First Potomac Realty Trust (FPO) 10-Q 28 Apr 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	Apr. 27, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	FIRST POTOMAC REALTY TRUST
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
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		58,716,398

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets:
Rental property, net	$ 1,024,605	$ 1,059,272
Assets held-for-sale	0	13,176
Cash and cash equivalents	13,269	14,144
Escrows and reserves	2,348	1,419
Accounts and other receivables, net of allowance for doubtful accounts of $922 and $655, respectively	5,611	6,892
Accrued straight-line rents, net of allowance for doubtful accounts of $471 and $414, respectively	45,211	42,745
Investment in affiliates	42,314	49,392
Deferred costs, net	41,603	42,712
Prepaid expenses and other assets	5,414	5,389
Intangible assets, net	23,622	25,106
Total assets	1,203,997	1,260,247
Liabilities:
Mortgage loans, net	295,523	296,212
Unsecured term loan, net	299,433	299,404
Unsecured revolving credit facility, net	48,758	141,555
Accounts payable and other liabilities	40,897	43,904
Accrued interest	1,470	1,537
Rents received in advance	6,493	6,234
Tenant security deposits	4,831	4,982
Deferred market rent, net	1,716	1,792
Total liabilities	699,121	795,620
Noncontrolling interests in the Operating Partnership	27,516	28,244
Equity:
Common shares, $0.001 par value per share, 150,000 shares authorized; 58,716 and 58,319 shares issued and outstanding, respectively	59	58
Additional paid-in capital	916,460	913,367
Accumulated other comprehensive loss	(273)	(844)
Dividends in excess of accumulated earnings	(438,886)	(476,198)
Total equity	477,360	436,383
Total liabilities, noncontrolling interests and equity	$ 1,203,997	$ 1,260,247

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts, accounts and other receivables	$ 908	$ 876
Allowance for doubtful accounts, accrued straight-line rents	$ 316	$ 105
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	600,000	6,400,000
Series A Preferred Shares, shares outstanding	600,000	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	58,129,000	57,718,000
Common stock, shares outstanding	58,129,000	57,718,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues:
Rental	$ 30,818	$ 33,844
Tenant reimbursements and other	7,005	8,853
Total revenues	37,823	42,697
Operating expenses:
Property operating	9,958	11,537
Real estate taxes and insurance	4,661	5,216
General and administrative	4,497	4,578
Depreciation and amortization	14,566	15,006
Total operating expenses	33,682	36,337
Operating income	4,141	6,360
Other expenses (income)
Interest expense	6,344	6,816
Interest and other income	(210)	(1,003)
Equity in earnings of affiliates	(4,223)	(555)
(Gain) loss on sale of rental property	42,799	(1,155)
Loss on debt extinguishment	0	48
Total other expenses (income)	(40,888)	6,461
Income from continuing operations	45,029	(101)
Discontinued operations:
Net income (loss)	45,029	(101)
Less: Net (income) loss attributable to noncontrolling interests	(1,884)	147
Net income attributable to First Potomac Realty Trust	43,145	46
Less: Dividends on preferred shares	0	(2,248)
Less: Issuance costs of redeemed preferred shares	0	(1,904)	[1]
Net income (loss) attributable to common shareholders	$ 43,145	$ (4,106)
Basic and diluted earnings per common share:
Net income (loss) attributable to common shareholders - basic	$ 0.75	$ (0.07)
Net income (loss) attributable to common shareholders - dilutive	$ 0.74
Weighted average common shares outstanding:
Basic	57,635	57,542
Diluted	57,907	57,542
[1]	Represents the original issuance costs associated with the redemption of 2.2 million 7.750% Series A Cumulative Redeemable Perpetual Preferred Shares (the “7.750% Series A Preferred Shares”) during the three months ended March 31, 2016.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 45,029	$ (101)
Unrealized gain on derivative instruments	596	169
Unrealized loss on derivative instruments	0	(1,031)
Total comprehensive income (loss)	45,625	(963)
Net (income) loss attributable to noncontrolling interests	(1,884)	147
Net (gain) loss from derivative instruments attributable to noncontrolling interests	(25)	36
Comprehensive income (loss) attributable to First Potomac Realty Trust	$ 43,716	$ (780)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Cash flows from operating activities:
Net income (loss)	$ 45,029	$ (101)
Discontinued operations:
Depreciation and amortization	14,823	15,303
Stock based compensation	829	488
Bad debt expense	324	105
Amortization of deferred market rent	50	79
Amortization of financing costs and discounts	434	472
Equity in earnings of affiliates	(4,223)	(555)
Distributions from investments in affiliates	0	425
Gain (Loss) on Sale of Properties	(42,799)	1,155
Changes in assets and liabilities:
Escrows and reserves	(929)	375
Accounts and other receivables	1,007	1,358
Accrued straight-line rents	(2,883)	(1,725)
Prepaid expenses and other assets	(6)	205
Tenant security deposits	(129)	(748)
Accounts payable and accrued expenses	(1,474)	(2,313)
Accrued interest	(67)	39
Rents received in advance	259	70
Deferred costs	(1,171)	(682)
Total adjustments	(35,955)	14,051
Net cash provided by operating activities	9,074	13,950
Cash flows from investing activities:
Proceeds from sale of rental property	85,754	90,501
Change In Escrow And Reserves	0	246
Additions to rental property and furniture, fixtures and equipment	(6,569)	(17,502)
Additions to construction in progress	(242)	(5,141)
Proceeds from Sale of Equity Method Investments	11,301	0
Net cash provided by investing activities	90,244	68,104
Cash flows from financing activities:
Financing costs	0	(245)
Issuance of debt	4,000	80,243
Repayments of debt	97,891	93,119
Dividends to common shareholders	(5,815)	(8,701)
Dividends to preferred shareholders	0	(2,776)
Distributions to noncontrolling interests	(255)	(393)
Repurchase of Common Shares	(232)	(122)
Redemption of preferred shares	0	(55,000)
Redemption of operating partnership units	0	(319)
Net cash used in financing activities	(100,193)	(80,432)
Net (decrease) increase in cash and cash equivalents	(875)	1,622
Cash and cash equivalents, beginning of period	14,144	13,527	$ 13,527
Cash and cash equivalents, end of period	13,269	15,149	14,144
Cash paid for interest, net	5,975		6,251
Non-cash investing and financing activities:
Value of common shares retired to settle employee income tax obligations	232	$ 122
Change in fair value of the outstanding common Operating Partnership units	(2,383)		(1,324)
Changes in accruals:
Additions to rental property and furniture, fixtures and equipment	1,610		(421)
Additions to development and redevelopment	$ (474)		$ 1,190

Consolidated Statements of Cas7

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Capitalized interest on indebtedness paid in cash	$ 0	$ (200)
Shares Tendered By Employees For Statutory Tax Withholdings Upon Issuance Of Common Stock	232	122
Fair value adjustment, cost basis	3,700
Change in redemption value, noncontrolling interest		2,900
Furniture and Fixtures [Member]
Accrued capital expenditure	4,600	10,300
Development and Redevelopment [Member]
Accrued capital expenditure	$ 600	$ 4,500

Description of Business

Description of Business	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Description of Business	Description of Business First Potomac Realty Trust (the “Company”) is a leader in the ownership, management, redevelopment and development of office and business park properties in the greater Washington, D.C. region. The Company’s focus is owning and operating properties that the Company believes can benefit from its market knowledge and intensive operational skills with a focus on increasing 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 March 31, 2017 , owned 95.8% 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 that are owned by unrelated parties. At March 31, 2017 , we wholly owned properties totaling 6.0 million square feet and had a noncontrolling ownership interest in properties totaling an additional 0.4 million square feet through two unconsolidated joint ventures. We also owned land that can support 0.4 million square feet of additional development. Our consolidated properties were 92.4% occupied by 372 tenants at March 31, 2017 . We do not include the square footage of properties in development or redevelopment, which totaled 0.1 million square feet at March 31, 2017 , in our occupancy calculation. We derive substantially all of our revenue from leases of space within our properties. As of March 31, 2017 , our largest tenant was the U.S. Government, which accounted for 14.0% of our total annualized cash basis rent, and the U.S. Government combined with government contractors accounted for 20.9% of our total annualized cash basis rent as of March 31, 2017 . 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	3 Months Ended
	Mar. 31, 2017
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, which we consider to be a variable interest entity (“VIE”), 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, 2016 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 March 31, 2017 and the results of our operations, our comprehensive income (loss) and our cash flows for the three months ended March 31, 2017 and 2016 . 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 unaudited 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, 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 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 binding contract pursuant to which the buyer has significant money at risk, or 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. We will also determine whether the disposal of a building qualifies as a discontinued operation in accordance with GAAP by assessing whether the disposal of the building, or group of buildings, represents a strategic shift that has, or will have, a major effect on the Company’s operations or financial results. If the building does not qualify as a discontinued operation in accordance with GAAP, 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 GAAP, 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 three months ended March 31, 2017 and 2016 . 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) Application of New Accounting Standards In January 2017, we adopted 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 adoption of ASU 2014-15 did not have a material impact on our unaudited condensed consolidated financial statements and related disclosures. In January 2017, we adopted Accounting Standards Update No. 2016-09, Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”) , which is intended to simplify several aspects of the accounting for employee share-based payment transactions, including income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 requires us to classify cash payments made on behalf of employees for taxes owed on the vesting of restricted common shares, for which we withhold vested common shares owed to the employee in an amount that equates to the value of the employee’s tax obligation, as a financing activity on our statements of cash flows. We elected to adopt ASU 2016-09 retrospectively and the adoption of ASU 2016-09 did not have a material impact on our unaudited condensed consolidated financial statements and related disclosures. In January 2017, we adopted Accounting Standards Update No. 2016-17, Consolidation (Topic 810): Interests Held through Related Parties That Are under Common Control (“ASU 2016-17”), which requires a single decision maker or service provider, in evaluating whether it is the primary beneficiary, to consider on a proportionate basis indirect interests held through related parties under common control. The adoption of ASU 2016-17 did not have a material impact on our unaudited condensed consolidated financial statements and related disclosures. In January 2017, we adopted Accounting Standards Update No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business (“ASU 2017-01”), which was issued by the Financial Accounting Standards Board (“FASB”) in January 2017. ASU 2017-01 provides a new framework for determining whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. We anticipate ASU 2017-01 will change our accounting treatment of future property acquisitions; however, the adoption of ASU 2017-01 did not have a material impact on our unaudited condensed consolidated financial statements and related disclosures. In May 2014, the 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 begun to evaluate each of the revenue streams under the new model and the pattern of recognition is not expected to change significantly. We have not yet selected a transition method and are evaluating the impact that ASU 2014-09 will have on our consolidated financial statements and related disclosures. In January 2016, the FASB issued Accounting Standards Update No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”), which requires, among other things, entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value disclosed for financial instruments measured at amortized cost on the balance sheet. ASU 2016-01 is effective for periods beginning after December 15, 2017; early adoption is not permitted. The guidance is not expected to have a material impact on our consolidated financial statements and related disclosures. In February 2016, the FASB issued Accounting Standards Update No. 2016-02, Leases (“ASU 2016-02”), which requires a lessee to record on the balance sheet a right-of-use asset with a corresponding lease liability created by lease terms of more than 12 months. Additional qualitative and quantitative disclosures will also be required. The guidance will become effective for periods beginning after December 15, 2018 and will be applied using a modified retrospective transition method. We are currently evaluating the impact that ASU 2016-02 will have on our consolidated financial statements and related disclosures. In August 2016, the FASB issued Accounting Standards Update No. 2016-15, Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”) . The guidance addresses eight classification issues related to the statement of cash flows, including debt prepayment or debt extinguishment costs and distributions received from equity-method investees. The guidance will become effective for periods beginning after December 15, 2017 and early adoption is permitted. ASU 2016-15 requires the use of a retrospective transition method to each period presented. If such retrospective transition is impracticable for certain issues, the adoption of ASU 2016-15 for the applicable issues may be applied prospectively as of the earliest date practicable. The guidance is not expected to have a material impact on our consolidated financial statements or related disclosures. In November 2016, the FASB issued Accounting Standards Update No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“ASU 2016-18”), which requires companies to include cash and cash equivalents that have restrictions on withdrawal or use in total cash and cash equivalents on the statement of cash flows. ASU 2016-18 is effective for periods beginning after December 15, 2017 and early adoption is permitted. The guidance is not expected to have a material impact on our consolidated financial statements and related disclosures. In January 2017, the FASB issued Accounting Standards Update No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), which requires an entity to no longer perform a hypothetical purchase price allocation to measure goodwill impairment. Instead, impairment will be measured using the difference between the carrying amount and the fair value of the reporting unit. ASU 2017-04 is effective for periods beginning after December 15, 2019 and early adoption is permitted for measurement dates after January 1, 2017. The guidance is not expected to have a material impact on our consolidated financial statements and related disclosures. In February 2017, the FASB issued Accounting Standards Update No. 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets (“ASU 2017-05”), which clarifies the guidance in Subtopic 610-20 on accounting for derecognition of a nonfinancial asset. The update also defines in-substance nonfinancial assets and includes guidance on partial sales of nonfinancial assets. The amendments in ASU 2017-05 are to be applied at the same time that ASU 2014-09 is applied. We are currently evaluating the impact that ASU 2017-05 will have on our consolidated financial statements and related disclosures. (e) Reclassifications Certain prior year amounts have been reclassified to conform to the current year presentation, primarily as a result of adopting ASU 2016-09 in January 2017. See note 2(d), Summary of Significant Accounting Policies - Application of New Accounting Standards for more information.

Earnings Per Common Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2017
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 and non-vested 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 (dollars in thousands, except per share amounts): Three Months Ended March 31, 2017 2016 Numerator for basic and diluted earnings per common share: Net income (loss) $ 45,029 $ (101 ) Less: Net (income) loss attributable to noncontrolling interests (1,884 ) 147 Net income attributable to First Potomac Realty Trust 43,145 46 Less: Dividends on preferred shares — (2,248 ) Less: Issuance costs of redeemed preferred shares (1) — (1,904 ) Net income (loss) attributable to common shareholders 43,145 (4,106 ) Less: Allocation to participating securities (55 ) (73 ) Net income (loss) attributable to common shareholders $ 43,090 $ (4,179 ) Denominator for basic and diluted earnings per common share: Weighted average common shares outstanding - basic 57,635 57,542 Weighted average common shares outstanding - diluted 57,907 57,542 Basic and diluted earnings per common share: Net income (loss) attributable to common shareholders - basic $ 0.75 $ (0.07 ) Net income (loss) attributable to common shareholders - diluted $ 0.74 $ (0.07 ) (1) Represents the original issuance costs associated with the redemption of 2.2 million 7.750% Series A Cumulative Redeemable Perpetual Preferred Shares (the “7.750% Series A Preferred Shares”) during the three months ended March 31, 2016. 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 2017 2016 Stock option awards 879 1,018 Non-vested share awards 595 484 1,474 1,502

Rental Property

Rental Property	3 Months Ended
	Mar. 31, 2017
Real Estate [Abstract]
Rental Property	Rental Property Rental property represents wholly-owned buildings and related improvements, net of accumulated depreciation, and developable land. All of our rental properties are located within the greater Washington, D.C. region. Rental property consists of the following (dollars in thousands): March 31, 2017 December 31, 2016 (1) Land and land improvements $ 269,920 $ 282,923 Buildings and improvements 766,394 824,867 Construction in progress 29,793 4,605 Tenant improvements 185,264 189,031 Furniture, fixtures and equipment 374 408 1,251,745 1,301,834 Less: accumulated depreciation (227,140 ) (242,562 ) $ 1,024,605 $ 1,059,272 (1) Excludes rental property totaling $13.2 million at December 31, 2016 related to One Fair Oaks, which was classified as held-for-sale at December 31, 2016 and was sold on January 9, 2017 . 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. At March 31, 2017, we owned developable land that can accommodate 0.4 million square feet of additional building space, of which 34 thousand is located in the Washington, D.C. reporting segment, 0.1 million in the Maryland reporting segment, 0.2 million in the Northern Virginia reporting segment and 0.1 million in the Southern Virginia reporting segment. In March 2017, the sole tenant of 540 Gaither Road at Redland (“Redland I”) exercised its early termination option and vacated the 133,895 square-foot building, which is located in our Maryland reporting segment. Upon the tenant vacating Redland I, the building was placed into redevelopment. At March 31, 2017, our total investment in the building under redevelopment was $23.6 million , which included the $23.0 million total original cost basis of the building and land. The majority of costs incurred as of March 31, 2017 in excess of the original cost basis of the building and land related to site planning and design costs. During the first quarter of 2017 , we did no t place in-service any completed development or redevelopment space. At March 31, 2017, we did not have any completed development or redevelopment space that had yet to be placed in-service.

Notes Receivable

Notes Receivable	3 Months Ended
	Mar. 31, 2017
Receivables [Abstract]
Notes Receivable	Notes Receivable On June 2, 2016, the owners of 950 F Street, NW, a ten-story, 287,000 square-foot office/retail building located in Washington, D.C., prepaid a mezzanine loan that was secured by a portion of the owners’ interest in the property and had an outstanding balance of $34.0 million . The mezzanine loan, which had a fixed interest rate of 9.75% was scheduled to mature on April 1, 2017 and had been prepayable since December 21, 2015. In addition to the prepayment of the loan's entire principal balance, we received interest through June 24, 2016 and an exit fee upon the loan's prepayment. We recognized $0.2 million of accelerated income in the second quarter of 2016 related to the payment of the exit fee, which is reflected in “Interest and other income” on our consolidated statement of operations for the nine months ended September 30, 2016. We used the proceeds from the prepayment of the note receivable to redeem the remaining 0.6 million 7.750% Series A Preferred Shares outstanding and to pay down a portion of our unsecured revolving credit facility. We recorded interest income related to our notes receivable of $0.8 million for the three months ended March 31, 2016 which is included within “Interest and other income” on our consolidated statements of operations. No interest income related to our notes receivable was recorded for the three months ended March 31, 2017.

Investment in Affiliates

Investment in Affiliates	3 Months Ended
	Mar. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Investment in Affiliates	Investment in Affiliates We own an interest in several unconsolidated joint ventures, two of which currently 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 non-controlled joint ventures are not consolidated within our unaudited condensed consolidated financial statements. Our investments in these joint ventures are recorded as “Investment in affiliates” on our consolidated balance sheets. On March 7, 2017 , three of our unconsolidated joint ventures collectively sold Aviation Business Park, a 120,284 square-foot office building, and Rivers Park I and II, a 307,984 square-foot business park, which were all located in our Maryland reporting segment. Based on our percentage ownership of the joint ventures, our share of gross proceeds from the sale totaled $19.0 million , which generated $18.4 million of net proceeds. We used the net proceeds from the sale to repay $7.0 million (our proportionate share) of mortgage debt encumbering Rivers Park I and II, and the remainder was used to repay a portion of the outstanding balance under our unsecured revolving credit facility. We have had, and will have, no continuing involvement in the ownership decisions of any of the unconsolidated joint ventures’ disposed properties subsequent to their disposal. Our investment in affiliates consisted of the following (dollars in thousands): Reporting Segment Ownership Investment at March 31, 2017 Investment at December 31, 2016 Prosperity Metro Plaza Northern Virginia 51% $ 26,772 $ 26,414 1750 H Street, NW Washington, D.C. 50% 14,594 14,624 Aviation Business Park (1) Maryland 50% 482 5,941 Rivers Park I and II (1)(2) Maryland 25% 466 2,413 $ 42,314 $ 49,392 (1) The unconsolidated joint ventures that owned Aviation Business Park and Rivers Park I and II sold these properties on March 7, 2017 . Our investment in these joint ventures at March 31, 2017 is primarily comprised of our share of cash that has not yet been distributed. (2) Rivers Park I and Rivers Park II were owned through two separate unconsolidated joint ventures. The following table provides a summary of the mortgage debt held by our unconsolidated joint ventures (dollars in thousands): FPO Ownership Effective Interest Rate Maturity Date Principal Balance at March 31, 2017 (1) Principal Balance at December 31, 2016 (1) Rivers Park I and II (2) 25% LIBOR + 1.90% (3) September 2017 $ — $ 28,000 1750 H Street, NW (4) 50% 3.92% August 2024 32,000 32,000 Prosperity Metro Plaza (5) 51% 3.91% December 2029 50,000 50,000 Weighted Average / Total 3.91% $ 82,000 $ 110,000 (1) Reflects the entire balance of the debt secured by the properties, not our portion of the debt. (2) The unconsolidated joint ventures that owned Rivers Park I and II sold these properties on March 7, 2017 . The unconsolidated joint venture partners used net proceeds from the sale to repay the mortgage debt encumbering the properties. At December 31, 2016, $2.8 million of the outstanding mortgage balance was recourse to us. (3) At March 31, 2017 , LIBOR was 0.98% . All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR. (4) The loan requires interest-only payments with a constant interest rate over the life of the loan. The loan is repayable in full, without penalty, on or after August 1, 2021. (5) The loan requires interest-only payments through December 2024, at which time the loan requires principal and interest payments through its maturity date. The loan is repayable in full, without penalty, on or after June 1, 2029. The net assets of our unconsolidated joint ventures consisted of the following (dollars in thousands): March 31, 2017 December 31, 2016 Assets: Rental property, net $ 144,065 $ 189,245 Cash and cash equivalents 11,122 9,887 Other assets 16,472 20,726 Total assets 171,659 219,858 Liabilities: Mortgage loans, net (1)(2) 81,416 109,372 Other liabilities 6,503 8,674 Total liabilities 87,919 118,046 Net assets $ 83,740 $ 101,812 (1) Of the total mortgage debt that encumbers our unconsolidated properties, none was recourse to us at March 31, 2017 and $2.8 million was recourse to us at December 31, 2016. (2) Mortgage loans, net at both March 31, 2017 and December 31, 2016 included $0.6 million of unamortized deferred financing costs Our share of earnings or losses related to our unconsolidated joint ventures is recorded in our consolidated statements of operations as “Equity in earnings of affiliates.” The following table summarizes the results of operations of our unconsolidated joint ventures for the periods presented, of which, our proportionate share is reflected in “Equity in earnings of affiliates” in our consolidated statements of operations based on our varying ownership interests in the unconsolidated joint ventures (dollars in thousands): Three Months Ended March 31, 2017 2016 Total revenues $ 5,679 $ 6,290 Total operating expenses (1,937 ) (2,166 ) Net operating income 3,742 4,124 Depreciation and amortization (1,863 ) (1,966 ) Interest expense, net (962 ) (993 ) Gain on sale of rental property 10,324 — Net income $ 11,241 $ 1,165 The following table summarizes the results of operations of Aviation Business Park and Rivers Park I and II, which were sold in March 2017, of which, our proportionate share is reflected in “Equity in earnings of affiliates” in our consolidated statements of operations based on our varying ownership interests in the unconsolidated joint ventures that owned the respective properties (dollars in thousands): Three Months Ended March 31, 2017 2016 Total revenues $ 1,113 $ 1,631 Total operating expenses (275 ) (641 ) Net operating income 838 990 Depreciation and amortization (420 ) (643 ) Interest expense, net (146 ) (175 ) Income from operations of disposed properties 272 172 Gain on sale of rental property 10,324 — Net income $ 10,596 $ 172 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 $0.1 million and $0.2 million for the three months ended March 31, 2017 and 2016, respectively, which are reflected within “Tenant reimbursements and other revenues” on our consolidated statements of operations.

Dispositions

Dispositions	3 Months Ended
	Mar. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Dispositions	Dispositions We will report a disposed or held-for-sale property or group of properties in discontinued operations only if the disposal represents a strategic shift that has, or will have, a major effect on our operations and financial results. All other disposed properties will have their operating results reflected within continuing operations on our consolidated statements of operations for all periods presented. We have had, and will have, no continuing involvement with any of our disposed properties subsequent to their disposal. The operations of the disposed properties were not subject to any income based taxes. Other than the properties discussed below in this note 6 , Dispositions , and in note 5 , Investment in Affiliates , we did not dispose of or enter into any agreements to sell any other properties during the three months ended March 31, 2017 and 2016 . Disposed or Held-for-Sale Properties within Continuing Operations The following table is a summary of property dispositions whose operating results are included in continuing operations in our consolidated statements of operations for the periods presented (dollars in thousands): Property Reporting Disposition Date Property Type Square Feet Net Sale Proceeds Plaza 500 Northern Virginia 2/17/2017 Industrial 502,830 $ 72,499 One Fair Oaks (1) Northern Virginia 1/9/2017 Office 214,214 13,255 Storey Park (2) Washington, D.C. 7/25/2016 Land — 52,659 NOVA Non-Core Portfolio (3) Northern Virginia 3/25/2016 Various 945,745 90,501 (1) One Fair Oaks was classified as held-for-sale at December 31, 2016, and the building was vacant at the time of sale. (2) This development site could have supported up to 712,000 rentable square feet. (3) Consists of Van Buren Office Park, Herndon Corporate Center, Windsor at Battlefield, Reston Business Campus, Enterprise Center, Gateway Centre Manassas, Linden Business Center and Prosperity Business Center (collectively, the “NOVA Non-Core Portfolio”). On February 17, 2017 , we sold Plaza 500 for net proceeds of $ 72.5 million and recorded a gain on sale of $ 42.7 million . The sale of Plaza 500 represented the divestiture of our last industrial property. We used the proceeds to pay down a portion of the outstanding balance under our unsecured revolving credit facility. On January 9, 2017 , we sold One Fair Oaks for net proceeds of $ 13.3 million and recorded a gain on sale of $ 0.1 million . We used the proceeds to pay down a portion of the outstanding balance under our unsecured revolving credit facility. One Fair Oaks met our held-for-sale criteria at December 31, 2016 and, therefore, the assets of the building were classified within “Assets-held-for-sale” on our consolidated balance sheet at December 31, 2016. The assets classified within held-for-sale as of December 31, 2016 primarily consisted of $ 17.6 million in building and building improvements, $ 1.6 million of land, and $ 6.0 million of accumulated depreciation. No material liabilities were classified as held-for-sale at December 31, 2016. The following table summarizes the aggregate results of operations for the disposed or held-for-sale properties that are included in continuing operations for the periods presented (dollars in thousands): Three Months Ended March 31, 2017 2016 Revenues $ 804 $ 7,043 Property operating expenses (304 ) (2,823 ) Depreciation and amortization (289 ) (1,343 ) Interest expense — (184 ) Loss on debt extinguishment — (48 ) Income from operations of disposed property 211 2,645 Gain (loss) on sale of rental property (1) 42,799 (1,155 ) Net income from continuing operations $ 43,010 $ 1,490 (1) During the first quarter of 2017, we recorded a $ 0.1 million gain on the sale of One Fair Oaks and a $42.7 million gain on the sale of Plaza 500. During the first quarter of 2016, we recorded a $1.2 million loss on the sale of the NOVA Non-Core Portfolio.

Debt

Debt	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Debt	Debt Our debt consisted of the following (dollars in thousands): March 31, (1) December 31, 2016 (1) Mortgage loans, net, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030 (2)(3) $ 295,523 $ 296,212 Unsecured term loan, net, effective interest rates ranging from LIBOR plus 1.45% to LIBOR plus 1.80%, with staggered maturity dates ranging from December 2020 to December 2022 (2) 299,433 299,404 Unsecured revolving credit facility, net, effective interest rate of LIBOR plus 1.50%, maturing December 2019 (2) 48,758 141,555 Total $ 643,714 $ 737,171 (1) The balances include a total of $5.8 million and $6.2 million of unamortized deferred financing costs at March 31, 2017 and December 31, 2016 , respectively. (2) At March 31, 2017 , LIBOR was 0.98% . (3) The balances at March 31, 2017 and December 31, 2016 include two construction loans. (a) Mortgage Loans The following table provides a summary of our mortgage debt, which includes two construction loans (dollars in thousands): Encumbered Property Contractual Effective Maturity March 31, December 31, 2016 440 First Street, NW Construction Loan (1)(2) LIBOR + 2.50% LIBOR + 2.50% May 2017 $ 32,216 $ 32,216 Redland II and III 4.20 % 4.64 % November 2017 62,873 63,214 Northern Virginia Construction Loan (3) LIBOR + 1.85% LIBOR + 1.85% September 2019 34,584 34,584 840 First Street, NE 5.72 % 6.01 % July 2020 35,023 35,201 Battlefield Corporate Center 4.26 % 4.40 % November 2020 3,309 3,353 1211 Connecticut Avenue, NW 4.22 % 4.47 % July 2022 28,347 28,503 1401 K Street, NW 4.80 % 4.93 % June 2023 35,384 35,556 11 Dupont Circle, NW 4.05 % 4.22 % September 2030 66,780 66,780 Principal balance 4.45 % (4) 298,516 299,407 Unamortized deferred financing costs (2,993 ) (3,195 ) Total balance, net $ 295,523 $ 296,212 (1) At March 31, 2017 , LIBOR was 0.98% . (2) This construction loan is collateralized by 440 First Street, NW. In May 2016, we extended the maturity date by one year to May 30, 2017 . We can repay all or a portion of the construction loan, without penalty, at any time during the term of the loan. At March 31, 2017, per the terms of the loan agreement, 50% of the outstanding principal balance and all of the outstanding accrued interest were recourse to us. (3) This construction loan has a borrowing capacity of up to $43.7 million and is collateralized by the NOVA build-to-suit, which was placed in-service in the third quarter of 2016. We can repay all or a portion of the Northern Virginia Construction Loan, without penalty, at any time during the term of the loan. (4) Represents the weighted average interest rate on total mortgage debt. (b) Unsecured Term Loan and Unsecured Revolving Credit Facility The table below shows the outstanding balances and the interest rates of the three tranches of the $300.0 million unsecured term loan and the unsecured revolving credit facility at March 31, 2017 and December 31, 2016 (dollars in thousands): Maturity Date Interest Rate (1) March 31, 2017 December 31, 2016 Unsecured Term Loan Tranche A December 2020 LIBOR + 1.45% $ 100,000 $ 100,000 Tranche B June 2021 LIBOR + 1.45% 100,000 100,000 Tranche C December 2022 LIBOR + 1.80% 100,000 100,000 Total 300,000 300,000 Unamortized deferred financing costs (567 ) (596 ) Total, net $ 299,433 $ 299,404 Unsecured Revolving Credit Facility Outstanding borrowings December 2019 (2) LIBOR + 1.50% (3) $ 51,000 $ 144,000 Unamortized deferred financing costs (2,242 ) (2,445 ) Total, net $ 48,758 $ 141,555 (1) Reflects the interest rate spreads at March 31, 2017. At March 31, 2017 , LIBOR was 0.98% . The interest rate spread is subject to change based on our maximum total indebtedness ratio. For more information, see note 7 ( d ), Debt – Financial Covenants . (2) The maturity date of the unsecured revolving credit facility may be extended for two, six-month terms at our option. (3) At March 31, 2017 , our outstanding borrowings under the unsecured revolving credit facility had a weighted average interest rate of 2.5% . During the three months ended March 31, 2017, we repaid $97.0 million of the outstanding balance under the unsecured revolving credit facility. In January 2017, we used the net proceeds from the sale of One Fair Oaks and available cash to repay $ 14.0 million of the outstanding balance under our unsecured revolving credit facility. In February 2017, we used a portion of the net proceeds from the sale of Plaza 500 to repay $ 70.0 million of the outstanding balance under our unsecured revolving credit facility. In March 2017, we used our proportionate share of the net proceeds from the sale of Aviation Business Park and Rivers Park I and II to repay $ 7.0 million of the mortgage loan that encumbered Rivers Park I and II (our proportionate share) and the remainder was used, together with available cash, to repay $ 13.0 million of the outstanding balance under our unsecured revolving credit facility. During the three months ended March 31, 2017, we borrowed $ 4.0 million under the unsecured revolving credit facility for general corporate purposes. For the three months ended March 31, 2017 , our weighted average borrowings outstanding under the unsecured revolving credit facility were $96.6 million with a weighted average interest rate of 2.3% compared with weighted average borrowings of $169.5 million and a weighted average interest rate of 1.9% for the three months ended March 31, 2016 . Our maximum outstanding borrowings were $144.0 million and $193.0 million during the three months ended March 31, 2017 and 2016 , respectively. As of the date of this filing, we had $51.0 million outstanding and $172.0 million available capacity under the unsecured revolving credit facility. We are required to pay a commitment fee at an annual rate of 0.15% of the unused capacity if our usage exceeds 50% of our total capacity under the revolving credit facility, or 0.25% if our usage does not exceed 50% . (c) Interest Rate Swap Agreements At March 31, 2017 , we had nine interest rate swap agreements outstanding that collectively fixed LIBOR, at a weighted average interest rate of 1.4% , on $240.0 million of our variable rate debt. See note 8 , Derivative Instruments , for more information about our interest rate swap agreements. ( d ) Financial Covenants The credit agreement governing our unsecured revolving credit facility and unsecured term loan contains various restrictive covenants, including with respect to liens, indebtedness, investments, distributions, mergers and asset sales. 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 under the agreement to be immediately due and payable. 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 March 31, 2017 , we were in compliance with the covenants of our amended, restated and consolidated unsecured revolving credit facility and unsecured term loan, the 440 First Street, NW Construction Loan and the Northern Virginia Construction 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 March 31, 2017, the applicable interest rate spreads on the unsecured revolving credit facility and the unsecured term loan will remain unchanged.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2017
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 March 31, 2017 , we had nine interest rate swap agreements outstanding that collectively fixed LIBOR, at a weighted average interest rate of 1.4% , on $240.0 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 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 $ 240,000 1.442 % 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 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 three months ended March 31, 2017 and 2016 . 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 losses as an increase to interest expense of $0.4 million and $0.8 million for the three months ended March 31, 2017 and 2016, respectively. As of March 31, 2017 , we estimated that $0.4 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	3 Months Ended
	Mar. 31, 2017
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 non-recurring and recurring basis as of March 31, 2017 and December 31, 2016 (dollars in thousands): Balance at Level 1 Level 2 Level 3 Recurring Measurements: Derivative instrument-swap assets $ 68 $ — $ 68 $ — Derivative instrument-swap liabilities 378 — 378 — Balance at Level 1 Level 2 Level 3 Recurring Measurements: Derivative instrument-swap liabilities $ 906 $ — $ 906 $ — 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 three months ended March 31, 2017 and 2016 . 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 three months ended March 31, 2017 and 2016 . Interest Rate Derivatives At March 31, 2017 , we had hedged $240.0 million of our variable rate debt through nine interest rate swap agreements. See note 8 , 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 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. The carrying amount and estimated fair value of our debt instruments are as follows (dollars in thousands): March 31, 2017 December 31, 2016 Carrying (1) Fair Carrying (1) Fair Financial Liabilities: Mortgage debt $ 298,516 $ 296,923 $ 299,407 $ 300,927 Unsecured term loan 300,000 300,000 300,000 300,000 Unsecured revolving credit facility 51,000 51,000 144,000 144,000 Total $ 649,516 $ 647,923 $ 743,407 $ 744,927 (1) The debt balances exclude a combined total of $5.8 million and $6.2 million of unamortized deferred financing costs at March 31, 2017 and December 31, 2016, respectively.

Equity

Equity	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Equity	Equity In December 2015, our Board of Trustees authorized the redemption of some or all of our 6.4 million outstanding 7.750% Series A Preferred Shares. On January 19, 2016 and April 27, 2016 , we used proceeds from dispositions to redeem 2.2 million shares and 3.6 million shares, respectively, of our 7.750% Series A Preferred Shares at a redemption price of $25.00 per share, plus accrued dividends up to the applicable dates of redemption. On July 6, 2016 , we used proceeds from the repayment of a mezzanine loan to redeem the remaining 0.6 million outstanding shares of our 7.750% Series A Preferred Shares at a redemption price of $25.00 per share, plus accrued dividends up to the date of redemption. The 7.750% Series A Preferred Shares (NYSE: FPO-PA) were delisted from trading on the New York Stock Exchange upon redemption of the remaining 0.6 million outstanding shares on July 6, 2016 . On January 24, 2017 , we declared a dividend of $0.10 per common share, equating to an annualized dividend of $0.40 per common share. The dividend was paid on February 15, 2017 to common shareholders of record as of February 8, 2017 . We record dividends on non-vested share awards as a reduction of shareholders’ equity. Dividends paid on non-vested share awards that subsequently do not vest are recorded as compensation expense in the period in which they are forfeited or expire. For each dividend paid by us on our common shares and, when applicable, preferred shares, the Operating Partnership distributes an equivalent distribution on our common and preferred Operating Partnership units, respectively. On April 25, 2017 , we declared a dividend of $0.10 per common share, equating to an annualized dividend of $0.40 per common share. The dividend will be paid on May 15, 2017 to common shareholders of record as of May 8, 2017 . Our unsecured revolving credit facility and unsecured term loan, the 440 First Street, NW Construction Loan and the Northern Virginia Construction Loan contain certain restrictions that include, among other things, requirements to maintain specified coverage ratios and other financial covenants, which may limit our ability to make distributions to our common and preferred shareholders, except for distributions required to maintain our qualification as a REIT. 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): Total Equity Redeemable noncontrolling interests Balance at December 31, 2016 $ 436,383 $ 28,244 Net income 43,145 1,884 Changes in ownership, net 3,076 (2,382 ) Distributions to owners (5,815 ) (255 ) Other comprehensive income, net 571 25 Balance at March 31, 2017 $ 477,360 $ 27,516 First Potomac Realty Trust Non-redeemable noncontrolling interests (1) Total Equity Redeemable noncontrolling interests Balance at December 31, 2015 $ 624,528 $ 800 $ 625,328 $ 28,813 Net income (loss) 46 (14 ) 32 (133 ) Changes in ownership, net (53,145 ) — (53,145 ) (1,644 ) Distributions to owners (10,948 ) — (10,948 ) (393 ) Other comprehensive loss, net (826 ) — (826 ) (36 ) Balance at March 31, 2016 $ 559,655 $ 786 $ 560,441 $ 26,607 (1) Our 97% owned consolidated joint venture sold Storey Park on July 25, 2016 , at which time all assets and liabilities owned by the joint venture were either sold or settled at the time of disposition and the remaining proceeds from the sale were distributed to the joint venture partners in accordance with the terms of the joint venture agreement. See note 6 , Dispositions , for more information. A summary of our accumulated other comprehensive loss is as follows (dollars in thousands): 2017 2016 Beginning balance at January 1, $ (844 ) $ (2,360 ) Net unrealized gain (loss) on derivative instruments 596 (862 ) Net (gain) loss attributable to noncontrolling interests (25 ) 36 Ending balance at March 31, $ (273 ) $ (3,186 )

Noncontrolling Interests

Noncontrolling Interests	3 Months Ended
	Mar. 31, 2017
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 March 31, 2017 , 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 $26.2 million . At March 31, 2017 and December 31, 2016 , we recorded adjustments of $3.7 million and $6.1 million , respectively, to present certain common Operating Partnership units at the greater of their carrying value or redemption value. At March 31, 2017 , 2,545,602 of the total common Operating Partnership units, or 4.2% , were not owned by us. During the three months ended March 31, 2017 , no common Operating Partnership units were redeemed with available cash. During the three months ended March 31, 2016 , 38,539 common Operating Partnership units were redeemed with available cash. No common Operating Partnership units were redeemed for common shares during the three months ended March 31, 2017 or 2016 . (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 (income) loss attributable to noncontrolling interests” on our consolidated statements of operations. On August 4, 2011, we formed a joint venture, in which we had a 97% interest, with an affiliate of Perseus Realty, LLC to acquire Storey Park in our Washington, D.C. reporting segment, which was placed into development in August 2013. Storey Park was sold July 25, 2016 , at which time all assets and liabilities owned by the joint venture were either sold or settled at the time of disposition and the remaining proceeds from the sale were distributed to the joint venture partners in accordance with the terms of the joint venture agreement. See note 6 , Dispositions , for more information.

Share-Based Payments

Share-Based Payments	3 Months Ended
	Mar. 31, 2017
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. During the first quarter of 2017, we granted a total of 160,349 non-vested time-based common shares to our officers and employees. The time-based awards will vest ratably on an annual basis over a three-year period from the grant date. In February 2017, we granted a total of 257,937 non-vested performance-based common shares to our officers. The number of shares that will be earned under the February 2017 performance-based awards will be determined at the end of 2019, based upon the achievement of specified market performance goals measured over the performance period from January 1, 2017 through December 31, 2019. Of the shares earned, 50% will vest on February 1, 2020 and the remaining earned shares will vest on February 1, 2021. Any shares that are not earned will be forfeited. We recognized compensation expense associated with all of our non-vested common share awards of $0.8 million and $0.4 million during the three months ended March 31, 2017 and 2016. 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 distributions over earnings related to participating securities is shown as a reduction in total earnings attributable to common shareholders in our computation of EPS. A summary of our non-vested common share awards at March 31, 2017 is as follows: Non-vested Common Shares Weighted Average Grant Date Fair Value Non-vested at December 31, 2016 711,374 $ 9.85 Granted 418,286 8.54 Vested (80,179 ) 10.99 Expired (1,630 ) 12.38 Forfeited (991 ) 11.03 Non-vested at March 31, 2017 1,046,860 $ 9.23 We value our non-vested time-based share awards at the grant date fair value, which is the market price of our common shares. For the non-vested performance-based common share awards granted in February 2017, we used a Monte Carlo Simulation (risk-neutral approach) to determine the number of shares that may be issued pursuant to the award as these awards were deemed to have a market condition. The risk-free interest rate assumptions used in the Monte Carlo Simulation were determined based on the zero coupon risk-free rate for the time frame of 0.25 years to 3 years, which ranged from 0.70% to 1.60% , respectively. The volatility used for our common share price in the Monte Carlo Simulation varied between 25.82% and 22.93% . Based on the Monte Carlo Simulation, the weighted average grant date fair value of the February 2017 non-vested performance-based common share awards was $7.11 . As of March 31, 2017 , we had $7.6 million of unrecognized compensation cost related to non-vested common shares. We anticipate this cost will be recognized over a weighted-average period of 3.2 years.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2016
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 in their operating results other than the impact of straight-line revenue and the amortization of deferred market rents, deferred lease incentives and deferred tenant improvement reimbursements. There are no inter-segment sales or transfers recorded between segments. The results of operations of our four reporting segments for the three months ended March 31, 2017 and 2016 are as follows (dollars in thousands): Three Months Ended March 31, 2017 Washington, D.C. Maryland (1) Northern Virginia Southern Virginia Consolidated Number of buildings 6 34 12 19 71 Square feet 917,643 1,886,177 1,168,990 2,023,858 5,996,668 Total revenues $ 11,722 $ 11,235 $ 7,312 $ 7,554 $ 37,823 Property operating expense (3,139 ) (2,657 ) (1,956 ) (2,206 ) (9,958 ) Real estate taxes and insurance (2,292 ) (982 ) (741 ) (646 ) (4,661 ) Total property operating income $ 6,291 $ 7,596 $ 4,615 $ 4,702 23,204 Depreciation and amortization expense (14,566 ) General and administrative (4,497 ) Other income 40,888 Net income $ 45,029 Total assets (2) $ 443,800 $ 322,738 $ 260,564 $ 159,487 $ 1,203,997 Capital expenditures (3) $ 1,522 $ 2,350 $ 2,295 $ 606 $ 6,810 Three Months Ended March 31, 2016 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Number of buildings 6 34 14 19 73 Square feet 918,566 1,885,630 1,715,730 2,023,858 6,543,784 Total revenues $ 11,290 $ 11,587 $ 12,307 $ 7,513 $ 42,697 Property operating expense (2,968 ) (3,235 ) (3,320 ) (2,014 ) (11,537 ) Real estate taxes and insurance (2,372 ) (929 ) (1,297 ) (618 ) (5,216 ) Total property operating income $ 5,950 $ 7,423 $ 7,690 $ 4,881 25,944 Depreciation and amortization expense (15,006 ) General and administrative (4,578 ) Other expenses (6,461 ) Net loss $ (101 ) Total assets (2) $ 468,561 $ 338,553 $ 294,480 $ 166,015 $ 1,359,943 Capital expenditures (3) $ 4,910 $ 959 $ 15,757 $ 897 $ 22,643 (1) Redland I within our Maryland reporting segment was placed into redevelopment during March 2017. (2) 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 5 , Investment in Affiliates . Corporate assets not allocated to any of our reportable segments totaled $ 17.4 million and $ 92.3 million at March 31, 2017 and 2016 , respectively. (3) Capital expenditures for corporate assets not allocated to any of our reportable segments were immaterial for the three months ended March 31, 2017 and $ 0.1 million for the three months ended March 31, 2016 .

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2017
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, which we consider to be a variable interest entity (“VIE”), 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, 2016 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 March 31, 2017 and the results of our operations, our comprehensive income (loss) and our cash flows for the three months ended March 31, 2017 and 2016 . 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 unaudited 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, 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 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 binding contract pursuant to which the buyer has significant money at risk, or 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. We will also determine whether the disposal of a building qualifies as a discontinued operation in accordance with GAAP by assessing whether the disposal of the building, or group of buildings, represents a strategic shift that has, or will have, a major effect on the Company’s operations or financial results. If the building does not qualify as a discontinued operation in accordance with GAAP, 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 GAAP, 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 three months ended March 31, 2017 and 2016 . 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.
Application of New Accounting Standards	Application of New Accounting Standards In January 2017, we adopted 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 adoption of ASU 2014-15 did not have a material impact on our unaudited condensed consolidated financial statements and related disclosures. In January 2017, we adopted Accounting Standards Update No. 2016-09, Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”) , which is intended to simplify several aspects of the accounting for employee share-based payment transactions, including income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. ASU 2016-09 requires us to classify cash payments made on behalf of employees for taxes owed on the vesting of restricted common shares, for which we withhold vested common shares owed to the employee in an amount that equates to the value of the employee’s tax obligation, as a financing activity on our statements of cash flows. We elected to adopt ASU 2016-09 retrospectively and the adoption of ASU 2016-09 did not have a material impact on our unaudited condensed consolidated financial statements and related disclosures. In January 2017, we adopted Accounting Standards Update No. 2016-17, Consolidation (Topic 810): Interests Held through Related Parties That Are under Common Control (“ASU 2016-17”), which requires a single decision maker or service provider, in evaluating whether it is the primary beneficiary, to consider on a proportionate basis indirect interests held through related parties under common control. The adoption of ASU 2016-17 did not have a material impact on our unaudited condensed consolidated financial statements and related disclosures. In January 2017, we adopted Accounting Standards Update No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business (“ASU 2017-01”), which was issued by the Financial Accounting Standards Board (“FASB”) in January 2017. ASU 2017-01 provides a new framework for determining whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. We anticipate ASU 2017-01 will change our accounting treatment of future property acquisitions; however, the adoption of ASU 2017-01 did not have a material impact on our unaudited condensed consolidated financial statements and related disclosures. In May 2014, the 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 begun to evaluate each of the revenue streams under the new model and the pattern of recognition is not expected to change significantly. We have not yet selected a transition method and are evaluating the impact that ASU 2014-09 will have on our consolidated financial statements and related disclosures. In January 2016, the FASB issued Accounting Standards Update No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”), which requires, among other things, entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value disclosed for financial instruments measured at amortized cost on the balance sheet. ASU 2016-01 is effective for periods beginning after December 15, 2017; early adoption is not permitted. The guidance is not expected to have a material impact on our consolidated financial statements and related disclosures. In February 2016, the FASB issued Accounting Standards Update No. 2016-02, Leases (“ASU 2016-02”), which requires a lessee to record on the balance sheet a right-of-use asset with a corresponding lease liability created by lease terms of more than 12 months. Additional qualitative and quantitative disclosures will also be required. The guidance will become effective for periods beginning after December 15, 2018 and will be applied using a modified retrospective transition method. We are currently evaluating the impact that ASU 2016-02 will have on our consolidated financial statements and related disclosures. In August 2016, the FASB issued Accounting Standards Update No. 2016-15, Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”) . The guidance addresses eight classification issues related to the statement of cash flows, including debt prepayment or debt extinguishment costs and distributions received from equity-method investees. The guidance will become effective for periods beginning after December 15, 2017 and early adoption is permitted. ASU 2016-15 requires the use of a retrospective transition method to each period presented. If such retrospective transition is impracticable for certain issues, the adoption of ASU 2016-15 for the applicable issues may be applied prospectively as of the earliest date practicable. The guidance is not expected to have a material impact on our consolidated financial statements or related disclosures. In November 2016, the FASB issued Accounting Standards Update No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (“ASU 2016-18”), which requires companies to include cash and cash equivalents that have restrictions on withdrawal or use in total cash and cash equivalents on the statement of cash flows. ASU 2016-18 is effective for periods beginning after December 15, 2017 and early adoption is permitted. The guidance is not expected to have a material impact on our consolidated financial statements and related disclosures. In January 2017, the FASB issued Accounting Standards Update No. 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), which requires an entity to no longer perform a hypothetical purchase price allocation to measure goodwill impairment. Instead, impairment will be measured using the difference between the carrying amount and the fair value of the reporting unit. ASU 2017-04 is effective for periods beginning after December 15, 2019 and early adoption is permitted for measurement dates after January 1, 2017. The guidance is not expected to have a material impact on our consolidated financial statements and related disclosures. In February 2017, the FASB issued Accounting Standards Update No. 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets (“ASU 2017-05”), which clarifies the guidance in Subtopic 610-20 on accounting for derecognition of a nonfinancial asset. The update also defines in-substance nonfinancial assets and includes guidance on partial sales of nonfinancial assets. The amendments in ASU 2017-05 are to be applied at the same time that ASU 2014-09 is applied. We are currently evaluating the impact that ASU 2017-05 will have on our consolidated financial statements and related disclosures.
Reclassifications	(e) Reclassifications Certain prior year amounts have been reclassified to conform to the current year presentation, primarily as a result of adopting ASU 2016-09 in January 2017. See note 2(d), Summary of Significant Accounting Policies - Application of New Accounting Standards for more information.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Estimated Useful Life of Assets	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 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)	3 Months Ended
	Mar. 31, 2017
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 (dollars in thousands, except per share amounts): Three Months Ended March 31, 2017 2016 Numerator for basic and diluted earnings per common share: Net income (loss) $ 45,029 $ (101 ) Less: Net (income) loss attributable to noncontrolling interests (1,884 ) 147 Net income attributable to First Potomac Realty Trust 43,145 46 Less: Dividends on preferred shares — (2,248 ) Less: Issuance costs of redeemed preferred shares (1) — (1,904 ) Net income (loss) attributable to common shareholders 43,145 (4,106 ) Less: Allocation to participating securities (55 ) (73 ) Net income (loss) attributable to common shareholders $ 43,090 $ (4,179 ) Denominator for basic and diluted earnings per common share: Weighted average common shares outstanding - basic 57,635 57,542 Weighted average common shares outstanding - diluted 57,907 57,542 Basic and diluted earnings per common share: Net income (loss) attributable to common shareholders - basic $ 0.75 $ (0.07 ) Net income (loss) attributable to common shareholders - diluted $ 0.74 $ (0.07 ) (1) Represents the original issuance costs associated with the redemption of 2.2 million 7.750% Series A Cumulative Redeemable Perpetual Preferred Shares (the “7.750% Series A Preferred Shares”) during the three months ended March 31, 2016.
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 2017 2016 Stock option awards 879 1,018 Non-vested share awards 595 484 1,474 1,502

Rental Property (Tables)

Rental Property (Tables)	3 Months Ended
	Mar. 31, 2017
Real Estate [Abstract]
Summary of Rental Property	Rental property consists of the following (dollars in thousands): March 31, 2017 December 31, 2016 (1) Land and land improvements $ 269,920 $ 282,923 Buildings and improvements 766,394 824,867 Construction in progress 29,793 4,605 Tenant improvements 185,264 189,031 Furniture, fixtures and equipment 374 408 1,251,745 1,301,834 Less: accumulated depreciation (227,140 ) (242,562 ) $ 1,024,605 $ 1,059,272 (1) Excludes rental property totaling $13.2 million at December 31, 2016 related to One Fair Oaks, which was classified as held-for-sale at December 31, 2016 and was sold on

Investment in Affiliates (Table

Investment in Affiliates (Tables)	3 Months Ended
	Mar. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
mortgage debt of joint ventures [Table Text Block]	The following table provides a summary of the mortgage debt held by our unconsolidated joint ventures (dollars in thousands): FPO Ownership Effective Interest Rate Maturity Date Principal Balance at March 31, 2017 (1) Principal Balance at December 31, 2016 (1) Rivers Park I and II (2) 25% LIBOR + 1.90% (3) September 2017 $ — $ 28,000 1750 H Street, NW (4) 50% 3.92% August 2024 32,000 32,000 Prosperity Metro Plaza (5) 51% 3.91% December 2029 50,000 50,000 Weighted Average / Total 3.91% $ 82,000 $ 110,000 (1) Reflects the entire balance of the debt secured by the properties, not our portion of the debt. (2) The unconsolidated joint ventures that owned Rivers Park I and II sold these properties on March 7, 2017 . The unconsolidated joint venture partners used net proceeds from the sale to repay the mortgage debt encumbering the properties. At December 31, 2016, $2.8 million of the outstanding mortgage balance was recourse to us. (3) At March 31, 2017 , LIBOR was 0.98% . All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR. (4) The loan requires interest-only payments with a constant interest rate over the life of the loan. The loan is repayable in full, without penalty, on or after August 1, 2021. (5) The loan requires interest-only payments through December 2024, at which time the loan requires principal and interest payments through its maturity date. The loan is repayable in full, without penalty, on or after June 1, 2029.
Schedule of Equity Method Investments [Line Items]
Components of Investments in Affiliates	Our investment in affiliates consisted of the following (dollars in thousands): Reporting Segment Ownership Investment at March 31, 2017 Investment at December 31, 2016 Prosperity Metro Plaza Northern Virginia 51% $ 26,772 $ 26,414 1750 H Street, NW Washington, D.C. 50% 14,594 14,624 Aviation Business Park (1) Maryland 50% 482 5,941 Rivers Park I and II (1)(2) Maryland 25% 466 2,413 $ 42,314 $ 49,392 (1) The unconsolidated joint ventures that owned Aviation Business Park and Rivers Park I and II sold these properties on March 7, 2017 . Our investment in these joint ventures at March 31, 2017 is primarily comprised of our share of cash that has not yet been distributed. (2) Rivers Park I and Rivers Park II were owned through two separate unconsolidated 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): March 31, 2017 December 31, 2016 Assets: Rental property, net $ 144,065 $ 189,245 Cash and cash equivalents 11,122 9,887 Other assets 16,472 20,726 Total assets 171,659 219,858 Liabilities: Mortgage loans, net (1)(2) 81,416 109,372 Other liabilities 6,503 8,674 Total liabilities 87,919 118,046 Net assets $ 83,740 $ 101,812 (1) Of the total mortgage debt that encumbers our unconsolidated properties, none was recourse to us at March 31, 2017 and $2.8 million was recourse to us at December 31, 2016. (2) Mortgage loans, net at both March 31, 2017 and December 31, 2016 included $0.6 million of unamortized deferred financing costs
Results of Operations of Company's Unconsolidated Joint Ventures	The following table summarizes the results of operations of our unconsolidated joint ventures for the periods presented, of which, our proportionate share is reflected in “Equity in earnings of affiliates” in our consolidated statements of operations based on our varying ownership interests in the unconsolidated joint ventures (dollars in thousands): Three Months Ended March 31, 2017 2016 Total revenues $ 5,679 $ 6,290 Total operating expenses (1,937 ) (2,166 ) Net operating income 3,742 4,124 Depreciation and amortization (1,863 ) (1,966 ) Interest expense, net (962 ) (993 ) Gain on sale of rental property 10,324 — Net income $ 11,241 $ 1,165

Dispositions (Tables)

Dispositions (Tables)	3 Months Ended
	Mar. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations Square Feet Area [Table Text Block]	The following table is a summary of property dispositions whose operating results are included in continuing operations in our consolidated statements of operations for the periods presented (dollars in thousands): Property Reporting Disposition Date Property Type Square Feet Net Sale Proceeds Plaza 500 Northern Virginia 2/17/2017 Industrial 502,830 $ 72,499 One Fair Oaks (1) Northern Virginia 1/9/2017 Office 214,214 13,255 Storey Park (2) Washington, D.C. 7/25/2016 Land — 52,659 NOVA Non-Core Portfolio (3) Northern Virginia 3/25/2016 Various 945,745 90,501 (1) One Fair Oaks was classified as held-for-sale at December 31, 2016, and the building was vacant at the time of sale. (2) This development site could have supported up to 712,000 rentable square feet. (3) Consists of Van Buren Office Park, Herndon Corporate Center, Windsor at Battlefield, Reston Business Campus, Enterprise Center, Gateway Centre Manassas, Linden Business Center and Prosperity Business Center (collectively, the “NOVA Non-Core Portfolio”).
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 disposed or held-for-sale properties that are included in continuing operations for the periods presented (dollars in thousands): Three Months Ended March 31, 2017 2016 Revenues $ 804 $ 7,043 Property operating expenses (304 ) (2,823 ) Depreciation and amortization (289 ) (1,343 ) Interest expense — (184 ) Loss on debt extinguishment — (48 ) Income from operations of disposed property 211 2,645 Gain (loss) on sale of rental property (1) 42,799 (1,155 ) Net income from continuing operations $ 43,010 $ 1,490

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Schedule of Borrowings	Our debt consisted of the following (dollars in thousands): March 31, (1) December 31, 2016 (1) Mortgage loans, net, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030 (2)(3) $ 295,523 $ 296,212 Unsecured term loan, net, effective interest rates ranging from LIBOR plus 1.45% to LIBOR plus 1.80%, with staggered maturity dates ranging from December 2020 to December 2022 (2) 299,433 299,404 Unsecured revolving credit facility, net, effective interest rate of LIBOR plus 1.50%, maturing December 2019 (2) 48,758 141,555 Total $ 643,714 $ 737,171 (1) The balances include a total of $5.8 million and $6.2 million of unamortized deferred financing costs at March 31, 2017 and December 31, 2016 , respectively. (2) At March 31, 2017 , LIBOR was 0.98% . (3) The balances at March 31, 2017 and December 31, 2016 include two construction loans.
Summary of Company's Mortgage Debt	The following table provides a summary of our mortgage debt, which includes two construction loans (dollars in thousands): Encumbered Property Contractual Effective Maturity March 31, December 31, 2016 440 First Street, NW Construction Loan (1)(2) LIBOR + 2.50% LIBOR + 2.50% May 2017 $ 32,216 $ 32,216 Redland II and III 4.20 % 4.64 % November 2017 62,873 63,214 Northern Virginia Construction Loan (3) LIBOR + 1.85% LIBOR + 1.85% September 2019 34,584 34,584 840 First Street, NE 5.72 % 6.01 % July 2020 35,023 35,201 Battlefield Corporate Center 4.26 % 4.40 % November 2020 3,309 3,353 1211 Connecticut Avenue, NW 4.22 % 4.47 % July 2022 28,347 28,503 1401 K Street, NW 4.80 % 4.93 % June 2023 35,384 35,556 11 Dupont Circle, NW 4.05 % 4.22 % September 2030 66,780 66,780 Principal balance 4.45 % (4) 298,516 299,407 Unamortized deferred financing costs (2,993 ) (3,195 ) Total balance, net $ 295,523 $ 296,212 (1) At March 31, 2017 , LIBOR was 0.98% . (2) This construction loan is collateralized by 440 First Street, NW. In May 2016, we extended the maturity date by one year to May 30, 2017 . We can repay all or a portion of the construction loan, without penalty, at any time during the term of the loan. At March 31, 2017, per the terms of the loan agreement, 50% of the outstanding principal balance and all of the outstanding accrued interest were recourse to us. (3) This construction loan has a borrowing capacity of up to $43.7 million and is collateralized by the NOVA build-to-suit, which was placed in-service in the third quarter of 2016. We can repay all or a portion of the Northern Virginia Construction Loan, without penalty, at any time during the term of the loan. (4) Represents the weighted average interest rate on total mortgage debt.
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 and the unsecured revolving credit facility at March 31, 2017 and December 31, 2016 (dollars in thousands): Maturity Date Interest Rate (1) March 31, 2017 December 31, 2016 Unsecured Term Loan Tranche A December 2020 LIBOR + 1.45% $ 100,000 $ 100,000 Tranche B June 2021 LIBOR + 1.45% 100,000 100,000 Tranche C December 2022 LIBOR + 1.80% 100,000 100,000 Total 300,000 300,000 Unamortized deferred financing costs (567 ) (596 ) Total, net $ 299,433 $ 299,404 Unsecured Revolving Credit Facility Outstanding borrowings December 2019 (2) LIBOR + 1.50% (3) $ 51,000 $ 144,000 Unamortized deferred financing costs (2,242 ) (2,445 ) Total, net $ 48,758 $ 141,555 (1) Reflects the interest rate spreads at March 31, 2017. At March 31, 2017 , LIBOR was 0.98% . The interest rate spread is subject to change based on our maximum total indebtedness ratio. For more information, see note 7 ( d ), Debt – Financial Covenants .

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2017
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 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 $ 240,000 1.442 %

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2017
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 non-recurring and recurring basis as of March 31, 2017 and December 31, 2016 (dollars in thousands): Balance at Level 1 Level 2 Level 3 Recurring Measurements: Derivative instrument-swap assets $ 68 $ — $ 68 $ — Derivative instrument-swap liabilities 378 — 378 — Balance at Level 1 Level 2 Level 3 Recurring Measurements: Derivative instrument-swap liabilities $ 906 $ — $ 906 $ —
Fair Value of Debt Instruments	The carrying amount and estimated fair value of our debt instruments are as follows (dollars in thousands): March 31, 2017 December 31, 2016 Carrying (1) Fair Carrying (1) Fair Financial Liabilities: Mortgage debt $ 298,516 $ 296,923 $ 299,407 $ 300,927 Unsecured term loan 300,000 300,000 300,000 300,000 Unsecured revolving credit facility 51,000 51,000 144,000 144,000 Total $ 649,516 $ 647,923 $ 743,407 $ 744,927 (1) The debt balances exclude a combined total of $5.8 million and $6.2 million of unamortized deferred financing costs at March 31, 2017 and December 31, 2016, respectively.

Equity (Tables)

Equity (Tables)	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Company's Allocation between Non-controlling Interests	Our equity and redeemable noncontrolling interests are as follows (dollars in thousands): Total Equity Redeemable noncontrolling interests Balance at December 31, 2016 $ 436,383 $ 28,244 Net income 43,145 1,884 Changes in ownership, net 3,076 (2,382 ) Distributions to owners (5,815 ) (255 ) Other comprehensive income, net 571 25 Balance at March 31, 2017 $ 477,360 $ 27,516 First Potomac Realty Trust Non-redeemable noncontrolling interests (1) Total Equity Redeemable noncontrolling interests Balance at December 31, 2015 $ 624,528 $ 800 $ 625,328 $ 28,813 Net income (loss) 46 (14 ) 32 (133 ) Changes in ownership, net (53,145 ) — (53,145 ) (1,644 ) Distributions to owners (10,948 ) — (10,948 ) (393 ) Other comprehensive loss, net (826 ) — (826 ) (36 ) Balance at March 31, 2016 $ 559,655 $ 786 $ 560,441 $ 26,607
Company's Accumulated Other Comprehensive Loss	A summary of our accumulated other comprehensive loss is as follows (dollars in thousands): 2017 2016 Beginning balance at January 1, $ (844 ) $ (2,360 ) Net unrealized gain (loss) on derivative instruments 596 (862 ) Net (gain) loss attributable to noncontrolling interests (25 ) 36 Ending balance at March 31, $ (273 ) $ (3,186 )

Share-Based Payments (Tables)

Share-Based Payments (Tables)	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Nonvested Share Activity	A summary of our non-vested common share awards at March 31, 2017 is as follows: Non-vested Common Shares Weighted Average Grant Date Fair Value Non-vested at December 31, 2016 711,374 $ 9.85 Granted 418,286 8.54 Vested (80,179 ) 10.99 Expired (1,630 ) 12.38 Forfeited (991 ) 11.03 Non-vested at March 31, 2017 1,046,860 $ 9.23

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Summary of Segment Information	The results of operations of our four reporting segments for the three months ended March 31, 2017 and 2016 are as follows (dollars in thousands): Three Months Ended March 31, 2017 Washington, D.C. Maryland (1) Northern Virginia Southern Virginia Consolidated Number of buildings 6 34 12 19 71 Square feet 917,643 1,886,177 1,168,990 2,023,858 5,996,668 Total revenues $ 11,722 $ 11,235 $ 7,312 $ 7,554 $ 37,823 Property operating expense (3,139 ) (2,657 ) (1,956 ) (2,206 ) (9,958 ) Real estate taxes and insurance (2,292 ) (982 ) (741 ) (646 ) (4,661 ) Total property operating income $ 6,291 $ 7,596 $ 4,615 $ 4,702 23,204 Depreciation and amortization expense (14,566 ) General and administrative (4,497 ) Other income 40,888 Net income $ 45,029 Total assets (2) $ 443,800 $ 322,738 $ 260,564 $ 159,487 $ 1,203,997 Capital expenditures (3) $ 1,522 $ 2,350 $ 2,295 $ 606 $ 6,810 Three Months Ended March 31, 2016 Washington, D.C. Maryland Northern Virginia Southern Virginia Consolidated Number of buildings 6 34 14 19 73 Square feet 918,566 1,885,630 1,715,730 2,023,858 6,543,784 Total revenues $ 11,290 $ 11,587 $ 12,307 $ 7,513 $ 42,697 Property operating expense (2,968 ) (3,235 ) (3,320 ) (2,014 ) (11,537 ) Real estate taxes and insurance (2,372 ) (929 ) (1,297 ) (618 ) (5,216 ) Total property operating income $ 5,950 $ 7,423 $ 7,690 $ 4,881 25,944 Depreciation and amortization expense (15,006 ) General and administrative (4,578 ) Other expenses (6,461 ) Net loss $ (101 ) Total assets (2) $ 468,561 $ 338,553 $ 294,480 $ 166,015 $ 1,359,943 Capital expenditures (3) $ 4,910 $ 959 $ 15,757 $ 897 $ 22,643 (1) Redland I within our Maryland reporting segment was placed into redevelopment during March 2017. (2) 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 5 , Investment in Affiliates . Corporate assets not allocated to any of our reportable segments totaled $ 17.4 million and $ 92.3 million at March 31, 2017 and 2016 , respectively. (3) Capital expenditures for corporate assets not allocated to any of our reportable segments were immaterial for the three months ended March 31, 2017 and $ 0.1 million for the three months ended March 31, 2016 .

Description of Business - Addit

Description of Business - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2017ft²joint_venturepersonIntegersegment	Mar. 31, 2016ft²
Real Estate Properties [Line Items]
Number of Reportable Segments | segment	4
Interest in Operating Partnership	95.80%
Area of Real Estate Property	5,996,668	6,543,784
Unconsolidated joint ventures | joint_venture	2
Square Footage Of Land For Additional Development	400,000
Occupancy rate in the Company's consolidated properties	92.40%
Number of tenants representing current occupancy rate | person	372
Percent of Annualized Cash Rent	20.90%
Wholly-owned Properties [Member]
Real Estate Properties [Line Items]
Number of Reportable Segments | Integer	4
Area of Real Estate Property	6,000,000
Unconsolidated Properties [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property	400,000
Development and Redevelopment [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property	100,000
US Government [Member]
Real Estate Properties [Line Items]
Percent of Annualized Cash Rent	14.00%
Washington D C Reporting Segment [Member]
Real Estate Properties [Line Items]
Area Of Land Available For Development In Additional Building Space	0

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Estimated Useful Lives of Company's Assets, by Class (Detail)	3 Months Ended
	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Useful life	39 years
Lease related intangible assets	the term of the lease
Tenant improvements	Shorter of the useful life of the asset or the term of the related lease
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 [Member] | Building improvements
Property, Plant and Equipment [Line Items]
Useful life	20 years
Maximum [Member] | Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Useful life	15 years

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Loans and Leases Receivable Disclosure [Line Items]
Allowance for credit losses for its notes receivable		$ 0
Nine Hundered And Fifty Street Nw [Member]
Loans and Leases Receivable Disclosure [Line Items]
Principal payments from note receivable	$ 34,000,000

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
	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016
Numerator for basic and diluted earnings per common share:
Income from continuing operations	$ 45,029			$ (101)
Net income (loss)	45,029			(101)
Less: Net (income) loss attributable to noncontrolling interests	(1,884)			147
Net income attributable to First Potomac Realty Trust	43,145			46
Less: Dividends on preferred shares	0			(2,248)
Less: Issuance costs of redeemed preferred shares	0			1,904	[1]
Net income (loss) attributable to common shareholders	43,145			(4,106)
Less: Allocation to participating securities	(55)			(73)
Net income (loss) attributable to common shareholders	$ 43,090			$ (4,179)
Denominator for basic and diluted earnings per common share:
Basic	57,635			57,542
Weighted Average Number of Shares Outstanding, Diluted	57,907			57,542
Basic and diluted earnings per common share:
Loss from continuing operations	$ 0.75			$ (0.07)
Net income (loss) attributable to common shareholders - dilutive	$ 0.74
Preferred Stock, Dividend Rate, Percentage				7.75%
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Stock Redeemed or Called During Period, Shares	2,200	600	3,600	2,200
[1]	Represents the original issuance costs associated with the redemption of 2.2 million 7.750% Series A Cumulative Redeemable Perpetual Preferred Shares (the “7.750% Series A Preferred Shares”) during the three months ended March 31, 2016.

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
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, Amount	1,474	1,502
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	879	1,018
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	595	484

Rental Property - Summary of Re

Rental Property - Summary of Rental Property (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Rental property, net		$ 1,024,605	$ 1,059,272
Rental Property [Member]
Property, Plant and Equipment [Line Items]
Land and land improvements		269,920	282,923
Buildings and improvements		766,394	824,867
Construction in process		29,793	4,605
Tenant Improvements		185,264	189,031
Furniture, fixtures and equipment		374	408
Rental property, gross		1,251,745	1,301,834
Less: accumulated depreciation		(227,140)	(242,562)
Real Estate Investment Property, Net		$ 1,024,605	$ 1,059,272
One Fair Oaks [Member]
Property, Plant and Equipment [Line Items]
Disposition Date Of Property	[1]	Jan. 9, 2017
One Fair Oaks [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Property, Plant and Equipment [Line Items]
Rental property, net		$ 13,200
NOVA Non-Core Portfolio [Member]
Property, Plant and Equipment [Line Items]
Disposition Date Of Property	[2]	Mar. 25, 2016
[1]	(1) One Fair Oaks was classified as held-for-sale at December 31, 2016, and the building was vacant at the time of sale.
[2]	Consists of Van Buren Office Park, Herndon Corporate Center, Windsor at Battlefield, Reston Business Campus, Enterprise Center, Gateway Centre Manassas, Linden Business Center and Prosperity Business Center (collectively, the “NOVA Non-Core Portfolio”).

Rental Property - Additional In

Rental Property - Additional Information (Detail) $ in Thousands		Jul. 25, 2016	Mar. 31, 2017USD ($)ft²		Dec. 31, 2016USD ($)ft²		Mar. 31, 2016ft²
Segment Reporting Information [Line Items]
Square Footage Of Land For Additional Development			400,000
Area of Real Estate Property			5,996,668				6,543,784
Placed in-service redevelopment efforts			0
One Fair Oaks [Member]
Segment Reporting Information [Line Items]
Proceeds from sale of properties | $	[1]		$ 13,255
Area of Real Estate Property	[1]		214,214,000
Disposition Date Of Property	[1]		Jan. 9, 2017
Storey Park [Member]
Segment Reporting Information [Line Items]
Proceeds from sale of properties | $	[2]		$ 52,659
Area of Real Estate Property			0		712,000	[2]
Disposition Date Of Property		Jul. 25, 2016	Jul. 25, 2016	[2]
Ownership Interest			97.00%
Five Hundred Forty Gaither Road Redland First [Member]
Segment Reporting Information [Line Items]
Area of Real Estate Property			133,895
Projected incremental investment in development project | $			$ 23,600
Original cost basis of the property | $			$ 23,000
Washington D C Reporting Segment [Member]
Segment Reporting Information [Line Items]
Area Of Land Available For Development In Additional Building Space			0
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			200,000
Southern Virginia [Member]
Segment Reporting Information [Line Items]
Area Of Land Available For Development In Additional Building Space			100,000
Rental Property [Member]
Segment Reporting Information [Line Items]
Original cost basis of the property | $			$ 766,394		$ 824,867
[1]	(1) One Fair Oaks was classified as held-for-sale at December 31, 2016, and the building was vacant at the time of sale.
[2]	) This development site could have supported up to 712,000 rentable square feet.

Notes Receivable - Additional I

Notes Receivable - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)ft²shares	Dec. 31, 2016USD ($)shares	Jul. 06, 2016shares	Mar. 31, 2016ft²	Dec. 31, 2015shares
Receivables with Imputed Interest [Line Items]
Area of Real Estate Property | ft²	5,996,668			6,543,784
Unsecured revolving credit facility, net | $	$ 48,758	$ 141,555
Series A Preferred Shares, shares outstanding | shares	600,000	6,400,000
America Square [Member]
Receivables with Imputed Interest [Line Items]
Maturity date of loan	Apr. 1, 2017
Nine Hundered And Fifty Street Nw [Member]
Receivables with Imputed Interest [Line Items]
Area of Real Estate Property | ft²	287,000
Recognition of Deferred Revenue | $		$ 200
Nine Hundered And Fifty Street Nw [Member] | Minimum [Member]
Receivables with Imputed Interest [Line Items]
Fixed interest rate on loan	9.75%
Series A Preferred Stock [Member]
Receivables with Imputed Interest [Line Items]
Series A Preferred Shares, shares outstanding | shares			600,000		6,400,000

Investment in Affiliates - Comp

Investment in Affiliates - Components of Investments in Affiliates (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016
Schedule of Equity Method Investments [Line Items]
Company Investment		$ 42,314	$ 49,392
Prosperity Metro Plaza [Member]
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Northern Virginia
Ownership Interest	[1]	51.00%
Company Investment		$ 26,772	26,414
One Thousand Seven Hundred Fifty H Street Nw [Member]
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Washington, D.C.
Ownership Interest	[2]	50.00%
Company Investment		$ 14,594	14,624
Aviation Business Park [Member]
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Maryland
Ownership Interest		50.00%
Company Investment		$ 482	5,941
Rivers Park One And Two [Member]
Schedule of Equity Method Investments [Line Items]
Reporting Segment		Maryland
Ownership Interest		25.00%
Company Investment		$ 466	$ 2,413
Mortgages [Member] | Rivers Park One And Two [Member]
Schedule of Equity Method Investments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted				$ 2,800
[1]	The loan requires interest-only payments through December 2024, at which time the loan requires principal and interest payments through its maturity date. The loan is repayable in full, without penalty, on or after June 1, 2029.
[2]	The loan requires interest-only payments with a constant interest rate over the life of the loan. The loan is repayable in full, without penalty, on or after August 1, 2021.

Investment in Affiliates - Net

Investment in Affiliates - Net Assets of Company's Unconsolidated Joint Ventures (Detail) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Assets:
Rental property, net		$ 1,024,605	$ 1,059,272
Cash and cash equivalents		13,269	14,144		$ 15,149	$ 13,527
Total assets		1,203,997	1,260,247		$ 1,359,943
Liabilities:
Total liabilities		699,121	795,620
Recourse mortgage debt		643,714	737,171
Unconsolidated Joint Ventures [Member]
Assets:
Rental property, net		144,065	189,245
Cash and cash equivalents		11,122	9,887
Other assets		16,472	20,726
Total assets		171,659	219,858
Liabilities:
Mortgage loans	[1],[2]	81,416	109,372
Other liabilities		6,503	8,674
Total liabilities		87,919	118,046
Net assets		83,740	101,812
Debt Issuance Costs, Line of Credit Arrangements, Net			600
Unconsolidated Entities
Liabilities:
Recourse mortgage debt		0
Mortgages [Member]
Liabilities:
Recourse mortgage debt	[3]	$ 82,000	$ 110,000
Mortgages [Member] | Rivers Park One And Two [Member]
Liabilities:
Guarantor Obligations, Maximum Exposure, Undiscounted				$ 2,800
[1]	(2) Mortgage loans, net at both March 31, 2017 and December 31, 2016 included $0.6 million of unamortized deferred financing costs
[2]	Of the total mortgage debt that encumbers our unconsolidated properties, none was recourse to us at March 31, 2017 and $2.8 million was recourse to us at December 31, 2016.
[3]	Reflects the entire balance of the debt secured by the properties, not our portion of the debt.

Investment in Affiliates - Addi

Investment in Affiliates - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)ft²	Mar. 31, 2016USD ($)ft²
Schedule of Equity Method Investments [Line Items]
Fees from joint ventures	$ 0.1	$ 0.2
Area of Real Estate Property | ft²	5,996,668	6,543,784
Rivers Park One And Two [Member]
Schedule of Equity Method Investments [Line Items]
Disposition Date Of Property	Mar. 7, 2017
Area of Real Estate Property | ft²	307,984
Proceeds from sale of properties	$ 18.4
Mortgage loans, net, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)(3)	7
Proceeds From Sale Of Properties Gross	$ 19
Aviation Business Park [Member]
Schedule of Equity Method Investments [Line Items]
Area of Real Estate Property | ft²	120,284

Investment in Affiliates - Resu

Investment in Affiliates - Results of Operations of Company's Unconsolidated Joint Ventures (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Schedule of Equity Method Investments [Line Items]
Total revenues	$ 37,823	$ 42,697
Total operating expenses	(33,682)	(36,337)
Operating income	4,141	6,360
Depreciation and amortization	(14,566)	(15,006)
Interest expense, net		(6,461)
(Gain) loss on sale of rental property	42,799	(1,155)
Net income	4,223	555
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Total revenues	5,679	6,290
Total operating expenses	(1,937)	(2,166)
Operating income	3,742	4,124
Depreciation and amortization	(1,863)	(1,966)
Interest expense, net	(962)	(993)
(Gain) loss on sale of rental property	10,324	0
Net income	11,241	1,165
Five Hundred Forty Gaither Road Redland First [Member]
Schedule of Equity Method Investments [Line Items]
Investment Building and Building Improvements	23,000
Aviation Business Park [Member] | Rivers Park One And Two [Member]
Schedule of Equity Method Investments [Line Items]
Total revenues	1,113	1,631
Total operating expenses	(275)	(641)
Operating income	838	990
Depreciation and amortization	(420)	(643)
Interest expense, net	(146)	(175)
Income (Loss) before Gain (Loss) on Sale of Properties	272	172
(Gain) loss on sale of rental property	10,324	0
Net income	$ 10,596	$ 172

Investment in Affiliates Invest

Investment in Affiliates Investment in Affiliates - Mortgage Debt Held by Unconsolidated Joint Ventures (Details) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016
Schedule of Equity Method Investments [Line Items]
Total long term debt		$ 643,714	$ 737,171
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Debt Issuance Costs, Line of Credit Arrangements, Net			600
Rivers Park One And Two [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Interest		25.00%
One Thousand Seven Hundred Fifty H Street Nw [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Interest	[1]	50.00%
Prosperity Metro Plaza [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Interest	[2]	51.00%
Mortgages [Member]
Schedule of Equity Method Investments [Line Items]
Total long term debt	[3]	$ 82,000	110,000
Effective Interest Rate		3.91%
Mortgages [Member] | Rivers Park One And Two [Member]
Schedule of Equity Method Investments [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted				$ 2,800
Mortgage and Other Indebtedness	[3]	$ 0	28,000
Mortgages [Member] | One Thousand Seven Hundred Fifty H Street Nw [Member]
Schedule of Equity Method Investments [Line Items]
Mortgage and Other Indebtedness	[1],[3]	$ 32,000	32,000
Effective Interest Rate	[1]	3.92%
Mortgages [Member] | Prosperity Metro Plaza [Member]
Schedule of Equity Method Investments [Line Items]
Mortgage and Other Indebtedness	[2],[3]	$ 50,000	$ 50,000
Effective Interest Rate	[2]	3.91%
London Interbank Offered Rate (LIBOR) [Member]
Schedule of Equity Method Investments [Line Items]
Effective Interest Rate		0.98%
London Interbank Offered Rate (LIBOR) [Member] | Mortgages [Member] | Rivers Park One And Two [Member]
Schedule of Equity Method Investments [Line Items]
Interest Rate	[4]	LIBOR
Derivative, Basis Spread on Variable Rate		1.90%
[1]	The loan requires interest-only payments with a constant interest rate over the life of the loan. The loan is repayable in full, without penalty, on or after August 1, 2021.
[2]	The loan requires interest-only payments through December 2024, at which time the loan requires principal and interest payments through its maturity date. The loan is repayable in full, without penalty, on or after June 1, 2029.
[3]	Reflects the entire balance of the debt secured by the properties, not our portion of the debt.
[4]	At March 31, 2017, LIBOR was 0.98%. All references to LIBOR in the condensed consolidated financial statements refer to one-month LIBOR.

Dispositions - Additional Infor

Dispositions - Additional Information (Detail) - USD ($) $ in Thousands		Jul. 25, 2016	Mar. 31, 2017		Mar. 31, 2016	Dec. 31, 2016
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
(Gain) loss on sale of rental property			$ 42,799		$ (1,155)
Assets			$ 1,203,997		$ 1,359,943	$ 1,260,247
FairOaks [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Disposition Date Of Property			Jan. 9, 2017
Buildings and improvements						17,600
Land and land improvements						1,600
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment						$ 6,000
NOVA Non-Core Portfolio [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Disposition Date Of Property	[1]		Mar. 25, 2016
Proceeds from sale of properties	[1]		$ 90,501
Storey Park [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Disposition Date Of Property		Jul. 25, 2016	Jul. 25, 2016	[2]
Proceeds from sale of properties	[2]		$ 52,659
Plaza Five Hundred [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Disposition Date Of Property			Feb. 17, 2017
Proceeds from sale of properties			$ 72,499
(Gain) loss on sale of rental property			$ 42,700
[1]	Consists of Van Buren Office Park, Herndon Corporate Center, Windsor at Battlefield, Reston Business Campus, Enterprise Center, Gateway Centre Manassas, Linden Business Center and Prosperity Business Center (collectively, the “NOVA Non-Core Portfolio”).
[2]	) This development site could have supported up to 712,000 rentable square feet.

Dispositions Dispositions - Dis

Dispositions Dispositions - Disposed or Held-for-Sale Properties within Continuing Operations (Details) $ in Thousands		Jul. 25, 2016	Mar. 31, 2017USD ($)ft²		Mar. 31, 2016USD ($)ft²	Dec. 31, 2016ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Real Estate Property | ft²			5,996,668		6,543,784
Gain (Loss) on Extinguishment of Debt			$ 0		$ (48)
(Gain) loss on sale of rental property			$ 42,799		(1,155)
Storey Park [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reporting Segment	[1]		Washington, D.C.
Disposition Date Of Property		Jul. 25, 2016	Jul. 25, 2016	[1]
Property Type	[1]		Land
Area of Real Estate Property | ft²			0			712,000	[1]
Proceeds from sale of properties	[1]		$ 52,659
NOVA Non-Core Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reporting Segment	[2]		Northern Virginia
Disposition Date Of Property	[2]		Mar. 25, 2016
Property Type	[2]		Various
Area of Real Estate Property | ft²	[2]					945,745
Proceeds from sale of properties	[2]		$ 90,501
Plaza Five Hundred [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reporting Segment	[1]		Northern Virginia
Disposition Date Of Property			Feb. 17, 2017
Property Type			Industrial
Area of Real Estate Property | ft²			502,830,000
Proceeds from sale of properties			$ 72,499
(Gain) loss on sale of rental property			$ 42,700
One Fair Oaks [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Reporting Segment	[1]		Northern Virginia
Disposition Date Of Property	[3]		Jan. 9, 2017
Property Type	[3]		Office
Area of Real Estate Property | ft²	[3]		214,214,000
Proceeds from sale of properties	[3]		$ 13,255
(Gain) loss on sale of rental property			100
Disposed or held-for-sale properties in continuing operations | Continuing Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues			804		7,043
Property operating expenses			(304)		(2,823)
Depreciation and amortization			(289)		(1,343)
Interest Expense			0		(184)
Gain (Loss) on Extinguishment of Debt			0		(48)
Operating Income (Loss) from Continuing Operations Attributable to Parent			211		2,645
(Gain) loss on sale of rental property			42,799		(1,155)
Net income from continuing operations			43,010		$ 1,490
Disposed or held-for-sale properties in continuing operations | NOVA Non-Core Portfolio [Member] | Continuing Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of rental property			$ 1,200
[1]	) This development site could have supported up to 712,000 rentable square feet.
[2]	Consists of Van Buren Office Park, Herndon Corporate Center, Windsor at Battlefield, Reston Business Campus, Enterprise Center, Gateway Centre Manassas, Linden Business Center and Prosperity Business Center (collectively, the “NOVA Non-Core Portfolio”).
[3]	(1) One Fair Oaks was classified as held-for-sale at December 31, 2016, and the building was vacant at the time of sale.

Dispositions - Summary of Compl

Dispositions - Summary of Completed Property Dispositions (Detail) - ft²	Mar. 31, 2017	Mar. 31, 2016
Schedule Of Discontinued Operations [Line Items]
Area of Real Estate Property	5,996,668	6,543,784

Debt - Schedule of Borrowings (

Debt - Schedule of Borrowings (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Repayments of debt		$ 97,891	$ 93,119
Debt Issuance Costs, Net		5,800		$ 6,200
Mortgage loans, net		295,523		296,212
Unsecured Debt		299,433		299,404
Unsecured revolving credit facility, net		48,758		141,555
Total long term debt		$ 643,714		737,171
Mortgage Loan [Member]
Debt Instrument [Line Items]
Debt instrument maturity date		September 2,030
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 Debt		$ 299,433		299,404
Debt instrument maturity date		December 2020 to December 2022
Debt Instrument Basis Spread On Variable Rate Minimum		1.45%
Debt Instrument Basis Spread On Variable Rate Maximum		1.80%
Unsecured revolving credit facility
Debt Instrument [Line Items]
Repayments of debt		$ 97,000
Unsecured revolving credit facility, net, effective interest rate of LIBOR plus 1.50%, maturing December 2019(2)		$ 51,000		$ 144,000
Effective interest rate on the notes	[1]	1.50%
Debt instrument maturity date	[2]	December 2,019
Minimum [Member] | Mortgage Loan [Member]
Debt Instrument [Line Items]
Effective interest rate on the notes		4.22%
Maximum [Member] | Mortgage Loan [Member]
Debt Instrument [Line Items]
Effective interest rate on the notes		6.01%
NOVA Non-Core Portfolio [Member]
Debt Instrument [Line Items]
Disposition Date Of Property	[3]	Mar. 25, 2016
[1]	(3) This construction loan has a borrowing capacity of up to $43.7 million and is collateralized by the NOVA build-to-suit, which was placed in-service in the third quarter of 2016. We can repay all or a portion of the Northern Virginia Construction Loan, without penalty, at any time during the term of the loan.
[2]	This construction loan is collateralized by 440 First Street, NW. In May 2016, we extended the maturity date by one year to May 30, 2017. We can repay all or a portion of the construction loan, without penalty, at any time during the term of the loan. At March 31, 2017, per the terms of the loan agreement, 50% of the outstanding principal balance and all of the outstanding accrued interest were recourse to us.
[3]	Consists of Van Buren Office Park, Herndon Corporate Center, Windsor at Battlefield, Reston Business Campus, Enterprise Center, Gateway Centre Manassas, Linden Business Center and Prosperity Business Center (collectively, the “NOVA Non-Core Portfolio”).

Debt - Summary of Company's Mor

Debt - Summary of Company's Mortgage Debt (Detail) - USD ($) $ in Thousands		Jul. 25, 2016	Mar. 31, 2017		Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Line of Credit Facility, Interest Rate During Period					2.30%	1.90%
Line of Credit Facility, Increase (Decrease), Net			$ 4,000
Repayments of debt			$ 97,891			$ 93,119
Debt, Weighted Average Interest Rate	[1]		4.45%
LIBOR plus interest rate			1.50%
440 First Street, NW Construction Loan
Debt Instrument [Line Items]
Contractual Interest Rate			2.50%
Contractual Interest Rate	[2]		LIBOR + 2.50%
Maturity Date			May 30, 2017
Percentage Of Principal Loan Amount And Unpaid Accrued Interest Recourse			50.00%
Total Mortgage Debt	[3]		$ 32,216				$ 32,216
Storey Park [Member]
Debt Instrument [Line Items]
Contractual Interest Rate			2.50%
Redland Corporate Center Buildings II & III
Debt Instrument [Line Items]
Contractual Interest Rate			0.00%
Effective Interest Rate			0.00%
Maturity Date			November 2,017
Total Mortgage Debt			$ 62,873				63,214
Effective Interest Rate			0.00%
840 First Street, NE
Debt Instrument [Line Items]
Contractual Interest Rate			0.00%
Effective Interest Rate			0.00%
Maturity Date			July 2,020
Total Mortgage Debt			$ 35,023				35,201
Effective Interest Rate			0.00%
Battlefield Corporate Center
Debt Instrument [Line Items]
Contractual Interest Rate			0.00%
Effective Interest Rate			0.00%
Maturity Date			November 2,020
Total Mortgage Debt			$ 3,309				3,353
Effective Interest Rate			0.00%
One thousand two hundred eleven Connecticut Avenue NW. [Member]
Debt Instrument [Line Items]
Contractual Interest Rate			0.00%
Effective Interest Rate			0.00%
Maturity Date			July 2,022
Total Mortgage Debt			$ 28,347				28,503
Effective Interest Rate			0.00%
1401 K Street, NW
Debt Instrument [Line Items]
Contractual Interest Rate			0.00%
Effective Interest Rate			0.00%
Maturity Date			June 1, 2023
Total Mortgage Debt			$ 35,384				35,556
Effective Interest Rate			0.00%
Eleven Dupont Circle [Member]
Debt Instrument [Line Items]
Contractual Interest Rate			0.00%
Effective Interest Rate			0.00%
Maturity Date			September 2,030
Total Mortgage Debt			$ 66,780				66,780
Effective Interest Rate			0.00%
Northern Virginia Development Project [Member]
Debt Instrument [Line Items]
Contractual Interest Rate			1.85%
Contractual Interest Rate	[2]		LIBOR + 1.85%
Maturity Date			September 2,019
Total Mortgage Debt	[4]		$ 34,584				34,584
Northern Virginia Development Project [Member]
Debt Instrument [Line Items]
Borrowing capacity of a construction loan							43,700
Storey Park [Member]
Debt Instrument [Line Items]
Ownership Interest			97.00%
Disposition Date Of Property		Jul. 25, 2016	Jul. 25, 2016	[5]
Continuing Operations
Debt Instrument [Line Items]
Total Mortgage Debt			$ 298,516				299,407
Unamortized fair value adjustments			(2,993)				(3,195)
Carrying amount of mortgages			$ 295,523				$ 296,212
Mortgages [Member]
Debt Instrument [Line Items]
Effective Interest Rate			3.91%
Effective Interest Rate			3.91%
[1]	Represents the weighted average interest rate
[2]	At March 31, 2017, LIBOR was 0.98%.
[3]	This construction loan is collateralized by 440 First Street, NW. In May 2016, we extended the maturity date by one year to May 30, 2017. We can repay all or a portion of the construction loan, without penalty, at any time during the term of the loan. At March 31, 2017, per the terms of the loan agreement, 50% of the outstanding principal balance and all of the outstanding accrued interest were recourse to us.
[4]	(3) This construction loan has a borrowing capacity of up to $43.7 million and is collateralized by the NOVA build-to-suit, which was placed in-service in the third quarter of 2016. We can repay all or a portion of the Northern Virginia Construction Loan, without penalty, at any time during the term of the loan.
[5]	) This development site could have supported up to 712,000 rentable square feet.

Debt - Additional Information (

Debt - Additional Information (Detail) $ in Thousands

Jul. 25, 2016

Mar. 31, 2017USD ($)TranchesRateshares

Sep. 30, 2016

Mar. 31, 2016USD ($)

Apr. 27, 2017USD ($)

Mar. 31, 2017Interest_Rate_Swaps

Mar. 31, 2017USD ($)

Mar. 31, 2017

Mar. 31, 2017Integer

Mar. 31, 2017Rate

Dec. 31, 2016USD ($)shares

Jul. 06, 2016shares

Dec. 31, 2015shares

Debt Instrument [Line Items]

Basis spread over variable rate | Rate

1.50%

Recourse mortgage debt

$ 643,714

$ 737,171

Repayments of debt

$ 97,891

$ 93,119

Line of Credit Facility, Interest Rate During Period

2.30%

1.90%

Maximum outstanding borrowings

$ 144,000

$ 193,000

Annual commitment fee

0.15%

Number of interest rate swap agreements

9

9

Fixed effective interest rate

1.40%

Line of Credit Facility, Increase (Decrease), Net

$ 4,000

Series A Preferred Shares, shares outstanding | shares

600,000

6,400,000

Unsecured Debt

299,433

$ 299,404

Unsecured Debt [Member]

Debt Instrument [Line Items]

Outstanding balance of three tranches

300,000

300,000

Unsecured term loan

Debt Instrument [Line Items]

Number of tranches | Tranches

3

Unsecured Debt

300,000

Unsecured revolving credit facility

Debt Instrument [Line Items]

Debt Instrument, Interest Rate, Stated Percentage

2.50%

Unsecured revolving credit facility, net, effective interest rate of LIBOR plus 1.50%, maturing December 2019(2)

51,000

144,000

Repayments of debt

$ 97,000

Tranche A

Debt Instrument [Line Items]

Basis spread over variable rate

1.45%

Debt Instrument, Interest Rate, Increase (Decrease)

0.00%

Tranche A | Unsecured Debt [Member]

Debt Instrument [Line Items]

Outstanding balance of three tranches

100,000

100,000

Northern Virginia Development Project [Member]

Debt Instrument [Line Items]

Mortgage loans, net, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)(3)

[1]

34,584

34,584

Debt Instrument, Interest Rate, Stated Percentage

1.85%

440 First Street, NW Construction Loan

Debt Instrument [Line Items]

Mortgage loans, net, effective interest rates ranging from 4.22% to 6.01%, maturing at various dates through September 2030(2)(3)

[2]

32,216

32,216

Debt Instrument, Interest Rate, Stated Percentage

2.50%

Percentage of outstanding principal

50.00%

Tranche C

Debt Instrument [Line Items]

Basis spread over variable rate

1.80%

Debt Instrument, Interest Rate, Increase (Decrease)

0.00%

Tranche C | Unsecured Debt [Member]

Debt Instrument [Line Items]

Outstanding balance of three tranches

100,000

100,000

Interest Rate Swap

Debt Instrument [Line Items]

Fixed effective interest rate

1.44%

0.00%

Amount on variable rate debt

$ 240,000

Unused lines of credit

Debt Instrument [Line Items]

Weighted average borrowings outstanding on unsecured revolving credit facility

$ 96,600

$ 169,500

NOVA Non-Core Portfolio

Debt Instrument [Line Items]

Disposition Date Of Property

[3]

Mar. 25, 2016

Proceeds from sale of properties

[3]

$ 90,501

Northern Virginia Development Project [Member]

Debt Instrument [Line Items]

Borrowing capacity of a construction loan

$ 43,700

Nine Hundered And Fifty Street Nw [Member]

Debt Instrument [Line Items]

Principal payments from note receivable

$ 34,000

Storey Park [Member]

Debt Instrument [Line Items]

Disposition Date Of Property

Jul. 25, 2016

Jul. 25, 2016

[4]

Proceeds from sale of properties

[4]

$ 52,659

Subsequent Event [Member]

Debt Instrument [Line Items]

Available capacity on the unsecured revolving credit facility

$ 172,000

Subsequent Event [Member] | Unsecured revolving credit facility

Debt Instrument [Line Items]

Unsecured revolving credit facility, net, effective interest rate of LIBOR plus 1.50%, maturing December 2019(2)

$ 51,000

Series A Preferred Stock [Member]

Debt Instrument [Line Items]

Series A Preferred Shares, shares outstanding | shares

600,000

6,400,000

Maximum [Member]

Debt Instrument [Line Items]

Annual commitment fee

0.25%

[1]

(3) This construction loan has a borrowing capacity of up to $43.7 million and is collateralized by the NOVA build-to-suit, which was placed in-service in the third quarter of 2016. We can repay all or a portion of the Northern Virginia Construction Loan, without penalty, at any time during the term of the loan.

[2]

This construction loan is collateralized by 440 First Street, NW. In May 2016, we extended the maturity date by one year to May 30, 2017. We can repay all or a portion of the construction loan, without penalty, at any time during the term of the loan. At March 31, 2017, per the terms of the loan agreement, 50% of the outstanding principal balance and all of the outstanding accrued interest were recourse to us.

[3]

Consists of Van Buren Office Park, Herndon Corporate Center, Windsor at Battlefield, Reston Business Campus, Enterprise Center, Gateway Centre Manassas, Linden Business Center and Prosperity Business Center (collectively, the “NOVA Non-Core Portfolio”).

[4]

) This development site could have supported up to 712,000 rentable square feet.

Debt - Unsecured Term Loan (Det

Debt - Unsecured Term Loan (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016	Apr. 27, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Repayments of debt		$ 97,891		$ 93,119
Line of Credit Facility, Increase (Decrease), Net		4,000
Debt Issuance Costs, Net		5,800				$ 6,200
Deferred costs, net		$ (41,603)				(42,712)
Basis spread over variable rate		1.50%
Unsecured Debt		$ 299,433				299,404
Tranche A
Debt Instrument [Line Items]
Maturity Date		December 2,020
Basis spread over variable rate		1.45%
Tranche B
Debt Instrument [Line Items]
Maturity Date		June 2,021
Basis spread over variable rate		1.45%
Tranche C
Debt Instrument [Line Items]
Maturity Date		December 2,022
Basis spread over variable rate		1.80%
Unsecured revolving credit facility
Debt Instrument [Line Items]
Repayments of debt		$ 97,000
Maturity Date	[1]	December 2,019
Unsecured revolving credit facility, net, effective interest rate of LIBOR plus 1.50%, maturing December 2019(2)		$ 51,000				144,000
Unsecured Debt [Member]
Debt Instrument [Line Items]
Carrying value of the debt instruments		300,000				300,000
Deferred costs, net		(567)				(596)
Unsecured Debt [Member] | Tranche A
Debt Instrument [Line Items]
Carrying value of the debt instruments		100,000				100,000
Unsecured Debt [Member] | Tranche B
Debt Instrument [Line Items]
Carrying value of the debt instruments		100,000				100,000
Unsecured Debt [Member] | Tranche C
Debt Instrument [Line Items]
Carrying value of the debt instruments		100,000				100,000
Continuing Operations
Debt Instrument [Line Items]
Unamortized fair value adjustments		(2,993)				(3,195)
Continuing Operations | Unsecured revolving credit facility
Debt Instrument [Line Items]
Unamortized fair value adjustments		(2,242)				$ (2,445)
One Fair Oaks [Member] | Unsecured revolving credit facility
Debt Instrument [Line Items]
Repayments of debt		14,000
Plaza Five Hundred [Member] | Unsecured revolving credit facility
Debt Instrument [Line Items]
Repayments of debt		70,000
Rivers Park One And Two [Member] | Unsecured revolving credit facility
Debt Instrument [Line Items]
Repayments of debt		$ 13,000
Rivers Park One And Two [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Repayments of debt			$ 7,000
Subsequent Event [Member] | Unsecured revolving credit facility
Debt Instrument [Line Items]
Unsecured revolving credit facility, net, effective interest rate of LIBOR plus 1.50%, maturing December 2019(2)					$ 51,000
[1]	This construction loan is collateralized by 440 First Street, NW. In May 2016, we extended the maturity date by one year to May 30, 2017. We can repay all or a portion of the construction loan, without penalty, at any time during the term of the loan. At March 31, 2017, per the terms of the loan agreement, 50% of the outstanding principal balance and all of the outstanding accrued interest were recourse to us.

Derivative Instruments - Summar

Derivative Instruments - Summary of Interest Rate Swap Agreements (Detail) - 3 months ended Mar. 31, 2017 - USD ($) $ in Thousands	Total	Total	Total
Derivatives, Fair Value [Line Items]
Fixed LIBOR Interest Rate		1.40%
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Notional Amount	$ 240,000
Fixed LIBOR Interest Rate		1.44%	0.00%
Interest Rate Swap One
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2016
Interest Rate Swap Two
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2016
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			0.00%
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			0.00%
Interest Rate Swap Five
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2017
Notional Amount	$ 25,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate			0.00%
Interest Rate Swap Six
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2017
Notional Amount	$ 12,500
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate			0.00%
Interest Rate Swap Seven [Member]
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2017
Notional Amount	$ 50,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate			0.00%
Interest Rate Swap Eight [Member]
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2018
Notional Amount	$ 12,500
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate			0.00%
Interest Rate Swap Nine [Member]
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2018
Notional Amount	$ 30,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate			0.00%
Interest Rate Swap Ten [Member]
Derivatives, Fair Value [Line Items]
Maturity Date	Jul. 31, 2018
Notional Amount	$ 25,000
Interest Rate Contractual Component	LIBOR
Fixed LIBOR Interest Rate			0.00%
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			0.00%

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)Interest_Rate_Swaps	Mar. 31, 2016USD ($)	Mar. 31, 2017USD ($)	Mar. 31, 2017	Mar. 31, 2017Integer	Mar. 31, 2017Rate
Derivatives, Fair Value [Line Items]
Number of interest rate swap agreements	9				9
Fixed effective interest rate				1.40%
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Fixed effective interest rate				1.44%		0.00%
Amount on variable rate debt			$ 240,000
Interest Rate Swap | Interest Expense
Derivatives, Fair Value [Line Items]
Accumulated other comprehensive loss reclassified as an increase in interest expense	$ 400
Interest Income		$ 800
Estimated accumulated other comprehensive loss reclassified as an increase in interest expense over the following twelve months	$ 400

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Assets and Liabilities (Detail) - Recurring Measurements - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Recurring Measurements:
Derivative instrument-swap assets	$ 68
Derivative instrument-swap liabilities	378	$ 906
Level 1
Recurring Measurements:
Derivative instrument-swap assets	0
Derivative instrument-swap liabilities	0	0
Level 2
Recurring Measurements:
Derivative instrument-swap assets	68
Derivative instrument-swap liabilities	378	906
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) $ in Thousands		3 Months Ended
		Mar. 31, 2017USD ($)snapshotInterest_Rate_Swaps	Mar. 31, 2016USD ($)	Mar. 31, 2017USD ($)	Mar. 31, 2017Integer	Dec. 31, 2016USD ($)
Derivatives, Fair Value [Line Items]
(Gain) loss on sale of rental property		$ 42,799	$ (1,155)
Number of Interest Rate Derivatives Held		9			9
Debt Issuance Costs, Net				$ 5,800		$ 6,200
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Notional Amount				$ 240,000
Minimum number of daily snapshot used for valuation of interest rate swap agreements | snapshot		7,500
NOVA Non-Core Portfolio [Member]
Derivatives, Fair Value [Line Items]
Disposition Date Of Property	[1]	Mar. 25, 2016
One Fair Oaks [Member]
Derivatives, Fair Value [Line Items]
Disposition Date Of Property	[2]	Jan. 9, 2017
(Gain) loss on sale of rental property		$ 100
[1]	Consists of Van Buren Office Park, Herndon Corporate Center, Windsor at Battlefield, Reston Business Campus, Enterprise Center, Gateway Centre Manassas, Linden Business Center and Prosperity Business Center (collectively, the “NOVA Non-Core Portfolio”).
[2]	(1) One Fair Oaks was classified as held-for-sale at December 31, 2016, and the building was vacant at the time of sale.

Fair Value Measurements - Fai58

Fair Value Measurements - Fair Value of Debt Instruments (Detail) $ in Thousands		Mar. 31, 2017USD ($)ft²	Dec. 31, 2016USD ($)	Mar. 31, 2016ft²
Fair Value Assets Liabilities Quantitative Information [Line Items]
Debt Issuance Costs, Net		$ 5,800	$ 6,200
Financial Liabilities:
Area of Real Estate Property | ft²		5,996,668		6,543,784
Carrying Value
Financial Liabilities:
Carrying value of the debt instruments		$ 649,516	743,407
Carrying Value | Mortgages [Member]
Financial Liabilities:
Carrying value of the debt instruments	[1]	298,516	299,407
Carrying Value | Unsecured Debt [Member]
Financial Liabilities:
Carrying value of the debt instruments	[1]	300,000	300,000
Carrying Value | Unsecured revolving credit facility
Financial Liabilities:
Carrying value of the debt instruments	[1]	51,000	144,000
Fair Value
Financial Liabilities:
Fair value of the debt instruments		647,923	744,927
Fair Value | Mortgages [Member]
Financial Liabilities:
Fair value of the debt instruments		296,923	300,927
Fair Value | Unsecured Debt [Member]
Financial Liabilities:
Fair value of the debt instruments		300,000	300,000
Fair Value | Unsecured revolving credit facility
Financial Liabilities:
Fair value of the debt instruments		$ 51,000	$ 144,000
[1]	The debt balances exclude a combined total of $5.8 million and $6.2 million of unamortized deferred financing costs at March 31, 2017 and December 31, 2016, respectively.

Equity - Additional Information

Equity - Additional Information (Detail) - $ / shares

May 15, 2017

May 08, 2017

Apr. 25, 2017

Feb. 15, 2017

Feb. 08, 2017

Jan. 24, 2017

Jul. 25, 2016

Jul. 06, 2016

Jan. 19, 2016

Apr. 27, 2016

Mar. 31, 2017

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2016

Dec. 31, 2015

Dividends Payable [Line Items]

Series A Preferred Shares, shares outstanding

600,000

6,400,000

Preferred Stock, Dividend Rate, Percentage

7.75%

Dividend declared date

Jan. 24, 2017

Series A Preferred Shares

Dividends Payable [Line Items]

Series A Preferred Shares, shares outstanding

600,000

6,400,000

Stock Redeemed or Called During Period, Shares

2,200,000

600,000

3,600,000

2,200,000

Preferred Stock, Redemption Price Per Share

$ 25

$ 25

Preferred Stock, Redemption Date

Jul. 6, 2016

Jan. 19, 2016

Apr. 27, 2016

Common Shares

Dividends Payable [Line Items]

Common share dividend per share declared

$ 0.10

Common share dividend per share annualized

$ 0.40

Dividend paid date

Feb. 15, 2017

Dividend record date

Feb. 8, 2017

Subsequent Event [Member]

Dividends Payable [Line Items]

Dividend declared date

Apr. 25, 2017

Subsequent Event [Member] | Common Shares

Dividends Payable [Line Items]

Common share dividend per share declared

$ 0.10

Common share dividend per share annualized

$ 0.40

Dividend paid date

May 15, 2017

Dividend record date

May 8, 2017

Storey Park [Member]

Dividends Payable [Line Items]

Ownership Interest

97.00%

Disposition Date Of Property

Jul. 25, 2016

Jul. 25, 2016

[1]

[1]

) This development site could have supported up to 712,000 rentable square feet.

Equity - Company's Allocation B

Equity - Company's Allocation Between Non-controlling Interests (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total equity	$ 477,360	$ 560,441	$ 436,383	$ 625,328
Net Income (Loss) Attributable to Parent	43,145	46
Net income (loss)		32
Changes in ownership, net		(53,145)
Distributions to owners		(10,948)
Other comprehensive income		(826)
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning Balance, Redeemable noncontrolling interests	28,244	28,813
Net income (loss), Redeemable noncontrolling interests	1,884	(133)
Change in ownership, net, Redeemable noncontrolling interests	(2,382)	(1,644)
Distributions to owners, Redeemable noncontrolling interests	(255)	(393)
Other comprehensive income, Redeemable noncontrolling interests	25	(36)
Ending Balance, Redeemable noncontrolling interests	27,516	26,607
Repurchase of Common Shares	(232)	(122)
First Potomac Realty Trust
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	436,383	624,528
Net Income (Loss) Attributable to Parent	43,145	46
Changes in ownership, net	3,076	(53,145)
Distributions to owners	(5,815)	(10,948)
Other comprehensive income	571	(826)
Ending Balance	$ 477,360	559,655
Non-redeemable Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling interests in a consolidated partnership		786		$ 800
Net income (loss)		(14)
Changes in ownership, net		0
Distributions to owners		0
Other comprehensive income		$ 0

Equity - Company's Accumulated

Equity - Company's Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Equity [Abstract]
Beginning balance	$ (844)
Net unrealized gain (loss) on derivative instruments	596	$ (862)
Ending balance	(273)	(3,186)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Noncontrolling Interest	$ 25	$ (36)

Noncontrolling Interests - Addi

Noncontrolling Interests - Additional Information (Detail) - USD ($) $ in Millions	Jul. 25, 2016	Mar. 31, 2017		Dec. 31, 2016	Mar. 31, 2016
Business Acquisition [Line Items]
Cost to acquire all of the outstanding common Operating Partnership units not owned by the Company		$ 26.2
Fair value adjustment, cost basis		$ 3.7		$ 6.1
Outstanding Operating Partnership units not owned by the Company		2,545,602
Operating Partnership units not owned by Company		0.00%
Common operating partnership units redeemed for cash					38,539
Common operating partnership units redeemed for common shares		0
Storey Park [Member]
Business Acquisition [Line Items]
Ownership Interest		97.00%
Disposition Date Of Property	Jul. 25, 2016	Jul. 25, 2016	[1]
[1]	) This development site could have supported up to 712,000 rentable square feet.

Share-Based Payments - Addition

Share-Based Payments - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Award, Shares Purchased for Award	418,286
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Award, Shares Purchased for Award	160,349
Compensation expense associated with trustee share based awards	$ 800,000		$ 400,000
Unrecognized compensation cost related to non-vested shares	$ (7,600,000)
Non-Vested Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average period for recognition of non-vested shares	3 years 2 months
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Other Value, Outstanding	$ 7.11
Executive Officer [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Award, Shares Purchased for Award		257,937
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	0.70%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	25.82%
Minimum [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	25.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	1.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	22.93%
Maximum [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	300.00%

Share-Based Payments - Summary

Share-Based Payments - Summary of Company's Non-vested Share Awards (Detail)	3 Months Ended
	Mar. 31, 2017$ / sharesshares
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	711,374
Non-vested Shares, Granted	418,286
Non-vested Shares, Ending Balance	1,046,860
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	80,179
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value | $ / shares	$ 10.99
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	9.85
Weighted Average Grant Date Fair Value, Granted | $ / shares	8.54
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 9.23
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested Shares, Granted	160,349
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Expired In Period Weighted Average Grant Date Fair Value | $ / shares	$ 12.38
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Expired In Period	(1,630)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(991)
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period Weighted Average Grant Date Fair Values | $ / shares	$ 11.03

Segment Information - Additiona

Segment Information - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)segment	Mar. 31, 2016USD ($)
Segment Reporting [Abstract]
Number of Reportable Segments | segment	4
Corporate Assets Not Allocated To Any Reportable Segments	$ 17,400	$ 92,300
Capital Expenditure For Corporate Assets Not Allocated To Any Reportable Segments		$ 100

Segment Information - Summary o

Segment Information - Summary of Segment Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)ft²Integerbuilding	Mar. 31, 2016USD ($)ft²Integer	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Interest Paid, Capitalized	$ 0	$ 200
Number of buildings | Integer	71	73
Area of Real Estate Property | ft²	5,996,668	6,543,784
Total revenues	$ 37,823	$ 42,697
Property operating expense	(9,958)	(11,537)
Real estate taxes and insurance	(4,661)	(5,216)
Total property operating income	23,204	25,944
Depreciation and amortization expense	(14,566)	(15,006)
General and administrative	(4,497)	(4,578)
Other Nonoperating Income	40,888
Other income		6,461
Net income (loss)	45,029	(101)
Total assets	1,203,997	1,359,943	$ 1,260,247
Capital expenditure	6,810	22,643
Shares Tendered By Employees For Statutory Tax Withholdings Upon Issuance Of Common Stock	232	122
Capital expenditures for corporate assets not allocated to any reportable segments		100
Corporate Assets Not Allocated To Any Reportable Segments	$ 17,400	$ 92,300
Washington, D.C.
Segment Reporting Information [Line Items]
Number of buildings	6	6
Area of Real Estate Property | ft²	917,643	918,566
Total revenues	$ 11,722	$ 11,290
Property operating expense	(3,139)	(2,968)
Real estate taxes and insurance	(2,292)	(2,372)
Total property operating income	6,291	5,950
Total assets	443,800	468,561
Capital expenditure	$ 1,522	$ 4,910
Maryland1
Segment Reporting Information [Line Items]
Number of buildings	34	34
Area of Real Estate Property | ft²	1,886,177	1,885,630
Total revenues	$ 11,235	$ 11,587
Property operating expense	(2,657)	(3,235)
Real estate taxes and insurance	(982)	(929)
Total property operating income	7,596	7,423
Total assets	322,738	338,553
Capital expenditure	$ 2,350	$ 959
Northern Virginia
Segment Reporting Information [Line Items]
Number of buildings	12	14
Area of Real Estate Property | ft²	1,168,990	1,715,730
Total revenues	$ 7,312	$ 12,307
Property operating expense	(1,956)	(3,320)
Real estate taxes and insurance	(741)	(1,297)
Total property operating income	4,615	7,690
Total assets	260,564	294,480
Capital expenditure	$ 2,295	$ 15,757
Southern Virginia
Segment Reporting Information [Line Items]
Number of buildings	19	19
Area of Real Estate Property | ft²	2,023,858	2,023,858
Total revenues	$ 7,554	$ 7,513
Property operating expense	(2,206)	(2,014)
Real estate taxes and insurance	(646)	(618)
Total property operating income	4,702	4,881
Total assets	159,487	166,015
Capital expenditure	606	897
Furniture and Fixtures [Member]
Segment Reporting Information [Line Items]
Accrued capital expenditure	$ 4,600	$ 10,300