First Potomac Realty Trust (FPO) 10-Q 31 Jul 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 29, 2015
Document And Entity Information [Abstract]
Entity Registrant Name	FIRST POTOMAC REALTY TRUST
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
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		58,758,040

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015		Dec. 31, 2014
Assets:
Rental property, net	$ 1,286,301	[1]	$ 1,288,873	[2]
Assets held-for-sale	11,677		59,717
Cash and cash equivalents	12,735		13,323
Escrows and reserves	2,529		2,986
Accounts and other receivables, net of allowance for doubtful accounts of $1,350 and $1,207, respectively	11,656		10,587
Accrued straight-line rents, net of allowance for doubtful accounts of $97 and $104, respectively	38,986		34,226
Notes receivable, net	34,000		63,679
Investment in affiliates	48,059		47,482
Deferred costs, net	45,403		43,991
Prepaid expenses and other assets	6,117		7,712
Intangible assets, net	40,019		45,884
Total assets	1,537,482	[3],[4]	1,618,460
Liabilities:
Mortgage and Construction loans	294,499		305,139
Unsecured term loan	300,000		300,000
Unsecured revolving credit facility	152,000		205,000
Disposal Group, Including Discontinued Operation, Liabilities	8,307		4,562
Accounts payable and other liabilities	44,178		41,113
Accrued interest	1,657		1,720
Rents received in advance	6,942		7,971
Tenant security deposits	5,904		5,891
Deferred market rent, net	2,510		2,827
Total liabilities	815,997		874,223
Noncontrolling interests in the Operating Partnership	30,389		33,332
Equity:
Common shares, $0.001 par value, 150,000 shares authorized; 58,758 and 58,815 shares issued and outstanding, respectively	59		59
Additional paid-in capital	916,385		913,282
Noncontrolling interests in a consolidated partnership	800		898
Accumulated other comprehensive loss	(3,582)		(3,268)
Dividends in excess of accumulated earnings	(382,566)		(360,066)
Total equity	691,096		710,905
Total liabilities, noncontrolling interests and equity	1,537,482		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 $10.9 million at June 30, 2015 related to Rumsey Center, which was classified as held-for-sale at June 30, 2015. The property was sold on July 28, 2015.
[2]	Excludes rental property totaling $57.7 million at December 31, 2014 related to the sale of the Richmond Portfolio (as defined in note 7, Dispositions), 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 $56,563 and $86,333 at June 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	Jun. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts, accounts and other receivables	$ 1,350	$ 1,207
Allowance for doubtful accounts, accrued straight-line rents	$ 97	$ 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	58,758,000	58,815,000
Common stock, shares outstanding	58,758,000	58,815,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues:
Rental	$ 34,844	$ 31,619	$ 69,224	$ 62,052
Tenant reimbursements and other	8,195	7,688	17,664	16,619
Total revenues	43,039	39,307	86,888	78,671
Operating expenses:
Property operating	10,661	10,224	23,775	22,261
Real estate taxes and insurance	4,811	4,241	9,854	8,373
General and administrative	4,979	5,218	10,505	10,414
Acquisition costs	0	1,111	0	1,179
Depreciation and amortization	16,817	14,829	33,151	29,139
Impairment of rental property	0	3,956	0	3,956
Total operating expenses	37,268	39,579	77,285	75,322
Operating income (loss)	5,771	(272)	9,603	3,349
Other expenses (income)
Interest expense	6,725	6,031	13,633	11,768
Interest and other income	(974)	(1,670)	(4,802)	(3,428)
Equity in (earnings) losses of affiliates	(456)	(199)	(803)	28
Gain on sale of rental property	0	(21,230)	0	(21,230)
Total other expenses (income)	5,295	(17,068)	8,028	(12,862)
Income from continuing operations	476	16,796	1,575	16,211
Discontinued operations:
Income (loss) from operations	0	254	(975)	(657)
Loss on debt extinguishment	0	0	(489)	0
Gain on sale of rental property	0	1,284	857	1,338
Income (loss) from discontinued operations	0	1,538	(607)	681
Net income	476	18,334	968	16,892
Less: Net loss (income) attributable to noncontrolling interests	114	(652)	227	(458)
Net income attributable to First Potomac Realty Trust	590	17,682	1,195	16,434
Less: Dividends on preferred shares	(3,100)	(3,100)	(6,200)	(6,200)
Net (loss) income attributable to common shareholders	$ (2,510)	$ 14,582	$ (5,005)	$ 10,234
Basic and diluted earnings per common share:
(Loss) income from continuing operations	$ (0.04)	$ 0.22	$ (0.08)	$ 0.16
Income (loss) from discontinued operations	0	0.03	(0.01)	0.01
Net (loss) income	$ (0.04)	$ 0.25	$ (0.09)	$ 0.17
Weighted average common shares outstanding:
Basic	58,280	58,146	58,241	58,122
Diluted	58,280	58,220	58,241	58,190

Consolidated Statements of Comp

Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 476	$ 18,334	$ 968	$ 16,892
Unrealized gain on derivative instruments	748	99	397	416
Unrealized loss on derivative instruments	0	(1,079)	(725)	(1,217)
Total comprehensive income	1,224	17,354	640	16,091
Net loss (income) attributable to noncontrolling interests	114	(652)	227	(458)
Net gain (loss) from derivative instruments attributable to noncontrolling interests	32	42	(14)	34
Comprehensive income attributable to First Potomac Realty Trust	$ 1,370	$ 16,744	$ 853	$ 15,667

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 968	$ 16,892
Discontinued operations:
Gain on sale of rental property	(857)	(1,338)
Depreciation and amortization	1,222	2,070
Depreciation and amortization	33,693	29,676
Stock based compensation	1,531	1,689
Bad debt expense	394	481
Amortization of deferred market rent	77	(55)
Amortization of financing costs and discounts	665	674
Equity in (earnings) losses of affiliates	(803)	28
Distributions from investments in affiliates	632	435
Gain (Loss) on Sale of Properties	0	21,230
Impairment of Real Estate	0	3,956
Changes in assets and liabilities:
Escrows and reserves	281	2,925
Accounts and other receivables	(1,555)	1,904
Accrued straight-line rents	(4,583)	(2,918)
Prepaid expenses and other assets	1,051	1,802
Tenant security deposits	(509)	240
Accounts payable and accrued expenses	2,123	(431)
Accrued interest	(63)	38
Rents received in advance	(1,330)	(436)
Deferred costs	(4,833)	(5,546)
Total adjustments	27,136	13,964
Net cash provided by operating activities	28,104	30,856
Cash flows from investing activities:
Investment in note receivable	0	(9,000)
Proceeds from sale of rental property	56,943	85,284
Principal payments from note receivable	29,720	90
Change In Escrow And Reserves	176	0
Additions to rental property and furniture, fixtures and equipment	(23,760)	(16,639)
Additions to construction in progress	(7,565)	(7,003)
Payments For Acquisition Of Rental Property And Associated Intangible Assets	0	(61,731)
Proceeds from Sale of Equity Method Investments	(405)	(590)
Net cash provided by (used in) investing activities	55,109	(9,589)
Cash flows from financing activities:
Financing costs	(108)	(405)
Issuance of debt	26,000	104,794
Repayments of debt	(84,883)	(96,697)
Dividends to common shareholders	(17,611)	(17,586)
Dividends to preferred shareholders	(6,200)	(6,200)
Contributions from consolidated joint venture partners	0	161
Distributions to consolidated joint venture partners	(96)	0
Distributions to noncontrolling interests	(788)	(789)
Operating partnership unit redemptions	(134)	0
Proceeds from stock option exercises	19	113
Net cash used in financing activities	(83,801)	(16,609)
Net (decrease) increase in cash and cash equivalents	(588)	4,658
Cash and cash equivalents, beginning of period	13,323	8,740
Cash and cash equivalents, end of period	12,735	13,398
Cash paid for interest, net	12,877	10,946
Non-cash investing and financing activities:
Noncash or Part Noncash Acquisition, Debt Assumed	0	37,269
Shares Tendered By Employees For Statutory Tax Withholdings Upon Issuance Of Common Stock	454	383
Issuance of common Operating Partnership units in connection with the acquisition of rental property	(1,783)	2,318
Changes in accruals:	0	40
Changes in accruals:
Additions to rental property and furniture, fixtures and equipment	(967)	(1,571)
Additions to development and redevelopment	$ 3,266	$ (426)

Consolidated Statements of Cas7

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Capitalized interest on indebtedness paid in cash	$ 900	$ 1,800
Surrendered common shares to satisfy statutory minimum federal income tax obligations	454	383
Change in redemption value, noncontrolling interest	$ 3,000	5,600
Operating Partnership units issued for acquisition	0
Furniture and Fixtures [Member]
Accrued capital expenditure	$ 8,300	6,600
Development and Redevelopment [Member]
Accrued capital expenditure	$ 4,600	$ 1,000
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	6 Months Ended
	Jun. 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 June 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 June 30, 2015 , we wholly owned or had a controlling interest in properties totaling 8.0 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 89.1% occupied by 504 tenants at June 30, 2015 . We did not include square footage that was in development or redevelopment, which totaled 0.2 million square feet at June 30, 2015 , in our occupancy calculation. We derive substantially all of our revenue from leases of space within our properties. As of June 30, 2015 , our largest tenant was the U.S. Government, which accounted for 13.4% of our total annualized cash basis rent, and the U.S. Government combined with government contractors, accounted for 25.5% of our total annualized cash basis rent as of June 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	6 Months Ended
	Jun. 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 June 30, 2015 , the results of our operations and our comprehensive income for the three and six months ended June 30, 2015 and 2014 and our cash flows for the six months ended June 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 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 six months ended June 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 six months ended June 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 January 1, 2017. 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	6 Months Ended
	Jun. 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 June 30, Six Months Ended June 30, 2015 2014 2015 2014 Numerator for basic and diluted earnings per common share: Income from continuing operations $ 476 $ 16,796 $ 1,575 $ 16,211 Income (loss) from discontinued operations — 1,538 (607 ) 681 Net income 476 18,334 968 16,892 Less: Net loss (income) from continuing operations attributable to noncontrolling interests 114 (582 ) 201 (429 ) Less: Net (income) loss from discontinued operations attributable to noncontrolling interests — (70 ) 26 (29 ) Net income attributable to First Potomac Realty Trust 590 17,682 1,195 16,434 Less: Dividends on preferred shares (3,100 ) (3,100 ) (6,200 ) (6,200 ) Net (loss) income attributable to common shareholders (2,510 ) 14,582 (5,005 ) 10,234 Less: Allocation to participating securities (69 ) (77 ) (142 ) (155 ) Net (loss) income attributable to common shareholders $ (2,579 ) $ 14,505 $ (5,147 ) $ 10,079 Denominator for basic and diluted earnings per common share: Weighted average common shares outstanding: Basic 58,280 58,146 58,241 58,122 Diluted 58,280 58,220 58,241 58,190 Basic and diluted earnings per common share: (Loss) income from continuing operations $ (0.04 ) $ 0.22 $ (0.08 ) $ 0.16 Income (loss) from discontinued operations — 0.03 (0.01 ) 0.01 Net (loss) income $ (0.04 ) $ 0.25 $ (0.09 ) $ 0.17 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 Six Months Ended 2015 2014 2015 2014 Stock option awards 1,046 1,145 1,069 1,170 Non-vested share awards 405 400 450 419 Series A Preferred Shares (1) 14,868 12,296 13,965 12,480 16,319 13,841 15,484 14,069 (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	6 Months Ended
	Jun. 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): June 30, 2015 (1) December 31, 2014 (2) Land and land improvements $ 322,538 $ 325,214 Buildings and improvements 941,248 949,683 Construction in progress 82,432 69,181 Tenant improvements 172,931 159,867 Furniture, fixtures and equipment 420 427 1,519,569 1,504,372 Less: accumulated depreciation (233,268 ) (215,499 ) $ 1,286,301 $ 1,288,873 (1) Excludes rental property totaling $10.9 million at June 30, 2015 related to Rumsey Center, which was classified as held-for-sale at June 30, 2015. The property was sold on July 28, 2015 . (2) Excludes rental property totaling $57.7 million at December 31, 2014 related to the sale of the Richmond Portfolio (as defined in note 7, Dispositions ), 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 the fourth quarter of 2016. At June 30, 2015, our total investment in the development project was $16.4 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 June 30, 2015 in excess of the original cost basis of the land relate to design and permit fees, site preparation costs, foundation work and beginning 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. The joint venture anticipates developing a mixed-use project on the 1.6 acre site, which can accommodate up to 712,000 square feet. At June 30, 2015, our total investment in the development project was $56.7 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 capitalized architectural fees and site preparation costs. 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. 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. At June 30, 2015, the property was 65.7% leased and 50.1% occupied. During the fourth quarter of 2014, all vacant space at the property was placed in service. At June 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 second quarter of 2015, we did no t place in-service any completed development or redevelopment space. At June 30, 2015, we had no completed development or redevelopment space that have yet to be placed in service.

Notes Receivable

Notes Receivable	6 Months Ended
	Jun. 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 June 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 9.0 % $ 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 $2.0 million for the three and six months ended June 30, 2015, respectively, and $1.5 million and $3.0 million for the three and six months ended June 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 June 30, 2015 and $5 thousand for the six months ended June 30, 2015. We recorded $7 thousand and $18 thousand of income from the amortization of origination fees for the three and six months ended June 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	6 Months Ended
	Jun. 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 June 30, 2015 December 31, 2014 Prosperity Metro Plaza Northern Virginia 51 % $ 24,657 $ 24,651 1750 H Street, NW Washington, D.C. 50 % 15,367 14,834 Aviation Business Park Maryland 50 % 5,867 5,748 RiversPark I and II (1) Maryland 25 % 2,168 2,249 $ 48,059 $ 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 25% owned unconsolidated joint venture amended a $28.0 million mortgage loan that encumbers Rivers Park 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): June 30, 2015 December 31, 2014 Assets: Rental property, net $ 193,861 $ 193,533 Cash and cash equivalents 5,828 4,567 Other assets 15,635 16,748 Total assets 215,324 214,848 Liabilities: Mortgage loans (1) 110,000 110,000 Other liabilities 6,470 7,256 Total liabilities 116,470 117,256 Net assets $ 98,854 $ 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 June 30, Six Months Ended June 30, 2015 2014 2015 2014 Total revenues $ 6,063 $ 5,780 $ 12,230 $ 11,531 Total operating expenses (1,756 ) (1,694 ) (3,912 ) (3,920 ) Net operating income 4,307 4,086 8,318 7,611 Depreciation and amortization (2,287 ) (2,264 ) (4,536 ) (5,067 ) Other expense, net (975 ) (1,077 ) (1,948 ) (2,087 ) Net income $ 1,045 $ 745 $ 1,834 $ 457 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 $0.3 million for both the three and six months ended June 30, 2015 and 2014, respectively, which are reflected within “Tenant reimbursements and other revenues” in our consolidated statements of operations.

Dispositions

Dispositions	6 Months Ended
	Jun. 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. (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): Reporting Disposition Date Property Type Square Feet Net Sale Proceeds Rumsey Center (1) 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) Rumsey Center was classified as held-for-sale at June 30, 2015. 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 . We intend to use the net proceeds from the sale of Rumsey Center to fund potential repurchases of our common shares, to repay a portion of the outstanding balance of our unsecured revolving credit facility and/or for general corporate purposes. At June 30, 2015, Rumsey 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 were classified within “Liabilities-held-for-sale” in our consolidated balance sheet. Rumsey Center, together with five other properties, served as collateral for our Jackson National Life Loan. On July 21, 2015, we prepaid, without penalty, the outstanding balance of the Jackson National Life Loan, $8.1 million of which was allocable to Rumsey Center and was included within “Liabilities held-for-sale” on our consolidated balance sheet at June 30, 2015. The assets classified within “Assets held-for-sale” at June 30, 2015 primarily consisted of $2.7 million in land, $10.8 million in buildings, $3.2 million in tenant improvements and $5.8 million in accumulated depreciation. The remaining $0.8 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. The "Liabilities held-for-sale" at June 30, 2015 primarily consisted of $8.1 million of mortgage debt. The remaining $0.2 million classified within "Liabilities held-for-sale" consisted of prepaid rent and security deposits. The operating results of Rumsey Center are reflected in continuing operations in our consolidated statements of operations for the three and six months ended June 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 six months ended June 30, 2014. The following table summarizes the aggregate results of operations for the three properties that are included in continuing operations for the periods presented (dollars in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Revenues $ 481 $ 1,745 $ 990 $ 3,659 Property operating expenses (129 ) (467 ) (339 ) (1,188 ) Depreciation and amortization (146 ) (593 ) (336 ) (1,205 ) Interest expense (110 ) (111 ) (220 ) (223 ) Impairment of rental property — (3,956 ) — (3,956 ) Income (loss) from operations of disposed property 96 (3,382 ) 95 (2,913 ) Gain on sale of rental property — 21,230 — 21,230 Net income from continuing operations of disposed property $ 96 $ 17,848 $ 95 $ 18,317 (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 Six Months Ended 2015 2014 2015 2014 Revenues $ — $ 1,948 $ 877 $ 3,756 Income (loss) from operations, before taxes (1) — 254 (975 ) (657 ) Loss on debt extinguishment — — (489 ) — Gain on sale of rental property — 1,284 857 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. 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. With the exception of Rumsey Center, we did not dispose of or enter into any other binding agreements to sell any other properties during the six months ended June 30, 2015 and 2014 .

Debt

Debt	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Debt	Debt Our borrowings consisted of the following (dollars in thousands): June 30, (1) December 31, 2014 (2) Mortgage and construction loans, effective interest rates ranging from 4.40% to 6.01%, maturing at various dates through June 2023 (3) $ 302,582 $ 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 (3) 300,000 300,000 Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017 (3) 152,000 205,000 $ 754,582 $ 813,637 (1) Includes the entire balance of the Jackson National Life Loan, which was prepaid, without penalty, on July 21, 2015. At June 30, 2015, $8.1 million of the outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. We sold Rumsey Center on July 28, 2015 . (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 June 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 June 30, 2015 and December 31, 2014 (dollars in thousands): Encumbered Property Contractual Effective Maturity June 30, December 31, 2014 Jackson National Life Loan (1) 5.19% 5.19% August 2015 $ 56,251 $ 64,943 440 First Street, NW (2) LIBOR + 2.50% LIBOR + 2.50% May 2016 32,216 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 324 432 Hillside I and II 5.75% 4.62% December 2016 12,745 12,949 Redland Corporate Center Buildings II & III 4.20% 4.64% November 2017 65,186 65,816 840 First Street, NE 5.72% 6.01% July 2020 36,217 36,539 Battlefield Corporate Center 4.26% 4.40% November 2020 3,610 3,692 1211 Connecticut Avenue, NW 4.22% 4.47% July 2022 29,404 29,691 1401 K Street, NW 4.80% 4.93% June 2023 36,546 36,861 4.75% (3) 294,499 305,139 Unamortized fair value adjustments (270 ) (370 ) Principal balance 294,229 304,769 Debt Classified within “Liabilities-Held-for-Sale” Rumsey Center (1) 5.19% 5.19% August 2015 8,083 — Richmond Portfolio (4) 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 8,083 3,498 Total unamortized fair value adjustments - Richmond — (73 ) Principal balance 8,083 3,425 Total principal balance $ 302,312 $ 308,194 (1) At June 30, 2015, the loan was secured by the following properties: Plaza 500, Van Buren Office Park, Rumsey Center, Snowden Center, Greenbrier Technology Center II and Norfolk Business Center. At June 30, 2015, $8.1 million of the $64.3 million outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. On July 21, 2015, we prepaid, without penalty, the outstanding balance on our Jackson National Life Loan, including the portion that was allocable to Rumsey Center, with a draw under our unsecured revolving credit facility. We subsequently sold Rumsey Center on July 28, 2015 . (2) At June 30, 2015, LIBOR was 0.19% . (3) Weighted average interest rate on total mortgage and construction debt. (4) 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 subsequently sold on July 28, 2015 . The loan was prepaid with a draw under our unsecured revolving credit facility. 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 June 30, 2015, we were in compliance with all the financial covenants of the Storey Park land loan. Construction Loan On June 5, 2013, we entered into a construction loan (the “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 Construction 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 Construction 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 Construction Loan, without penalty, at any time during the term of the loan. At June 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 June 30, 2015, we were in compliance with all the financial covenants of the 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 June 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 June 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 June 30, 2015, we were in compliance with all the financial covenants of the unsecured term loan. (c) Unsecured Revolving Credit Facility During the second quarter of 2015, we borrowed $13.0 million under the unsecured revolving credit facility, which was used for general corporate purposes, and repaid $4.0 million of the outstanding balance under the unsecured revolving credit facility with available cash. For the three and six months ended June 30, 2015, our weighted average borrowings under the unsecured revolving credit facility were $149.4 million and $171.3 million , respectively, with a weighted average interest rate of 1.9% for both periods, compared with weighted average borrowings of $112.7 million and $104.9 million for the three and six months ended June 30, 2014, respectively, with a weighted average interest rate of 1.7% for both periods in 2014. Our maximum outstanding borrowings were $156.0 million and $218.0 million for the three and six months ended June 30, 2015, respectively, and $158.0 million for both the three and six months ended June 30, 2014. At June 30, 2015, outstanding borrowings under the unsecured revolving credit facility were $152.0 million with a weighted average interest rate of 1.9% . At June 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 $ 92.0 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 June 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 June 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 June 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 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 June 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	6 Months Ended
	Jun. 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 June 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 six months ended June 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 June 30, 2015 and 2014, and $2.0 million and $2.1 million for the six months ended June 30, 2015 and 2014, respectively. As of June 30, 2015 , we estimated that $3.6 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	6 Months Ended
	Jun. 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 June 30, 2015 and December 31, 2014 (dollars in thousands): Balance at Level 1 Level 2 Level 3 Recurring Measurements: Derivative instrument-swap liabilities $ 3,770 $ — $ 3,770 $ — 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 June 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 six months ended June 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 six months ended June 30, 2015 and 2014. Interest Rate Derivatives At June 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): June 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)(3) $ 302,582 $ 293,426 $ 308,637 $ 292,882 Unsecured term loan 300,000 300,375 300,000 300,000 Unsecured revolving credit facility 152,000 152,034 205,000 205,000 Total $ 754,582 $ 745,835 $ 813,637 $ 797,882 (1) The principal amount of our notes receivable was $34.0 million and $63.7 million at June 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) Includes the entire balance of the Jackson National Life Loan, which was prepaid, without penalty, on July 21, 2015. At June 30, 2015, $8.1 million of the outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. We subsequently sold Rumsey Center on July 28, 2015 . (3) 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	6 Months Ended
	Jun. 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 over the next twelve months in open market transactions at prevailing prices or in negotiated private transactions. As of the date of this filing, we had 58.8 million common shares outstanding. 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. 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 will be 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 will be paid on August 17, 2015 to preferred shareholders of record as of August 10, 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 April 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 May 15, 2015 to common shareholders of record as of May 8, 2015 . We also declared a dividend of $0.484375 per share on our Series A Preferred Shares. The dividend was paid on May 15, 2015 to preferred shareholders of record as of May 8, 2015 . Our unsecured revolving credit facility, unsecured term loan, the 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. 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) 1,195 (2 ) 1,193 (225 ) Changes in ownership, net 3,219 — 3,219 (1,916 ) Distributions to owners (23,811 ) (96 ) (23,907 ) (788 ) Other comprehensive loss (314 ) — (314 ) (14 ) Balance at June 30, 2015 $ 690,296 $ 800 $ 691,096 $ 30,389 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 16,434 — 16,434 458 Changes in ownership, net (886 ) 161 (725 ) 2,358 Distributions to owners (23,786 ) — (23,786 ) (789 ) Other comprehensive loss (767 ) — (767 ) (34 ) Balance at June 30, 2014 $ 729,505 $ 942 $ 730,447 $ 35,214 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 on derivative instruments (328 ) (801 ) Net loss attributable to noncontrolling interests 14 34 Ending balance at June 30, $ (3,582 ) $ (4,603 )

Noncontrolling Interests

Noncontrolling Interests	6 Months Ended
	Jun. 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 June 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 $27.0 million . At June 30, 2015 and December 31, 2014 , we recorded adjustments of $3.0 million and $4.7 million , respectively, to present certain common Operating Partnership units at the greater of their carrying value or redemption value. At June 30, 2015 , 2,619,069 of the total common Operating Partnership units, or 4.3% , were not owned by us. During the three months ended June 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 six months ended June 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. The joint venture anticipates developing a mixed-use project on the 1.6 acre site, which can accommodate up to 712,000 square feet. At June 30, 2015 , our total investment in the development project was $56.7 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 capitalized architectural fees and site preparation costs. 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.

Share-Based Payments

Share-Based Payments	6 Months Ended
	Jun. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Payments	Share-Based Payments We record costs related to our share-based compensation based on the grant-date fair value calculated in accordance with GAAP. We recognize share-based compensation costs on a straight-line basis over the requisite service period for each award and these costs are recorded within “General and administrative expense” or “Property operating expense” in our consolidated statements of operations based on the employee’s job function. Non-Vested Share Awards We issue non-vested common share awards that either vest over a specific time period that is identified at the time of issuance or vest upon the achievement of specific performance goals that are identified at the time of issuance. We issue new common shares, subject to restrictions, upon each grant of non-vested common share awards. In May 2015, we granted a total of 31,218 non-vested common shares to our non-employee trustees, all of which will vest on the earlier of the first anniversary of the award date or the date of our 2016 annual meeting of shareholders, subject to continued service by the trustee until that date. We recognized compensation expense associated with our non-vested common share awards of $0.7 million and $1.3 million during the three and six months ended June 30, 2015, respectively, compared with $0.7 million and $1.4 million during the three and six months ended June 30, 2014, respectively. Dividends on all non-vested common share awards are recorded as a reduction of equity. We apply the two-class method for determining EPS as our outstanding non-vested common shares with non-forfeitable dividend rights are considered participating securities. Our excess of dividends over earnings related to participating securities are shown as a reduction in net income or loss attributable to common shareholders in our computation of EPS. A summary of our non-vested common share awards at June 30, 2015 is as follows: Non-vested Common Shares Weighted Average Grant Date Fair Value Non-vested at March 31, 2015 461,615 $ 12.83 Granted 31,218 10.57 Vested (34,835 ) 12.96 Non-vested at June 30, 2015 457,998 $ 12.67 We value our non-vested time-based share awards at the grant date fair value, which is the market price of our common shares. As of June 30, 2015 , we had $3.7 million of unrecognized compensation cost related to non-vested common shares. We anticipate this cost will be recognized over a weighted-average period of 2.0 years.

Segment Information

Segment Information	6 Months Ended
	Jun. 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 operations of our four reporting segments for the three and six months ended June 30, 2015 and 2014 are as follows (dollars in thousands): Three Months Ended June 30, 2015 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Number of buildings (1) 6 38 49 19 112 Square feet (1) 914,912 1,997,789 3,020,388 2,023,927 7,957,016 Total revenues $ 11,154 $ 11,034 $ 13,700 $ 7,151 $ 43,039 Property operating expense (2,987 ) (2,645 ) (3,191 ) (1,838 ) (10,661 ) Real estate taxes and insurance (1,956 ) (896 ) (1,345 ) (614 ) (4,811 ) Total property operating income $ 6,211 $ 7,493 $ 9,164 $ 4,699 27,567 Depreciation and amortization expense (16,817 ) General and administrative (4,979 ) Other expenses (5,295 ) Net income $ 476 Capital expenditures (2) $ 3,983 $ 2,153 $ 5,037 $ 910 $ 12,083 Three Months Ended June 30, 2014 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Number of buildings (1)(3) 5 42 49 38 134 Square feet (1)(3) 649,107 2,178,379 3,021,597 2,851,568 8,700,651 Total revenues $ 7,827 $ 11,227 $ 13,146 $ 7,107 $ 39,307 Property operating expense (2,407 ) (2,427 ) (3,107 ) (2,283 ) (10,224 ) Real estate taxes and insurance (1,247 ) (975 ) (1,465 ) (554 ) (4,241 ) Total property operating income $ 4,173 $ 7,825 $ 8,574 $ 4,270 24,842 Depreciation and amortization expense (14,829 ) General and administrative (5,218 ) Acquisition costs (1,111 ) Impairment of rental property (3,956 ) Other income 17,068 Income from discontinued operations 1,538 Net income $ 18,334 Capital expenditures (2) $ 4,901 $ 2,701 $ 1,537 $ 2,749 $ 12,249 Six Months Ended June 30, 2015 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Total revenues $ 22,186 $ 22,739 $ 27,815 $ 14,148 $ 86,888 Property operating expense (6,126 ) (6,663 ) (7,257 ) (3,729 ) (23,775 ) Real estate taxes and insurance (3,979 ) (1,788 ) (2,894 ) (1,193 ) (9,854 ) Total property operating income $ 12,081 $ 14,288 $ 17,664 $ 9,226 53,259 Depreciation and amortization expense (33,151 ) General and administrative (10,505 ) Other expenses (8,028 ) Loss from discontinued operations (607 ) Net income $ 968 Total assets (4)(5) $ 505,270 $ 357,422 $ 450,367 $ 167,860 $ 1,537,482 Capital expenditures (2) $ 7,419 $ 4,317 $ 15,880 $ 3,400 $ 31,325 Six Months Ended June 30, 2014 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Total revenues $ 14,767 $ 22,872 $ 26,813 $ 14,219 $ 78,671 Property operating expense (4,393 ) (6,373 ) (7,083 ) (4,412 ) (22,261 ) Real estate taxes and insurance (2,301 ) (1,978 ) (2,989 ) (1,105 ) (8,373 ) Total property operating income $ 8,073 $ 14,521 $ 16,741 $ 8,702 48,037 Depreciation and amortization expense (29,139 ) General and administrative (10,414 ) Acquisition costs (1,179 ) Impairment of rental property (3,956 ) Other income 12,862 Income from discontinued operations 681 Net income $ 16,892 Total assets (4)(5) $ 410,000 $ 374,416 $ 438,254 $ 229,263 $ 1,538,266 Capital expenditures (2) $ 11,382 $ 5,091 $ 2,359 $ 4,172 $ 23,642 (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 none and $361 for the three months ended June 30, 2015 and 2014, respectively, and $309 and $638 for the six months ended June 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) 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) Corporate assets not allocated to any of our reportable segments totaled $56,563 and $86,333 at June 30, 2015 and 2014, respectively.

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 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 June 30, 2015 , the results of our operations and our comprehensive income for the three and six months ended June 30, 2015 and 2014 and our cash flows for the six months ended June 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 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 six months ended June 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 six months ended June 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 January 1, 2017. 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 Accoun23

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 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)	6 Months Ended
	Jun. 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 June 30, Six Months Ended June 30, 2015 2014 2015 2014 Numerator for basic and diluted earnings per common share: Income from continuing operations $ 476 $ 16,796 $ 1,575 $ 16,211 Income (loss) from discontinued operations — 1,538 (607 ) 681 Net income 476 18,334 968 16,892 Less: Net loss (income) from continuing operations attributable to noncontrolling interests 114 (582 ) 201 (429 ) Less: Net (income) loss from discontinued operations attributable to noncontrolling interests — (70 ) 26 (29 ) Net income attributable to First Potomac Realty Trust 590 17,682 1,195 16,434 Less: Dividends on preferred shares (3,100 ) (3,100 ) (6,200 ) (6,200 ) Net (loss) income attributable to common shareholders (2,510 ) 14,582 (5,005 ) 10,234 Less: Allocation to participating securities (69 ) (77 ) (142 ) (155 ) Net (loss) income attributable to common shareholders $ (2,579 ) $ 14,505 $ (5,147 ) $ 10,079 Denominator for basic and diluted earnings per common share: Weighted average common shares outstanding: Basic 58,280 58,146 58,241 58,122 Diluted 58,280 58,220 58,241 58,190 Basic and diluted earnings per common share: (Loss) income from continuing operations $ (0.04 ) $ 0.22 $ (0.08 ) $ 0.16 Income (loss) from discontinued operations — 0.03 (0.01 ) 0.01 Net (loss) income $ (0.04 ) $ 0.25 $ (0.09 ) $ 0.17
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 Six Months Ended 2015 2014 2015 2014 Stock option awards 1,046 1,145 1,069 1,170 Non-vested share awards 405 400 450 419 Series A Preferred Shares (1) 14,868 12,296 13,965 12,480 16,319 13,841 15,484 14,069 (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)	6 Months Ended
	Jun. 30, 2015
Real Estate [Abstract]
Summary of Rental Property	Rental property consists of the following (dollars in thousands): June 30, 2015 (1) December 31, 2014 (2) Land and land improvements $ 322,538 $ 325,214 Buildings and improvements 941,248 949,683 Construction in progress 82,432 69,181 Tenant improvements 172,931 159,867 Furniture, fixtures and equipment 420 427 1,519,569 1,504,372 Less: accumulated depreciation (233,268 ) (215,499 ) $ 1,286,301 $ 1,288,873 (1) Excludes rental property totaling $10.9 million at June 30, 2015 related to Rumsey Center, which was classified as held-for-sale at June 30, 2015. The property was sold on July 28, 2015 . (2) Excludes rental property totaling $57.7 million at December 31, 2014 related to the sale of the Richmond Portfolio (as defined in note 7, Dispositions ), which was classified as held-for-sale at December 31, 2014 and was sold on March 19, 2015 .

Notes Receivable (Tables)

Notes Receivable (Tables)	6 Months Ended
	Jun. 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 June 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 9.0 % $ 63,720 $ (41 ) $ 63,679

Investment in Affiliates (Table

Investment in Affiliates (Tables)	6 Months Ended
	Jun. 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 June 30, 2015 December 31, 2014 Prosperity Metro Plaza Northern Virginia 51 % $ 24,657 $ 24,651 1750 H Street, NW Washington, D.C. 50 % 15,367 14,834 Aviation Business Park Maryland 50 % 5,867 5,748 RiversPark I and II (1) Maryland 25 % 2,168 2,249 $ 48,059 $ 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): June 30, 2015 December 31, 2014 Assets: Rental property, net $ 193,861 $ 193,533 Cash and cash equivalents 5,828 4,567 Other assets 15,635 16,748 Total assets 215,324 214,848 Liabilities: Mortgage loans (1) 110,000 110,000 Other liabilities 6,470 7,256 Total liabilities 116,470 117,256 Net assets $ 98,854 $ 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 June 30, Six Months Ended June 30, 2015 2014 2015 2014 Total revenues $ 6,063 $ 5,780 $ 12,230 $ 11,531 Total operating expenses (1,756 ) (1,694 ) (3,912 ) (3,920 ) Net operating income 4,307 4,086 8,318 7,611 Depreciation and amortization (2,287 ) (2,264 ) (4,536 ) (5,067 ) Other expense, net (975 ) (1,077 ) (1,948 ) (2,087 ) Net income $ 1,045 $ 745 $ 1,834 $ 457

Dispositions (Tables)

Dispositions (Tables)	6 Months Ended
	Jun. 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): Reporting Disposition Date Property Type Square Feet Net Sale Proceeds Rumsey Center (1) 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) Rumsey Center was classified as held-for-sale at June 30, 2015.
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 three properties that are included in continuing operations for the periods presented (dollars in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Revenues $ 481 $ 1,745 $ 990 $ 3,659 Property operating expenses (129 ) (467 ) (339 ) (1,188 ) Depreciation and amortization (146 ) (593 ) (336 ) (1,205 ) Interest expense (110 ) (111 ) (220 ) (223 ) Impairment of rental property — (3,956 ) — (3,956 ) Income (loss) from operations of disposed property 96 (3,382 ) 95 (2,913 ) Gain on sale of rental property — 21,230 — 21,230 Net income from continuing operations of disposed property $ 96 $ 17,848 $ 95 $ 18,317
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 Six Months Ended 2015 2014 2015 2014 Revenues $ — $ 1,948 $ 877 $ 3,756 Income (loss) from operations, before taxes (1) — 254 (975 ) (657 ) Loss on debt extinguishment — — (489 ) — Gain on sale of rental property — 1,284 857 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)	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Schedule of Borrowings	Our borrowings consisted of the following (dollars in thousands): June 30, (1) December 31, 2014 (2) Mortgage and construction loans, effective interest rates ranging from 4.40% to 6.01%, maturing at various dates through June 2023 (3) $ 302,582 $ 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 (3) 300,000 300,000 Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017 (3) 152,000 205,000 $ 754,582 $ 813,637 (1) Includes the entire balance of the Jackson National Life Loan, which was prepaid, without penalty, on July 21, 2015. At June 30, 2015, $8.1 million of the outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. We sold Rumsey Center on July 28, 2015 . (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 June 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 June 30, 2015 and December 31, 2014 (dollars in thousands): Encumbered Property Contractual Effective Maturity June 30, December 31, 2014 Jackson National Life Loan (1) 5.19% 5.19% August 2015 $ 56,251 $ 64,943 440 First Street, NW (2) LIBOR + 2.50% LIBOR + 2.50% May 2016 32,216 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 324 432 Hillside I and II 5.75% 4.62% December 2016 12,745 12,949 Redland Corporate Center Buildings II & III 4.20% 4.64% November 2017 65,186 65,816 840 First Street, NE 5.72% 6.01% July 2020 36,217 36,539 Battlefield Corporate Center 4.26% 4.40% November 2020 3,610 3,692 1211 Connecticut Avenue, NW 4.22% 4.47% July 2022 29,404 29,691 1401 K Street, NW 4.80% 4.93% June 2023 36,546 36,861 4.75% (3) 294,499 305,139 Unamortized fair value adjustments (270 ) (370 ) Principal balance 294,229 304,769 Debt Classified within “Liabilities-Held-for-Sale” Rumsey Center (1) 5.19% 5.19% August 2015 8,083 — Richmond Portfolio (4) 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 8,083 3,498 Total unamortized fair value adjustments - Richmond — (73 ) Principal balance 8,083 3,425 Total principal balance $ 302,312 $ 308,194 (1) At June 30, 2015, the loan was secured by the following properties: Plaza 500, Van Buren Office Park, Rumsey Center, Snowden Center, Greenbrier Technology Center II and Norfolk Business Center. At June 30, 2015, $8.1 million of the $64.3 million outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. On July 21, 2015, we prepaid, without penalty, the outstanding balance on our Jackson National Life Loan, including the portion that was allocable to Rumsey Center, with a draw under our unsecured revolving credit facility. We subsequently sold Rumsey Center on July 28, 2015 . (2) At June 30, 2015, LIBOR was 0.19% . (3) Weighted average interest rate on total mortgage and construction debt. (4) 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 June 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 June 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)	6 Months Ended
	Jun. 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)	6 Months Ended
	Jun. 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 June 30, 2015 and December 31, 2014 (dollars in thousands): Balance at Level 1 Level 2 Level 3 Recurring Measurements: Derivative instrument-swap liabilities $ 3,770 $ — $ 3,770 $ — 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): June 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)(3) $ 302,582 $ 293,426 $ 308,637 $ 292,882 Unsecured term loan 300,000 300,375 300,000 300,000 Unsecured revolving credit facility 152,000 152,034 205,000 205,000 Total $ 754,582 $ 745,835 $ 813,637 $ 797,882 (1) The principal amount of our notes receivable was $34.0 million and $63.7 million at June 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) Includes the entire balance of the Jackson National Life Loan, which was prepaid, without penalty, on July 21, 2015. At June 30, 2015, $8.1 million of the outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. We subsequently sold Rumsey Center on July 28, 2015 . (3) 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)	6 Months Ended
	Jun. 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) 1,195 (2 ) 1,193 (225 ) Changes in ownership, net 3,219 — 3,219 (1,916 ) Distributions to owners (23,811 ) (96 ) (23,907 ) (788 ) Other comprehensive loss (314 ) — (314 ) (14 ) Balance at June 30, 2015 $ 690,296 $ 800 $ 691,096 $ 30,389 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 16,434 — 16,434 458 Changes in ownership, net (886 ) 161 (725 ) 2,358 Distributions to owners (23,786 ) — (23,786 ) (789 ) Other comprehensive loss (767 ) — (767 ) (34 ) Balance at June 30, 2014 $ 729,505 $ 942 $ 730,447 $ 35,214
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 on derivative instruments (328 ) (801 ) Net loss attributable to noncontrolling interests 14 34 Ending balance at June 30, $ (3,582 ) $ (4,603 )

Share-Based Payments (Tables)

Share-Based Payments (Tables)	6 Months Ended
	Jun. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Nonvested Share Activity	A summary of our non-vested common share awards at June 30, 2015 is as follows: Non-vested Common Shares Weighted Average Grant Date Fair Value Non-vested at March 31, 2015 461,615 $ 12.83 Granted 31,218 10.57 Vested (34,835 ) 12.96 Non-vested at June 30, 2015 457,998 $ 12.67

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2015
Segment Reporting [Abstract]
Summary of Segment Information	The results of operations of our four reporting segments for the three and six months ended June 30, 2015 and 2014 are as follows (dollars in thousands): Three Months Ended June 30, 2015 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Number of buildings (1) 6 38 49 19 112 Square feet (1) 914,912 1,997,789 3,020,388 2,023,927 7,957,016 Total revenues $ 11,154 $ 11,034 $ 13,700 $ 7,151 $ 43,039 Property operating expense (2,987 ) (2,645 ) (3,191 ) (1,838 ) (10,661 ) Real estate taxes and insurance (1,956 ) (896 ) (1,345 ) (614 ) (4,811 ) Total property operating income $ 6,211 $ 7,493 $ 9,164 $ 4,699 27,567 Depreciation and amortization expense (16,817 ) General and administrative (4,979 ) Other expenses (5,295 ) Net income $ 476 Capital expenditures (2) $ 3,983 $ 2,153 $ 5,037 $ 910 $ 12,083 Three Months Ended June 30, 2014 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Number of buildings (1)(3) 5 42 49 38 134 Square feet (1)(3) 649,107 2,178,379 3,021,597 2,851,568 8,700,651 Total revenues $ 7,827 $ 11,227 $ 13,146 $ 7,107 $ 39,307 Property operating expense (2,407 ) (2,427 ) (3,107 ) (2,283 ) (10,224 ) Real estate taxes and insurance (1,247 ) (975 ) (1,465 ) (554 ) (4,241 ) Total property operating income $ 4,173 $ 7,825 $ 8,574 $ 4,270 24,842 Depreciation and amortization expense (14,829 ) General and administrative (5,218 ) Acquisition costs (1,111 ) Impairment of rental property (3,956 ) Other income 17,068 Income from discontinued operations 1,538 Net income $ 18,334 Capital expenditures (2) $ 4,901 $ 2,701 $ 1,537 $ 2,749 $ 12,249 Six Months Ended June 30, 2015 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Total revenues $ 22,186 $ 22,739 $ 27,815 $ 14,148 $ 86,888 Property operating expense (6,126 ) (6,663 ) (7,257 ) (3,729 ) (23,775 ) Real estate taxes and insurance (3,979 ) (1,788 ) (2,894 ) (1,193 ) (9,854 ) Total property operating income $ 12,081 $ 14,288 $ 17,664 $ 9,226 53,259 Depreciation and amortization expense (33,151 ) General and administrative (10,505 ) Other expenses (8,028 ) Loss from discontinued operations (607 ) Net income $ 968 Total assets (4)(5) $ 505,270 $ 357,422 $ 450,367 $ 167,860 $ 1,537,482 Capital expenditures (2) $ 7,419 $ 4,317 $ 15,880 $ 3,400 $ 31,325 Six Months Ended June 30, 2014 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Total revenues $ 14,767 $ 22,872 $ 26,813 $ 14,219 $ 78,671 Property operating expense (4,393 ) (6,373 ) (7,083 ) (4,412 ) (22,261 ) Real estate taxes and insurance (2,301 ) (1,978 ) (2,989 ) (1,105 ) (8,373 ) Total property operating income $ 8,073 $ 14,521 $ 16,741 $ 8,702 48,037 Depreciation and amortization expense (29,139 ) General and administrative (10,414 ) Acquisition costs (1,179 ) Impairment of rental property (3,956 ) Other income 12,862 Income from discontinued operations 681 Net income $ 16,892 Total assets (4)(5) $ 410,000 $ 374,416 $ 438,254 $ 229,263 $ 1,538,266 Capital expenditures (2) $ 11,382 $ 5,091 $ 2,359 $ 4,172 $ 23,642 (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 none and $361 for the three months ended June 30, 2015 and 2014, respectively, and $309 and $638 for the six months ended June 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) 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) Corporate assets not allocated to any of our reportable segments totaled $56,563 and $86,333 at June 30, 2015 and 2014, respectively.

Description of Business - Addit

Description of Business - Additional Information (Detail)		3 Months Ended
		Jun. 30, 2015ft²JointVenturePersonIntegerExecutivessegment	Jun. 30, 2014ft²	[2]
Real Estate Properties [Line Items]
Number of Reportable Segments | segment		4
Operating Partnership in preferred		100.00%
Interest in Operating Partnership		95.70%
Number of officers who owned limited partnership interests | Executives		2
Number of Trustees Owning Interest in Limited Partnership | Integer		1
Area of real estate property	[1]	7,957,016	8,700,651
Unconsolidated joint ventures | JointVenture		5
Square footage of land for additional development		1,300,000
Occupancy rate in the Company's consolidated properties		89.10%
Number of tenants representing current occupancy rate | Person		504
Square footage in development or redevelopment not included on occupancy calculation		200,000
Percent of Annualized Cash Rent		25.50%
Wholly-owned Properties [Member]
Real Estate Properties [Line Items]
Number of Reportable Segments | Integer		4
Area of real estate property		8,000,000
Unconsolidated Properties [Member]
Real Estate Properties [Line Items]
Area of real estate property		900,000
US Government [Member]
Real Estate Properties [Line Items]
Percent of Annualized Cash Rent		13.40%
[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 Accoun36

Summary of Significant Accounting Policies - Estimated Useful Lives of Company's Assets, by Class (Detail) - Jun. 30, 2015	Total	Total
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 [Member] | Building improvements
Property, Plant and Equipment [Line Items]
Useful life	5 years
Minimum [Member] | 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 Accoun37

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 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		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Numerator for basic and diluted earnings per common share:
Income from continuing operations	$ 476	$ 16,796	$ 1,575	$ 16,211
Income (loss) from discontinued operations	0	1,538	(607)	681
Net income	476	18,334	968	16,892
Less: Net loss (income) from continuing operations attributable to noncontrolling interests	114	(582)	201	(429)
Less: Net (income) loss from discontinued operations attributable to noncontrolling interests	0	(70)	26	(29)
Net income attributable to First Potomac Realty Trust	590	17,682	1,195	16,434
Less: Dividends on preferred shares	(3,100)	(3,100)	(6,200)	(6,200)
Net (loss) income attributable to common shareholders	(2,510)	14,582	(5,005)	10,234
Less: Allocation to participating securities	(69)	(77)	(142)	(155)
Net (loss) income attributable to common shareholders	$ (2,579)	$ 14,505	$ (5,147)	$ 10,079
Denominator for basic and diluted earnings per common share:
Basic	58,280	58,146	58,241	58,122
Diluted	58,280	58,220	58,241	58,190
Basic and diluted earnings per common share:
Loss from continuing operations	$ (0.04)	$ 0.22	$ (0.08)	$ 0.16
Income (loss) from discontinued operations	0	0.03	(0.01)	0.01
Net (loss) income	$ (0.04)	$ 0.25	$ (0.09)	$ 0.17

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		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, Amount		16,319	13,841	15,484	14,069
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		1,046	1,145	1,069	1,170
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		405	400	450	419
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]	14,868	12,296	13,965	12,480
[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
	Jun. 30, 2015		Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Rental property, net	$ 1,286,301	[1]	$ 1,288,873	[2]
Rental Property [Member]
Property, Plant and Equipment [Line Items]
Land and land improvements	322,538	[1]	325,214	[2]
Buildings and improvements	941,248	[1]	949,683	[2]
Construction in process	82,432	[1]	69,181	[2]
Tenant Improvements	172,931	[1]	159,867	[2]
Furniture, fixtures and equipment	420	[1]	427	[2]
Rental property, gross	1,519,569	[1]	1,504,372	[2]
Less: accumulated depreciation	(233,268)	[1]	(215,499)	[2]
Maryland Reporting Segment [Member] | Rental Property [Member]
Property, Plant and Equipment [Line Items]
Rental property, net	$ 10,900
Disposition Date Of Property	Jul. 28, 2015
Southern Virginia | Rental Property [Member]
Property, Plant and Equipment [Line Items]
Rental property, net			$ 57,700
Disposition Date Of Property	Mar. 19, 2015
[1]	Excludes rental property totaling $10.9 million at June 30, 2015 related to Rumsey Center, which was classified as held-for-sale at June 30, 2015. The property was sold on July 28, 2015.
[2]	Excludes rental property totaling $57.7 million at December 31, 2014 related to the sale of the Richmond Portfolio (as defined in note 7, Dispositions), 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	Jun. 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		89.10%
Placed in-service redevelopment efforts		0
Redevelopment Efforts Yet To Be Placed In Service		0
Greyhound Property [Member]
Segment Reporting Information [Line Items]
Percentage Of Interest In Joint Venture Owned By Entity | Rate	97.00%
440 First Street, NW [Member]
Segment Reporting Information [Line Items]
Original cost basis of the property | $		$ 23.6
Projected incremental investment in redevelopment project | $		$ 55.5
Anticipated completion of redevelopment		139,000
Occupancy rate in the Company's consolidated properties		65.70%
Leased in Company Consolidated Properties		50.10%
Washington D C Reporting Segment
Segment Reporting Information [Line Items]
Area of land available for development in additional building space		700,000
Lease expiration date	Aug. 31, 2013
Development of area for operations by joint venture | a	1.6
Projected incremental investment in development project | $		$ 56.7
Original cost basis of the property | $		$ 43.3
Washington D C Reporting Segment | Greyhound Property [Member]
Segment Reporting Information [Line Items]
Percentage Of Interest In Joint Venture Owned By Entity	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
Projected incremental investment in development project | $		$ 16.4
Original cost basis of the property | $		$ 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
	Jun. 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

Jun. 30, 2015USD ($)ft²

Mar. 31, 2015USD ($)

Jun. 30, 2014USD ($)ft²

Mar. 31, 2014USD ($)

Jun. 30, 2015USD ($)ft²

Jun. 30, 2014USD ($)ft²

Dec. 31, 2014USD ($)

Dec. 31, 2010USD ($)ft²

Feb. 24, 2015USD ($)

Apr. 30, 2011USD ($)ft²

Receivables with Imputed Interest [Line Items]

Area of real estate property | ft²

[1]

7,957,016

8,700,651

[2]

7,957,016

8,700,651

[2]

Unsecured revolving credit facility

$ 152,000

$ 152,000

$ 205,000

Interest income

800

2,000

Income from amortization of origination fees

$ 0

$ 7

$ 5

$ 18

America Square [Member]

Receivables with Imputed Interest [Line Items]

Area of real estate property | ft²

461,000

Mezzanine loan provided to owners

$ 29,700

$ 30,000

Maturity date of loan

May 1, 2016

Prepayment Fee Income

$ 2,400

Fixed interest rate on loan

9.00%

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

$ 3,000

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 [Member]

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		3 Months Ended
		Jun. 30, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Company Investment		$ 48,059	$ 47,482
Prosperity Metro Plaza
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Northern Virginia
Ownership Interest		51.00%
Company Investment		$ 24,657	24,651
1750 H Street, NW
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Washington, D.C.
Ownership Interest		50.00%
Company Investment		$ 15,367	14,834
Aviation Business Park
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Maryland
Ownership Interest		50.00%
Company Investment		$ 5,867	5,748
RiversPark I and II
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Maryland
Ownership Interest	[1]	25.00%
Company Investment	[1]	$ 2,168	$ 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		Jun. 30, 2015		Dec. 31, 2014		Jun. 30, 2014		Dec. 31, 2013
Assets:
Rental property, net		$ 1,286,301	[1]	$ 1,288,873	[2]
Cash and cash equivalents		12,735		13,323		$ 13,398		$ 8,740
Total assets		1,537,482	[3],[4]	1,618,460		$ 1,538,266	[3],[4]
Liabilities:
Total liabilities		815,997		874,223
Recourse mortgage debt		754,582		813,637
Unconsolidated Joint Ventures
Assets:
Rental property, net		193,861		193,533
Cash and cash equivalents		5,828		4,567
Other assets		15,635		16,748
Total assets		215,324		214,848
Liabilities:
Mortgage loans	[5]	110,000		110,000
Other liabilities		6,470		7,256
Total liabilities		116,470		117,256
Net assets		98,854		$ 97,592
Unconsolidated Entities
Liabilities:
Recourse mortgage debt		$ 2,800
[1]	Excludes rental property totaling $10.9 million at June 30, 2015 related to Rumsey Center, which was classified as held-for-sale at June 30, 2015. The property was sold on July 28, 2015.
[2]	Excludes rental property totaling $57.7 million at December 31, 2014 related to the sale of the Richmond Portfolio (as defined in note 7, Dispositions), 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 $56,563 and $86,333 at June 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, 2017	Sep. 26, 2014USD ($)Rate	Jun. 30, 2015USD ($)ft²	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 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	$ 0.3	$ 0.3
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
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
Percentage of outstanding principal		25.00%	10.00%		10.00%
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
Subsequent Event | RiversPark I and II
Schedule of Equity Method Investments [Line Items]
Loan maturity date	Sep. 26, 2017

Investment in Affiliates - Resu

Investment in Affiliates - Results of Operations of Company's Unconsolidated Joint Ventures (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Equity Method Investments [Line Items]
Total revenues	$ 43,039	$ 39,307	$ 86,888	$ 78,671
Total operating expenses	(37,268)	(39,579)	(77,285)	(75,322)
Operating income (loss)	5,771	(272)	9,603	3,349
Depreciation and amortization	(16,817)	(14,829)	(33,151)	(29,139)
Other expense, net	(5,295)	17,068	(8,028)	12,862
Net income	456	199	803	(28)
Unconsolidated Joint Ventures
Schedule of Equity Method Investments [Line Items]
Total revenues	6,063	5,780	12,230	11,531
Total operating expenses	(1,756)	(1,694)	(3,912)	(3,920)
Operating income (loss)	4,307	4,086	8,318	7,611
Depreciation and amortization	(2,287)	(2,264)	(4,536)	(5,067)
Other expense, net	(975)	(1,077)	(1,948)	(2,087)
Net income	$ 1,045	$ 745	$ 1,834	$ 457

Dispositions - Additional Infor

Dispositions - Additional Information (Detail) - Segments [Domain] $ in Thousands		3 Months Ended					6 Months Ended
		Jun. 30, 2015USD ($)ft²	Mar. 31, 2015USD ($)	Jun. 30, 2014USD ($)ft²		Mar. 31, 2014USD ($)	Jun. 30, 2015USD ($)ft²	Jun. 30, 2014USD ($)ft²
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Square feet | ft²	[1]	7,957,016		8,700,651	[2]		7,957,016	8,700,651	[2]
Gain (Loss) on Sale of Properties		$ 0		$ 21,230			$ 0	$ 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					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					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		3 Months Ended			6 Months Ended
		Jun. 30, 2015USD ($)ft²Integer	Jun. 30, 2014USD ($)ft²		Jun. 30, 2015USD ($)ft²Integer	Jun. 30, 2014USD ($)ft²		Oct. 16, 2014ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Square feet | ft²	[1]	7,957,016	8,700,651	[2]	7,957,016	8,700,651	[2]
Impairment Of Properties		$ 0	$ (3,956)		$ 0	$ (3,956)
Gain (Loss) on Sale of Properties		0	21,230		0	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
Mortgages Held-for-sale, Fair Value Disclosure		8,100			8,100
Land and Land Improvements		2,700			2,700
Buildings and Improvements, Gross		10,800			10,800
Tenant Improvements		3,200			3,200
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		5,800			5,800
Other assets		800			800
Accrued Rent		200			200
Rumsey Center [Domain] | Continuing Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues		481			990
Property operating expenses		(129)			(339)
Depreciation and amortization		(146)			(336)
Interest Expense		(110)			(220)
Impairment Of Properties		0			0
Operating Income (Loss) from Continuing Operations Attributable to Parent		96			95
Gain (Loss) on Sale of Properties		0			0
Net income from continuing operations of disposed property		$ 96			$ 95
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			1,745			3,659
Property operating expenses			(467)			(1,188)
Depreciation and amortization			(593)			(1,205)
Interest Expense			(111)			(223)
Impairment Of Properties			(3,956)			(3,956)
Operating Income (Loss) from Continuing Operations Attributable to Parent			(3,382)			(2,913)
Gain (Loss) on Sale of Properties			21,230			21,230
Net income from continuing operations of disposed property			$ 17,848			$ 18,317
MARYLAND | Rumsey Center [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reporting Segment	[3]	Maryland
Disposition Date Of Property	[3]	Jul. 28, 2015
Property Type	[3]	Business Park
Square feet | ft²	[3]							135,015
Proceeds from sale of properties	[3]	$ 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 | 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			194,184
Proceeds from sale of properties		$ 39,910
Jackson Loan [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Properties Collateralizing a Loan | Integer		5			5
[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]	Rumsey Center was classified as held-for-sale at June 30, 2015.

Dispositions - Summary of Compl

Dispositions - Summary of Completed Property Dispositions (Detail) $ in Thousands		3 Months Ended
		Jun. 30, 2015USD ($)ft²	Jun. 30, 2014ft²	[2]
Schedule Of Discontinued Operations [Line Items]
Square feet	[1]	7,957,016	8,700,651
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		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 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	1,948	877	3,756
Income (loss) from operations, before taxes(1)	[1]	0	254	(975)	(657)
Loss on debt extinguishment		0	0	(489)	0
Gain on sale of rental property		$ 0	$ 1,284	$ 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		6 Months Ended
		Jun. 30, 2015		Jun. 30, 2015		Dec. 31, 2014
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.40% to 6.01%, maturing at various dates through June 2023(3)	[1]	$ 302,582	[2]	$ 302,582	[2]	$ 308,637	[3]
Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017(3)	[1]	152,000	[2]	152,000	[2]	205,000	[3]
Total long term debt		$ 754,582		$ 754,582		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				4.40%
Debt instrument, interest rate, effective percentage rate range, maximum				6.01%
Debt instrument maturity date
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(3)	[1]	$ 300,000	[2]	$ 300,000	[2]	300,000	[3]
Debt instrument maturity date
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(3)		$ 13,000		$ 13,000
Effective interest rate on the notes		1.70%		1.70%
Debt instrument maturity date
Rumsey Center [Domain]
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.40% to 6.01%, maturing at various dates through June 2023(3)	[4]	$ 8,083		$ 8,083		0
Mortgages Held-for-sale, Fair Value Disclosure		$ 8,100		$ 8,100
Effective interest rate on the notes	[4]	5.19%		5.19%
Debt instrument maturity date	[4]
Richmond
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.40% to 6.01%, maturing at various dates through June 2023(3)						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 4.40% to 6.01%, maturing at various dates through June 2023(3)	[4]	$ 56,251		$ 56,251		$ 64,943
Effective interest rate on the notes	[4]	5.19%		5.19%
Debt instrument maturity date	[4]
Jackson Loan [Member] | Properties Secured by Jackson Loan [Domain]
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.40% to 6.01%, maturing at various dates through June 2023(3)	[4]	$ 64,300		$ 64,300
[1]	At June 30, 2015, LIBOR was 0.19%. All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR.
[2]	Includes the entire balance of the Jackson National Life Loan, which was prepaid, without penalty, on July 21, 2015. At June 30, 2015, $8.1 million of the outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. We sold Rumsey Center on July 28, 2015.
[3]	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.
[4]	At June 30, 2015, the loan was secured by the following properties: Plaza 500, Van Buren Office Park, Rumsey Center, Snowden Center, Greenbrier Technology Center II and Norfolk Business Center. At June 30, 2015, $8.1 million of the $64.3 million outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. On July 21, 2015, we prepaid, without penalty, the outstanding balance on our Jackson National Life Loan, including the portion that was allocable to Rumsey Center, with a draw under our unsecured revolving credit facility. We subsequently sold Rumsey Center on July 28, 2015.

Debt - Summary of Company's Mor

Debt - Summary of Company's Mortgage Debt (Detail) - USD ($) $ in Thousands		Jun. 05, 2013	Jun. 30, 2015		Dec. 31, 2014
Debt Instrument [Line Items]
Effective Interest Rate			0.19%
Total Mortgage Debt	[1]		$ 302,582	[2]	$ 308,637	[3]
Debt, Weighted Average Interest Rate	[4]		4.75%
Carrying amount of mortgages			$ 302,312		308,194
Effective Interest Rate			0.19%
LIBOR plus interest rate		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	[5]		5.19%
Effective Interest Rate	[5]		5.19%
Maturity Date	[5]
Total Mortgage Debt	[5]		$ 56,251		64,943
Effective Interest Rate	[5]		5.19%
440 First Street, NW Construction Loan
Debt Instrument [Line Items]
Contractual Interest Rate			2.50%
Contractual Interest Rate	[6]		LIBOR + 2.50%
Maturity Date	[6]
Total Mortgage Debt	[6]		$ 32,216		32,216
Storey Park
Debt Instrument [Line Items]
Contractual Interest Rate			2.50%
Contractual Interest Rate	[6]		LIBOR + 2.50%
Maturity Date	[6]
Total Mortgage Debt	[6]		$ 22,000		22,000
Gateway Centre Manassas Building I
Debt Instrument [Line Items]
Contractual Interest Rate			7.35%
Effective Interest Rate			5.88%
Maturity Date
Total Mortgage Debt			$ 324		432
Effective Interest Rate			5.88%
Hillside I and II
Debt Instrument [Line Items]
Contractual Interest Rate			5.75%
Effective Interest Rate			4.62%
Maturity Date
Total Mortgage Debt			$ 12,745		12,949
Effective Interest Rate			4.62%
Redland Corporate Center Buildings II & III
Debt Instrument [Line Items]
Contractual Interest Rate			4.20%
Effective Interest Rate			4.64%
Maturity Date
Total Mortgage Debt			$ 65,186		65,816
Effective Interest Rate			4.64%
840 First Street, NE
Debt Instrument [Line Items]
Contractual Interest Rate			5.72%
Effective Interest Rate			6.01%
Maturity Date
Total Mortgage Debt			$ 36,217		36,539
Effective Interest Rate			6.01%
Battlefield Corporate Center
Debt Instrument [Line Items]
Contractual Interest Rate			4.26%
Effective Interest Rate			4.40%
Maturity Date
Total Mortgage Debt			$ 3,610		3,692
Effective Interest Rate			4.40%
One thousand two hundred eleven Connecticut Avenue NW. [Member]
Debt Instrument [Line Items]
Contractual Interest Rate			4.22%
Effective Interest Rate			4.47%
Maturity Date
Total Mortgage Debt			$ 29,404		29,691
Effective Interest Rate			4.47%
1401 K Street, NW
Debt Instrument [Line Items]
Contractual Interest Rate			4.80%
Effective Interest Rate			4.93%
Maturity Date
Total Mortgage Debt			$ 36,546		36,861
Effective Interest Rate			4.93%
Hanover Business Center Building D
Debt Instrument [Line Items]
Contractual Interest Rate	[7]		8.88%
Effective Interest Rate	[7]		6.63%
Maturity Date	[7]
Total Mortgage Debt	[7]		$ 0		104
Effective Interest Rate	[7]		6.63%
Chesterfield Business Center Buildings C,D,G and H
Debt Instrument [Line Items]
Contractual Interest Rate	[7]		8.50%
Effective Interest Rate	[7]		6.63%
Maturity Date	[7]
Total Mortgage Debt	[7]		$ 0		302
Effective Interest Rate	[7]		6.63%
Hanover Business Center Building C
Debt Instrument [Line Items]
Contractual Interest Rate	[7]		7.88%
Effective Interest Rate	[7]		6.63%
Maturity Date	[7]
Total Mortgage Debt	[7]		$ 0		505
Effective Interest Rate	[7]		6.63%
Buildings Abe And F
Debt Instrument [Line Items]
Contractual Interest Rate	[7]		7.45%
Effective Interest Rate	[7]		6.63%
Maturity Date	[7]
Total Mortgage Debt	[7]		$ 0		1,674
Effective Interest Rate	[7]		6.63%
Airpark Business Center
Debt Instrument [Line Items]
Contractual Interest Rate	[7]		7.45%
Effective Interest Rate	[7]		6.63%
Maturity Date	[7]
Total Mortgage Debt	[7]		$ 0		913
Effective Interest Rate	[7]		6.63%
Continuing Operations
Debt Instrument [Line Items]
Total Mortgage Debt			$ 294,499		305,139
Total unamortized fair value adjustments - Richmond			(270)		(370)
Carrying amount of mortgages			$ 294,229		304,769
Rumsey Center [Domain]
Debt Instrument [Line Items]
Contractual Interest Rate	[5]		5.19%
Effective Interest Rate	[5]		5.19%
Maturity Date	[5]
Total Mortgage Debt	[5]		$ 8,083		0
Effective Interest Rate	[5]		5.19%
Rumsey Center [Domain] | Mortgage Loans
Debt Instrument [Line Items]
Carrying amount of mortgages			$ 8,083
Richmond
Debt Instrument [Line Items]
Total Mortgage Debt					3,498
Total unamortized fair value adjustments - Richmond			$ 0		$ (73)
[1]	At June 30, 2015, LIBOR was 0.19%. All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR.
[2]	Includes the entire balance of the Jackson National Life Loan, which was prepaid, without penalty, on July 21, 2015. At June 30, 2015, $8.1 million of the outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. We sold Rumsey Center on July 28, 2015.
[3]	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.
[4]	Weighted average interest rate on total mortgage and construction debt.
[5]	At June 30, 2015, the loan was secured by the following properties: Plaza 500, Van Buren Office Park, Rumsey Center, Snowden Center, Greenbrier Technology Center II and Norfolk Business Center. At June 30, 2015, $8.1 million of the $64.3 million outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. On July 21, 2015, we prepaid, without penalty, the outstanding balance on our Jackson National Life Loan, including the portion that was allocable to Rumsey Center, with a draw under our unsecured revolving credit facility. We subsequently sold Rumsey Center on July 28, 2015.
[6]	At June 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		Oct. 16, 2014USD ($)Rate	Jun. 05, 2013USD ($)	May. 31, 2016	Jan. 31, 2014USD ($)	Jun. 30, 2015USD ($)TranchesIntegerRate		Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)IntegerRate		Jun. 30, 2014USD ($)	Jul. 21, 2015USD ($)	Dec. 31, 2014USD ($)		Aug. 04, 2011Rate
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.40% to 6.01%, maturing at various dates through June 2023(3)	[1]					$ 302,582	[2]		$ 302,582	[2]			$ 308,637	[3]
Amount borrowed								$ 21,700
Basis spread over variable rate			2.50%			1.70%
Recourse mortgage debt						$ 754,582			754,582				813,637
Outstanding balance of three tranches						300,000			300,000				300,000
Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017(3)	[1]					$ 152,000	[2]		152,000	[2]			205,000	[3]
Proceed to pay loan									84,883		$ 96,697
Interest rate during period						1.90%
Average interest rate at prior period end								1.70%
Maximum outstanding borrowings						$ 156,000		$ 158,000	$ 218,000		158,000
Weighted average interest rate						1.90%			1.90%
Available capacity on the unsecured revolving credit facility						$ 92,000			$ 92,000
Annual commitment fee						0.25%
Number of interest rate swap agreements						11			11
Fixed effective interest rate						1.50%			1.50%
Unsecured term loan
Debt Instrument [Line Items]
Number of tranches | Tranches						3
Outstanding balance of three tranches						$ 300,000			$ 300,000
Unsecured revolving credit facility
Debt Instrument [Line Items]
Unsecured revolving credit facility, effective interest rate of LIBOR plus 1.70%, maturing October 2017(3)						13,000			13,000
Proceed to pay loan						4,000
Jackson Loan [Member]
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.40% to 6.01%, maturing at various dates through June 2023(3)	[4]					$ 56,251			$ 56,251				64,943
Debt Instrument, Interest Rate, Stated Percentage	[4]					5.19%			5.19%
440 First Street, NW Construction Loan
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.40% to 6.01%, maturing at various dates through June 2023(3)	[5]					$ 32,216			$ 32,216				$ 32,216
Debt Instrument, Interest Rate, Stated Percentage						2.50%			2.50%
Interest Rate Swap
Debt Instrument [Line Items]
Fixed effective interest rate						1.505%			1.505%
Amount on variable rate debt						$ 300,000			$ 300,000
Unused lines of credit
Debt Instrument [Line Items]
Weighted average borrowings outstanding on unsecured revolving credit facility						$ 149,400		$ 112,700	$ 171,300		$ 104,900
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
Maturity Period											1 year
Percentage of outstanding principal						50.00%			50.00%
Subsequent Event [Member] | Jackson Loan [Member]
Debt Instrument [Line Items]
Mortgage and construction loans, effective interest rates ranging from 4.40% to 6.01%, maturing at various dates through June 2023(3)	[4]											$ 64,200
Subsequent Event [Member] | 440 First Street, NW [Member]
Debt Instrument [Line Items]
Maturity date				May 30, 2016
[1]	At June 30, 2015, LIBOR was 0.19%. All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR.
[2]	Includes the entire balance of the Jackson National Life Loan, which was prepaid, without penalty, on July 21, 2015. At June 30, 2015, $8.1 million of the outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. We sold Rumsey Center on July 28, 2015.
[3]	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.
[4]	At June 30, 2015, the loan was secured by the following properties: Plaza 500, Van Buren Office Park, Rumsey Center, Snowden Center, Greenbrier Technology Center II and Norfolk Business Center. At June 30, 2015, $8.1 million of the $64.3 million outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. On July 21, 2015, we prepaid, without penalty, the outstanding balance on our Jackson National Life Loan, including the portion that was allocable to Rumsey Center, with a draw under our unsecured revolving credit facility. We subsequently sold Rumsey Center on July 28, 2015.
[5]	At June 30, 2015, LIBOR was 0.19%.

Debt - Unsecured Term Loan (Det

Debt - Unsecured Term Loan (Detail) - USD ($) $ in Thousands		Jun. 05, 2013	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Amount			$ 300,000	$ 300,000
Basis spread over variable rate		2.50%	1.70%
Tranche A
Debt Instrument [Line Items]
Maturity Date
Amount			$ 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
Amount			$ 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
Amount			$ 100,000
Interest Rate	[1]		LIBOR, plus 205 basis points
Basis spread over variable rate			2.05%
[1]	At June 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) - Jun. 30, 2015 - USD ($) $ in Thousands	Total
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		6 Months Ended
	Jun. 30, 2015USD ($)Integer	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)Integer	Jun. 30, 2014USD ($)
Derivatives, Fair Value [Line Items]
Number of interest rate swap agreements	11		11
Fixed effective interest rate	1.50%		1.50%
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Fixed effective interest rate	1.505%		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	2,000	$ 2,100
Estimated accumulated other comprehensive loss reclassified as an increase in interest expense over the following twelve months			$ 3,600

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Assets and Liabilities (Detail) - Recurring Measurements - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Recurring Measurements:
Derivative instrument-swap assets		$ 133
Derivative instrument-swap liabilities	$ 3,770	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	3,770	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) - Jun. 30, 2015 $ in Thousands	USD ($)Interest_Rate_Swapssnapshot
Derivatives, Fair Value [Line Items]
Number of Interest Rate Derivatives Held	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 - Fai60

Fair Value Measurements - Fair Value of Debt Instruments (Detail) $ in Thousands		Jun. 30, 2015USD ($)ft²	Feb. 24, 2015USD ($)	Dec. 31, 2014USD ($)	Oct. 16, 2014ft²	Jun. 30, 2014ft²	[2]	Apr. 30, 2011USD ($)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]	7,957,016				8,700,651
Carrying Value
Financial Assets:
Carrying value of notes receivable	[3]	$ 34,000		63,679
Financial Liabilities:
Carrying value of the debt instruments		754,582		813,637
Carrying Value | Mortgage debt
Financial Liabilities:
Carrying value of the debt instruments	[4],[5]	302,582		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		152,000		205,000
Fair Value
Financial Assets:
Fair value of notes receivable	[3]	34,000		63,720
Financial Liabilities:
Fair value of the debt instruments		745,835		797,882
Fair Value | Mortgage debt
Financial Liabilities:
Fair value of the debt instruments	[4],[5]	293,426		292,882
Fair Value | Unsecured term loan
Financial Liabilities:
Fair value of the debt instruments		300,375		300,000
Fair Value | Unsecured revolving credit facility
Financial Liabilities:
Fair value of the debt instruments		152,034		$ 205,000
America Square [Member]
Financial Liabilities:
Area of real estate property | ft²								461,000
Mezzanine loan provided to owners			$ 29,700					$ 30,000
Rumsey Center [Domain]
Financial Liabilities:
Area of real estate property | ft²					135,000
Mortgages Held-for-sale, Fair Value Disclosure		$ 8,100
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 June 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]	Includes the entire balance of the Jackson National Life Loan, which was prepaid, without penalty, on July 21, 2015. At June 30, 2015, $8.1 million of the outstanding balance of the Jackson National Life Loan was allocable to Rumsey Center and was classified within “Liabilities held-for-sale” on our consolidated balance sheet. We subsequently sold Rumsey Center on July 28, 2015.
[5]	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) - $ / shares	Jul. 28, 2015	Apr. 28, 2015	Jun. 30, 2015	Dec. 31, 2014
Dividends Payable [Line Items]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased			5,000,000
Stock Repurchase Program, Period in Force			12 months
Common stock, shares outstanding			58,758,000	58,815,000
Dividend declared date		Apr. 28, 2015
Series A Preferred Shares
Dividends Payable [Line Items]
Dividend paid date		May 15, 2015
Dividend record date		May 8, 2015
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		May 15, 2015
Dividend record date		May 8, 2015
Subsequent Event [Member]
Dividends Payable [Line Items]
Dividend declared date	Jul. 28, 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	Aug. 17, 2015
Dividend record date	Aug. 10, 2015

Equity - Company's Allocation B

Equity - Company's Allocation Between Non-controlling Interests (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling interests in a consolidated partnership	$ 800		$ 898
Total equity	691,096	$ 730,447	710,905	$ 739,291
Net income (loss)	1,193	16,434
Changes in ownership, net	3,219	(725)
Distributions to owners	(23,907)	(23,786)
Other comprehensive income	(314)	(767)
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning Balance, Redeemable noncontrolling interests	33,332	33,221
Net income (loss), Redeemable noncontrolling interests	(225)	458
Change in ownership, net, Redeemable noncontrolling interests	(1,916)	2,358
Distributions to owners, Redeemable noncontrolling interests	(788)	(789)
Other comprehensive income, Redeemable noncontrolling interests	(14)	(34)
Ending Balance, Redeemable noncontrolling interests	30,389	35,214
First Potomac Realty Trust
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	710,007	738,510
Net income (loss)	1,195	16,434
Changes in ownership, net	3,219	(886)
Distributions to owners	(23,811)	(23,786)
Other comprehensive income	(314)	(767)
Ending Balance	690,296	729,505
Non-redeemable Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling interests in a consolidated partnership	800	942	$ 898	$ 781
Net income (loss)	(2)	0
Changes in ownership, net	0	161
Distributions to owners	(96)	0
Other comprehensive income	$ 0	$ 0

Equity - Company's Accumulated

Equity - Company's Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Equity [Abstract]
Beginning balance	$ (3,268)	$ (3,836)
Net unrealized loss on derivative instruments	(328)	(801)
Net loss attributable to noncontrolling interests	14	34
Ending balance	$ (3,582)	$ (4,603)

Noncontrolling Interests - Addi

Noncontrolling Interests - Additional Information (Detail) $ in Millions	Aug. 04, 2011aft²	Jun. 30, 2015USD ($)ft²shares	Mar. 31, 2014shares	Jun. 30, 2015USD ($)shares	Jun. 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 | $		$ 27		$ 27
Fair value adjustment, cost basis | $		$ 3		$ 3		$ 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
Area of land available for development in additional building space | ft²		700,000
Projected incremental investment in development project | $		$ 56.7		$ 56.7
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%
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

Share-Based Payments - Addition

Share-Based Payments - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Award, Shares Purchased for Award	31,218
Non-Vested Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense associated with trustee share based awards	$ 0.7	$ 0.7	$ 1.3	$ 1.4
Unrecognized compensation cost related to non-vested shares	$ 3.7		$ 3.7
Weighted-average period for recognition of non-vested shares	2 years

Share-Based Payments - Summary

Share-Based Payments - Summary of Company's Non-vested Share Awards (Detail) - 3 months ended Jun. 30, 2015 - $ / shares	Total
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested Shares, Beginning Balance	461,615
Non-vested Shares, Granted	31,218
Non-vested Shares, Vested	(34,835)
Non-vested Shares, Ending Balance	457,998
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted Average Grant Date Fair Value, Beginning Balance	$ 12.83
Weighted Average Grant Date Fair Value, Granted	10.57
Weighted Average Grant Date Fair Value, Vested	12.96
Weighted Average Grant Date Fair Value, Ending Balance	$ 12.67

Segment Information - Additiona

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

Segment Information - Summary o

Segment Information - Summary of Segment Information (Detail) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2015USD ($)ft²Integer		Jun. 30, 2014USD ($)ft²Integer		Jun. 30, 2015USD ($)ft²Integer		Jun. 30, 2014USD ($)ft²Integer		Dec. 31, 2014USD ($)
Segment Reporting Information [Line Items]
Number of buildings | Integer	[1]	112		134	[2]	112		134	[2]
Square feet | ft²	[1]	7,957,016		8,700,651	[2]	7,957,016		8,700,651	[2]
Total revenues		$ 43,039		$ 39,307		$ 86,888		$ 78,671
Property operating expense		(10,661)		(10,224)		(23,775)		(22,261)
Real estate taxes and insurance		(4,811)		(4,241)		(9,854)		(8,373)
Total property operating income		27,567		24,842		53,259		48,037
Depreciation and amortization expense		(16,817)		(14,829)		(33,151)		(29,139)
General and administrative		(4,979)		(5,218)		(10,505)		(10,414)
Acquisition costs		0		(1,111)		0		(1,179)
Impairment Of Properties		0		(3,956)		0		(3,956)
Other income		(5,295)		17,068		(8,028)		12,862
Income from discontinued operations		0		(1,538)		607		(681)
Net income		476		18,334		968		16,892
Total assets		1,537,482	[3],[4]	1,538,266	[3],[4]	1,537,482	[3],[4]	1,538,266	[3],[4]	$ 1,618,460
Capital expenditure	[5]	12,083		12,249		31,325		23,642
Capital expenditures for corporate assets not allocated to any reportable segments		0		361		309		638
Corporate assets not allocated to any reportable segments		$ 56,563		$ 86,333		$ 56,563		$ 86,333
Washington, D.C.
Segment Reporting Information [Line Items]
Number of buildings | Integer	[1]	6		5	[2]	6		5	[2]
Square feet | ft²	[1]	914,912		649,107	[2]	914,912		649,107	[2]
Total revenues		$ 11,154		$ 7,827		$ 22,186		$ 14,767
Property operating expense		(2,987)		(2,407)		(6,126)		(4,393)
Real estate taxes and insurance		(1,956)		(1,247)		(3,979)		(2,301)
Total property operating income		6,211		4,173		12,081		8,073
Total assets	[3],[4]	505,270		410,000		505,270		410,000
Capital expenditure	[5]	$ 3,983		$ 4,901		$ 7,419		$ 11,382
Maryland
Segment Reporting Information [Line Items]
Number of buildings | Integer	[1]	38		42	[2]	38		42	[2]
Square feet | ft²	[1]	1,997,789		2,178,379	[2]	1,997,789		2,178,379	[2]
Total revenues		$ 11,034		$ 11,227		$ 22,739		$ 22,872
Property operating expense		(2,645)		(2,427)		(6,663)		(6,373)
Real estate taxes and insurance		(896)		(975)		(1,788)		(1,978)
Total property operating income		7,493		7,825		14,288		14,521
Total assets	[3],[4]	357,422		374,416		357,422		374,416
Capital expenditure	[5]	$ 2,153		$ 2,701		$ 4,317		$ 5,091
Northern Virginia
Segment Reporting Information [Line Items]
Number of buildings | Integer	[1]	49		49	[2]	49		49	[2]
Square feet | ft²	[1]	3,020,388		3,021,597	[2]	3,020,388		3,021,597	[2]
Total revenues		$ 13,700		$ 13,146		$ 27,815		$ 26,813
Property operating expense		(3,191)		(3,107)		(7,257)		(7,083)
Real estate taxes and insurance		(1,345)		(1,465)		(2,894)		(2,989)
Total property operating income		9,164		8,574		17,664		16,741
Total assets	[3],[4]	$ 450,367		438,254		450,367		438,254
Capital expenditure	[5]			$ 1,537		$ 15,880		$ 2,359
Southern Virginia
Segment Reporting Information [Line Items]
Number of buildings | Integer	[1]	19		38	[2]	19		38	[2]
Square feet | ft²	[1]	2,023,927		2,851,568	[2]	2,023,927		2,851,568	[2]
Total revenues		$ 7,151		$ 7,107		$ 14,148		$ 14,219
Property operating expense		(1,838)		(2,283)		(3,729)		(4,412)
Real estate taxes and insurance		(614)		(554)		(1,193)		(1,105)
Total property operating income		4,699		4,270		9,226		8,702
Total assets	[3],[4]	167,860		229,263		167,860		229,263
Capital expenditure	[5]	910		$ 2,749		$ 3,400		$ 4,172
Northern Virginia
Segment Reporting Information [Line Items]
Capital expenditure	[5]	$ 5,037
[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]	Corporate assets not allocated to any of our reportable segments totaled $56,563 and $86,333 at June 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]	Capital expenditures for corporate assets not allocated to any of our reportable segments totaled none and $361 for the three months ended June 30, 2015 and 2014, respectively, and $309 and $638 for the six months ended June 30, 2015 and 2014, respectively.