4,507 $ — $ 4,507 $ — Balance at Level 1 Level 2 Level 3 Recurring Measurements: Derivative instrument-swap assets $ 133 $ — $ 133 $ — Derivative instrument-swap liabilities 3,569 — 3,569 —
Fair Value of Debt Instruments	The carrying amount and estimated fair value of our notes receivable and debt instruments are as follows (amounts in thousands): September 30, 2015 December 31, 2014 Carrying Fair Carrying Fair Financial Assets: Notes receivable (1) $ 34,000 $ 34,000 $ 63,679 $ 63,720 Financial Liabilities: Mortgage debt (2) $ 313,217 $ 303,465 $ 308,637 $ 292,882 Unsecured term loan 300,000 303,163 300,000 300,000 Unsecured revolving credit facility 155,000 155,623 205,000 205,000 Total $ 768,217 $ 762,251 $ 813,637 $ 797,882 (1) The principal amount of our notes receivable was $34.0 million and $63.7 million at September 30, 2015 and December 31, 2014 , respectively. On February 24, 2015, the owners of America’s Square, a 461,000 square foot office complex located in Washington, D.C., prepaid a mezzanine loan, which had an outstanding $29.7 million balance of the $30.0 million mezzanine loan that we provided them in April 2011. (2) The balances at December 31, 2014, include five mortgage loans that were repaid with the sale of the Richmond Portfolio on March 19, 2015. At December 31, 2014, the mortgage loans had an aggregate principal balance of $3.5 million and were classified within “Liabilities held-for-sale” on our consolidated balance sheet for December 31, 2014.

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Company's Allocation between Non-controlling Interests	Our equity and redeemable noncontrolling interests are as follows (dollars in thousands): First Potomac Realty Trust Non-redeemable noncontrolling interests Total Equity Redeemable noncontrolling interests Balance at December 31, 2014 $ 710,007 $ 898 $ 710,905 $ 33,332 Net income (loss) 5,154 (3 ) 5,151 (186 ) Changes in ownership, net 3,289 — 3,289 (1,257 ) Distributions to owners (35,725 ) (96 ) (35,821 ) (1,181 ) Other comprehensive loss (1,015 ) — (1,015 ) (45 ) Repurchase of common shares $ (10,180 ) $ — $ (10,180 ) $ — Balance at September 30, 2015 $ 671,530 $ 799 $ 672,329 $ 30,663 First Potomac Realty Trust Non-redeemable noncontrolling interests Total Equity Redeemable noncontrolling interests Balance at December 31, 2013 $ 738,510 $ 781 $ 739,291 $ 33,221 Net income 16,614 — 16,614 327 Changes in ownership, net 2,018 161 2,179 390 Distributions to owners (35,691 ) — (35,691 ) (1,183 ) Other comprehensive income 1,059 — 1,059 47 Balance at September 30, 2014 $ 722,510 $ 942 $ 723,452 $ 32,802
Company's Accumulated Other Comprehensive Loss	A summary of our accumulated other comprehensive loss is as follows (dollars in thousands): 2015 2014 Beginning balance at January 1, $ (3,268 ) $ (3,836 ) Net unrealized (loss) gain on derivative instruments (1,060 ) 1,106 Net loss (gain) attributable to noncontrolling interests 45 (47 ) Ending balance at September 30, $ (4,283 ) $ (2,777 )

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Summary of Segment Information	The results of continuing operations of our four reporting segments for the three and nine months ended September 30, 2015 and 2014 are as follows (dollars in thousands): Three Months Ended September 30, 2015 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Number of buildings (1) 6 34 49 19 108 Square feet (1) 915,692 1,884,741 3,020,293 2,021,667 7,842,393 Total revenues $ 11,337 $ 10,575 $ 13,715 $ 7,227 $ 42,854 Property operating expense (2,962 ) (2,467 ) (3,347 ) (2,125 ) (10,901 ) Real estate taxes and insurance (2,015 ) (893 ) (1,285 ) (622 ) (4,815 ) Total property operating income $ 6,360 $ 7,215 $ 9,083 $ 4,480 27,138 Depreciation and amortization expense (16,758 ) General and administrative (4,605 ) Other expenses (1,778 ) Net income $ 3,997 Capital expenditures (2) $ 2,440 $ 2,649 $ 11,309 $ 2,019 $ 18,521 Three Months Ended September 30, 2014 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Number of buildings (1)(3) 6 42 49 38 135 Square feet (1)(3) 815,093 2,179,366 3,020,975 2,852,212 8,867,646 Total revenues $ 8,489 $ 11,154 $ 13,309 $ 7,103 $ 40,055 Property operating expense (2,496 ) (2,540 ) (3,121 ) (2,407 ) (10,564 ) Real estate taxes and insurance (1,278 ) (956 ) (1,228 ) (597 ) (4,059 ) Total property operating income $ 4,715 $ 7,658 $ 8,960 $ 4,099 25,432 Depreciation and amortization expense (15,217 ) General and administrative (4,955 ) Acquisition costs (1,488 ) Other expenses (4,020 ) Discontinued operations (4) 297 Net income $ 49 Capital expenditures (2) $ 5,320 $ 1,875 $ 1,516 $ 2,001 $ 10,767 Nine Months Ended September 30, 2015 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Total revenues $ 33,522 $ 33,315 $ 41,529 $ 21,375 $ 129,741 Property operating expense (9,088 ) (9,129 ) (10,603 ) (5,856 ) (34,676 ) Real estate taxes and insurance (5,994 ) (2,681 ) (4,178 ) (1,815 ) (14,668 ) Total property operating income $ 18,440 $ 21,505 $ 26,748 $ 13,704 80,397 Depreciation and amortization expense (49,909 ) General and administrative (15,110 ) Other expenses (9,806 ) Discontinued operations (4) (607 ) Net income $ 4,965 Total assets (5)(6) $ 515,625 $ 344,676 $ 452,962 $ 167,903 $ 1,526,524 Capital expenditures (2) $ 9,859 $ 6,965 $ 27,190 $ 5,419 $ 49,846 Nine Months Ended September 30, 2014 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Total revenues $ 23,256 $ 34,025 $ 40,122 $ 21,322 $ 118,725 Property operating expense (6,889 ) (8,913 ) (10,203 ) (6,820 ) (32,825 ) Real estate taxes and insurance (3,579 ) (2,934 ) (4,217 ) (1,701 ) (12,431 ) Total property operating income $ 12,788 $ 22,178 $ 25,702 $ 12,801 73,469 Depreciation and amortization expense (44,357 ) General and administrative (15,370 ) Acquisition costs (2,667 ) Impairment of rental property (3,956 ) Other income 8,843 Discontinued operations (4) 979 Net income $ 16,941 Total assets (5)(6) $ 501,536 $ 375,399 $ 437,909 $ 228,655 $ 1,628,737 Capital expenditures (2) $ 16,702 $ 6,966 $ 3,876 $ 6,173 $ 34,410 (1) Excludes Storey Park from our Washington, D.C. reporting segment, which was placed in development in the third quarter of 2013. (2) Capital expenditures for corporate assets not allocated to any of our reportable segments totaled $104 and $55 for the three months ended September 30, 2015 and 2014, respectively, and $413 and $693 for the nine months ended September 30, 2015 and 2014, respectively. (3) Includes occupied space at 440 First Street, NW in our Washington, D.C. reporting segment, which was substantially completed in the third quarter of 2013. In October 2014, the property was placed in service. (4) Includes the operating results from the Richmond Portfolio, Patrick Center, West Park, Girard Business Center and Gateway Center. For information, see note 7 (b), Dispositions - Discontinued Operations . (5) Total assets include our investment in properties that are owned through joint ventures that are not consolidated within our condensed consolidated financial statements. For more information on our unconsolidated investments, including location within our reportable segments, see note 6 , Investment in Affiliates . (6) Corporate assets not allocated to any of our reportable segments totaled $45,358 and $85,238 at September 30, 2015 and 2014, respectively.

Description of Business - Addit

Description of Business - Additional Information (Detail)		3 Months Ended	9 Months Ended
		Sep. 30, 2015ft²IntegerExecutivessegment	Sep. 30, 2015ft²JointVenturePersonIntegerExecutivessegment	Sep. 30, 2014ft²	[2]
Real Estate Properties [Line Items]
Number of Reportable Segments | segment		4	4
Operating Partnership in preferred		100.00%	100.00%
Interest in Operating Partnership		95.70%	95.70%
Number of officers who owned limited partnership interests | Executives		2	2
Number of Trustees Owning Interest in Limited Partnership | Integer		1	1
Area of real estate property	[1]	7,842,393	7,842,393	8,867,646
Unconsolidated joint ventures | JointVenture			5
Square footage of land for additional development		1,300,000	1,300,000
Occupancy rate in the Company's consolidated properties		89.90%	89.90%
Number of tenants representing current occupancy rate | Person			491
Square footage in development or redevelopment not included on occupancy calculation		200,000	200,000
Percent of Annualized Cash Rent			25.70%
US Government [Member]
Real Estate Properties [Line Items]
Percent of Annualized Cash Rent			13.50%
Wholly-owned Properties [Member]
Real Estate Properties [Line Items]
Number of Reportable Segments | Integer			4
Area of real estate property		7,800,000	7,800,000
Unconsolidated Properties [Member]
Real Estate Properties [Line Items]
Area of real estate property		900,000	900,000
[1]	Excludes Storey Park from our Washington, D.C. reporting segment, which was placed in development in the third quarter of 2013.
[2]	Includes occupied space at 440 First Street, NW in our Washington, D.C. reporting segment, which was substantially completed in the third quarter of 2013. In October 2014, the property was placed in service.

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Estimated Useful Lives of Company's Assets, by Class (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Property, Plant and Equipment [Line Items]
Lease related intangible assets		The term of the related lease
Tenant improvements		Shorter of the useful life of the asset or the term of the related lease
Buildings
Property, Plant and Equipment [Line Items]
Useful life		39 years
Minimum | Building improvements
Property, Plant and Equipment [Line Items]
Useful life	5 years
Minimum | Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Useful life	5 years
Maximum | Building improvements
Property, Plant and Equipment [Line Items]
Useful life	20 years
Maximum | Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Useful life	15 years

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Accounting Policies [Abstract]
Allowance for credit losses for its notes receivable	$ 0	$ 0

Earnings Per Common Share - Com

Earnings Per Common Share - Computation of Company's Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014
Numerator for basic and diluted earnings per common share:
Income (loss) from continuing operations	$ 3,997	$ (248)	$ 5,572		$ 15,962
Income (loss) from discontinued operations	0	297	(607)	[1]	979	[1]
Net income	3,997	49	4,965		16,941
Less: Net (income) loss from continuing operations attributable to noncontrolling interests	(38)	144	163		(285)
Less: Net (income) loss from discontinued operations attributable to noncontrolling interests	0	(13)	26		(42)
Net income attributable to First Potomac Realty Trust	3,959	180	5,154		16,614
Less: Dividends on preferred shares	(3,100)	(3,100)	(9,300)		(9,300)
Net income (loss) attributable to common shareholders	859	(2,920)	(4,146)		7,314
Less: Allocation to participating securities	(69)	(80)	(211)		(235)
Net income (loss) attributable to common shareholders	$ 790	$ (3,000)	$ (4,357)		$ 7,079
Denominator for basic and diluted earnings per common share:
Basic (in shares)	57,961	58,167	58,155		58,137
Diluted (in shares)	58,045	58,167	58,155		58,209
Basic and diluted earnings per common share:
Loss from continuing operations (in dollars per share)	$ 0.01	$ (0.05)	$ (0.06)		$ 0.10
(Loss) income from discontinued operations (in dollars per share)	0	0	(0.01)		0.02
Net income (loss) (in dollars per share)	$ 0.01	$ (0.05)	$ (0.07)		$ 0.12
[1]	Includes the operating results from the Richmond Portfolio, Patrick Center, West Park, Girard Business Center and Gateway Center. For information, see note 7(b), Dispositions - Discontinued Operations.

Earnings Per Common Share - Ant

Earnings Per Common Share - Anti-Dilutive Shares Not Included in Calculation of Diluted Earnings Per Share (Detail) - shares shares in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, Amount		15,921	13,892	15,601	13,982
Stock option awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, Amount		987	1,103	1,037	1,143
Non-vested share awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, Amount		307	433	374	401
Series A Preferred Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, Amount	[1]	14,627	12,356	14,190	12,438
[1]	Our Series A Preferred Shares are only convertible into our common shares upon certain changes in control of our Company. The dilutive shares are calculated as the daily average of the face value of the Series A Preferred Shares divided by the outstanding common share price.

Rental Property - Summary of Re

Rental Property - Summary of Rental Property (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015		Sep. 30, 2015		Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Rental property, net	$ 1,276,960	[1]	$ 1,276,960	[1]	$ 1,288,873	[2]
Rental Property [Member]
Property, Plant and Equipment [Line Items]
Land and land improvements	319,569	[1]	319,569	[1]	325,214	[2]
Buildings and improvements	931,749	[1]	931,749	[1]	949,683	[2]
Construction in process	83,778	[1]	83,778	[1]	69,181	[2]
Tenant Improvements	179,728	[1]	179,728	[1]	159,867	[2]
Furniture, fixtures and equipment	431	[1]	431	[1]	427	[2]
Rental property, gross	1,515,255	[1]	1,515,255	[1]	1,504,372	[2]
Less: accumulated depreciation	(238,295)	[1]	(238,295)	[1]	(215,499)	[2]
Northern Virginia
Property, Plant and Equipment [Line Items]
Buildings and improvements	5,200		5,200
Northern Virginia | Rental Property [Member]
Property, Plant and Equipment [Line Items]
Rental property, net	$ 11,500		$ 11,500
Southern Virginia | Rental Property [Member]
Property, Plant and Equipment [Line Items]
Rental property, net					$ 57,700
Disposition Date Of Property			Mar. 19, 2015
Maryland Reporting Segment [Member] | Rental Property [Member]
Property, Plant and Equipment [Line Items]
Disposition Date Of Property	Jul. 28, 2015
[1]	Excludes rental property totaling $11.5 million at September 30, 2015 related to Newington Business Park Center, which was classified as held-for-sale at September 30, 2015.
[2]	Excludes rental property totaling $57.7 million at December 31, 2014 related to the sale of the Richmond Portfolio, which was classified as held-for-sale at December 31, 2014 and was sold on March 19, 2015.

Rental Property - Additional In

Rental Property - Additional Information (Detail) $ in Millions	Aug. 04, 2011aft²Rate	Aug. 04, 2011aRate	Sep. 30, 2015USD ($)ft²	Sep. 30, 2015USD ($)ft²
Segment Reporting Information [Line Items]
Area of land available for development in additional building space				1,300,000
Occupancy rate in the Company's consolidated properties			89.90%	89.90%
Placed in-service redevelopment efforts			0
Redevelopment Efforts Yet To Be Placed In Service			0	0
Greyhound Property [Member]
Segment Reporting Information [Line Items]
Percentage Of Interest In Joint Venture Owned By Entity | Rate	97.00%	97.00%
440 First Street, NW [Member]
Segment Reporting Information [Line Items]
Original cost basis of the property | $			$ 23.6	$ 23.6
Anticipated completion of redevelopment			139,000	139,000
Occupancy rate in the Company's consolidated properties			67.40%	67.40%
Leased in Company Consolidated Properties			51.20%	51.20%
Projected incremental investment in redevelopment project | $			$ 55.5	$ 55.5
Washington D C Reporting Segment
Segment Reporting Information [Line Items]
Area of land available for development in additional building space				700,000
Projected incremental investment in development project | $			57.2	$ 57.2
Original cost basis of the property | $			$ 43.3	$ 43.3
Lease expiration date		Aug. 31, 2013
Development of area for operations by joint venture | a	1.6	1.6
Washington D C Reporting Segment | Greyhound Property [Member]
Segment Reporting Information [Line Items]
Percentage Of Interest In Joint Venture Owned By Entity	97.00%	97.00%
Washington D C Reporting Segment | Maximum | Greyhound Property [Member]
Segment Reporting Information [Line Items]
Area of land available for development in additional building space	712,000
Maryland Reporting Segment [Member]
Segment Reporting Information [Line Items]
Area of land available for development in additional building space				100,000
Northern Virginia
Segment Reporting Information [Line Items]
Area of land available for development in additional building space				400,000
Area of land placed under development			167,000	167,000
Projected incremental investment in development project | $			$ 18.7	$ 18.7
Original cost basis of the property | $			$ 5.2	$ 5.2
Southern Virginia [Member]
Segment Reporting Information [Line Items]
Area of land available for development in additional building space				100,000

Notes Receivable - Summary of N

Notes Receivable - Summary of Notes Receivable (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Receivables with Imputed Interest [Line Items]
Face Amount		$ 63,720
Unamortized Origination Fees		(41)
Balance		63,679
Notes Receivables Issued on December 2010 [Member]
Receivables with Imputed Interest [Line Items]
Face Amount	$ 34,000	34,000
Unamortized Origination Fees	0	0
Balance	$ 34,000	$ 34,000
Interest Rate	9.75%	9.75%
America Square [Member]
Receivables with Imputed Interest [Line Items]
Face Amount		$ 29,720
Unamortized Origination Fees		(41)
Balance		$ 29,679
Interest Rate		9.00%

Notes Receivable - Additional I

Notes Receivable - Additional Information (Detail) $ in Thousands

Jan. 10, 2014USD ($)

Apr. 01, 2011

Sep. 30, 2015USD ($)ft²

Mar. 31, 2015USD ($)

Sep. 30, 2014USD ($)ft²

Mar. 31, 2014USD ($)

Sep. 30, 2015USD ($)ft²

Sep. 30, 2014USD ($)ft²

Dec. 31, 2014USD ($)

Dec. 31, 2010USD ($)ft²

Feb. 24, 2015USD ($)ft²

Apr. 30, 2011USD ($)ft²

Receivables with Imputed Interest [Line Items]

Area of real estate property | ft²

[1]

7,842,393

8,867,646

[2]

7,842,393

8,867,646

[2]

Unsecured revolving credit facility

$ 155,000

$ 155,000

$ 205,000

Interest income

800

2,900

Income from amortization of origination fees

$ 0

$ 7

$ 5

$ 25

America Square [Member]

Receivables with Imputed Interest [Line Items]

Area of real estate property | ft²

461,000

461,000

Mezzanine loan provided to owners

$ 29,700

$ 30,000

Maturity date of loan

May 1, 2016

Fixed interest rate on loan

9.00%

Prepayment Fee Income

$ 2,400

America Square [Member] | Maximum

Receivables with Imputed Interest [Line Items]

Fixed interest rate on loan

9.00%

Notes Receivables Issued on December 2010 [Member]

Receivables with Imputed Interest [Line Items]

Area of real estate property | ft²

287,000

Mezzanine loan provided to owners

$ 34,000

$ 25,000

Maturity date of loan

Apr. 1, 2017

Unsecured revolving credit facility

$ 9,000

Fixed interest rate on loan

9.75%

9.75%

Interest income

$ 1,500

$ 4,500

Write-off of unamortized origination fees

$ 100

Notes Receivables Issued on December 2010 [Member] | Maximum

Receivables with Imputed Interest [Line Items]

Fixed interest rate on loan

12.50%

Notes Receivables Issued on December 2010 [Member] | Minimum

Receivables with Imputed Interest [Line Items]

Fixed interest rate on loan

9.75%

[1]

Excludes Storey Park from our Washington, D.C. reporting segment, which was placed in development in the third quarter of 2013.

[2]

Includes occupied space at 440 First Street, NW in our Washington, D.C. reporting segment, which was substantially completed in the third quarter of 2013. In October 2014, the property was placed in service.

Investment in Affiliates - Comp

Investment in Affiliates - Components of Investments in Affiliates (Detail) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Company Investment		$ 48,490	$ 47,482
Prosperity Metro Plaza
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Northern Virginia
Ownership Interest		51.00%
Company Investment		$ 24,980	24,651
1750 H Street, NW
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Washington, D.C.
Ownership Interest		50.00%
Company Investment		$ 15,444	14,834
Aviation Business Park
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Maryland
Ownership Interest		50.00%
Company Investment		$ 5,879	5,748
RiversPark I and II
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Maryland
Ownership Interest	[1]	25.00%
Company Investment	[1]	$ 2,187	$ 2,249
[1]	RiversPark I and RiversPark II are owned through two separate joint ventures.

Investment in Affiliates - Net

Investment in Affiliates - Net Assets of Company's Unconsolidated Joint Ventures (Detail) - USD ($) $ in Thousands		Sep. 30, 2015		Dec. 31, 2014		Sep. 30, 2014		Dec. 31, 2013
Assets:
Rental property, net		$ 1,276,960	[1]	$ 1,288,873	[2]
Cash and cash equivalents		12,875		13,323		$ 11,993		$ 8,740
Total assets		1,526,524	[3],[4]	1,618,460		$ 1,628,737	[3],[4]
Liabilities:
Total liabilities		823,532		874,223
Recourse mortgage debt		768,217		813,637
Unconsolidated Entities
Liabilities:
Recourse mortgage debt		2,800
Unconsolidated Joint Ventures
Assets:
Rental property, net		194,442		193,533
Cash and cash equivalents		5,510		4,567
Other assets		15,162		16,748
Total assets		215,114		214,848
Liabilities:
Mortgage loans	[5]	110,000		110,000
Other liabilities		5,413		7,256
Total liabilities		115,413		117,256
Net assets		$ 99,701		$ 97,592
[1]	Excludes rental property totaling $11.5 million at September 30, 2015 related to Newington Business Park Center, which was classified as held-for-sale at September 30, 2015.
[2]	Excludes rental property totaling $57.7 million at December 31, 2014 related to the sale of the Richmond Portfolio, which was classified as held-for-sale at December 31, 2014 and was sold on March 19, 2015.
[3]	Corporate assets not allocated to any of our reportable segments totaled $45,358 and $85,238 at September 30, 2015 and 2014, respectively.
[4]	Total assets include our investment in properties that are owned through joint ventures that are not consolidated within our condensed consolidated financial statements. For more information on our unconsolidated investments, including location within our reportable segments, see note 6, Investment in Affiliates.
[5]	Of the total mortgage debt that encumbers our unconsolidated properties, $2.8 million is recourse to us. We believe the fair value of the potential liability to us under this guaranty is inconsequential as the likelihood of our need to perform under the debt agreement is remote.

Investment in Affiliates - Addi

Investment in Affiliates - Additional Information (Detail) ft² in Thousands, $ in Millions	Sep. 26, 2014USD ($)Rate	Sep. 30, 2015USD ($)ft²	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)ft²	Sep. 30, 2014USD ($)	Nov. 12, 2014USD ($)	Jul. 10, 2014USD ($)
Schedule of Equity Method Investments [Line Items]
Ownership percentage in unconsolidated joint venture		51.00%		51.00%
Repaid mortgage						$ 48.3
Investment in affiliates variable interest entity square feet | ft²				327
Financing						$ 50
Mortgage interest rate		3.91%		3.91%
Loan Interest only payment date				Dec. 31, 2024
Loan maturity date				Dec. 1, 2029
Loan prepayment date				Jun. 1, 2029
Interest rate increase (decrease) | Rate	60.00%
Fees from joint ventures		$ 0.2	$ 0.2	$ 0.5	$ 0.5
RiversPark I and II
Schedule of Equity Method Investments [Line Items]
Ownership percentage in unconsolidated joint venture	25.00%
Investment in affiliates variable interest entity square feet | ft²		308
Financing	$ 28
Loan maturity date	Sep. 26, 2017
Percentage of outstanding principal	25.00%	10.00%		10.00%
1750 H Street
Schedule of Equity Method Investments [Line Items]
Repaid mortgage							$ 27.9
Financing							$ 32
Mortgage interest rate		3.92%		3.92%
Loan maturity date				Aug. 1, 2024
Loan prepayment date				Aug. 1, 2021
Washington D C Reporting Segment | 1750 H Street
Schedule of Equity Method Investments [Line Items]
Ownership percentage in unconsolidated joint venture		50.00%		50.00%
Washington D C Reporting Segment | Maximum | 1750 H Street
Schedule of Equity Method Investments [Line Items]
Investment in affiliates variable interest entity square feet | ft²				113

Investment in Affiliates - Resu

Investment in Affiliates - Results of Operations of Company's Unconsolidated Joint Ventures (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Schedule of Equity Method Investments [Line Items]
Total revenues	$ 42,854	$ 40,055	$ 129,741	$ 118,725
Total operating expenses	(37,079)	(36,283)	(114,363)	(111,606)
Operating income	5,775	3,772	15,378	7,119
Depreciation and amortization	(16,758)	(15,217)	(49,909)	(44,357)
Other expense, net	(1,778)	(4,020)	(9,806)
Net income	432	412	1,235	385
Unconsolidated Joint Ventures
Schedule of Equity Method Investments [Line Items]
Total revenues	5,975	5,713	18,205	17,245
Total operating expenses	(1,866)	(1,818)	(5,778)	(5,738)
Operating income	4,109	3,895	12,427	11,507
Depreciation and amortization	(2,254)	(2,256)	(6,790)	(7,323)
Other expense, net	(980)	(890)	(2,928)	(2,978)
Net income	$ 875	$ 749	$ 2,709	$ 1,206

Dispositions - Additional Infor

Dispositions - Additional Information (Detail) $ in Thousands		Mar. 19, 2015USD ($)ft²	Jan. 29, 2014USD ($)ft²	Sep. 30, 2015USD ($)ft²	Mar. 31, 2015USD ($)	Sep. 30, 2014USD ($)ft²		Mar. 31, 2014USD ($)	Sep. 30, 2015USD ($)ft²	Sep. 30, 2014USD ($)ft²
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Square feet | ft²	[1]			7,842,393		8,867,646	[2]		7,842,393	8,867,646	[2]
Gain (Loss) on Sale of Properties				$ 3,384		$ 0			$ 3,384	$ 21,230
Richmond
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Disposition Date Of Property									Mar. 19, 2015
Square feet | ft²		827,900
Proceeds from sale of properties		$ 53,768
Unamortized straight-line rent					$ 2,000
Girard Business Center and Gateway Center [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Disposition Date Of Property									Jan. 29, 2014
Square feet | ft²			341,973
Proceeds from sale of properties			$ 31,616
Unamortized straight-line rent								$ 1,500
[1]	Excludes Storey Park from our Washington, D.C. reporting segment, which was placed in development in the third quarter of 2013.
[2]	Includes occupied space at 440 First Street, NW in our Washington, D.C. reporting segment, which was substantially completed in the third quarter of 2013. In October 2014, the property was placed in service.

Dispositions Dispositions - Dis

Dispositions Dispositions - Disposed or Held-for-Sale Properties within Continuing Operations (Details) $ in Thousands		Jul. 28, 2015USD ($)ft²	Oct. 16, 2014USD ($)ft²	Jun. 26, 2014USD ($)ft²	Sep. 30, 2015USD ($)ft²	Sep. 30, 2014USD ($)ft²		Sep. 30, 2015USD ($)ft²	Sep. 30, 2014USD ($)ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Square feet | ft²	[1]				7,842,393	8,867,646	[2]	7,842,393	8,867,646	[2]
Impairment Of Properties					$ 0	$ 0		$ 0	$ (3,956)
Gain (Loss) on Sale of Properties					3,384	0		3,384	21,230
Rumsey Center [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Square feet | ft²			135,000
Rumsey Center [Domain] | Continuing Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues					890			3,422
Property operating expenses					(299)			(1,222)
Depreciation and amortization					(98)			(714)
Interest Expense					(24)			(244)
Impairment Of Properties					0			0
Operating Income (Loss) from Continuing Operations Attributable to Parent					469			1,242
Gain (Loss) on Sale of Properties					3,384			3,384
Net income from continuing operations of disposed property					$ 3,853			$ 4,626
Corporate Campus at Ashburn Center and Owings Mills Business Park | Continuing Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues						1,279			6,356
Property operating expenses						(529)			(2,289)
Depreciation and amortization						(530)			(2,132)
Interest Expense						(111)			(334)
Impairment Of Properties						0			(3,956)
Operating Income (Loss) from Continuing Operations Attributable to Parent						109			(2,355)
Gain (Loss) on Sale of Properties						0			21,230
Net income from continuing operations of disposed property						$ 109			$ 18,875
MARYLAND | Rumsey Center [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reporting Segment								Maryland
Disposition Date Of Property								Jul. 28, 2015
Property Type								Business Park
Square feet | ft²		135,015
Proceeds from sale of properties		$ 14,956
MARYLAND | Owings Mills Business Park
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reporting Segment								Maryland
Disposition Date Of Property								Oct. 16, 2014
Property Type								Business Park
Square feet | ft²			180,475
Proceeds from sale of properties			$ 12,417
Northern Virginia | Newington Business Park Center [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reporting Segment	[3]							Northern Virginia
Property Type	[3]							Business Park
Square feet | ft²	[3]				255,600			255,600
Accounts Payable and Other Accrued Liabilities					$ 200			$ 200
Land and Land Improvements					3,100			3,100
Buildings and Improvements, Gross					13,700			13,700
Tenant Improvements					800			800
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment					6,100			6,100
Other assets					$ 500			$ 500
Northern Virginia | Corporate Campus at Ashburn Center
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reporting Segment								Northern Virginia
Disposition Date Of Property								Jun. 26, 2014
Property Type								Business Park
Square feet | ft²				194,184
Proceeds from sale of properties				$ 39,910
[1]	Excludes Storey Park from our Washington, D.C. reporting segment, which was placed in development in the third quarter of 2013.
[2]	Includes occupied space at 440 First Street, NW in our Washington, D.C. reporting segment, which was substantially completed in the third quarter of 2013. In October 2014, the property was placed in service.
[3]	Newington Business Park Center was classified as held-for-sale at September 30, 2015. The sale is expected to be completed in the fourth quarter of 2015 or in early 2016; however, we can provide no assurances regarding the timing or pricing of the sale, or that such sale will occur at all.

Dispositions - Summary of Compl

Dispositions - Summary of Completed Property Dispositions (Detail) $ in Thousands		Mar. 19, 2015USD ($)ft²	Apr. 16, 2014USD ($)ft²	Apr. 02, 2014USD ($)ft²	Jan. 29, 2014USD ($)ft²	Sep. 30, 2015ft²	Sep. 30, 2014ft²	[2]
Schedule Of Discontinued Operations [Line Items]
Square feet	[1]					7,842,393	8,867,646
Richmond
Schedule Of Discontinued Operations [Line Items]
Reporting Segment						Southern Virginia
Disposition Date Of Property						Mar. 19, 2015
Property Type						Business Park
Square feet		827,900
Proceeds from sale of properties | $		$ 53,768
Patrick Center
Schedule Of Discontinued Operations [Line Items]
Reporting Segment						Maryland
Disposition Date Of Property						Apr. 16, 2014
Property Type						Office
Square feet			66,269
Proceeds from sale of properties | $			$ 10,888
West Park
Schedule Of Discontinued Operations [Line Items]
Reporting Segment						Maryland
Disposition Date Of Property						Apr. 2, 2014
Property Type						Office
Square feet				28,333
Proceeds from sale of properties | $				$ 2,871
Girard Business Center and Gateway Center
Schedule Of Discontinued Operations [Line Items]
Reporting Segment						Maryland
Disposition Date Of Property						Jan. 29, 2014
Property Type						Business Park and Office
Square feet					341,973
Proceeds from sale of properties | $					$ 31,616
[1]	Excludes Storey Park from our Washington, D.C. reporting segment, which was placed in development in the third quarter of 2013.
[2]	Includes occupied space at 440 First Street, NW in our Washington, D.C. reporting segment, which was substantially completed in the third quarter of 2013. In October 2014, the property was placed in service.

Dispositions - Net (Loss) Incom

Dispositions - Net (Loss) Income from Discontinued Operations (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on debt extinguishment		$ 0	$ 0	$ (489)	$ 0
Discontinued Operations [Member] | All properties classified within discontinued operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues		0	1,949	877	5,705
Income (loss) from operations, before taxes(1)	[1]	0	297	(975)	(359)
Loss on debt extinguishment		0	0	(489)	0
Gain on sale of rental property		$ 0	$ 0	$ 857	$ 1,338
[1]	During the first quarter of 2015, we accelerated $2.0 million of unamortized straight-line rents, deferred rent abatements and leasing commissions related to the sale of the Richmond Portfolio in March 2015. During the first quarter of 2014, we accelerated $1.5 million of unamortized straight-line rents, deferred rent abatements and leasing commissions related to the sale of both Girard Business Center and Gateway Center in January 2014.

Debt - Schedule of Borrowings (

Debt - Schedule of Borrowings (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015		Sep. 30, 2015		Jul. 21, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)	[1]	$ 313,217		$ 313,217			$ 308,637	[2]
Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017(2)	[1]	155,000		155,000			205,000	[2]
Total long term debt		$ 768,217		$ 768,217			813,637
Effective interest rate on the notes		0.19%		0.19%
Mortgage Loan [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, effective percentage rate range, minimum				4.22%
Debt instrument, interest rate, effective percentage rate range, maximum				6.01%
Maturity Date				9/1/2030
Unsecured Term Loan, Effective Interest Rates Ranging from LIBOR Plus 1.45% to LIBOR Plus 1.90%, with Staggered Maturity Dates ranging from October 2018 to October 2020
Debt Instrument [Line Items]
Unsecured term loan, effective interest rates ranging from LIBOR plus 1.65% to LIBOR plus 2.05%, with staggered maturity dates ranging from October 2018 to October 2020(2)	[1]	$ 300,000		$ 300,000			300,000	[2]
Maturity Date				October 2018 to October 2020
Debt Instrument Basis Spread On Variable Rate Minimum				1.65%
Debt Instrument Basis Spread On Variable Rate Maximum				2.05%
Unsecured revolving credit facility
Debt Instrument [Line Items]
Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017(2)		$ 79,000		$ 79,000
Effective interest rate on the notes		1.70%		1.70%
Maturity Date				October 2,017
Rumsey Center [Domain]
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)		$ 0		$ 0
Richmond
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)							3,498
Mortgages Held-for-sale, Fair Value Disclosure		$ 3,500		$ 3,500
Disposition Date Of Property				Mar. 19, 2015
Rental Property [Member] | Maryland Reporting Segment [Member]
Debt Instrument [Line Items]
Disposition Date Of Property		Jul. 28, 2015
Jackson Loan [Member]
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)		$ 0	[3]	$ 0	[3]	$ 64,200	$ 64,943	[3]
Effective interest rate on the notes	[3]	5.19%		5.19%
Maturity Date	[3]			August 2,015
[1]	At September 30, 2015, LIBOR was 0.19%. All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR.
[2]	The balance at December 31, 2014, includes five mortgage loans that were repaid with the sale of the Richmond Portfolio on March 19, 2015. At December 31, 2014, the mortgage loans had an aggregate principal balance of $3.5 million and were classified within “Liabilities held-for-sale” on our consolidated balance sheet for December 31, 2014.
[3]	On July 21, 2015, we prepaid, without penalty, the $64.2 million outstanding balance on our Jackson National Life Loan, which was scheduled to mature in August 2015 and was secured by the following properties: Plaza 500, Van Buren Office Park, Greenbrier Technology Center II, Norfolk Business Center, Snowden Center and Rumsey Center, which was subsequently sold on July 28, 2015.

Debt - Summary of Company's Mor

Debt - Summary of Company's Mortgage Debt (Detail) - USD ($) $ in Thousands		Sep. 01, 2015	Jun. 05, 2013	Sep. 30, 2015		Sep. 30, 2015		Aug. 07, 2015	Jul. 21, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Effective Interest Rate				0.19%		0.19%
Total Mortgage Debt	[1]			$ 313,217		$ 313,217				$ 308,637	[2]
Debt, Weighted Average Interest Rate	[3]			4.54%		4.54%
Carrying amount of mortgages				$ 312,996		$ 312,996				308,194
Effective Interest Rate				0.19%		0.19%
LIBOR plus interest rate		1.85%	2.50%	1.70%
Mortgage Loans
Debt Instrument [Line Items]
Carrying amount of mortgages										3,425
Jackson National Life Loan
Debt Instrument [Line Items]
Contractual Interest Rate	[4]			5.19%		5.19%
Effective Interest Rate	[4]			5.19%		5.19%
Maturity Date	[4]					August 2,015
Total Mortgage Debt				$ 0	[4]	$ 0	[4]		$ 64,200	64,943	[4]
Effective Interest Rate	[4]			5.19%		5.19%
Eleven Dupont Circle [Member]
Debt Instrument [Line Items]
Contractual Interest Rate	[5]			4.05%		4.05%
Effective Interest Rate	[5]			4.22%		4.22%
Maturity Date						September 1, 2030
Total Mortgage Debt	[5]			$ 66,780		$ 66,780				0
Effective Interest Rate	[5]			4.22%		4.22%
440 First Street, NW Construction Loan
Debt Instrument [Line Items]
Contractual Interest Rate				2.50%		2.50%
Contractual Interest Rate	[6]					LIBOR + 2.50%
Maturity Date	[6]					May 2,016
Total Mortgage Debt	[6]			$ 32,217		$ 32,217				32,216
Storey Park
Debt Instrument [Line Items]
Contractual Interest Rate				2.50%		2.50%
Contractual Interest Rate	[6]					LIBOR + 2.50%
Maturity Date	[6]					October 2,016
Total Mortgage Debt	[6]			$ 22,000		$ 22,000				22,000
Gateway Centre Manassas Building I
Debt Instrument [Line Items]
Contractual Interest Rate				7.35%		7.35%
Effective Interest Rate				5.88%		5.88%
Maturity Date						November 2016
Total Mortgage Debt				$ 269		$ 269				432
Effective Interest Rate				5.88%		5.88%
Hillside I and II
Debt Instrument [Line Items]
Contractual Interest Rate				5.75%		5.75%
Effective Interest Rate				4.62%		4.62%
Maturity Date						December 2,016
Total Mortgage Debt				$ 12,644		$ 12,644				12,949
Effective Interest Rate				4.62%		4.62%
Redland Corporate Center Buildings II & III
Debt Instrument [Line Items]
Contractual Interest Rate				4.20%		4.20%
Effective Interest Rate				4.64%		4.64%
Maturity Date						November 2,017
Total Mortgage Debt				$ 64,866		$ 64,866				65,816
Effective Interest Rate				4.64%		4.64%
Northern Virginia Development Project [Member]
Debt Instrument [Line Items]
Contractual Interest Rate	[6]					LIBOR + 1.85%
Maturity Date	[6]					9/1/2019
Total Mortgage Debt	[6]			$ 9,176		$ 9,176				0
840 First Street, NE
Debt Instrument [Line Items]
Contractual Interest Rate				5.72%		5.72%
Effective Interest Rate				6.01%		6.01%
Maturity Date						July 2,020
Total Mortgage Debt				$ 36,054		$ 36,054				36,539
Effective Interest Rate				6.01%		6.01%
Battlefield Corporate Center
Debt Instrument [Line Items]
Contractual Interest Rate				4.26%		4.26%
Effective Interest Rate				4.40%		4.40%
Maturity Date						November 2,020
Total Mortgage Debt				$ 3,568		$ 3,568				3,692
Effective Interest Rate				4.40%		4.40%
One thousand two hundred eleven Connecticut Avenue NW. [Member]
Debt Instrument [Line Items]
Contractual Interest Rate				4.22%		4.22%
Effective Interest Rate				4.47%		4.47%
Maturity Date						July 2,022
Total Mortgage Debt				$ 29,257		$ 29,257				29,691
Effective Interest Rate				4.47%		4.47%
1401 K Street, NW
Debt Instrument [Line Items]
Contractual Interest Rate				4.80%		4.80%
Effective Interest Rate				4.93%		4.93%
Maturity Date						June 1, 2023
Total Mortgage Debt				$ 36,386		$ 36,386				36,861
Effective Interest Rate				4.93%		4.93%
Hanover Business Center Building D
Debt Instrument [Line Items]
Contractual Interest Rate	[7]			8.88%		8.88%
Effective Interest Rate	[7]			6.63%		6.63%
Maturity Date	[7]					August 2,015
Total Mortgage Debt	[7]			$ 0		$ 0				104
Effective Interest Rate	[7]			6.63%		6.63%
Chesterfield Business Center Buildings C,D,G and H
Debt Instrument [Line Items]
Contractual Interest Rate	[7]			8.50%		8.50%
Effective Interest Rate	[7]			6.63%		6.63%
Maturity Date	[7]					September 2,015
Total Mortgage Debt	[7]			$ 0		$ 0				302
Effective Interest Rate	[7]			6.63%		6.63%
Hanover Business Center Building C
Debt Instrument [Line Items]
Contractual Interest Rate	[7]			7.88%		7.88%
Effective Interest Rate	[7]			6.63%		6.63%
Maturity Date	[7]					December 2,017
Total Mortgage Debt	[7]			$ 0		$ 0				505
Effective Interest Rate	[7]			6.63%		6.63%
Buildings Abe And F
Debt Instrument [Line Items]
Contractual Interest Rate	[7]			7.45%		7.45%
Effective Interest Rate	[7]			6.63%		6.63%
Maturity Date	[7]					June 2,021
Total Mortgage Debt	[7]			$ 0		$ 0				1,674
Effective Interest Rate	[7]			6.63%		6.63%
Airpark Business Center
Debt Instrument [Line Items]
Contractual Interest Rate	[7]			7.45%		7.45%
Effective Interest Rate	[7]			6.63%		6.63%
Maturity Date	[7]					June 2,021
Total Mortgage Debt	[7]			$ 0		$ 0				913
Effective Interest Rate	[7]			6.63%		6.63%
Continuing Operations
Debt Instrument [Line Items]
Total Mortgage Debt				$ 313,217		$ 313,217				305,139
Total unamortized fair value adjustments				(221)		(221)				(370)
Carrying amount of mortgages				312,996		312,996				304,769
Rumsey Center [Domain]
Debt Instrument [Line Items]
Total Mortgage Debt				0		0
Rumsey Center [Domain] | Mortgage Loans
Debt Instrument [Line Items]
Carrying amount of mortgages				0		0
Richmond
Debt Instrument [Line Items]
Total Mortgage Debt										3,498
Total unamortized fair value adjustments				$ 0		$ 0				$ (73)
Disposition Date Of Property						Mar. 19, 2015
Eleven Dupont Circle [Member]
Debt Instrument [Line Items]
Mortgage Loans on Real Estate								$ 66,800
Maryland Reporting Segment [Member] | Equipment Leased to Other Party [Member]
Debt Instrument [Line Items]
Disposition Date Of Property				Jul. 28, 2015
[1]	At September 30, 2015, LIBOR was 0.19%. All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR.
[2]	The balance at December 31, 2014, includes five mortgage loans that were repaid with the sale of the Richmond Portfolio on March 19, 2015. At December 31, 2014, the mortgage loans had an aggregate principal balance of $3.5 million and were classified within “Liabilities held-for-sale” on our consolidated balance sheet for December 31, 2014.
[3]	Weighted average interest rate on total mortgage and construction debt.
[4]	On July 21, 2015, we prepaid, without penalty, the $64.2 million outstanding balance on our Jackson National Life Loan, which was scheduled to mature in August 2015 and was secured by the following properties: Plaza 500, Van Buren Office Park, Greenbrier Technology Center II, Norfolk Business Center, Snowden Center and Rumsey Center, which was subsequently sold on July 28, 2015.
[5]	On August 7, 2015, we entered into a $66.8 million mortgage loan, which encumbers our 11 Dupont Circle, NW property. The new loan, which is interest only until September 1, 2025, has a fixed interest rate of 4.05%, matures on September 1, 2030 and is prepayable in full, without penalty, on or after August 8, 2025.
[6]	At September 30, 2015, LIBOR was 0.19%.
[7]	The mortgage loans and unamortized fair value adjustments that encumbered properties within the Richmond Portfolio were classified within “Liabilities held-for-sale” on our consolidated balance sheet at December 31, 2014. The loans were prepaid upon the sale of the Richmond Portfolio on March 19, 2015.

Debt - Additional Information (

Debt - Additional Information (Detail) $ in Thousands

Sep. 01, 2015USD ($)

Oct. 16, 2014USD ($)Rate

Jun. 05, 2013USD ($)

Jun. 05, 2013USD ($)

Jan. 31, 2014USD ($)

Sep. 30, 2015USD ($)ft²Rate

Sep. 30, 2014USD ($)

Sep. 30, 2015USD ($)ft²TranchesRate

Sep. 30, 2014USD ($)

Sep. 30, 2015USD ($)

Sep. 30, 2015

Sep. 30, 2015Integer

Sep. 30, 2015Interest_Rate_Swaps

Aug. 07, 2015USD ($)

Jul. 21, 2015USD ($)

Dec. 31, 2014USD ($)

Aug. 04, 2011Rate

Debt Instrument [Line Items]

Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)

[1]

$ 313,217

$ 308,637

[2]

Amount borrowed

$ 9,200

$ 21,700

Borrowing capacity of a construction loan

$ 43,700

Basis spread over variable rate

1.85%

2.50%

1.70%

Recourse mortgage debt

768,217

813,637

Outstanding balance of three tranches

300,000

300,000

Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017(2)

[1]

155,000

205,000

[2]

Proceed to pay loan

$ 226,155

$ 106,127

Interest rate during period

1.90%

Average interest rate at prior period end

1.70%

1.70%

Maximum outstanding borrowings

$ 217,000

$ 216,000

$ 218,000

$ 216,000

Weighted average interest rate

1.90%

Available capacity on the unsecured revolving credit facility

142,000

Annual commitment fee

0.25%

Number of interest rate swap agreements

11

11

Fixed effective interest rate

1.50%

Unsecured term loan

Debt Instrument [Line Items]

Number of tranches | Tranches

3

Outstanding balance of three tranches

300,000

Unsecured revolving credit facility

Debt Instrument [Line Items]

Debt Instruments Maturity Date

October 2,017

Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017(2)

79,000

Proceed to pay loan

$ 76,000

Northern Virginia Development Project [Member]

Debt Instrument [Line Items]

Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)

[3]

9,176

0

Debt Instruments Maturity Date

[3]

9/1/2019

Jackson Loan [Member]

Debt Instrument [Line Items]

Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)

0

[4]

$ 64,200

64,943

[4]

Debt Instrument, Interest Rate, Stated Percentage

[4]

5.19%

Debt Instruments Maturity Date

[4]

August 2,015

440 First Street, NW Construction Loan

Debt Instrument [Line Items]

Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)

[3]

32,217

32,216

Debt Instrument, Interest Rate, Stated Percentage

2.50%

Debt Instruments Maturity Date

[3]

May 2,016

Eleven Dupont Circle [Member]

Debt Instrument [Line Items]

Mortgage and construction loans, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)

[5]

66,780

$ 0

Debt Instrument, Interest Rate, Stated Percentage

[5]

4.05%

Debt Instruments Maturity Date

September 1, 2030

Interest Rate Swap

Debt Instrument [Line Items]

Fixed effective interest rate

1.505%

Amount on variable rate debt

$ 300,000

Unused lines of credit

Debt Instrument [Line Items]

Weighted average borrowings outstanding on unsecured revolving credit facility

$ 164,200

$ 125,900

$ 168,900

$ 112,000

Eleven Dupont Circle [Member]

Debt Instrument [Line Items]

Mortgage Loans on Real Estate

$ 66,800

Greyhound Property [Member]

Debt Instrument [Line Items]

Percentage Of Interest In Joint Venture Owned By Entity | Rate

97.00%

Mortgage Loans on Real Estate

$ 22,000

Debt Instrument, Interest Rate, Stated Percentage | Rate

5.00%

5.00%

Basis spread over variable rate | Rate

2.50%

Maturity date

Oct. 16, 2016

Maturity Period

1 year

Recourse mortgage debt

$ 6,000

440 First Street, NW [Member]

Debt Instrument [Line Items]

Amount borrowed

$ 10,500

Borrowing capacity of a construction loan

$ 43,500

$ 43,500

Maturity date

May 30, 2016

Maturity Period

1 year

Percentage of outstanding principal

50.00%

Northern Virginia Reporting Segment [Member]

Debt Instrument [Line Items]

Area of land placed under development | ft²

167,000

167,000

[1]

At September 30, 2015, LIBOR was 0.19%. All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR.

[2]

The balance at December 31, 2014, includes five mortgage loans that were repaid with the sale of the Richmond Portfolio on March 19, 2015. At December 31, 2014, the mortgage loans had an aggregate principal balance of $3.5 million and were classified within “Liabilities held-for-sale” on our consolidated balance sheet for December 31, 2014.

[3]

At September 30, 2015, LIBOR was 0.19%.

[4]

On July 21, 2015, we prepaid, without penalty, the $64.2 million outstanding balance on our Jackson National Life Loan, which was scheduled to mature in August 2015 and was secured by the following properties: Plaza 500, Van Buren Office Park, Greenbrier Technology Center II, Norfolk Business Center, Snowden Center and Rumsey Center, which was subsequently sold on July 28, 2015.

[5]

On August 7, 2015, we entered into a $66.8 million mortgage loan, which encumbers our 11 Dupont Circle, NW property. The new loan, which is interest only until September 1, 2025, has a fixed interest rate of 4.05%, matures on September 1, 2030 and is prepayable in full, without penalty, on or after August 8, 2025.

Debt - Unsecured Term Loan (Det

Debt - Unsecured Term Loan (Detail) - USD ($) $ in Thousands		Sep. 01, 2015	Jun. 05, 2013	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Amount				$ 300,000	$ 300,000	$ 300,000
Basis spread over variable rate		1.85%	2.50%	1.70%
Tranche A
Debt Instrument [Line Items]
Maturity Date					October 2018
Amount				$ 100,000	$ 100,000
Interest Rate	[1]				LIBOR, plus 165 basis points
Basis spread over variable rate				1.65%
Tranche B
Debt Instrument [Line Items]
Maturity Date					October 2019
Amount				$ 100,000	$ 100,000
Interest Rate	[1]				LIBOR, plus 180 basis points
Basis spread over variable rate				1.80%
Tranche C
Debt Instrument [Line Items]
Maturity Date					October 2020
Amount				$ 100,000	$ 100,000
Interest Rate	[1]				LIBOR, plus 205 basis points
Basis spread over variable rate				2.05%
[1]	At September 30, 2015, LIBOR was 0.19%. The interest rate spread is subject to change based on our maximum total indebtedness ratio. For more information, see note 8(e) Debt – Financial Covenants.

Derivative Instruments - Summar

Derivative Instruments - Summary of Interest Rate Swap Agreements (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015USD ($)
Derivatives, Fair Value [Line Items]
Fixed LIBOR Interest Rate	1.50%
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Notional Amount	$ 300,000
Fixed LIBOR Interest Rate	1.505%
Interest Rate Swap One
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2016
Notional Amount	$ 35,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	1.754%
Interest Rate Swap Two
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2016
Notional Amount	$ 25,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	1.763%
Interest Rate Swap Three
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2017
Notional Amount	$ 30,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	2.093%
Interest Rate Swap Four
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2017
Notional Amount	$ 30,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	2.093%
Interest Rate Swap Five
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2018
Notional Amount	$ 30,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	1.66%
Interest Rate Swap Six
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2018
Notional Amount	$ 25,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	1.394%
Interest Rate Swap Seven
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2017
Notional Amount	$ 25,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	1.129%
Interest Rate Swap Eight
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2017
Notional Amount	$ 12,500
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	1.129%
Interest Rate Swap Nine
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2018
Notional Amount	$ 12,500
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	1.383%
Interest Rate Swap Ten
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2017
Notional Amount	$ 50,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	0.955%
Interest Rate Swap Eleven
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2018
Notional Amount	$ 25,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate	1.135%

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2015	Sep. 30, 2015Integer	Sep. 30, 2015Interest_Rate_Swaps
Derivatives, Fair Value [Line Items]
Number of interest rate swap agreements						11	11
Fixed effective interest rate					1.50%
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Fixed effective interest rate					1.505%
Amount on variable rate debt	$ 300,000		$ 300,000
Interest Rate Swap | Interest Expense
Derivatives, Fair Value [Line Items]
Accumulated other comprehensive loss reclassified as an increase in interest expense	$ 1,000	$ 1,000	3,000	$ 3,100
Estimated accumulated other comprehensive loss reclassified as an increase in interest expense over the following twelve months			$ 4,300

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Assets and Liabilities (Detail) - Recurring Measurements - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Recurring Measurements:
Derivative instrument-swap assets		$ 133
Derivative instrument-swap liabilities	$ 4,507	3,569
Level 1
Recurring Measurements:
Derivative instrument-swap assets		0
Derivative instrument-swap liabilities	0	0
Level 2
Recurring Measurements:
Derivative instrument-swap assets		133
Derivative instrument-swap liabilities	4,507	3,569
Level 3
Recurring Measurements:
Derivative instrument-swap assets		0
Derivative instrument-swap liabilities	$ 0	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - 3 months ended Sep. 30, 2015 $ in Thousands	USD ($)snapshot	Integer	Interest_Rate_Swaps
Derivatives, Fair Value [Line Items]
Number of Interest Rate Derivatives Held		11	11
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Notional Amount	$ 300,000
Minimum number of daily snapshot used for valuation of interest rate swap agreements | snapshot	7,500

Fair Value Measurements - Fai58

Fair Value Measurements - Fair Value of Debt Instruments (Detail) $ in Thousands		Sep. 30, 2015USD ($)ft²	Mar. 19, 2015ft²	Feb. 24, 2015USD ($)ft²	Dec. 31, 2014USD ($)	Sep. 30, 2014ft²	[2]	Apr. 30, 2011USD ($)ft²
Financial Assets:
Carrying value of notes receivable		$ 34,000			$ 63,679
Fair value of notes receivable		$ 34,000			63,700
Financial Liabilities:
Area of real estate property | ft²	[1]	7,842,393				8,867,646
Carrying Value
Financial Assets:
Carrying value of notes receivable	[3]	$ 34,000			63,679
Financial Liabilities:
Carrying value of the debt instruments		768,217			813,637
Carrying Value | Mortgage debt
Financial Liabilities:
Carrying value of the debt instruments	[4]	313,217			308,637
Carrying Value | Unsecured term loan
Financial Liabilities:
Carrying value of the debt instruments		300,000			300,000
Carrying Value | Unsecured revolving credit facility
Financial Liabilities:
Carrying value of the debt instruments		155,000			205,000
Fair Value
Financial Assets:
Fair value of notes receivable	[3]	34,000			63,720
Financial Liabilities:
Fair value of the debt instruments		762,251			797,882
Fair Value | Mortgage debt
Financial Liabilities:
Fair value of the debt instruments	[4]	303,465			292,882
Fair Value | Unsecured term loan
Financial Liabilities:
Fair value of the debt instruments		303,163			300,000
Fair Value | Unsecured revolving credit facility
Financial Liabilities:
Fair value of the debt instruments		155,623			$ 205,000
America Square [Member]
Financial Liabilities:
Area of real estate property | ft²				461,000				461,000
Mezzanine loan provided to owners				$ 29,700				$ 30,000
Richmond
Financial Liabilities:
Area of real estate property | ft²			827,900
Mortgages Held-for-sale, Fair Value Disclosure		$ 3,500
[1]	Excludes Storey Park from our Washington, D.C. reporting segment, which was placed in development in the third quarter of 2013.
[2]	Includes occupied space at 440 First Street, NW in our Washington, D.C. reporting segment, which was substantially completed in the third quarter of 2013. In October 2014, the property was placed in service.
[3]	The principal amount of our notes receivable was $34.0 million and $63.7 million at September 30, 2015 and December 31, 2014, respectively. On February 24, 2015, the owners of America’s Square, a 461,000 square foot office complex located in Washington, D.C., prepaid a mezzanine loan, which had an outstanding $29.7 million balance of the $30.0 million mezzanine loan that we provided them in April 2011.
[4]	The balances at December 31, 2014, include five mortgage loans that were repaid with the sale of the Richmond Portfolio on March 19, 2015. At December 31, 2014, the mortgage loans had an aggregate principal balance of $3.5 million and were classified within “Liabilities held-for-sale” on our consolidated balance sheet for December 31, 2014.

Equity - Additional Information

Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Oct. 27, 2015	Jul. 28, 2015	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014
Dividends Payable [Line Items]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased			5,000,000	5,000,000
Stock Repurchased and Retired During Period, Shares			924,198
Stock Repurchased and Retired During Period, Weighted Average Share Price			$ 10.99
Repurchases of common shares			$ 10,200	$ (10,180)	$ 0
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased			4,100,000	4,100,000
Dividend declared date		Jul. 28, 2015
Series A Preferred Shares
Dividends Payable [Line Items]
Dividends declared on Series A Preferred Shares		$ 0.484375
Common Shares
Dividends Payable [Line Items]
Common share dividend per share declared		0.15
Common share dividend per share annualized		$ 0.60
Dividend paid date		Aug. 17, 2015
Dividend record date		Aug. 10, 2015
Subsequent Event [Member]
Dividends Payable [Line Items]
Dividend declared date	Oct. 27, 2015
Subsequent Event [Member] | Series A Preferred Shares
Dividends Payable [Line Items]
Dividends declared on Series A Preferred Shares	$ 0.484375
Subsequent Event [Member] | Common Shares
Dividends Payable [Line Items]
Common share dividend per share declared	0.15
Common share dividend per share annualized	$ 0.60
Dividend paid date	Nov. 16, 2015
Dividend record date	Nov. 9, 2015

Equity - Company's Allocation B

Equity - Company's Allocation Between Non-controlling Interests (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling interests in a consolidated partnership		$ 898
Total equity		710,905	$ 739,291
Net income (loss)		5,151	16,614
Changes in ownership, net		3,289	2,179
Distributions to owners		(35,821)	(35,691)
Other comprehensive income		(1,015)	1,059
Repurchases of common shares	$ 10,200	(10,180)	0
Noncontrolling interests in a consolidated partnership	800	800
Total equity	672,329	672,329	723,452
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning Balance, Redeemable noncontrolling interests		33,332	33,221
Net income (loss), Redeemable noncontrolling interests		(186)	327
Change in ownership, net, Redeemable noncontrolling interests		(1,257)	390
Distributions to owners, Redeemable noncontrolling interests		(1,181)	(1,183)
Other comprehensive income, Redeemable noncontrolling interests		(45)	47
Temporary Equity Stock Repurchased and Retired During Period		0
Ending Balance, Redeemable noncontrolling interests	30,663	30,663	32,802
First Potomac Realty Trust
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance		710,007	738,510
Net income (loss)		5,154	16,614
Changes in ownership, net		3,289	2,018
Distributions to owners		(35,725)	(35,691)
Other comprehensive income		(1,015)	1,059
Repurchases of common shares		(10,180)
Ending Balance	671,530	671,530	722,510
Non-redeemable Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling interests in a consolidated partnership		898	781
Net income (loss)		(3)	0
Changes in ownership, net		0	161
Distributions to owners		(96)	0
Other comprehensive income		0	0
Repurchases of common shares		0
Noncontrolling interests in a consolidated partnership	$ 799	$ 799	$ 942

Equity - Company's Accumulated

Equity - Company's Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Increase (Decrease) in Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ (3,268)	$ (3,836)
Net unrealized (loss) gain on derivative instruments	(1,060)	1,106
Net loss (gain) attributable to noncontrolling interests	45	(47)
Ending balance	$ (4,283)	$ (2,777)

Noncontrolling Interests - Addi

Noncontrolling Interests - Additional Information (Detail) $ in Millions	Aug. 04, 2011aft²	Aug. 04, 2011a	Sep. 30, 2015USD ($)shares	Mar. 31, 2014shares	Sep. 30, 2015USD ($)ft²shares	Sep. 30, 2014shares	Dec. 31, 2014USD ($)
Business Acquisition [Line Items]
Cost to acquire all of the outstanding common Operating Partnership units not owned by the Company | $			$ 28.8		$ 28.8
Fair value adjustment, cost basis | $			$ 3.6		$ 3.6		$ 4.7
Outstanding Operating Partnership units not owned by the Company					2,619,069
Operating Partnership units not owned by Company			4.30%
Common operating partnership units redeemed for cash			11,508		11,508
Common operating partnership units redeemed for common shares			0		0
Operating Partnership units issued for acquisition					0
Area of land available for development in additional building space | ft²					1,300,000
Washington D C Reporting Segment
Business Acquisition [Line Items]
Development of area for operations by joint venture | a	1.6	1.6
Area of land available for development in additional building space | ft²					700,000
Projected incremental investment in development project | $			$ 57.2		$ 57.2
Original cost basis of the property | $			$ 43.3		$ 43.3
840 First Street, NE [Member]
Business Acquisition [Line Items]
Operating Partnership units issued for acquisition				3,125		3,125
Greyhound Property [Member] | Washington D C Reporting Segment
Business Acquisition [Line Items]
Percentage of interest in joint venture	97.00%	97.00%
Greyhound Property [Member] | Washington D C Reporting Segment | Maximum
Business Acquisition [Line Items]
Area of land available for development in additional building space | ft²	712,000

Segment Information - Additiona

Segment Information - Additional Information (Detail) - segment	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Segment Reporting [Abstract]
Number of Reportable Segments	4	4

Segment Information - Summary o

Segment Information - Summary of Segment Information (Detail) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2015USD ($)ft²Integer		Sep. 30, 2014USD ($)ft²Integer		Sep. 30, 2015USD ($)ft²Integer		Sep. 30, 2014USD ($)ft²Integer		Dec. 31, 2014USD ($)
Segment Reporting Information [Line Items]
Number of buildings | Integer	[1]	108		135	[2]	108		135	[2]
Square feet | ft²	[1]	7,842,393		8,867,646	[2]	7,842,393		8,867,646	[2]
Total revenues		$ 42,854		$ 40,055		$ 129,741		$ 118,725
Property operating expense		(10,901)		(10,564)		(34,676)		(32,825)
Real estate taxes and insurance		(4,815)		(4,059)		(14,668)		(12,431)
Total property operating income		27,138		25,432		80,397		73,469
Depreciation and amortization expense		(16,758)		(15,217)		(49,909)		(44,357)
General and administrative		(4,605)		(4,955)		(15,110)		(15,370)
Acquisition costs		0		(1,488)		0		(2,667)
Impairment Of Properties		0		0		0		(3,956)
Other Nonoperating Income (Expense)								8,843
Other expenses		(1,778)		(4,020)		(9,806)
Income from discontinued operations		0		297		(607)	[3]	979	[3]
Net income		3,997		49		4,965		16,941
Total assets		1,526,524	[4],[5]	1,628,737	[4],[5]	1,526,524	[4],[5]	1,628,737	[4],[5]	$ 1,618,460
Capital expenditure	[6]	18,521		10,767		49,846		34,410
Capital expenditures for corporate assets not allocated to any reportable segments		104		55		413		693
Corporate assets not allocated to any reportable segments		$ 45,358		$ 85,238		$ 45,358		$ 85,238
Washington, D.C.
Segment Reporting Information [Line Items]
Number of buildings | Integer	[1]	6		6	[2]	6		6	[2]
Square feet | ft²	[1]	915,692		815,093	[2]	915,692		815,093	[2]
Total revenues		$ 11,337		$ 8,489		$ 33,522		$ 23,256
Property operating expense		(2,962)		(2,496)		(9,088)		(6,889)
Real estate taxes and insurance		(2,015)		(1,278)		(5,994)		(3,579)
Total property operating income		6,360		4,715		18,440		12,788
Total assets	[4],[5]	515,625		501,536		515,625		501,536
Capital expenditure	[6]	$ 2,440		$ 5,320		$ 9,859		$ 16,702
Maryland
Segment Reporting Information [Line Items]
Number of buildings | Integer	[1]	34		42	[2]	34		42	[2]
Square feet | ft²	[1]	1,884,741		2,179,366	[2]	1,884,741		2,179,366	[2]
Total revenues		$ 10,575		$ 11,154		$ 33,315		$ 34,025
Property operating expense		(2,467)		(2,540)		(9,129)		(8,913)
Real estate taxes and insurance		(893)		(956)		(2,681)		(2,934)
Total property operating income		7,215		7,658		21,505		22,178
Total assets	[4],[5]	344,676		375,399		344,676		375,399
Capital expenditure	[6]	$ 2,649		$ 1,875		$ 6,965		$ 6,966
Northern Virginia
Segment Reporting Information [Line Items]
Number of buildings | Integer	[1]	49		49	[2]	49		49	[2]
Square feet | ft²	[1]	3,020,293		3,020,975	[2]	3,020,293		3,020,975	[2]
Total revenues		$ 13,715		$ 13,309		$ 41,529		$ 40,122
Property operating expense		(3,347)		(3,121)		(10,603)		(10,203)
Real estate taxes and insurance		(1,285)		(1,228)		(4,178)		(4,217)
Total property operating income		9,083		8,960		26,748		25,702
Total assets	[4],[5]	$ 452,962		437,909		$ 452,962		437,909
Capital expenditure	[6]			$ 1,516				$ 3,876
Southern Virginia
Segment Reporting Information [Line Items]
Number of buildings | Integer	[1]	19		38	[2]	19		38	[2]
Square feet | ft²	[1]	2,021,667		2,852,212	[2]	2,021,667		2,852,212	[2]
Total revenues		$ 7,227		$ 7,103		$ 21,375		$ 21,322
Property operating expense		(2,125)		(2,407)		(5,856)		(6,820)
Real estate taxes and insurance		(622)		(597)		(1,815)		(1,701)
Total property operating income		4,480		4,099		13,704		12,801
Total assets	[4],[5]	167,903		228,655		167,903		228,655
Capital expenditure	[6]	2,019		$ 2,001		5,419		$ 6,173
Northern Virginia
Segment Reporting Information [Line Items]
Capital expenditure	[6]	$ 11,309				$ 27,190
[1]	Excludes Storey Park from our Washington, D.C. reporting segment, which was placed in development in the third quarter of 2013.
[2]	Includes occupied space at 440 First Street, NW in our Washington, D.C. reporting segment, which was substantially completed in the third quarter of 2013. In October 2014, the property was placed in service.
[3]	Includes the operating results from the Richmond Portfolio, Patrick Center, West Park, Girard Business Center and Gateway Center. For information, see note 7(b), Dispositions - Discontinued Operations.
[4]	Corporate assets not allocated to any of our reportable segments totaled $45,358 and $85,238 at September 30, 2015 and 2014, respectively.
[5]	Total assets include our investment in properties that are owned through joint ventures that are not consolidated within our condensed consolidated financial statements. For more information on our unconsolidated investments, including location within our reportable segments, see note 6, Investment in Affiliates.
[6]	Capital expenditures for corporate assets not allocated to any of our reportable segments totaled $104 and $55 for the three months ended September 30, 2015 and 2014, respectively, and $413 and $693 for the nine months ended September 30, 2015 and 2014, respectively.