Piedmont Office Realty Trust (PDM) 10-Q 30 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 29, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	Piedmont Office Realty Trust, Inc.
Entity Central Index Key	1,042,776
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		128,371,442

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Real estate assets, at cost:
Land	$ 523,994	$ 521,186
Buildings and improvements, less accumulated depreciation of $797,222 and $728,134 as of September 30, 2018 and December 31, 2017, respectively	2,309,803	2,325,282
Intangible lease assets, less accumulated amortization of $84,268 and $99,145 as of September 30, 2018 and December 31, 2017, respectively	65,527	77,805
Construction in progress	22,753	11,681
Real estate assets held for sale, net	113,918	448,788
Total real estate assets	3,035,995	3,384,742
Amounts due from unconsolidated joint ventures	0	10
Cash and cash equivalents	6,807	7,382
Tenant receivables, net of allowance for doubtful accounts of $599 and $539 as of September 30, 2018 and December 31, 2017, respectively	10,522	12,139
Straight-line rent receivables	168,745	154,384
Note receivable	3,200	0
Restricted cash and escrows	1,374	1,373
Prepaid expenses and other assets	31,470	21,222
Goodwill	98,918	98,918
Interest rate swaps	4,069	688
Deferred lease costs, less accumulated amortization of $177,412 and $181,579 as of September 30, 2018 and December 31, 2017, respectively	250,038	257,916
Other assets held for sale, net	12,752	61,193
Total assets	3,623,890	3,999,967
Liabilities:
Unsecured debt, net of discount and unamortized debt issuance costs of $10,382 and $7,689 as of September 30, 2018 and December 31, 2017, respectively	1,524,618	1,535,311
Secured debt, net of premiums and unamortized debt issuance costs of $720 and $946 as of September 30, 2018 and December 31, 2017, respectively	190,753	191,616
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	109,087	216,653
Deferred income	27,450	29,582
Intangible lease liabilities, less accumulated amortization of $56,876 and $55,847 as of September 30, 2018 and December 31, 2017, respectively	37,986	38,458
Interest rate swaps	0	1,478
Other liabilities held for sale, net	0	380
Total liabilities	1,889,894	2,013,478
Commitments and Contingencies
Stockholders’ Equity:
Shares-in-trust, 150,000,000 shares authorized; none outstanding as of September 30, 2018 or December 31, 2017	0	0
Preferred stock, no par value, 100,000,000 shares authorized; none outstanding as of September 30, 2018 or December 31, 2017	0	0
Common stock, $.01 par value, 750,000,000 shares authorized; 128,371,442 and 142,358,940 shares issued and outstanding as of September 30, 2018 and December 31, 2017, respectively	1,284	1,424
Additional paid-in capital	3,682,209	3,677,360
Cumulative distributions in excess of earnings	(1,964,135)	(1,702,281)
Other comprehensive income	12,851	8,164
Piedmont stockholders’ equity	1,732,209	1,984,667
Noncontrolling interest	1,787	1,822
Total stockholders’ equity	1,733,996	1,986,489
Total liabilities and stockholders’ equity	$ 3,623,890	$ 3,999,967

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets:
Intangible lease assets, accumulated amortization	$ 84,268	$ 99,145
Tenant receivables, allowance for doubtful accounts	599	539
Deferred lease costs, accumulated amortization	177,412	181,579
Liabilities:
Intangible lease liabilities, accumulated amortization	56,876	55,847
Commitments and Contingencies
Stockholders’ Equity:
Shares-in-trust, shares authorized (in shares)	150,000,000	150,000,000
Shares-in-trust, shares outstanding (in shares)	0	0
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized (in shares)	100,000,000	100,000,000
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	750,000,000	750,000,000
Common stock, shares issued (in shares)	128,371,442	142,358,940
Common stock, shares outstanding (in shares)	128,371,442	142,358,940
Unsecured Debt
Liabilities:
Discount, (premiums) and unamortized debt issuance costs	$ 10,382	$ 7,689
Secured Debt
Liabilities:
Discount, (premiums) and unamortized debt issuance costs	(720)	(946)
Building and improvements
Assets:
Buildings and improvements, accumulated depreciation	$ 797,222	$ 728,134

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Rental income	$ 101,348	$ 108,868	$ 304,280	$ 345,399
Tenant reimbursements	23,170	24,253	68,211	73,375
Total revenues	129,708	137,587	388,782	434,729
Expenses:
Property operating costs	49,679	54,518	154,175	166,635
Depreciation	26,852	30,000	81,112	90,827
Amortization	14,840	18,123	46,818	57,852
General and administrative	6,677	6,190	21,487	21,868
Operating expenses	98,048	108,831	303,592	337,182
Real estate operating income	31,660	28,756	85,190	97,547
Other income (expense):
Interest expense	(15,849)	(16,183)	(45,294)	(52,661)
Other income	303	290	1,480	228
Equity in income of unconsolidated joint ventures	0	3,754	0	3,872
Loss on extinguishment of debt	0	0	(1,680)	0
Gain on sale of real estate assets	0	109,512	45,186	115,951
Net income	16,114	126,129	84,882	164,937
Plus: Net loss applicable to noncontrolling interest	0	4	4	10
Net income applicable to Piedmont	$ 16,114	$ 126,133	$ 84,886	$ 164,947
Per share information – basic and diluted:
Net income applicable to common stockholders (in usd per share)	$ 0.13	$ 0.87	$ 0.65	$ 1.13
Weighted-average common shares outstanding – basic (in shares)	128,371,062	145,415,678	130,837,223	145,372,182
Weighted-average common shares outstanding – diluted (in shares)	128,818,658	145,719,431	131,187,127	145,679,582
Property management fee revenue
Revenues:
Property management and other property related revenue	$ 368	$ 454	$ 1,059	$ 1,379
Other property related income
Revenues:
Property management and other property related revenue	$ 4,822	$ 4,012	$ 15,232	$ 14,576

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income applicable to Piedmont	$ 16,114	$ 126,133	$ 84,886	$ 164,947
Other comprehensive income:
Effective portion of gain on derivative instruments that are designated and qualify as cash flow hedges (See Note 6)	1,145	175	4,408	307
Plus: Reclassification of net (gain)/loss included in net income (See Note 6)	(434)	653	373	2,936
Gain on investment in available for sale securities	0	25	0	53
Other comprehensive income	711	853	4,781	3,296
Comprehensive income applicable to Piedmont	$ 16,825	$ 126,986	$ 89,667	$ 168,243

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Cumulative Distributions in Excess of Earnings	Other Comprehensive Income/(Loss)	Non- controlling Interest
Balance at Dec. 31, 2016	$ 2,097,703	$ 1,452	$ 3,673,128	$ (1,580,863)	$ 2,104	$ 1,882
Balance (in shares) at Dec. 31, 2016		145,235,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Plus: Net loss applicable to noncontrolling interest	10
Net income applicable to Piedmont	164,947
Other comprehensive income	$ 3,296
Balance (in shares) at Sep. 30, 2017	145,295,000
Balance at Dec. 31, 2016	$ 2,097,703	$ 1,452	3,673,128	(1,580,863)	2,104	1,882
Balance (in shares) at Dec. 31, 2016		145,235,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share repurchases as part of an announced plan	(61,750)	$ (31)		(61,719)
Share repurchases as part of an announced plan (in shares)		(3,133,000)
Offering costs	(182)		(182)
Dividends to common stockholders, stockholders of subsidiaries, and dividends reinvested	(193,541)		(233)	(193,263)		(45)
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax	4,650	$ 3	4,647
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax (in shares)		257,000
Plus: Net loss applicable to noncontrolling interest	(15)					(15)
Net income applicable to Piedmont	133,564			133,564
Other comprehensive income	6,060				6,060
Balance at Dec. 31, 2017	$ 1,986,489	$ 1,424	3,677,360	(1,702,281)	8,164	1,822
Balance (in shares) at Dec. 31, 2017	142,358,940	142,359,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change (adoption of ASU 2016-01)	$ 0			94	(94)
Share repurchases as part of an announced plan	(264,785)	$ (143)		(264,642)
Share repurchases as part of an announced plan (in shares)		(14,343,000)
Dividends to common stockholders, stockholders of subsidiaries, and dividends reinvested	(82,279)		(56)	(82,192)		(31)
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax	4,908	$ 3	4,905
Shares issued and amortized under the 2007 Omnibus Incentive Plan, net of tax (in shares)		355,000
Plus: Net loss applicable to noncontrolling interest	4					4
Net income applicable to Piedmont	84,886			84,886
Other comprehensive income	4,781				4,781
Balance at Sep. 30, 2018	$ 1,733,996	$ 1,284	$ 3,682,209	$ (1,964,135)	$ 12,851	$ 1,787
Balance (in shares) at Sep. 30, 2018	128,371,442	128,371,000

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividends to common stockholders per share (in USD per share)	$ 0.63	$ 1.34

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows from Operating Activities:
Net income	$ 84,882	$ 164,937
Operating distributions received from unconsolidated joint ventures	10	0
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	81,112	90,827
Amortization of debt issuance costs net of favorable settlement of interest rate swaps	(215)	1,214
Other amortization	42,882	57,146
Loss on extinguishment of debt	1,665	0
Stock compensation expense	6,671	6,657
Equity in income of unconsolidated joint ventures	0	(3,872)
Gain on sale of real estate assets	(45,186)	(115,951)
Changes in assets and liabilities:
Increase in tenant and straight-line rent receivables, net	(12,361)	(15,040)
Increase in prepaid expenses and other assets	(8,496)	(5,188)
Decrease in accounts payable and accrued expenses	(10,377)	(5,863)
(Decrease)/increase in deferred income	(2,265)	1,513
Net cash provided by operating activities	138,322	176,380
Cash Flows from Investing Activities:
Acquisition of real estate assets and related intangibles	(28,176)	0
Capitalized expenditures	(44,998)	(65,407)
Net sales proceeds from wholly-owned properties	419,554	375,199
Net sales proceeds from unconsolidated joint ventures	0	12,334
Investments in unconsolidated joint ventures	0	(1,162)
Note receivable issuance	(3,200)	0
Deferred lease costs paid	(15,831)	(19,419)
Net cash provided by investing activities	327,349	301,545
Cash Flows from Financing Activities:
Debt issuance and other costs paid	(947)	(101)
Proceeds from debt	820,061	147,000
Repayments of debt	(833,005)	(466,046)
Costs of issuance of common stock	0	(97)
Value of shares withheld for payment of taxes related to employee stock compensation	(2,219)	(3,385)
Repurchases of common stock as part of announced plan	(266,062)	(3,895)
Dividends paid and discount on dividend reinvestments	(184,073)	(122,237)
Net cash used in financing activities	(466,245)	(448,761)
Net (decrease)/increase in cash, cash equivalents, and restricted cash and escrows	(574)	29,164
Cash, cash equivalents, and restricted cash and escrows, beginning of period	8,755	8,204
Cash, cash equivalents, and restricted cash and escrows, end of period	$ 8,181	$ 37,368

Organization

Organization	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Piedmont Office Realty Trust, Inc. (“Piedmont”) (NYSE: PDM) is a Maryland corporation that operates in a manner so as to qualify as a real estate investment trust (“REIT”) for federal income tax purposes and engages in the acquisition, development, management, and ownership of commercial real estate properties located primarily in the Eastern-half of the United States, including properties that are under construction, are newly constructed, or have operating histories. Piedmont was incorporated in 1997 and commenced operations in 1998. Piedmont conducts business primarily through Piedmont Operating Partnership, L.P. (“Piedmont OP”), a Delaware limited partnership, as well as performing the management of its buildings through two wholly-owned subsidiaries, Piedmont Government Services, LLC and Piedmont Office Management, LLC. Piedmont owns 99.9% of, and is the sole general partner of, Piedmont OP and as such, possesses full legal control and authority over the operations of Piedmont OP. The remaining 0.1% ownership interest of Piedmont OP is held indirectly by Piedmont through its wholly-owned subsidiary, Piedmont Office Holdings, Inc. ("POH"), the sole limited partner of Piedmont OP. Piedmont OP owns properties directly, through wholly-owned subsidiaries, and through various joint ventures which we control. References to Piedmont herein shall include Piedmont and all of its subsidiaries, including Piedmont OP and its subsidiaries and joint ventures. As of September 30, 2018 , Piedmont owned 53 in-service office properties and one redevelopment asset, comprising approximately 487,000 square feet. As of September 30, 2018 , Piedmont's 53 in-service office properties comprise approximately 16.2 million square feet of primarily Class A commercial office space and were approximately 93.2% leased. As of September 30, 2018 , approximately 90% of Piedmont's Annualized Lease Revenue (unaudited) was generated from select sub-markets located primarily within eight major office markets located in the Eastern-half of the United States: Atlanta, Boston, Chicago, Dallas, Minneapolis, New York, Orlando, and Washington, D.C. Piedmont internally evaluates all of its real estate assets as one

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The consolidated financial statements of Piedmont have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”), including the instructions to Form 10-Q and Article 10 of Regulation S-X, and do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, the statements for the unaudited interim periods presented include all adjustments, which are of a normal and recurring nature, necessary for a fair presentation of the results for such periods. Results for these interim periods are not necessarily indicative of a full year’s results. Piedmont’s consolidated financial statements include the accounts of Piedmont, Piedmont’s wholly-owned subsidiaries, any variable interest entity ("VIE") for which Piedmont or any of its wholly-owned subsidiaries is considered to have the power to direct the activities of the entity and the obligation to absorb losses/right to receive benefits, or any entity in which Piedmont or any of its wholly-owned subsidiaries owns a controlling interest. In determining whether Piedmont or Piedmont OP has a controlling interest, the following factors, among others, are considered: equity ownership, voting rights, protective rights of investors, and participatory rights of investors. For further information, refer to the financial statements and footnotes included in Piedmont’s Annual Report on Form 10-K for the year ended December 31, 2017 . All intercompany balances and transactions have been eliminated upon consolidation. Further, Piedmont has formed special purpose entities to acquire and hold real estate. Each special purpose entity is a separate legal entity. Consequently, the assets of these special purpose entities are not available to all creditors of Piedmont. The assets owned by these special purpose entities are being reported on a consolidated basis with Piedmont’s assets for financial reporting purposes only. Use of Estimates The preparation of the accompanying consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying consolidated financial statements and notes. Actual results could differ from those estimates. Income Taxes Piedmont has elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended, and has operated as such, beginning with its taxable year ended December 31, 1998. To qualify as a REIT, Piedmont must meet certain organizational and operational requirements, including a requirement to distribute at least 90% of its annual REIT taxable income. As a REIT, Piedmont is generally not subject to federal income taxes, subject to fulfilling, among other things, its taxable income distribution requirement. Piedmont is subject to certain taxes related to the operations of properties in certain locations, as well as operations conducted by its taxable REIT subsidiary, POH, which have been provided for in the financial statements. Tax Cuts and Jobs Act The Tax Cuts and Jobs Act ("H.R. 1"), which generally took effect for taxable years that began on or after January 1, 2018 (subject to certain exceptions), made many significant changes to the U.S. federal income tax laws that will profoundly impact the taxation of individuals and corporations (including both regular C corporations and corporations that have elected to be taxed as REITs). For example, H.R. 1 limits the ability of corporations to utilize net operating loss carryforwards and limits the deductibility of business interest for all taxpayers, subject to an exception for taxpayers that are engaged in certain specified real property trades or business who make an irrevocable election not to apply the limitation to a particular real property trade or business and to depreciate their real property investments held in such trade or business using the less favorable alternative depreciation system. To date, the IRS has issued limited guidance with respect to certain of the provisions of H.R. 1, and there are numerous interpretive issues that will require guidance. In addition, changes made by H.R. 1 may require Piedmont to accrue certain income for U.S. federal income tax purposes no later than when such income is taken into account as revenue on its GAAP-based financial statements, unless the income is already subject to certain special methods of accounting under the Code. This could cause Piedmont to recognize taxable income prior to the receipt of the associated cash and accordingly, increase its distribution levels in order to maintain its status as a REIT. H.R. 1 also includes limitations on the deductibility of certain compensation paid to Piedmont's executives, certain interest payments, and certain net operating loss carryforwards, each of which could potentially increase Piedmont's taxable income and its required distributions. Piedmont recorded an approximate $ 0.2 million reduction to its tax liability related to its taxable REIT subsidiary as a result of the rate reduction included in H.R. 1 during the nine months ended September 30, 2018. Although management is still evaluating the other effects of H.R. 1, Piedmont does not believe that H.R. 1 will significantly impact its financial statements. Reclassifications Certain prior period amounts presented in the accompanying consolidated statements of income have been reclassified to conform to the current period financial statement presentation. These amounts included: (i) the reclassification of approximately $4.0 million and $14.6 million for the three and nine months ended September 30, 2017 , respectively, of parking, antennae license and fiber income that was previously included in rental income into other property related income, as well as certain other miscellaneous revenue into tenant reimbursements and/or property management fee revenue in conjunction with the adoption of the Revenue Recognition Amendments, as further defined and described below; and (ii) the reclassification of $0.4 million and $1.4 million for the three and nine months ended September 30, 2017 , respectively, of expense related to certain regional employees who are primarily engaged in the operation and management of properties that was previously included in general and administrative expense to property operating costs. Accounting Pronouncements Adopted during the Nine Months Ended September 30, 2018 Revenue Recognition On January 1, 2018, Piedmont adopted Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09") and Accounting Standards Update No. 2016-08, Revenue from Contracts with Customers (Topic 606) Principal versus Agent Considerations (Reporting Revenue Gross versus Net) ("ASU 2016-08") issued by the Financial Accounting Standards Board (the "FASB"). The amendments in ASU 2014-09, which are further clarified in ASU 2016-08, as well as Accounting Standards Update 2016-10, Accounting Standards Update 2016-12, and Accounting Standards Update 2016-20 (collectively the "Revenue Recognition Amendments") change the criteria for the recognition of certain revenue streams to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services using a five-step determination process. Piedmont's revenues which are included in the scope of the Revenue Recognition Amendments include its property management fee revenue, the majority of its parking revenue, as well as certain license agreements which allow third-parties to place their antennas or fiber-optic cabling on or inside Piedmont's buildings. Lease contracts are specifically excluded from the Revenue Recognition Amendments and, Piedmont intends to utilize a leasing practical expedient (see further discussion below) to group certain non-lease components related to operating expense reimbursements with other leasing components, provided they meet certain criteria. Because the timing and pattern of transfer of Piedmont's non-lease related revenue already followed the prescribed method of the Revenue Recognition Amendments, Piedmont was able to effectively adopt these amendments on a full retrospective basis, with no impact to the timing of recognition of the related revenue; however, such non-lease revenues are now being presented as "Other property related income" in the accompanying consolidated statements of income. Further, for comparative purposes, Piedmont reclassified approximately $4.0 million and $14.6 million for the three and nine months ended September 30, 2017 , respectively, of parking, antennae license, and fiber income that was previously included in rental income into other property related income, as well as certain other miscellaneous revenue into tenant reimbursements and/or property management fee revenue. Piedmont did not elect to adopt any practical expedients provided by the Revenue Recognition Amendments. A detail of Piedmont's total revenues for the three months ended September 30, 2018 and 2017 (after reclassifications as a result of the adoption of the Revenue Recognition Amendments), including a detailed description of each line item is as follows: (After Adoption of Revenue Recognition Amendments) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Rental income $ 101,348 $ 108,868 Tenant reimbursements 23,170 24,253 Property management fee revenue 368 454 Other property related income 4,822 4,012 Total revenues $ 129,708 $ 137,587 Rental income - consists of revenue from leases with Piedmont's tenants, which is not within the scope of the Revenue Recognition Amendments. Tenant reimbursements - consists of separately billed revenue derived from reimbursements for services prescribed by leases with Piedmont's tenants separate from, but in conjunction with, the revenue generated from leasing office space. Such income is not within the scope of the Revenue Recognition Amendments. Property management fee revenue - consists of revenue earned by Piedmont related to operating and managing office properties owned by other third-parties. Such income is within the scope of the Revenue Recognition Amendments; however, because the property management services represent a performance obligation that would be satisfied over the length of the contract, not at any specific point in time, and has the same measure of transfer (time elapsed), property management fee revenue will be recognized over time, consistent with the timing of Piedmont’s historic recognition. Any variable consideration transferred as part of these management agreements will continue to be recognized in the quarter that the underlying cash receipts are collected, consistent with the allocation objective of allocating the transaction price in an amount that depicts the amount of consideration to which Piedmont expects to be entitled in exchange for transferring the promised service to the customer. Other property related income - consists of all other property related income from Piedmont's customers (tenants) that is not derived from a contract meeting the definition of a lease. Examples of such income include parking revenue and income from licenses with unrelated third-parties to place antennae and/or fiber optic cables in or on Piedmont's buildings. Since these services are substantially the same and have the same pattern of transfer, there is no timing difference between the recognition of other property related income and the recognition of the underlying expense/delivery of “service” under the new Revenue Recognition Amendments. Additionally, no modification to the timing of Piedmont’s previous revenue recognition is necessary, as these items have been recognized historically in accordance with this pattern of transfer. Gain/(loss) on Sale of Real Estate Assets On January 1, 2018, Piedmont adopted 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") concurrent with the Revenue Recognition Amendments mentioned above. Piedmont elected to apply the amendments of ASU 2017-05 on a full retrospective basis; however, there were no adjustments to previously recorded gains/(losses) on sale of real estate as a result of the transition. Equity Investments Held in Non-qualified Deferred Compensation Plan On January 1, 2018, Piedmont adopted Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic 825-10), Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"), as well as Accounting Standards Update No. 2018-03 Technical Corrections and Improvements to Financial Instruments-Overall (Subtopic 825-10) ("ASU 2018-03"). These amendments require equity investments, except those accounted for under the equity method of accounting, to be measured at estimated fair value with changes in fair value recognized in net income. Investments in trading securities held in a "rabbi trust" by Piedmont are the only securities affected by ASU 2016-01 and ASU 2018-03. As such, Piedmont has made a cumulative-effect adjustment to its consolidated balance sheet and consolidated statements of stockholders' equity of approximately $0.1 million from other comprehensive income ("OCI") to cumulative distributions in excess of earnings, and has recorded changes in fair value in net income for the three and nine months ended September 30, 2018 related to these investment securities. Interest Rate Derivatives On January 1, 2018, Piedmont early adopted Accounting Standards Update No. 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12"). Piedmont adopted ASU 2017-12 using the modified retrospective transition method; however, no adjustment was necessary to account for the cumulative effect of the change on the opening balance of each affected component of equity in the consolidated balance sheet as of the date of adoption because there was no cumulative ineffectiveness that had been recorded on Piedmont's existing interest rate swaps as of December 31, 2017, and all trades were highly effective. The amended presentation and disclosure guidance which is required to be presented prospectively is provided in Note 6 . Other Recent Accounting Pronouncements The FASB has issued Accounting Standards Update No. 2016-02, Leases (Topic 842) ("ASU 2016-02"), which fundamentally changes the definition of a lease, as well as the accounting for operating leases by requiring lessees to recognize assets and liabilities which arise from the lease, consisting of a liability to make lease payments (the lease liability) and a right-of-use asset, representing the right to use the leased asset over the term of the lease. Accounting for leases by lessors is substantially unchanged from prior practice as lessors will continue to recognize lease revenue on a straight-line basis. Additionally, the FASB has subsequently issued a number of clarifying and technical corrections to ASU 2016-02 through several Accounting Standards Updates ("ASU") as follows: ASU Title Summary Anticipated Impact on Piedmont's Consolidated Financial Statements Based on Management’s Assessment to Date ASU 2018-01 Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842 Clarifies that a land easement is required to be evaluated to determine whether it should be accounted for as a lease upon adoption of ASU 2016-02; also provides an optional practical transition expedient allowing entities not currently assessing land easements under existing leasing guidance prior to adoption of ASU 2016-02 to not apply the new guidance to land easements existing at the date of initial adoption of ASU 2016-02. Not applicable as Piedmont has no land easements. ASU 2018-10 Codification Improvements to Topic 842, Leases Clarifications and technical corrections to ASU 2016-02. No material impact expected. ASU 2018-11 Leases (Topic 842) Targeted Improvements Allows certain non-lease operating expense reimbursements which are included in the underlying stated lease rate to be accounted for as part of the lease provided certain criteria are met under an optional practical expedient. All of Piedmont’s operating expense reimbursements are expected to qualify to be accounted for as a part of the underlying lease. Although management continues to evaluate the guidance and disclosures required by all of the above ASUs, Piedmont does not anticipate any material impact to its consolidated financial statements as a result of adoption related to lessor accounting. However, Piedmont does anticipate recording an immaterial right-to-use asset and offsetting lease liability under lessee accounting on its balance sheet upon adoption of ASU 2016-02 on January 1, 2019. The FASB has issued Accounting Standards Update No. 2018-07, Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07"). The provisions of ASU 2018-07 align accounting for stock based compensation for non-employees for goods and services with existing accounting for similar compensation for employees. The amendments supersede previous guidance on accounting for share-based payments to non-employees codified in the FASB's Accounting Standards Codification ("ASC") 505-50. ASU 2018-07 is effective in the first quarter of 2019, with early adoption permitted at any time provided that the entity has already adopted the provisions of ASC 606. P iedmont does not anticipate any material impact to its consolidated financial statements as a result of adoption. The FASB has issued Accounting Standards Update No. 2016-13, Financial Instruments—Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Acquisitions	Acquisitions During the nine months ended September 30, 2018 , Piedmont acquired one property using proceeds available as a result of dispositions (see Note 9 ) in January 2018 and cash on hand, as noted below: Property Metropolitan Statistical Area Date of Acquisition Ownership Percentage Acquired Rentable Square Feet Percentage Leased as of Acquisition Net Contractual Purchase Price (in millions) 501 West Church Street Orlando, Florida February 23, 2018 100 % 182,461 100 % $ 28.2

Debt

Debt	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt	Debt During the nine months ended September 30, 2018 , Piedmont fully repaid the balances of the $300 Million Unsecured 2013 Term Loan and the $170 Million Unsecured 2015 Term Loan using proceeds from the 2017 Disposition Portfolio (see Note 9 ) and cash on hand, as well as drawing on its $500 Million Unsecured 2015 Line of Credit. Additionally, during the nine months ended September 30, 2018, Piedmont replaced its $500 Million Unsecured 2015 Line of Credit ("the 2015 Line of Credit") with a new $500 Million Unsecured Line of Credit (the " $500 Million Unsecured 2018 Line of Credit"). The 2015 Line of Credit was scheduled to expire on June 18, 2019, and was terminated concurrently with the closing of the new facility. The term of the new $500 Million Unsecured 2018 Line of Credit is four years with a maturity date of September 30, 2022, and Piedmont may extend the term for up to one additional year (through two available six-month extensions) provided Piedmont is not then in default and all representations and warranties are true and correct in all material respects and upon payment of applicable extension fees. Additionally, under certain terms of the agreement, Piedmont may increase the new facility by up to an additional $500 million , to an aggregate size of $1.0 billion , provided that no existing bank has any obligation to participate in such increase. Piedmont paid customary arrangement and upfront fees to the lenders in connection with the closing of the new facility. The $500 Million Unsecured 2018 Line of Credit has the option to bear interest at varying levels (determined with reference to the greater of the credit rating for Piedmont or Piedmont OP) based on the London Interbank Offered Rate (“LIBOR”) or the Base Rate, defined as the greater of the prime rate, the federal funds rate plus 0.5% , or LIBOR for a one-month period plus 1.0% . LIBOR loans are available with interest periods selected by Piedmont of one, two (if available), three, or six months, or to the extent available from all lenders in each case, one year or periods of less than one month. The stated interest rate spread over LIBOR can vary from 0.775% to 1.45% based upon the greater of the then current credit rating of Piedmont. As of the closing of the $500 Million Unsecured 2018 Line of Credit, based upon Piedmont's current credit rating, the current stated LIBOR spread on the loan is 0.9% , down from 1.0% for the 2015 Line of Credit. Further, during the nine months ended September 30, 2018, Piedmont amended and restated its $300 Million Unsecured 2011 Term Loan (the "Amended and Restated $300 Million Unsecured 2011 Term Loan") to extend its maturity date 22 months, from January 15, 2020 to November 30, 2021. The amendment also decreases the stated interest rate spread over LIBOR from a range of 0.9% to 1.90% to a range of 0.85% to 1.65% . The specific spread in effect from time to time is based upon the greater of the credit rating for Piedmont or Piedmont OP. As of the closing of the Amended and Restated $300 Million Unsecured 2011 Term Loan, based upon the Piedmont's current credit rating, the current stated LIBOR spread on the loan was 1.0% , down from 1.15% for the $300 Million Unsecured 2011 Term Loan. All other material terms of the facility remain unchanged. Finally, during the nine months ended September 30, 2018, Piedmont entered into a $250 million unsecured term loan facility (the “ $250 Million Unsecured 2018 Term Loan”) with a consortium of lenders. The term of the $250 Million Unsecured 2018 Term Loan is seven years with a maturity date of March 31, 2025; however, Piedmont may prepay the $250 Million Unsecured 2018 Term Loan, in whole or in part, at any time after March 29, 2020 without premium or penalty. The $250 Million Unsecured 2018 Term Loan has the option to bear interest at varying levels based on either (i) LIBOR for an interest period selected by Piedmont of one, two, three, or six months, or to the extent available from all lenders in each case, one year or periods of less than one month, or (ii) Base Rate, defined as the greater of the prime rate, the federal funds rate plus 0.5% , or LIBOR for a one-month period plus 1% ; plus a stated interest rate spread based on the higher credit rating level issued for either Piedmont or Piedmont OP. The stated interest rate spread over LIBOR can vary from 1.45% to 2.40% based upon the then current credit rating of Piedmont or Piedmont OP, whichever is higher. Further, Piedmont entered into three interest rate swap agreements for a total notional amount of $150 million which effectively fixed $150 million of the $250 Million Unsecured 2018 Term Loan at an interest rate of approximately 4.11% . The $500 Million Unsecured 2018 Line of Credit, the Amended and Restated $300 Million Unsecured 2011 Term Loan, and the $250 Million Unsecured 2018 Term Loan all have certain financial covenants that require, among other things, the maintenance of an unencumbered interest coverage ratio of at least 1.75 , an unencumbered leverage ratio of at least 1.60 , a fixed charge coverage ratio of at least 1.50 , a leverage ratio of no more than 0.60 , and a secured debt ratio of no more than 0.40 . The following table summarizes the terms of Piedmont’s indebtedness outstanding as of September 30, 2018 and December 31, 2017 (in thousands): Facility (1) Stated Rate Effective Rate (2) Maturity Amount Outstanding as of September 30, 2018 December 31, 2017 Secured (Fixed) $35 Million Fixed-Rate Loan (3) 5.55 % 3.75 % 9/1/2021 $ 30,033 $ 30,670 $160 Million Fixed-Rate Loan (4) 3.48 % 3.58 % 7/5/2022 160,000 160,000 Net premium and unamortized debt issuance costs 720 946 Subtotal/Weighted Average (5) 3.81 % 190,753 191,616 Unsecured (Variable and Fixed) $170 Million Unsecured 2015 Term Loan LIBOR + 1.125% 2.54 % 5/15/2018 — 170,000 $300 Million Unsecured 2013 Term Loan LIBOR + 1.20% 2.78 % (7) 1/31/2019 — 300,000 $500 Million Unsecured 2015 Line of Credit (6) LIBOR + 1.00% 3.17 % 6/18/2019 — 23,000 $500 Million Unsecured 2018 Line of Credit (6) LIBOR + 0.90% 3.15 % 9/30/2022 (8) 235,000 — Amended and Restated $300 Million Unsecured 2011 Term Loan LIBOR + 1.00% 3.20 % (7) 11/30/2021 300,000 300,000 $350 Million Senior Notes 3.40 % 3.43 % 6/01/2023 350,000 350,000 $400 Million Senior Notes 4.45 % 4.10 % 3/15/2024 400,000 400,000 $250 Million Unsecured 2018 Term Loan LIBOR + 1.60% 4.00 % (9) 3/31/2025 250,000 — Discounts and unamortized debt issuance costs (10,382) (7,689) Subtotal/Weighted Average (5) 3.69 % 1,524,618 1,535,311 Total/Weighted Average (5) 3.71 % $ 1,715,371 $ 1,726,927 (1) Other than the $35 Million Fixed-Rate Loan, all of Piedmont’s outstanding debt as of September 30, 2018 and December 31, 2017 is interest-only. (2) Effective rate after consideration of settled or in-place interest rate swap agreements, issuance premiums/discounts, and/or fair market value adjustments upon assumption of debt. (3) Collateralized by the 5 Wall Street building in Burlington, Massachusetts. (4) Collateralized by the 1901 Market Street building in Philadelphia, Pennsylvania. (5) Weighted average is based on contractual balance of outstanding debt and the stated or effectively fixed interest rates as of September 30, 2018 . (6) On a periodic basis, Piedmont may select from multiple interest rate options, including the prime rate and various-length LIBOR locks on all or a portion of the principal. All LIBOR selections are subject to an additional spread over the selected rate based on Piedmont’s current credit rating. (7) The facility has a stated variable rate; however, Piedmont has entered into interest rate swap agreements which effectively fix, exclusive of changes in Piedmont's credit rating, the rate to that shown as the effective rate through the maturity date of the interest rate swap agreements (see Note 6 for more detail). (8) Piedmont may extend the term for up to one additional year (through two available six month extensions to a final extended maturity date of September 29, 2023) provided Piedmont is not then in default and upon payment of extension fees. (9) The facility has a stated variable rate; however, Piedmont has entered into interest rate swap agreements which effectively fix, exclusive of changes to Piedmont's credit rating, $150 million of the principal balance to 4.11% through March 29, 2020, and $100 million of the principal balance to 4.21% from March 30, 2020 through the maturity date of the loan. For the remaining variable portion of the loan, Piedmont may periodically select from multiple interest rate options, including the prime rate and various-length LIBOR locks on all or a portion of the principal. All LIBOR selections are subject to an additional spread over the selected rate based on Piedmont’s current credit rating. The rate presented is the weighted-average rate for the effectively fixed and variable portions of the debt outstanding as of September 30, 2018 . Piedmont made interest payments on all debt facilities, including interest rate swap cash settlements, of approximately $18.0 million for both the three months ended September 30, 2018 and 2017 , respectively, and approximately $48.7 million and $54.0 million for the nine months ended September 30, 2018 and 2017 , respectively. Also, Piedmont capitalized interest of approximately $375,000 and $37,000 for the three months ended September 30, 2018 and 2017 , respectively, and approximately $0.8 million and $0.2 million for the nine months ended September 30, 2018 and 2017 , respectively. As of September 30, 2018 , Piedmont believes it was in compliance with all financial covenants associated with its debt instruments. See Note 7 for a description of Piedmont’s estimated fair value of debt as of September 30, 2018

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	Variable Interest Entities Variable interest holders who have the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and have the obligation to absorb the majority of losses of the entity or the right to receive significant benefits of the entity must consolidate the VIE. Each of the following VIEs has the sole purpose of holding land and office buildings and their resulting operations, and are classified in the accompanying consolidated balance sheets in the same manner as Piedmont’s wholly-owned properties. A summary of Piedmont’s interests in its consolidated VIEs and their related carrying values as of September 30, 2018 and December 31, 2017 is as follows (net carrying amount in millions): Piedmont's % Net Carrying Amount as of Net Carrying Amount as of Entity Ownership of Entity Related Building September 30, 2018 December 31, 2017 Primary Beneficiary Considerations 1201 Eye Street N.W. Associates, LLC 98.6% 1201 Eye Street $ 89.2 $ 81.1 In accordance with the partnership’s governing documents, Piedmont currently receives 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building. 1225 Eye Street N.W. Associates, LLC 98.1% 1225 Eye Street $ 64.8 $ 65.2 In accordance with the partnership’s governing documents, Piedmont currently receives 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building. Piedmont 500 W. Monroe Fee, LLC 100% 500 W. Monroe $ 256.2 $ 263.2 The Omnibus Agreement with the previous owner includes equity participation rights upon sale of the property for the previous owner, if certain financial returns are achieved; however, Piedmont has sole decision making authority and is entitled to 100% of the economic benefits of the property until such returns are met.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Risk Management Objective of Using Derivatives In addition to operational risks which arise in the normal course of business, Piedmont is exposed to economic risks such as interest rate, liquidity, and credit risk. In certain situations, Piedmont has entered into derivative financial instruments such as interest rate swap agreements and other similar agreements to manage interest rate risk exposure arising from current or future variable rate debt transactions. Interest rate swap agreements involve the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. Piedmont’s objective in using interest rate derivatives is to add stability to interest expense and to manage its exposure to interest rate movements. Cash Flow Hedges of Interest Rate Risk Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for Piedmont making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. As of September 30, 2018 , Piedmont was party to interest rate swap agreements, all of which are designated as effective cash flow hedges and fully hedge the variable cash flows covering the entire outstanding balance of the Amended and Restated $300 Million Unsecured 2011 Term Loan through January 2020, and $150 million of the $250 Million Unsecured 2018 Term Loan. The maximum length of time over which Piedmont is hedging its exposure to the variability in future cash flows for forecasted transactions is 78 months. A detail of Piedmont’s interest rate derivatives outstanding as of September 30, 2018 is as follows: Interest Rate Derivatives: Number of Swap Agreements Associated Debt Instrument Total Notional Amount (in millions) Effective Date Maturity Date Interest rate swaps 3 Amended and Restated $300 Million Unsecured 2011 Term Loan $ 300 11/22/2016 1/15/2020 Interest rate swaps 2 $250 Million Unsecured 2018 Term Loan $ 100 3/29/2018 3/31/2025 Interest rate swaps 1 $250 Million Unsecured 2018 Term Loan $ 50 3/29/2018 3/29/2020 Total $ 450 Piedmont presents its interest rate derivatives on its consolidated balance sheets on a gross basis as interest rate swap assets and interest rate swap liabilities. A detail of Piedmont’s interest rate derivatives on a gross and net basis as of September 30, 2018 and December 31, 2017 , respectively, is as follows (in thousands): Interest rate swaps classified as: September 30, December 31, Gross derivative assets $ 4,069 $ 688 Gross derivative liabilities — (1,478 ) Net derivative asset/(liability) $ 4,069 $ (790 ) The gain/(loss) on Piedmont's interest rate derivatives, including previously settled forward swaps, that was recorded in OCI and the accompanying consolidated statements of income as a component of interest expense for the three and nine months ended September 30, 2018 and 2017 , respectively, was as follows (in thousands): Three Months Ended Nine Months Ended Interest Rate Swaps in Cash Flow Hedging Relationships September 30, September 30, September 30, September 30, Amount of gain recognized in OCI $ 1,145 $ 175 $ 4,408 $ 307 Amount of previously recorded gain/(loss) reclassified from OCI into Interest Expense $ 434 $ (653 ) $ 885 $ (2,936 ) Amount of loss recognized on derivatives reclassified from OCI into Loss on Extinguishment of Debt $ — $ — $ (1,258 ) $ — Total amount of Interest Expense presented in the consolidated statements of income $ 15,849 $ 16,183 $ 45,294 $ 52,661 Total amount of Loss on Extinguishment of Debt presented in the consolidated statements of income (1) $ — $ — $ 1,680 $ — (1) Includes the write-off of approximately $0.4 million of discounts and unamortized debt issuance costs associated with the repayment of debt (see Note 4 ). Piedmont estimates that approximately $3.6 million will be reclassified from OCI as a reduction of interest expense over the next twelve months. Piedmont recognized no hedge ineffectiveness on its cash flow hedges during the three and nine months ended September 30, 2018 and 2017 , respectively. Additionally, see Note 7 for fair value disclosures of Piedmont's derivative instruments. Credit-risk-related Contingent Features Piedmont has agreements with its derivative counterparties that contain a provision whereby if Piedmont defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then Piedmont could also be declared in default on its derivative obligations. Because all of Piedmont's interest rate swaps are in an asset position, if Piedmont were to breach any of the contractual provisions of the derivative contracts, the settlement of its obligations under the agreements would not result in a penalty as of September 30, 2018

Fair Value Measurement of Finan

Fair Value Measurement of Financial Instruments	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurement of Financial Instruments	Fair Value Measurement of Financial Instruments Piedmont considers its cash and cash equivalents, tenant receivables, notes receivable, restricted cash and escrows, accounts payable and accrued expenses, interest rate swap agreements, and debt to meet the definition of financial instruments. The following table sets forth the carrying and estimated fair value for each of Piedmont’s financial instruments, as well as its level within the GAAP fair value hierarchy, as of September 30, 2018 and December 31, 2017 , respectively (in thousands): September 30, 2018 December 31, 2017 Financial Instrument Carrying Value Estimated Fair Value Level Within Fair Value Hierarchy Carrying Value Estimated Fair Value Level Within Fair Value Hierarchy Assets: Cash and cash equivalents (1) $ 6,807 $ 6,807 Level 1 $ 7,382 $ 7,382 Level 1 Tenant receivables, net (1) $ 10,522 $ 10,522 Level 1 $ 12,139 $ 12,139 Level 1 Notes receivable (1) $ 3,200 $ 3,200 Level 1 $ — $ — Level 1 Restricted cash and escrows (1) $ 1,374 $ 1,374 Level 1 $ 1,373 $ 1,373 Level 1 Interest rate swaps $ 4,069 $ 4,069 Level 2 $ 688 $ 688 Level 2 Liabilities: Accounts payable and accrued expenses (1) $ 14,584 $ 14,584 Level 1 $ 126,429 $ 126,429 Level 1 Interest rate swaps $ — $ — Level 2 $ 1,478 $ 1,478 Level 2 Debt, net $ 1,715,371 $ 1,714,923 Level 2 $ 1,726,927 $ 1,759,905 Level 2 (1) For the periods presented, the carrying value of these financial instruments approximates estimated fair value due to their short-term maturity. Piedmont's debt was carried at book value as of September 30, 2018 and December 31, 2017 ; however, to estimate its fair value as disclosed in the table above, Piedmont used widely accepted valuation techniques including discounted cash flow analysis based on the contractual terms of the debt facilities, including the period to maturity of each instrument, and observable market-based inputs for similar debt facilities which have transacted recently in the market. Therefore, the estimated fair values determined are considered to be based on significant other observable inputs (Level 2). Scaling adjustments are made to these inputs to make them applicable to the remaining life of Piedmont's outstanding debt. Piedmont has not changed its valuation technique for estimating the fair value of its debt. Piedmont’s interest rate swap agreements presented above (further discussed in Note 6 ) are classified as “Interest rate swap” assets and liabilities in the accompanying consolidated balance sheets and were carried at estimated fair value as of September 30, 2018 and December 31, 2017 . The estimated fair value of these derivative instruments was determined using widely accepted valuation techniques such as discounted cash flow analysis based on the contractual terms of the derivatives including the period to maturity of each instrument. Observable market-based inputs, including interest rate curves and implied volatilities, were also used. Therefore, the estimated fair values determined are considered to be based on significant other observable inputs (Level 2). In addition, Piedmont considered both its own and the respective counterparties’ risk of nonperformance in determining the estimated fair value of its derivative financial instruments by estimating the current and potential future exposure under the derivative financial instruments for both Piedmont and the counterparties that were at risk as of the valuation date. The credit risks of both Piedmont and its counterparties were factored into the calculation of the estimated fair value of the interest rate swaps; however, as of September 30, 2018 and December 31, 2017

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments Under Existing Lease Agreements Under its existing lease agreements, Piedmont may be required to fund significant tenant improvements, leasing commissions, and building improvements. In addition, certain agreements contain provisions that require Piedmont to issue corporate or property guarantees to provide funding for capital improvements or other financial obligations. Piedmont classifies its capital improvements into two categories: (i) improvements which maintain the building's existing asset value and its revenue generating capacity (“non-incremental capital expenditures”) and (ii) improvements which incrementally enhance the building's asset value by expanding its revenue generating capacity (“incremental capital expenditures”). As of September 30, 2018 , commitments to fund potential non-incremental capital expenditures over the next five years for tenant improvements totaled approximately $47.0 million related to Piedmont's existing lease portfolio over the respective lease terms, the majority of which Piedmont estimates may be required to be funded over the next three years based on when the underlying leases commence. For most of Piedmont’s leases, the timing of the actual funding of these tenant improvements is largely dependent upon tenant requests for reimbursement. In some cases, these obligations may expire with the leases without further recourse to Piedmont. As of September 30, 2018 , commitments for incremental capital expenditures for tenant improvements associated with executed leases totaled approximately $34.9 million . Contingencies Related to Tenant Audits/Disputes Certain lease agreements include provisions that grant tenants the right to engage independent auditors to audit their annual operating expense reconciliations. Such audits may result in the re-interpretation of language in the lease agreements which could result in the refund of previously recognized tenant reimbursement revenues, resulting in financial loss to Piedmont. Piedmont recorded $61,000 and $0 of such reductions in reimbursement revenues related to such tenant audits/disputes during the three months ended September 30, 2018 and 2017 , respectively, and $0.5 million and $0.3 million of such reductions in reimbursement revenues related to such tenant audits/disputes during the nine months ended September 30, 2018 and 2017

Assets Held for Sale

Assets Held for Sale	9 Months Ended
	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Assets Held for Sale	Assets Held for Sale As of September 30, 2018, the 800 North Brand Boulevard building in Glendale, California met the criteria for held for sale classification; consequently its assets and liabilities as of December 31, 2017 have also been reclassified as held for sale in the accompanying consolidated balance sheets for comparability purposes. In addition, during the nine months ended September 30, 2018 , Piedmont sold a portfolio of 14 properties (the "2017 Disposition Portfolio") which was also classified as held for sale as of December 31, 2017 in the consolidated balance sheets. Details of assets held for sale as of September 30, 2018 and December 31, 2017 are presented below (in thousands): September 30, 2018 December 31, 2017 Real estate assets held for sale, net: Land $ 23,608 $ 98,106 Building and improvements, less accumulated depreciation of $60,434 and $226,188 as of September 30, 2018 and December 31, 2017, respectively 90,281 348,374 Construction in progress 29 2,308 Total real estate assets held for sale, net $ 113,918 $ 448,788 Other assets held for sale, net: Straight-line rent receivables $ 7,607 $ 34,750 Prepaid expenses and other assets 1,157 1,624 Deferred lease costs, less accumulated amortization of $2,364 and $18,710 as of September 30, 2018 and December 31, 2017, respectively 3,988 24,819 Total other assets held for sale, net $ 12,752 $ 61,193 Other liabilities held for sale, net: Intangible lease liabilities, less accumulated amortization of $0 and $935 as of September 30, 2018 and December 31, 2017, respectively $ — $ 380

Stock Based Compensation

Stock Based Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Based Compensation	Stock Based Compensation The Compensation Committee of Piedmont's Board of Directors has periodically granted deferred stock awards to all of Piedmont's employees and independent directors. Employee awards typically vest ratably over a multi-year period and independent director awards vest over one year. Certain employees' long-term equity incentive program is split equally between the time-vested awards described above and a multi-year performance share program whereby the actual awards are contingent upon Piedmont's total stockholder return ("TSR") relative to a peer group of office REITs' TSR. The peer group is predetermined by the Board of Directors, advised by an outside compensation consultant. Any shares earned are awarded at the end of the multi-year performance period and vest upon award. A rollforward of Piedmont's equity based award activity for the nine months ended September 30, 2018 is as follows: Shares Weighted-Average Grant Date Fair Value Unvested and Potential Stock Awards as of December 31, 2017 868,437 $ 21.69 Deferred Stock Awards Granted 354,236 $ 17.84 Increase in Estimated Potential Share Award 313,827 $ 23.80 Performance Stock Awards Vested (161,005 ) $ 18.47 Deferred Stock Awards Vested (332,019 ) $ 19.21 Deferred Stock Awards Forfeited (8,481 ) $ 19.77 Unvested and Potential Stock Awards as of September 30, 2018 1,034,995 $ 22.36 The following table provides additional information regarding stock award activity during the three and nine months ended September 30, 2018 and 2017 , respectively (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Weighted-Average Grant Date Fair Value of Deferred Stock Granted During the Period $ — $ — $ 17.84 $ 21.38 Total Grant Date Fair Value of Deferred Stock Vested During the Period $ 16 $ 11 $ 6,378 $ 5,852 Share-based Liability Awards Paid During the Period (1) $ — $ — $ 2,947 $ 2,877 (1) Amounts reflect the issuance of performance share awards related to the 2014-16 and 2015-17 Performance Share Plans during the nine months ended September 30, 2018 and 2017 , respectively. A detail of Piedmont’s outstanding stock awards as of September 30, 2018 is as follows: Date of grant Type of Award Net Shares Granted (1) Grant Date Fair Value Vesting Schedule Unvested Shares January 3, 2014 Deferred Stock Award 72,969 $ 16.45 Of the shares granted, 20% vested or will vest on January 3, 2015, 2016, 2017, 2018, and 2019, respectively. 16,416 May 24, 2016 Deferred Stock Award 208,003 $ 19.91 Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on May 24, 2017, 2018, and 2019, respectively. 60,591 May 24, 2016 Fiscal Year 2016-2018 Performance Share Program — $ 23.02 Shares awarded, if any, will vest immediately upon determination of award in 2019. 99,337 (2) May 18, 2017 Deferred Stock Award 219,863 $ 21.38 Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on May 18, 2018, 2019, and 2020, respectively. 123,507 May 18, 2017 Fiscal Year 2017-2019 Performance Share Program — $ 30.45 Shares awarded, if any, will vest immediately upon determination of award in 2020. 143,335 (2) May 17, 2018 Deferred Stock Award-Board of Directors 31,388 $ 17.84 Of the shares granted, 100% will vest by May 17, 2019. 31,388 May 17, 2018 Deferred Stock Award 302,706 $ 17.84 Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on May 17, 2019, 2020, and 2021, respectively. 239,777 May 17, 2018 Fiscal Year 2018-2020 Performance Share Program — $ 23.52 Shares awarded, if any, will vest immediately upon determination of award in 2021. 320,644 (2) Total 1,034,995 (1) Amounts reflect the total grant to employees and independent directors, net of shares surrendered upon vesting to satisfy required minimum tax withholding obligations through September 30, 2018 . (2) Estimated based on Piedmont's cumulative TSR for the respective performance period through September 30, 2018 . Share estimates are subject to change in future periods based upon Piedmont's relative performance compared to its peer group of office REITs' total stockholder return. During the three months ended September 30, 2018 and 2017 , Piedmont recognized approximately $1.7 million and $1.3 million of compensation expense related to stock awards all of which is related to the amortization of unvested shares. During the nine months ended September 30, 2018 and 2017 , Piedmont recognized approximately $6.7 million and $7.0 million of compensation expense related to stock awards, of which $5.6 million and $5.4 million is related to the amortization of unvested shares, respectively. During the nine months ended September 30, 2018 , a net total of 355,055 shares were issued to employees. As of September 30, 2018 , approximately $5.1 million

Supplemental Disclosures for th

Supplemental Disclosures for the Statement of Consolidated Cash Flows	9 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosures for the Statement of Consolidated Cash Flows	Supplemental Disclosures for the Statement of Consolidated Cash Flows Certain noncash investing and financing activities for the nine months ended September 30, 2018 and 2017 , (in thousands) are outlined below: Nine Months Ended September 30, 2018 September 30, 2017 Accrued capital expenditures and deferred lease costs $ 21,784 $ 8,590 Change in accrued dividends and discount on dividend reinvestments $ (101,794 ) $ (30,531 ) Change in accrued share repurchases as part of an announced plan $ (1,277 ) $ — Investment in consolidated joint venture $ — $ 63,026 The following table provides a reconciliation of cash, cash equivalents, and restricted cash and escrows as reported, or previously reported, within the consolidated balance sheet to the consolidated statement of cash flows as of the nine months ended September 30, 2018 and 2017 , respectively (in thousands). Nine Months Ended September 30, 2018 September 30, 2017 Cash and cash equivalents, beginning of period $ 7,382 $ 6,992 Restricted cash and escrows, beginning of period 1,373 1,212 Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows, beginning of period $ 8,755 $ 8,204 Cash and cash equivalents, end of period $ 6,807 $ 36,108 Restricted cash and escrows, end of period 1,374 1,260 Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows, end of period $ 8,181 $ 37,368

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share There are no adjustments to “Net income applicable to Piedmont” for the diluted earnings per share computations. Net income per share-basic is calculated as net income available to common stockholders divided by the weighted average number of common shares outstanding during the period. Net income per share-diluted is calculated as net income available to common stockholders divided by the diluted weighted average number of common shares outstanding during the period, including unvested deferred stock awards. Diluted weighted average number of common shares reflects the potential dilution under the treasury stock method that would occur if the remaining unvested deferred stock awards vested and resulted in additional common shares outstanding. Unvested deferred stock awards which are determined to be anti-dilutive are not included in the calculation of diluted weighted average common shares. The following table reconciles the denominator for the basic and diluted earnings per share computations shown on the consolidated statements of income for the three and nine months ended September 30, 2018 and 2017 , respectively (in thousands): Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Weighted-average common shares – basic 128,371 145,416 130,837 145,372 Plus: Incremental weighted-average shares from time-vested deferred and performance stock awards 448 303 350 308 Weighted-average common shares – diluted 128,819 145,719 131,187 145,680 Common stock issued and outstanding as of period end 128,371 145,295

Guarantor and Non-Guarantor Fin

Guarantor and Non-Guarantor Financial Information	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Guarantor and Non-Guarantor Financial Information	Guarantor and Non-Guarantor Financial Information The following condensed consolidating financial information for Piedmont (the "Parent", "Guarantor", and/or "Consolidated"), Piedmont OP (the "Issuer"), and the other directly and indirectly owned subsidiaries of Piedmont as the Guarantor (the "Non-Guarantors") is provided pursuant to the requirements of Rule 3-10 of Regulation S-X regarding financial statements of guarantors and issuers of guaranteed registered securities. The Issuer is a wholly-owned subsidiary of the Guarantor, and all guarantees by the Guarantor of securities issued by the Issuer are full and unconditional. The principal elimination entries relate to investments in subsidiaries and intercompany balances and transactions, including transactions with the Non-Guarantors. Condensed Consolidating Balance Sheets As of September 30, 2018 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Piedmont (Consolidated) Assets: Real estate assets, at cost: Land $ — $ 36,094 $ 487,900 $ — $ 523,994 Buildings and improvements, less accumulated depreciation — 174,627 2,135,476 (300 ) 2,309,803 Intangible lease assets, less accumulated amortization — — 65,527 — 65,527 Construction in progress — 2,915 19,838 — 22,753 Real estate assets held for sale, net — — 113,918 — 113,918 Total real estate assets — 213,636 2,822,659 (300 ) 3,035,995 Cash and cash equivalents 150 3,024 3,633 — 6,807 Tenant and straight-line rent receivables, net — 15,757 163,510 — 179,267 Investment in subsidiaries 1,734,476 2,789,292 168 (4,523,936 ) — Notes receivable — 810 147,700 (145,310 ) 3,200 Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets 80 8,971 27,871 (9 ) 36,913 Goodwill — 98,918 — — 98,918 Deferred lease costs, net — 15,625 234,413 — 250,038 Other assets held for sale, net — 12,752 — 12,752 Total assets $ 1,734,706 $ 3,146,033 $ 3,412,706 $ (4,669,555 ) $ 3,623,890 Liabilities: Debt, net $ — $ 1,524,558 $ 336,123 $ (145,310 ) $ 1,715,371 Accounts payable, accrued expenses, and accrued capital expenditures 710 14,321 94,065 (9 ) 109,087 Deferred income — 1,853 25,597 — 27,450 Intangible lease liabilities, net — — 37,986 — 37,986 Total liabilities 710 1,540,732 493,771 (145,319 ) 1,889,894 Equity: Total stockholders’ equity 1,733,996 1,605,301 2,918,935 (4,524,236 ) 1,733,996 Total liabilities and stockholders’ equity $ 1,734,706 $ 3,146,033 $ 3,412,706 $ (4,669,555 ) $ 3,623,890 Condensed Consolidating Balance Sheets As of December 31, 2017 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Piedmont (Consolidated) Assets: Real estate assets, at cost: Land $ — $ 36,094 $ 485,092 $ — $ 521,186 Buildings and improvements, less accumulated depreciation — 180,886 2,144,696 (300 ) 2,325,282 Intangible lease assets, less accumulated amortization — 181 77,624 — 77,805 Construction in progress — 85 11,596 — 11,681 Real estate assets held for sale, net — 32,815 415,973 — 448,788 Total real estate assets — 250,061 3,134,981 (300 ) 3,384,742 Cash and cash equivalents 150 3,890 3,342 — 7,382 Tenant and straight-line rent receivables, net, and amounts due from unconsolidated joint ventures — 16,891 149,642 — 166,533 Advances to affiliates 1,674,276 6,297,632 — (7,971,908 ) — Investment in subsidiary 3,437,299 — 172 (3,437,471 ) — Notes receivable — 88,810 144,500 (233,310 ) — Prepaid expenses, restricted cash, escrows, interest rate swaps and other assets 2 5,094 18,927 (740 ) 23,283 Goodwill — 98,918 — — 98,918 Deferred lease costs, net — 16,611 241,305 — 257,916 Other assets held for sale, net — 2,266 58,927 — 61,193 Total assets $ 5,111,727 $ 6,780,173 $ 3,751,796 $ (11,643,729 ) $ 3,999,967 Liabilities: Debt, net $ — $ 1,535,239 $ 424,998 $ (233,310 ) $ 1,726,927 Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures 104,028 20,279 93,086 (740 ) 216,653 Advances from affiliates 5,277,957 941,494 1,850,712 (8,070,163 ) — Deferred income — 3,631 25,951 — 29,582 Intangible lease liabilities, net — — 38,458 — 38,458 Interest rate swaps — 1,478 — — 1,478 Liabilities held for sale, net — — 380 — 380 Total liabilities 5,381,985 2,502,121 2,433,585 (8,304,213 ) 2,013,478 Equity: Total stockholders’ equity (270,258 ) 4,278,052 1,318,211 (3,339,516 ) 1,986,489 Total liabilities and stockholders’ equity $ 5,111,727 $ 6,780,173 $ 3,751,796 $ (11,643,729 ) $ 3,999,967 Consolidating Statements of Income For the three months ended September 30, 2018 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Consolidated Revenues: Rental income $ — $ 8,403 $ 93,498 $ (553 ) $ 101,348 Tenant reimbursements — 2,458 20,853 (141 ) 23,170 Property management fee revenue — — 4,296 (3,928 ) 368 Other property related income — 35 4,787 — 4,822 — 10,896 123,434 (4,622 ) 129,708 Expenses: Property operating costs — 4,973 49,328 (4,622 ) 49,679 Depreciation — 2,816 24,036 — 26,852 Amortization — 446 14,394 — 14,840 General and administrative 42 1,424 5,211 — 6,677 42 9,659 92,969 (4,622 ) 98,048 Real estate operating income/(loss) (42 ) 1,237 30,465 — 31,660 Other income (expense): Interest expense — (14,119 ) (3,624 ) 1,894 (15,849 ) Other income/(expense) — 40 2,157 (1,894 ) 303 — (14,079 ) (1,467 ) — (15,546 ) Income/(loss) before consolidated subsidiaries (42 ) (12,842 ) 28,998 — 16,114 Income from subsidiaries 16,156 26,787 — (42,943 ) — Net income 16,114 13,945 28,998 (42,943 ) 16,114 Plus: Net loss applicable to noncontrolling interest — — — — — Net income applicable to Piedmont $ 16,114 $ 13,945 $ 28,998 $ (42,943 ) $ 16,114 Consolidating Statements of Income For the three months ended September 30, 2017 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Consolidated Revenues: Rental income $ — $ 10,185 $ 99,109 $ (426 ) $ 108,868 Tenant reimbursements — 2,381 22,014 (142 ) 24,253 Property management fee revenue — — 4,566 (4,112 ) 454 Other property related income — 42 3,970 — 4,012 — 12,608 129,659 (4,680 ) 137,587 Expenses: Property operating costs — 5,372 53,826 (4,680 ) 54,518 Depreciation — 3,199 26,801 — 30,000 Amortization — 740 17,383 — 18,123 General and administrative 77 1,539 4,574 — 6,190 77 10,850 102,584 (4,680 ) 108,831 Real estate operating income/(loss) (77 ) 1,758 27,075 — 28,756 Other income (expense): Interest expense — (13,795 ) (6,354 ) 3,966 (16,183 ) Other income/(expense) — 2,404 1,852 (3,966 ) 290 Equity in income of unconsolidated joint ventures — 3,754 — — 3,754 Gain/(loss) on sale of real estate assets, net — (4 ) 109,516 — 109,512 Net income/(loss) (77 ) (5,883 ) 132,089 — 126,129 Plus: Net loss applicable to noncontrolling interest — — 4 — 4 Net income/(loss) applicable to Piedmont $ (77 ) $ (5,883 ) $ 132,093 $ — $ 126,133 Consolidating Statements of Income For the nine months ended September 30, 2018 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Consolidated Revenues: Rental income $ — $ 26,456 $ 279,292 $ (1,468 ) $ 304,280 Tenant reimbursements — 7,298 61,247 (334 ) 68,211 Property management fee revenue — — 12,625 (11,566 ) 1,059 Other property related income — 92 15,140 — 15,232 — 33,846 368,304 (13,368 ) 388,782 Expenses: Property operating costs — 14,614 152,929 (13,368 ) 154,175 Depreciation — 8,527 72,585 — 81,112 Amortization — 1,520 45,298 — 46,818 General and administrative 228 4,849 16,410 — 21,487 228 29,510 287,222 (13,368 ) 303,592 Real estate operating income/(loss) (228 ) 4,336 81,082 — 85,190 Other income (expense): Interest expense — (40,093 ) (10,937 ) 5,736 (45,294 ) Other income/(expense) — 200 7,016 (5,736 ) 1,480 Loss on extinguishment of debt — (1,680 ) — — (1,680 ) Gain on sale of real estate assets, net — 1,417 43,769 — 45,186 — (40,156 ) 39,848 — (308 ) Income/(loss) before consolidated subsidiaries (228 ) (35,820 ) 120,930 — 84,882 Income from subsidiaries 85,114 119,013 — (204,127 ) — Net income 84,886 83,193 120,930 (204,127 ) 84,882 Plus: Net loss applicable to noncontrolling interest — — 4 — 4 Net income applicable to Piedmont $ 84,886 $ 83,193 $ 120,934 $ (204,127 ) $ 84,886 Consolidating Statements of Income For the nine months ended September 30, 2017 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Consolidated Revenues: Rental income $ — $ 32,641 $ 314,128 $ (1,370 ) $ 345,399 Tenant reimbursements — 8,352 65,396 (373 ) 73,375 Property management fee revenue — — 13,791 (12,412 ) 1,379 Other property related income — 97 14,479 — 14,576 — 41,090 407,794 (14,155 ) 434,729 Expenses: Property operating costs — 17,027 163,763 (14,155 ) 166,635 Depreciation — 9,943 80,884 — 90,827 Amortization — 2,399 55,453 — 57,852 General and administrative 261 4,798 16,809 — 21,868 261 34,167 316,909 (14,155 ) 337,182 Real estate operating income/(loss) (261 ) 6,923 90,885 — 97,547 Other income (expense): Interest expense — (43,049 ) (20,868 ) 11,256 (52,661 ) Other income/(expense) — 6,873 4,611 (11,256 ) 228 Equity in income of unconsolidated joint ventures — 3,872 — — 3,872 Gain on sale of real estate assets, net — 6,430 109,521 — 115,951 Net income/(loss) (261 ) (18,951 ) 184,149 — 164,937 Plus: Net loss applicable to noncontrolling interest — — 10 — 10 Net income/(loss) applicable to Piedmont $ (261 ) $ (18,951 ) $ 184,159 $ — $ 164,947 Consolidating Statements of Comprehensive Income For the Three Months Ended September 30, 2018 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Piedmont (Consolidated) Net income $ 16,114 $ 13,945 $ 28,998 $ (42,943 ) $ 16,114 Effective portion of gain on derivative instruments that are designated and qualify as cash flow hedges 1,145 1,145 — (1,145 ) 1,145 Plus: Reclassification of gain included in net income (434 ) (434 ) — 434 (434 ) Other comprehensive income 711 711 — (711 ) 711 Comprehensive income $ 16,825 $ 14,656 $ 28,998 $ (43,654 ) $ 16,825 Consolidating Statements of Comprehensive Income For the Nine Months Ended September 30, 2018 (in thousands) Piedmont Piedmont OP Non-Guarantors Eliminations Piedmont Net income $ 84,886 $ 83,193 $ 120,934 $ (204,127 ) $ 84,886 Effective portion of gain on derivatives instruments that are designated and qualify as cash flow hedges 4,408 4,408 — (4,408 ) 4,408 Plus: Reclassification of net loss included in net income 373 373 — (373 ) 373 Other comprehensive income 4,781 4,781 — (4,781 ) 4,781 Comprehensive income $ 89,667 $ 87,974 $ 120,934 $ (208,908 ) $ 89,667 Condensed Consolidating Statements of Cash Flows For the nine months ended September 30, 2018 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Piedmont (Consolidated) Net Cash Provided by Operating Activities $ 89,540 $ 89,639 $ 164,063 $ (204,920 ) $ 138,322 Cash Flows from Investing Activities: Investment in real estate assets and real estate related intangibles — (6,074 ) (67,100 ) — (73,174 ) Intercompany note receivable — 88,000 — (88,000 ) — Net sales proceeds from wholly-owned properties — 36,572 382,982 — 419,554 Note receivable issuance — — (3,200 ) — (3,200 ) Deferred lease costs paid — (1,826 ) (14,005 ) — (15,831 ) Distributions from subsidiaries 362,784 64,633 — (427,417 ) — Net cash provided by investing activities 362,784 181,305 298,677 (515,417 ) 327,349 Cash Flows from Financing Activities: Debt issuance and other costs paid — (947 ) — — (947 ) Proceeds from debt — 820,061 — — 820,061 Repayments of debt — (832,000 ) (1,005 ) — (833,005 ) Intercompany note payable — — (88,000 ) 88,000 — Value of shares withheld for payment of taxes related to employee stock compensation (2,219 ) — — — (2,219 ) Repurchases of common stock as part of announced plan (266,062 ) — — — (266,062 ) Distributions (184,043 ) (258,907 ) (373,460 ) 632,337 (184,073 ) Net cash used in financing activities (452,324 ) (271,793 ) (462,465 ) 720,337 (466,245 ) Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows — (849 ) 275 — (574 ) Cash, cash equivalents, and restricted cash and escrows, beginning of period 150 3,906 4,699 — 8,755 Cash, cash equivalents, and restricted cash and escrows, end of period $ 150 $ 3,057 $ 4,974 $ — $ 8,181 Condensed Consolidating Statements of Cash Flows For the nine months ended September 30, 2017 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Piedmont (Consolidated) Net Cash Provided by/(Used in) Operating Activities $ 4,335 $ (15,468 ) $ 187,513 $ — $ 176,380 Cash Flows from Investing Activities: Investment in real estate assets, and real estate related intangibles — (793 ) (64,614 ) — (65,407 ) Intercompany note receivable — — (48,710 ) 48,710 — Investments in unconsolidated joint ventures — (1,162 ) — — (1,162 ) Net sales proceeds from wholly-owned properties — 23,028 352,171 — 375,199 Net sales proceeds received from unconsolidated joint ventures — 12,334 — — 12,334 Deferred lease costs paid — (858 ) (18,561 ) — (19,419 ) Net cash provided by investing activities — 32,549 220,286 48,710 301,545 Cash Flows from Financing Activities: Debt issuance costs paid — (102 ) 1 — (101 ) Proceeds from debt — 147,000 — — 147,000 Repayments of debt — (325,000 ) (141,046 ) — (466,046 ) Intercompany note payable — (14,289 ) 62,999 (48,710 ) — Costs of issuance of common stock (97 ) — — — (97 ) Value of shares withheld for payment of taxes related to employee stock compensation (3,385 ) — — — (3,385 ) Repurchases of common stock as part of announced plan (3,895 ) — — — (3,895 ) (Distributions to)/repayments from affiliates 125,271 197,519 (322,790 ) — — Dividends paid and discount on dividend reinvestments (122,229 ) — (8 ) — (122,237 ) Net cash provided by/(used in) financing activities (4,335 ) 5,128 (400,844 ) (48,710 ) (448,761 ) Net increase in cash, cash equivalents, and restricted cash and escrows — 22,209 6,955 — 29,164 Cash, cash equivalents, and restricted cash and escrows, beginning of period 150 3,693 4,361 — 8,204 Cash, cash equivalents, and restricted cash and escrows, end of period $ 150 $ 25,902 $ 11,316 $ — $ 37,368

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Fourth Quarter Dividend Declaration On October 30, 2018 , the Board of Directors of Piedmont declared dividends for the fourth quarter 2018 in the amount of $0.21 per common share outstanding to stockholders of record as of the close of business on November 30, 2018 . Such dividends are to be paid on January 3, 2019 . Transactional Activity On October 25, 2018, Piedmont purchased 9320 Excelsior Boulevard in Hopkins, Minnesota for $49.4 million . 9320 Excelsior Boulevard is a 7-story, approximately 268,000 square foot, Class AA office building situated on 5.84 acres in close proximity to Piedmont's Norman Pointe I building acquired in 2017. 9320 Excelsior Boulevard is 100%

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	The consolidated financial statements of Piedmont have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”), including the instructions to Form 10-Q and Article 10 of Regulation S-X, and do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, the statements for the unaudited interim periods presented include all adjustments, which are of a normal and recurring nature, necessary for a fair presentation of the results for such periods. Results for these interim periods are not necessarily indicative of a full year’s results.
Principles of Consolidation	Piedmont’s consolidated financial statements include the accounts of Piedmont, Piedmont’s wholly-owned subsidiaries, any variable interest entity ("VIE") for which Piedmont or any of its wholly-owned subsidiaries is considered to have the power to direct the activities of the entity and the obligation to absorb losses/right to receive benefits, or any entity in which Piedmont or any of its wholly-owned subsidiaries owns a controlling interest. In determining whether Piedmont or Piedmont OP has a controlling interest, the following factors, among others, are considered: equity ownership, voting rights, protective rights of investors, and participatory rights of investors. For further information, refer to the financial statements and footnotes included in Piedmont’s Annual Report on Form 10-K for the year ended December 31, 2017 . All intercompany balances and transactions have been eliminated upon consolidation. Further, Piedmont has formed special purpose entities to acquire and hold real estate. Each special purpose entity is a separate legal entity. Consequently, the assets of these special purpose entities are not available to all creditors of Piedmont. The assets owned by these special purpose entities are being reported on a consolidated basis with Piedmont’s assets for financial reporting purposes only.
Use of Estimates	Use of Estimates
Income Taxes	Income Taxes Piedmont has elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended, and has operated as such, beginning with its taxable year ended December 31, 1998. To qualify as a REIT, Piedmont must meet certain organizational and operational requirements, including a requirement to distribute at least 90% of its annual REIT taxable income. As a REIT, Piedmont is generally not subject to federal income taxes, subject to fulfilling, among other things, its taxable income distribution requirement. Piedmont is subject to certain taxes related to the operations of properties in certain locations, as well as operations conducted by its taxable REIT subsidiary, POH, which have been provided for in the financial statements. Tax Cuts and Jobs Act The Tax Cuts and Jobs Act ("H.R. 1"), which generally took effect for taxable years that began on or after January 1, 2018 (subject to certain exceptions), made many significant changes to the U.S. federal income tax laws that will profoundly impact the taxation of individuals and corporations (including both regular C corporations and corporations that have elected to be taxed as REITs). For example, H.R. 1 limits the ability of corporations to utilize net operating loss carryforwards and limits the deductibility of business interest for all taxpayers, subject to an exception for taxpayers that are engaged in certain specified real property trades or business who make an irrevocable election not to apply the limitation to a particular real property trade or business and to depreciate their real property investments held in such trade or business using the less favorable alternative depreciation system. To date, the IRS has issued limited guidance with respect to certain of the provisions of H.R. 1, and there are numerous interpretive issues that will require guidance. In addition, changes made by H.R. 1 may require Piedmont to accrue certain income for U.S. federal income tax purposes no later than when such income is taken into account as revenue on its GAAP-based financial statements, unless the income is already subject to certain special methods of accounting under the Code. This could cause Piedmont to recognize taxable income prior to the receipt of the associated cash and accordingly, increase its distribution levels in order to maintain its status as a REIT. H.R. 1 also includes limitations on the deductibility of certain compensation paid to Piedmont's executives, certain interest payments, and certain net operating loss carryforwards, each of which could potentially increase Piedmont's taxable income and its required distributions. Piedmont recorded an approximate $ 0.2 million
Reclassifications	Reclassifications Certain prior period amounts presented in the accompanying consolidated statements of income have been reclassified to conform to the current period financial statement presentation. These amounts included: (i) the reclassification of approximately $4.0 million and $14.6 million for the three and nine months ended September 30, 2017 , respectively, of parking, antennae license and fiber income that was previously included in rental income into other property related income, as well as certain other miscellaneous revenue into tenant reimbursements and/or property management fee revenue in conjunction with the adoption of the Revenue Recognition Amendments, as further defined and described below; and (ii) the reclassification of $0.4 million and $1.4 million for the three and nine months ended September 30, 2017
Recent Accounting Pronouncements	Accounting Pronouncements Adopted during the Nine Months Ended September 30, 2018 Revenue Recognition On January 1, 2018, Piedmont adopted Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) ("ASU 2014-09") and Accounting Standards Update No. 2016-08, Revenue from Contracts with Customers (Topic 606) Principal versus Agent Considerations (Reporting Revenue Gross versus Net) ("ASU 2016-08") issued by the Financial Accounting Standards Board (the "FASB"). The amendments in ASU 2014-09, which are further clarified in ASU 2016-08, as well as Accounting Standards Update 2016-10, Accounting Standards Update 2016-12, and Accounting Standards Update 2016-20 (collectively the "Revenue Recognition Amendments") change the criteria for the recognition of certain revenue streams to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services using a five-step determination process. Piedmont's revenues which are included in the scope of the Revenue Recognition Amendments include its property management fee revenue, the majority of its parking revenue, as well as certain license agreements which allow third-parties to place their antennas or fiber-optic cabling on or inside Piedmont's buildings. Lease contracts are specifically excluded from the Revenue Recognition Amendments and, Piedmont intends to utilize a leasing practical expedient (see further discussion below) to group certain non-lease components related to operating expense reimbursements with other leasing components, provided they meet certain criteria. Because the timing and pattern of transfer of Piedmont's non-lease related revenue already followed the prescribed method of the Revenue Recognition Amendments, Piedmont was able to effectively adopt these amendments on a full retrospective basis, with no impact to the timing of recognition of the related revenue; however, such non-lease revenues are now being presented as "Other property related income" in the accompanying consolidated statements of income. Further, for comparative purposes, Piedmont reclassified approximately $4.0 million and $14.6 million for the three and nine months ended September 30, 2017 , respectively, of parking, antennae license, and fiber income that was previously included in rental income into other property related income, as well as certain other miscellaneous revenue into tenant reimbursements and/or property management fee revenue. Piedmont did not elect to adopt any practical expedients provided by the Revenue Recognition Amendments. A detail of Piedmont's total revenues for the three months ended September 30, 2018 and 2017 (after reclassifications as a result of the adoption of the Revenue Recognition Amendments), including a detailed description of each line item is as follows: (After Adoption of Revenue Recognition Amendments) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Rental income $ 101,348 $ 108,868 Tenant reimbursements 23,170 24,253 Property management fee revenue 368 454 Other property related income 4,822 4,012 Total revenues $ 129,708 $ 137,587 Rental income - consists of revenue from leases with Piedmont's tenants, which is not within the scope of the Revenue Recognition Amendments. Tenant reimbursements - consists of separately billed revenue derived from reimbursements for services prescribed by leases with Piedmont's tenants separate from, but in conjunction with, the revenue generated from leasing office space. Such income is not within the scope of the Revenue Recognition Amendments. Property management fee revenue - consists of revenue earned by Piedmont related to operating and managing office properties owned by other third-parties. Such income is within the scope of the Revenue Recognition Amendments; however, because the property management services represent a performance obligation that would be satisfied over the length of the contract, not at any specific point in time, and has the same measure of transfer (time elapsed), property management fee revenue will be recognized over time, consistent with the timing of Piedmont’s historic recognition. Any variable consideration transferred as part of these management agreements will continue to be recognized in the quarter that the underlying cash receipts are collected, consistent with the allocation objective of allocating the transaction price in an amount that depicts the amount of consideration to which Piedmont expects to be entitled in exchange for transferring the promised service to the customer. Other property related income - consists of all other property related income from Piedmont's customers (tenants) that is not derived from a contract meeting the definition of a lease. Examples of such income include parking revenue and income from licenses with unrelated third-parties to place antennae and/or fiber optic cables in or on Piedmont's buildings. Since these services are substantially the same and have the same pattern of transfer, there is no timing difference between the recognition of other property related income and the recognition of the underlying expense/delivery of “service” under the new Revenue Recognition Amendments. Additionally, no modification to the timing of Piedmont’s previous revenue recognition is necessary, as these items have been recognized historically in accordance with this pattern of transfer. Gain/(loss) on Sale of Real Estate Assets On January 1, 2018, Piedmont adopted 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") concurrent with the Revenue Recognition Amendments mentioned above. Piedmont elected to apply the amendments of ASU 2017-05 on a full retrospective basis; however, there were no adjustments to previously recorded gains/(losses) on sale of real estate as a result of the transition. Equity Investments Held in Non-qualified Deferred Compensation Plan On January 1, 2018, Piedmont adopted Accounting Standards Update No. 2016-01, Financial Instruments - Overall (Subtopic 825-10), Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"), as well as Accounting Standards Update No. 2018-03 Technical Corrections and Improvements to Financial Instruments-Overall (Subtopic 825-10) ("ASU 2018-03"). These amendments require equity investments, except those accounted for under the equity method of accounting, to be measured at estimated fair value with changes in fair value recognized in net income. Investments in trading securities held in a "rabbi trust" by Piedmont are the only securities affected by ASU 2016-01 and ASU 2018-03. As such, Piedmont has made a cumulative-effect adjustment to its consolidated balance sheet and consolidated statements of stockholders' equity of approximately $0.1 million from other comprehensive income ("OCI") to cumulative distributions in excess of earnings, and has recorded changes in fair value in net income for the three and nine months ended September 30, 2018 related to these investment securities. Interest Rate Derivatives On January 1, 2018, Piedmont early adopted Accounting Standards Update No. 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities ("ASU 2017-12"). Piedmont adopted ASU 2017-12 using the modified retrospective transition method; however, no adjustment was necessary to account for the cumulative effect of the change on the opening balance of each affected component of equity in the consolidated balance sheet as of the date of adoption because there was no cumulative ineffectiveness that had been recorded on Piedmont's existing interest rate swaps as of December 31, 2017, and all trades were highly effective. The amended presentation and disclosure guidance which is required to be presented prospectively is provided in Note 6 . Other Recent Accounting Pronouncements The FASB has issued Accounting Standards Update No. 2016-02, Leases (Topic 842) ("ASU 2016-02"), which fundamentally changes the definition of a lease, as well as the accounting for operating leases by requiring lessees to recognize assets and liabilities which arise from the lease, consisting of a liability to make lease payments (the lease liability) and a right-of-use asset, representing the right to use the leased asset over the term of the lease. Accounting for leases by lessors is substantially unchanged from prior practice as lessors will continue to recognize lease revenue on a straight-line basis. Additionally, the FASB has subsequently issued a number of clarifying and technical corrections to ASU 2016-02 through several Accounting Standards Updates ("ASU") as follows: ASU Title Summary Anticipated Impact on Piedmont's Consolidated Financial Statements Based on Management’s Assessment to Date ASU 2018-01 Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842 Clarifies that a land easement is required to be evaluated to determine whether it should be accounted for as a lease upon adoption of ASU 2016-02; also provides an optional practical transition expedient allowing entities not currently assessing land easements under existing leasing guidance prior to adoption of ASU 2016-02 to not apply the new guidance to land easements existing at the date of initial adoption of ASU 2016-02. Not applicable as Piedmont has no land easements. ASU 2018-10 Codification Improvements to Topic 842, Leases Clarifications and technical corrections to ASU 2016-02. No material impact expected. ASU 2018-11 Leases (Topic 842) Targeted Improvements Allows certain non-lease operating expense reimbursements which are included in the underlying stated lease rate to be accounted for as part of the lease provided certain criteria are met under an optional practical expedient. All of Piedmont’s operating expense reimbursements are expected to qualify to be accounted for as a part of the underlying lease. Although management continues to evaluate the guidance and disclosures required by all of the above ASUs, Piedmont does not anticipate any material impact to its consolidated financial statements as a result of adoption related to lessor accounting. However, Piedmont does anticipate recording an immaterial right-to-use asset and offsetting lease liability under lessee accounting on its balance sheet upon adoption of ASU 2016-02 on January 1, 2019. The FASB has issued Accounting Standards Update No. 2018-07, Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07"). The provisions of ASU 2018-07 align accounting for stock based compensation for non-employees for goods and services with existing accounting for similar compensation for employees. The amendments supersede previous guidance on accounting for share-based payments to non-employees codified in the FASB's Accounting Standards Codification ("ASC") 505-50. ASU 2018-07 is effective in the first quarter of 2019, with early adoption permitted at any time provided that the entity has already adopted the provisions of ASC 606. P iedmont does not anticipate any material impact to its consolidated financial statements as a result of adoption. The FASB has issued Accounting Standards Update No. 2016-13, Financial Instruments—Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments
Risk Management Objective of Using Derivatives	Risk Management Objective of Using Derivatives

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	A detail of Piedmont's total revenues for the three months ended September 30, 2018 and 2017 (after reclassifications as a result of the adoption of the Revenue Recognition Amendments), including a detailed description of each line item is as follows: (After Adoption of Revenue Recognition Amendments) Three Months Ended September 30, 2018 Three Months Ended September 30, 2017 Rental income $ 101,348 $ 108,868 Tenant reimbursements 23,170 24,253 Property management fee revenue 368 454 Other property related income 4,822 4,012 Total revenues $ 129,708 $ 137,587

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Schedule of Purchased Assets	During the nine months ended September 30, 2018 , Piedmont acquired one property using proceeds available as a result of dispositions (see Note 9 ) in January 2018 and cash on hand, as noted below: Property Metropolitan Statistical Area Date of Acquisition Ownership Percentage Acquired Rentable Square Feet Percentage Leased as of Acquisition Net Contractual Purchase Price (in millions) 501 West Church Street Orlando, Florida February 23, 2018 100 % 182,461 100 % $ 28.2

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of Debt	The following table summarizes the terms of Piedmont’s indebtedness outstanding as of September 30, 2018 and December 31, 2017 (in thousands): Facility (1) Stated Rate Effective Rate (2) Maturity Amount Outstanding as of September 30, 2018 December 31, 2017 Secured (Fixed) $35 Million Fixed-Rate Loan (3) 5.55 % 3.75 % 9/1/2021 $ 30,033 $ 30,670 $160 Million Fixed-Rate Loan (4) 3.48 % 3.58 % 7/5/2022 160,000 160,000 Net premium and unamortized debt issuance costs 720 946 Subtotal/Weighted Average (5) 3.81 % 190,753 191,616 Unsecured (Variable and Fixed) $170 Million Unsecured 2015 Term Loan LIBOR + 1.125% 2.54 % 5/15/2018 — 170,000 $300 Million Unsecured 2013 Term Loan LIBOR + 1.20% 2.78 % (7) 1/31/2019 — 300,000 $500 Million Unsecured 2015 Line of Credit (6) LIBOR + 1.00% 3.17 % 6/18/2019 — 23,000 $500 Million Unsecured 2018 Line of Credit (6) LIBOR + 0.90% 3.15 % 9/30/2022 (8) 235,000 — Amended and Restated $300 Million Unsecured 2011 Term Loan LIBOR + 1.00% 3.20 % (7) 11/30/2021 300,000 300,000 $350 Million Senior Notes 3.40 % 3.43 % 6/01/2023 350,000 350,000 $400 Million Senior Notes 4.45 % 4.10 % 3/15/2024 400,000 400,000 $250 Million Unsecured 2018 Term Loan LIBOR + 1.60% 4.00 % (9) 3/31/2025 250,000 — Discounts and unamortized debt issuance costs (10,382) (7,689) Subtotal/Weighted Average (5) 3.69 % 1,524,618 1,535,311 Total/Weighted Average (5) 3.71 % $ 1,715,371 $ 1,726,927 (1) Other than the $35 Million Fixed-Rate Loan, all of Piedmont’s outstanding debt as of September 30, 2018 and December 31, 2017 is interest-only. (2) Effective rate after consideration of settled or in-place interest rate swap agreements, issuance premiums/discounts, and/or fair market value adjustments upon assumption of debt. (3) Collateralized by the 5 Wall Street building in Burlington, Massachusetts. (4) Collateralized by the 1901 Market Street building in Philadelphia, Pennsylvania. (5) Weighted average is based on contractual balance of outstanding debt and the stated or effectively fixed interest rates as of September 30, 2018 . (6) On a periodic basis, Piedmont may select from multiple interest rate options, including the prime rate and various-length LIBOR locks on all or a portion of the principal. All LIBOR selections are subject to an additional spread over the selected rate based on Piedmont’s current credit rating. (7) The facility has a stated variable rate; however, Piedmont has entered into interest rate swap agreements which effectively fix, exclusive of changes in Piedmont's credit rating, the rate to that shown as the effective rate through the maturity date of the interest rate swap agreements (see Note 6 for more detail). (8) Piedmont may extend the term for up to one additional year (through two available six month extensions to a final extended maturity date of September 29, 2023) provided Piedmont is not then in default and upon payment of extension fees. (9) The facility has a stated variable rate; however, Piedmont has entered into interest rate swap agreements which effectively fix, exclusive of changes to Piedmont's credit rating, $150 million of the principal balance to 4.11% through March 29, 2020, and $100 million of the principal balance to 4.21% from March 30, 2020 through the maturity date of the loan. For the remaining variable portion of the loan, Piedmont may periodically select from multiple interest rate options, including the prime rate and various-length LIBOR locks on all or a portion of the principal. All LIBOR selections are subject to an additional spread over the selected rate based on Piedmont’s current credit rating. The rate presented is the weighted-average rate for the effectively fixed and variable portions of the debt outstanding as of September 30, 2018 .

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Variable Interest Entities	A summary of Piedmont’s interests in its consolidated VIEs and their related carrying values as of September 30, 2018 and December 31, 2017 is as follows (net carrying amount in millions): Piedmont's % Net Carrying Amount as of Net Carrying Amount as of Entity Ownership of Entity Related Building September 30, 2018 December 31, 2017 Primary Beneficiary Considerations 1201 Eye Street N.W. Associates, LLC 98.6% 1201 Eye Street $ 89.2 $ 81.1 In accordance with the partnership’s governing documents, Piedmont currently receives 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building. 1225 Eye Street N.W. Associates, LLC 98.1% 1225 Eye Street $ 64.8 $ 65.2 In accordance with the partnership’s governing documents, Piedmont currently receives 100% of the cash flow of the entity and has sole discretion in directing the management and leasing activities of the building. Piedmont 500 W. Monroe Fee, LLC 100% 500 W. Monroe $ 256.2 $ 263.2 The Omnibus Agreement with the previous owner includes equity participation rights upon sale of the property for the previous owner, if certain financial returns are achieved; however, Piedmont has sole decision making authority and is entitled to 100% of the economic benefits of the property until such returns are met.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts of Outstanding Derivative Positions	A detail of Piedmont’s interest rate derivatives outstanding as of September 30, 2018 is as follows: Interest Rate Derivatives: Number of Swap Agreements Associated Debt Instrument Total Notional Amount (in millions) Effective Date Maturity Date Interest rate swaps 3 Amended and Restated $300 Million Unsecured 2011 Term Loan $ 300 11/22/2016 1/15/2020 Interest rate swaps 2 $250 Million Unsecured 2018 Term Loan $ 100 3/29/2018 3/31/2025 Interest rate swaps 1 $250 Million Unsecured 2018 Term Loan $ 50 3/29/2018 3/29/2020 Total $ 450
Schedule of Interest Rate Derivatives	A detail of Piedmont’s interest rate derivatives on a gross and net basis as of September 30, 2018 and December 31, 2017 , respectively, is as follows (in thousands): Interest rate swaps classified as: September 30, December 31, Gross derivative assets $ 4,069 $ 688 Gross derivative liabilities — (1,478 ) Net derivative asset/(liability) $ 4,069 $ (790 )
Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss)	The gain/(loss) on Piedmont's interest rate derivatives, including previously settled forward swaps, that was recorded in OCI and the accompanying consolidated statements of income as a component of interest expense for the three and nine months ended September 30, 2018 and 2017 , respectively, was as follows (in thousands): Three Months Ended Nine Months Ended Interest Rate Swaps in Cash Flow Hedging Relationships September 30, September 30, September 30, September 30, Amount of gain recognized in OCI $ 1,145 $ 175 $ 4,408 $ 307 Amount of previously recorded gain/(loss) reclassified from OCI into Interest Expense $ 434 $ (653 ) $ 885 $ (2,936 ) Amount of loss recognized on derivatives reclassified from OCI into Loss on Extinguishment of Debt $ — $ — $ (1,258 ) $ — Total amount of Interest Expense presented in the consolidated statements of income $ 15,849 $ 16,183 $ 45,294 $ 52,661 Total amount of Loss on Extinguishment of Debt presented in the consolidated statements of income (1) $ — $ — $ 1,680 $ — (1) Includes the write-off of approximately $0.4 million of discounts and unamortized debt issuance costs associated with the repayment of debt (see Note 4 ).

Fair Value Measurement of Fin_2

Fair Value Measurement of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value, by Balance Sheet Grouping	The following table sets forth the carrying and estimated fair value for each of Piedmont’s financial instruments, as well as its level within the GAAP fair value hierarchy, as of September 30, 2018 and December 31, 2017 , respectively (in thousands): September 30, 2018 December 31, 2017 Financial Instrument Carrying Value Estimated Fair Value Level Within Fair Value Hierarchy Carrying Value Estimated Fair Value Level Within Fair Value Hierarchy Assets: Cash and cash equivalents (1) $ 6,807 $ 6,807 Level 1 $ 7,382 $ 7,382 Level 1 Tenant receivables, net (1) $ 10,522 $ 10,522 Level 1 $ 12,139 $ 12,139 Level 1 Notes receivable (1) $ 3,200 $ 3,200 Level 1 $ — $ — Level 1 Restricted cash and escrows (1) $ 1,374 $ 1,374 Level 1 $ 1,373 $ 1,373 Level 1 Interest rate swaps $ 4,069 $ 4,069 Level 2 $ 688 $ 688 Level 2 Liabilities: Accounts payable and accrued expenses (1) $ 14,584 $ 14,584 Level 1 $ 126,429 $ 126,429 Level 1 Interest rate swaps $ — $ — Level 2 $ 1,478 $ 1,478 Level 2 Debt, net $ 1,715,371 $ 1,714,923 Level 2 $ 1,726,927 $ 1,759,905 Level 2 (1) For the periods presented, the carrying value of these financial instruments approximates estimated fair value due to their short-term maturity.

Assets Held for Sale (Tables)

Assets Held for Sale (Tables)	9 Months Ended
	Sep. 30, 2018
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Assets Held for Sale	Details of assets held for sale as of September 30, 2018 and December 31, 2017 are presented below (in thousands): September 30, 2018 December 31, 2017 Real estate assets held for sale, net: Land $ 23,608 $ 98,106 Building and improvements, less accumulated depreciation of $60,434 and $226,188 as of September 30, 2018 and December 31, 2017, respectively 90,281 348,374 Construction in progress 29 2,308 Total real estate assets held for sale, net $ 113,918 $ 448,788 Other assets held for sale, net: Straight-line rent receivables $ 7,607 $ 34,750 Prepaid expenses and other assets 1,157 1,624 Deferred lease costs, less accumulated amortization of $2,364 and $18,710 as of September 30, 2018 and December 31, 2017, respectively 3,988 24,819 Total other assets held for sale, net $ 12,752 $ 61,193 Other liabilities held for sale, net: Intangible lease liabilities, less accumulated amortization of $0 and $935 as of September 30, 2018 and December 31, 2017, respectively $ — $ 380

Stock Based Compensation (Table

Stock Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Nonvested Share Activity	A rollforward of Piedmont's equity based award activity for the nine months ended September 30, 2018 is as follows: Shares Weighted-Average Grant Date Fair Value Unvested and Potential Stock Awards as of December 31, 2017 868,437 $ 21.69 Deferred Stock Awards Granted 354,236 $ 17.84 Increase in Estimated Potential Share Award 313,827 $ 23.80 Performance Stock Awards Vested (161,005 ) $ 18.47 Deferred Stock Awards Vested (332,019 ) $ 19.21 Deferred Stock Awards Forfeited (8,481 ) $ 19.77 Unvested and Potential Stock Awards as of September 30, 2018 1,034,995 $ 22.36 The following table provides additional information regarding stock award activity during the three and nine months ended September 30, 2018 and 2017 , respectively (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, Weighted-Average Grant Date Fair Value of Deferred Stock Granted During the Period $ — $ — $ 17.84 $ 21.38 Total Grant Date Fair Value of Deferred Stock Vested During the Period $ 16 $ 11 $ 6,378 $ 5,852 Share-based Liability Awards Paid During the Period (1) $ — $ — $ 2,947 $ 2,877 (1) Amounts reflect the issuance of performance share awards related to the 2014-16 and 2015-17 Performance Share Plans during the nine months ended September 30, 2018 and 2017
Schedule of Outstanding Employee Stock Awards	A detail of Piedmont’s outstanding stock awards as of September 30, 2018 is as follows: Date of grant Type of Award Net Shares Granted (1) Grant Date Fair Value Vesting Schedule Unvested Shares January 3, 2014 Deferred Stock Award 72,969 $ 16.45 Of the shares granted, 20% vested or will vest on January 3, 2015, 2016, 2017, 2018, and 2019, respectively. 16,416 May 24, 2016 Deferred Stock Award 208,003 $ 19.91 Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on May 24, 2017, 2018, and 2019, respectively. 60,591 May 24, 2016 Fiscal Year 2016-2018 Performance Share Program — $ 23.02 Shares awarded, if any, will vest immediately upon determination of award in 2019. 99,337 (2) May 18, 2017 Deferred Stock Award 219,863 $ 21.38 Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on May 18, 2018, 2019, and 2020, respectively. 123,507 May 18, 2017 Fiscal Year 2017-2019 Performance Share Program — $ 30.45 Shares awarded, if any, will vest immediately upon determination of award in 2020. 143,335 (2) May 17, 2018 Deferred Stock Award-Board of Directors 31,388 $ 17.84 Of the shares granted, 100% will vest by May 17, 2019. 31,388 May 17, 2018 Deferred Stock Award 302,706 $ 17.84 Of the shares granted, 25% vested on the date of grant, and 25% vested or will vest on May 17, 2019, 2020, and 2021, respectively. 239,777 May 17, 2018 Fiscal Year 2018-2020 Performance Share Program — $ 23.52 Shares awarded, if any, will vest immediately upon determination of award in 2021. 320,644 (2) Total 1,034,995 (1) Amounts reflect the total grant to employees and independent directors, net of shares surrendered upon vesting to satisfy required minimum tax withholding obligations through September 30, 2018 . (2) Estimated based on Piedmont's cumulative TSR for the respective performance period through September 30, 2018 . Share estimates are subject to change in future periods based upon Piedmont's relative performance compared to its peer group of office REITs' total stockholder return.

Supplemental Disclosures for _2

Supplemental Disclosures for the Statement of Consolidated Cash Flows (Tables)	9 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Certain noncash investing and financing activities for the nine months ended September 30, 2018 and 2017 , (in thousands) are outlined below: Nine Months Ended September 30, 2018 September 30, 2017 Accrued capital expenditures and deferred lease costs $ 21,784 $ 8,590 Change in accrued dividends and discount on dividend reinvestments $ (101,794 ) $ (30,531 ) Change in accrued share repurchases as part of an announced plan $ (1,277 ) $ — Investment in consolidated joint venture $ — $ 63,026 The following table provides a reconciliation of cash, cash equivalents, and restricted cash and escrows as reported, or previously reported, within the consolidated balance sheet to the consolidated statement of cash flows as of the nine months ended September 30, 2018 and 2017 , respectively (in thousands). Nine Months Ended September 30, 2018 September 30, 2017 Cash and cash equivalents, beginning of period $ 7,382 $ 6,992 Restricted cash and escrows, beginning of period 1,373 1,212 Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows, beginning of period $ 8,755 $ 8,204 Cash and cash equivalents, end of period $ 6,807 $ 36,108 Restricted cash and escrows, end of period 1,374 1,260 Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows, end of period $ 8,181 $ 37,368

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of Weighted Average Number of Shares	The following table reconciles the denominator for the basic and diluted earnings per share computations shown on the consolidated statements of income for the three and nine months ended September 30, 2018 and 2017 , respectively (in thousands): Three Months Ended Nine Months Ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Weighted-average common shares – basic 128,371 145,416 130,837 145,372 Plus: Incremental weighted-average shares from time-vested deferred and performance stock awards 448 303 350 308 Weighted-average common shares – diluted 128,819 145,719 131,187 145,680 Common stock issued and outstanding as of period end 128,371 145,295

Guarantor and Non-Guarantor F_2

Guarantor and Non-Guarantor Financial Information (Tables)	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Condensed Consolidated Balance Sheets	Condensed Consolidating Balance Sheets As of September 30, 2018 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Piedmont (Consolidated) Assets: Real estate assets, at cost: Land $ — $ 36,094 $ 487,900 $ — $ 523,994 Buildings and improvements, less accumulated depreciation — 174,627 2,135,476 (300 ) 2,309,803 Intangible lease assets, less accumulated amortization — — 65,527 — 65,527 Construction in progress — 2,915 19,838 — 22,753 Real estate assets held for sale, net — — 113,918 — 113,918 Total real estate assets — 213,636 2,822,659 (300 ) 3,035,995 Cash and cash equivalents 150 3,024 3,633 — 6,807 Tenant and straight-line rent receivables, net — 15,757 163,510 — 179,267 Investment in subsidiaries 1,734,476 2,789,292 168 (4,523,936 ) — Notes receivable — 810 147,700 (145,310 ) 3,200 Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets 80 8,971 27,871 (9 ) 36,913 Goodwill — 98,918 — — 98,918 Deferred lease costs, net — 15,625 234,413 — 250,038 Other assets held for sale, net — 12,752 — 12,752 Total assets $ 1,734,706 $ 3,146,033 $ 3,412,706 $ (4,669,555 ) $ 3,623,890 Liabilities: Debt, net $ — $ 1,524,558 $ 336,123 $ (145,310 ) $ 1,715,371 Accounts payable, accrued expenses, and accrued capital expenditures 710 14,321 94,065 (9 ) 109,087 Deferred income — 1,853 25,597 — 27,450 Intangible lease liabilities, net — — 37,986 — 37,986 Total liabilities 710 1,540,732 493,771 (145,319 ) 1,889,894 Equity: Total stockholders’ equity 1,733,996 1,605,301 2,918,935 (4,524,236 ) 1,733,996 Total liabilities and stockholders’ equity $ 1,734,706 $ 3,146,033 $ 3,412,706 $ (4,669,555 ) $ 3,623,890 Condensed Consolidating Balance Sheets As of December 31, 2017 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Piedmont (Consolidated) Assets: Real estate assets, at cost: Land $ — $ 36,094 $ 485,092 $ — $ 521,186 Buildings and improvements, less accumulated depreciation — 180,886 2,144,696 (300 ) 2,325,282 Intangible lease assets, less accumulated amortization — 181 77,624 — 77,805 Construction in progress — 85 11,596 — 11,681 Real estate assets held for sale, net — 32,815 415,973 — 448,788 Total real estate assets — 250,061 3,134,981 (300 ) 3,384,742 Cash and cash equivalents 150 3,890 3,342 — 7,382 Tenant and straight-line rent receivables, net, and amounts due from unconsolidated joint ventures — 16,891 149,642 — 166,533 Advances to affiliates 1,674,276 6,297,632 — (7,971,908 ) — Investment in subsidiary 3,437,299 — 172 (3,437,471 ) — Notes receivable — 88,810 144,500 (233,310 ) — Prepaid expenses, restricted cash, escrows, interest rate swaps and other assets 2 5,094 18,927 (740 ) 23,283 Goodwill — 98,918 — — 98,918 Deferred lease costs, net — 16,611 241,305 — 257,916 Other assets held for sale, net — 2,266 58,927 — 61,193 Total assets $ 5,111,727 $ 6,780,173 $ 3,751,796 $ (11,643,729 ) $ 3,999,967 Liabilities: Debt, net $ — $ 1,535,239 $ 424,998 $ (233,310 ) $ 1,726,927 Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures 104,028 20,279 93,086 (740 ) 216,653 Advances from affiliates 5,277,957 941,494 1,850,712 (8,070,163 ) — Deferred income — 3,631 25,951 — 29,582 Intangible lease liabilities, net — — 38,458 — 38,458 Interest rate swaps — 1,478 — — 1,478 Liabilities held for sale, net — — 380 — 380 Total liabilities 5,381,985 2,502,121 2,433,585 (8,304,213 ) 2,013,478 Equity: Total stockholders’ equity (270,258 ) 4,278,052 1,318,211 (3,339,516 ) 1,986,489 Total liabilities and stockholders’ equity $ 5,111,727 $ 6,780,173 $ 3,751,796 $ (11,643,729 ) $ 3,999,967
Condensed Consolidated Statements of Income	Consolidating Statements of Income For the three months ended September 30, 2018 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Consolidated Revenues: Rental income $ — $ 8,403 $ 93,498 $ (553 ) $ 101,348 Tenant reimbursements — 2,458 20,853 (141 ) 23,170 Property management fee revenue — — 4,296 (3,928 ) 368 Other property related income — 35 4,787 — 4,822 — 10,896 123,434 (4,622 ) 129,708 Expenses: Property operating costs — 4,973 49,328 (4,622 ) 49,679 Depreciation — 2,816 24,036 — 26,852 Amortization — 446 14,394 — 14,840 General and administrative 42 1,424 5,211 — 6,677 42 9,659 92,969 (4,622 ) 98,048 Real estate operating income/(loss) (42 ) 1,237 30,465 — 31,660 Other income (expense): Interest expense — (14,119 ) (3,624 ) 1,894 (15,849 ) Other income/(expense) — 40 2,157 (1,894 ) 303 — (14,079 ) (1,467 ) — (15,546 ) Income/(loss) before consolidated subsidiaries (42 ) (12,842 ) 28,998 — 16,114 Income from subsidiaries 16,156 26,787 — (42,943 ) — Net income 16,114 13,945 28,998 (42,943 ) 16,114 Plus: Net loss applicable to noncontrolling interest — — — — — Net income applicable to Piedmont $ 16,114 $ 13,945 $ 28,998 $ (42,943 ) $ 16,114 Consolidating Statements of Income For the three months ended September 30, 2017 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Consolidated Revenues: Rental income $ — $ 10,185 $ 99,109 $ (426 ) $ 108,868 Tenant reimbursements — 2,381 22,014 (142 ) 24,253 Property management fee revenue — — 4,566 (4,112 ) 454 Other property related income — 42 3,970 — 4,012 — 12,608 129,659 (4,680 ) 137,587 Expenses: Property operating costs — 5,372 53,826 (4,680 ) 54,518 Depreciation — 3,199 26,801 — 30,000 Amortization — 740 17,383 — 18,123 General and administrative 77 1,539 4,574 — 6,190 77 10,850 102,584 (4,680 ) 108,831 Real estate operating income/(loss) (77 ) 1,758 27,075 — 28,756 Other income (expense): Interest expense — (13,795 ) (6,354 ) 3,966 (16,183 ) Other income/(expense) — 2,404 1,852 (3,966 ) 290 Equity in income of unconsolidated joint ventures — 3,754 — — 3,754 Gain/(loss) on sale of real estate assets, net — (4 ) 109,516 — 109,512 Net income/(loss) (77 ) (5,883 ) 132,089 — 126,129 Plus: Net loss applicable to noncontrolling interest — — 4 — 4 Net income/(loss) applicable to Piedmont $ (77 ) $ (5,883 ) $ 132,093 $ — $ 126,133 Consolidating Statements of Income For the nine months ended September 30, 2018 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Consolidated Revenues: Rental income $ — $ 26,456 $ 279,292 $ (1,468 ) $ 304,280 Tenant reimbursements — 7,298 61,247 (334 ) 68,211 Property management fee revenue — — 12,625 (11,566 ) 1,059 Other property related income — 92 15,140 — 15,232 — 33,846 368,304 (13,368 ) 388,782 Expenses: Property operating costs — 14,614 152,929 (13,368 ) 154,175 Depreciation — 8,527 72,585 — 81,112 Amortization — 1,520 45,298 — 46,818 General and administrative 228 4,849 16,410 — 21,487 228 29,510 287,222 (13,368 ) 303,592 Real estate operating income/(loss) (228 ) 4,336 81,082 — 85,190 Other income (expense): Interest expense — (40,093 ) (10,937 ) 5,736 (45,294 ) Other income/(expense) — 200 7,016 (5,736 ) 1,480 Loss on extinguishment of debt — (1,680 ) — — (1,680 ) Gain on sale of real estate assets, net — 1,417 43,769 — 45,186 — (40,156 ) 39,848 — (308 ) Income/(loss) before consolidated subsidiaries (228 ) (35,820 ) 120,930 — 84,882 Income from subsidiaries 85,114 119,013 — (204,127 ) — Net income 84,886 83,193 120,930 (204,127 ) 84,882 Plus: Net loss applicable to noncontrolling interest — — 4 — 4 Net income applicable to Piedmont $ 84,886 $ 83,193 $ 120,934 $ (204,127 ) $ 84,886 Consolidating Statements of Income For the nine months ended September 30, 2017 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Consolidated Revenues: Rental income $ — $ 32,641 $ 314,128 $ (1,370 ) $ 345,399 Tenant reimbursements — 8,352 65,396 (373 ) 73,375 Property management fee revenue — — 13,791 (12,412 ) 1,379 Other property related income — 97 14,479 — 14,576 — 41,090 407,794 (14,155 ) 434,729 Expenses: Property operating costs — 17,027 163,763 (14,155 ) 166,635 Depreciation — 9,943 80,884 — 90,827 Amortization — 2,399 55,453 — 57,852 General and administrative 261 4,798 16,809 — 21,868 261 34,167 316,909 (14,155 ) 337,182 Real estate operating income/(loss) (261 ) 6,923 90,885 — 97,547 Other income (expense): Interest expense — (43,049 ) (20,868 ) 11,256 (52,661 ) Other income/(expense) — 6,873 4,611 (11,256 ) 228 Equity in income of unconsolidated joint ventures — 3,872 — — 3,872 Gain on sale of real estate assets, net — 6,430 109,521 — 115,951 Net income/(loss) (261 ) (18,951 ) 184,149 — 164,937 Plus: Net loss applicable to noncontrolling interest — — 10 — 10 Net income/(loss) applicable to Piedmont $ (261 ) $ (18,951 ) $ 184,159 $ — $ 164,947
Condensed Statement of Comprehensive Income	Consolidating Statements of Comprehensive Income For the Three Months Ended September 30, 2018 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Piedmont (Consolidated) Net income $ 16,114 $ 13,945 $ 28,998 $ (42,943 ) $ 16,114 Effective portion of gain on derivative instruments that are designated and qualify as cash flow hedges 1,145 1,145 — (1,145 ) 1,145 Plus: Reclassification of gain included in net income (434 ) (434 ) — 434 (434 ) Other comprehensive income 711 711 — (711 ) 711 Comprehensive income $ 16,825 $ 14,656 $ 28,998 $ (43,654 ) $ 16,825 Consolidating Statements of Comprehensive Income For the Nine Months Ended September 30, 2018 (in thousands) Piedmont Piedmont OP Non-Guarantors Eliminations Piedmont Net income $ 84,886 $ 83,193 $ 120,934 $ (204,127 ) $ 84,886 Effective portion of gain on derivatives instruments that are designated and qualify as cash flow hedges 4,408 4,408 — (4,408 ) 4,408 Plus: Reclassification of net loss included in net income 373 373 — (373 ) 373 Other comprehensive income 4,781 4,781 — (4,781 ) 4,781 Comprehensive income $ 89,667 $ 87,974 $ 120,934 $ (208,908 ) $ 89,667
Condensed Consolidated Statements of Cash Flows	Condensed Consolidating Statements of Cash Flows For the nine months ended September 30, 2018 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Piedmont (Consolidated) Net Cash Provided by Operating Activities $ 89,540 $ 89,639 $ 164,063 $ (204,920 ) $ 138,322 Cash Flows from Investing Activities: Investment in real estate assets and real estate related intangibles — (6,074 ) (67,100 ) — (73,174 ) Intercompany note receivable — 88,000 — (88,000 ) — Net sales proceeds from wholly-owned properties — 36,572 382,982 — 419,554 Note receivable issuance — — (3,200 ) — (3,200 ) Deferred lease costs paid — (1,826 ) (14,005 ) — (15,831 ) Distributions from subsidiaries 362,784 64,633 — (427,417 ) — Net cash provided by investing activities 362,784 181,305 298,677 (515,417 ) 327,349 Cash Flows from Financing Activities: Debt issuance and other costs paid — (947 ) — — (947 ) Proceeds from debt — 820,061 — — 820,061 Repayments of debt — (832,000 ) (1,005 ) — (833,005 ) Intercompany note payable — — (88,000 ) 88,000 — Value of shares withheld for payment of taxes related to employee stock compensation (2,219 ) — — — (2,219 ) Repurchases of common stock as part of announced plan (266,062 ) — — — (266,062 ) Distributions (184,043 ) (258,907 ) (373,460 ) 632,337 (184,073 ) Net cash used in financing activities (452,324 ) (271,793 ) (462,465 ) 720,337 (466,245 ) Net increase/(decrease) in cash, cash equivalents, and restricted cash and escrows — (849 ) 275 — (574 ) Cash, cash equivalents, and restricted cash and escrows, beginning of period 150 3,906 4,699 — 8,755 Cash, cash equivalents, and restricted cash and escrows, end of period $ 150 $ 3,057 $ 4,974 $ — $ 8,181 Condensed Consolidating Statements of Cash Flows For the nine months ended September 30, 2017 (in thousands) Piedmont (Parent) (Guarantor) Piedmont OP (the Issuer) Non-Guarantors Eliminations Piedmont (Consolidated) Net Cash Provided by/(Used in) Operating Activities $ 4,335 $ (15,468 ) $ 187,513 $ — $ 176,380 Cash Flows from Investing Activities: Investment in real estate assets, and real estate related intangibles — (793 ) (64,614 ) — (65,407 ) Intercompany note receivable — — (48,710 ) 48,710 — Investments in unconsolidated joint ventures — (1,162 ) — — (1,162 ) Net sales proceeds from wholly-owned properties — 23,028 352,171 — 375,199 Net sales proceeds received from unconsolidated joint ventures — 12,334 — — 12,334 Deferred lease costs paid — (858 ) (18,561 ) — (19,419 ) Net cash provided by investing activities — 32,549 220,286 48,710 301,545 Cash Flows from Financing Activities: Debt issuance costs paid — (102 ) 1 — (101 ) Proceeds from debt — 147,000 — — 147,000 Repayments of debt — (325,000 ) (141,046 ) — (466,046 ) Intercompany note payable — (14,289 ) 62,999 (48,710 ) — Costs of issuance of common stock (97 ) — — — (97 ) Value of shares withheld for payment of taxes related to employee stock compensation (3,385 ) — — — (3,385 ) Repurchases of common stock as part of announced plan (3,895 ) — — — (3,895 ) (Distributions to)/repayments from affiliates 125,271 197,519 (322,790 ) — — Dividends paid and discount on dividend reinvestments (122,229 ) — (8 ) — (122,237 ) Net cash provided by/(used in) financing activities (4,335 ) 5,128 (400,844 ) (48,710 ) (448,761 ) Net increase in cash, cash equivalents, and restricted cash and escrows — 22,209 6,955 — 29,164 Cash, cash equivalents, and restricted cash and escrows, beginning of period 150 3,693 4,361 — 8,204 Cash, cash equivalents, and restricted cash and escrows, end of period $ 150 $ 25,902 $ 11,316 $ — $ 37,368

Organization (Details)

Organization (Details) ft² in Thousands	9 Months Ended
	Sep. 30, 2018ft²segmentsubsidiarypropertyassetmarket
Real Estate Properties [Line Items]
Number of wholly-owned subsidiaries | subsidiary	2
Percentage ownership by sole general partner	99.90%
Percentage ownership by sole limited partner	0.10%
Number of redevelopment assets | asset	1
Percentage of annualized lease revenue	90.00%
Number of operating segments | segment	1
U.S.
Real Estate Properties [Line Items]
Number of major U.S. office markets | market	8
In Service Office Properties
Real Estate Properties [Line Items]
Number of real estate properties | property	53
Square footage of real estate property	16,200
Percentage leased	93.20%
Redevelopment Asset
Real Estate Properties [Line Items]
Square footage of real estate property	487

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Concentration Risk [Line Items]
Reduction in tax liability			$ 200
Reclassification out of rental income	$ (101,348)	$ (108,868)	(304,280)	$ (345,399)
Reclassification out of general and administrative expenses	(6,677)	(6,190)	(21,487)	(21,868)
Reclassification into property operating costs	$ 49,679	54,518	$ 154,175	166,635
Cumulative effect of accounting change (adoption of ASU 2016-01)					$ 0
Accounting Standards Update 2016-01
Concentration Risk [Line Items]
Cumulative effect of accounting change (adoption of ASU 2016-01)					$ 100
Reclassification Adjustment
Concentration Risk [Line Items]
Reclassification out of general and administrative expenses		400		1,400
Reclassification into property operating costs		400		1,400
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Concentration Risk [Line Items]
Reclassification out of rental income		4,000		14,600
Reclassification into other property related income		$ 4,000		$ 14,600

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Revenue Recognition Amendments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Rental income	$ 101,348	$ 108,868	$ 304,280	$ 345,399
Tenant reimbursements	23,170	24,253	68,211	73,375
Total revenues	129,708	137,587	388,782	434,729
Property management fee revenue
Disaggregation of Revenue [Line Items]
Property management and other property related revenue	368	454	1,059	1,379
Other property related income
Disaggregation of Revenue [Line Items]
Property management and other property related revenue	$ 4,822	$ 4,012	$ 15,232	$ 14,576

Acquisitions (Details)

Acquisitions (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)ft²building
Business Acquisition [Line Items]
Properties acquired | building	1
501 West Church Street
Business Acquisition [Line Items]
Ownership Percentage Acquired	100.00%
Rentable Square Feet | ft²	182,461
Percentage Leased as of Acquisition	100.00%
Net Contractual Purchase Price (in millions) | $	$ 28.2

Debt (Narrative) (Details)

Debt (Narrative) (Details)	Sep. 30, 2018USD ($)contract	Sep. 30, 2018USD ($)contract	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)contractperiod	Sep. 30, 2017USD ($)	Dec. 31, 2017
Debt Instrument [Line Items]
Interest paid		$ 18,000,000	$ 18,000,000	$ 48,700,000	$ 54,000,000
Interest costs capitalized		375,000	$ 37,000	800,000	$ 200,000
$300 Million Unsecured 2013 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Repayment of long-term debt				300,000,000
Face amount of debt instrument	$ 300,000,000	300,000,000		300,000,000
$170 Million Unsecured 2015 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Repayment of long-term debt				170,000,000
Face amount of debt instrument	170,000,000	170,000,000		170,000,000
$500 Million Unsecured 2018 Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Face amount of debt instrument	500,000,000	500,000,000		$ 500,000,000
Debt instrument term				4 years
Amended and Restated $300 Million Unsecured 2011 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Face amount of debt instrument	300,000,000	300,000,000		$ 300,000,000
Maximum extension period				22 months
$250 Million Unsecured 2018 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Face amount of debt instrument	250,000,000	250,000,000		$ 250,000,000
Debt instrument term				7 years
Notional amount of interest rate swap agreements	150,000,000	150,000,000		$ 150,000,000
Unsecured, 2018 $500 Million Line Of Credit, 2011 $300 Million Term Loan And 2018 $250 Million Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Unencumbered interest coverage ratio				1.75
Unencumbered leverage ratio				1.60
Fixed charge coverage ratio				1.50
Maximum leverage ratio				0.60
Maximum secured debt ratio				0.40
Line of Credit | $500 Million Unsecured 2015 Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Amount of line of credit	500,000,000	500,000,000		$ 500,000,000
Face amount of debt instrument	500,000,000	500,000,000		500,000,000
Line of Credit | $500 Million Unsecured 2018 Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Amount of line of credit	500,000,000	500,000,000		$ 500,000,000
Number of extension periods | period				2
Optional increase to maximum borrowing capacity	500,000,000	500,000,000		$ 500,000,000
Maximum borrowing capacity after optional increase	$ 1,000,000,000	1,000,000,000		$ 1,000,000,000
Maximum extension period				1 year
Federal Funds Rate | $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate				0.50%
Federal Funds Rate | Line of Credit | $500 Million Unsecured 2018 Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				0.50%
London Interbank Offered Rate (LIBOR) | $300 Million Unsecured 2013 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				1.20%
London Interbank Offered Rate (LIBOR) | $170 Million Unsecured 2015 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				1.125%
London Interbank Offered Rate (LIBOR) | $500 Million Unsecured 2018 Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				0.90%
London Interbank Offered Rate (LIBOR) | Amended and Restated $300 Million Unsecured 2011 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				1.00%
London Interbank Offered Rate (LIBOR) | $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate				1.00%
London Interbank Offered Rate (LIBOR) | $250 Million Unsecured 2018 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				1.60%
London Interbank Offered Rate (LIBOR) | Line of Credit | $500 Million Unsecured 2015 Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate						1.00%
London Interbank Offered Rate (LIBOR) | Line of Credit | $500 Million Unsecured 2018 Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate	0.90%			1.00%
London Interbank Offered Rate (LIBOR) | Line of Credit | Amended and Restated $300 Million Unsecured 2011 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				1.00%		1.15%
Minimum | Line of Credit | $500 Million Unsecured 2018 Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				0.775%
Minimum | Line of Credit | Amended and Restated $300 Million Unsecured 2011 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				0.85%		0.90%
Minimum | London Interbank Offered Rate (LIBOR) | $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate				1.45%
Maximum | Line of Credit | $500 Million Unsecured 2018 Line of Credit | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				1.45%
Maximum | Line of Credit | Amended and Restated $300 Million Unsecured 2011 Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Basis spread on variable rate				1.65%		1.90%
Maximum | London Interbank Offered Rate (LIBOR) | $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate				2.40%
Interest rate swaps
Debt Instrument [Line Items]
Notional amount of interest rate swap agreements	$ 450,000,000	$ 450,000,000		$ 450,000,000
Interest rate swaps | $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Number of Swap Agreements | contract	3	3		3
Notional amount of interest rate swap agreements	$ 150,000,000	$ 150,000,000		$ 150,000,000

Debt (Schedule of Debt) (Detail

Debt (Schedule of Debt) (Details)	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)period	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Weighted average rate	3.71%	3.71%
Amount Outstanding	$ 1,715,371,000	$ 1,715,371,000	$ 1,726,927,000
Interest rate swaps
Debt Instrument [Line Items]
Notional amount of interest rate swap agreements	450,000,000	450,000,000
$250 Million Unsecured 2018 Term Loan | Interest rate swaps
Debt Instrument [Line Items]
Notional amount of interest rate swap agreements	150,000,000	$ 150,000,000
$250 Million Unsecured 2018 Term Loan | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%
Seven-Year Interest Rate Swap Agreement | Interest rate swaps
Debt Instrument [Line Items]
Notional amount of interest rate swap agreements	$ 100,000,000	$ 100,000,000
Secured Debt
Debt Instrument [Line Items]
Weighted average rate	3.81%	3.81%
Amount Outstanding	$ 190,753,000	$ 190,753,000	191,616,000
Discounts and unamortized debt issuance costs	$ 720,000	$ 720,000	946,000
Secured Debt | $35 Million Fixed-Rate Loan
Debt Instrument [Line Items]
Stated Rate	5.55%	5.55%
Effective interest rate	3.75%	3.75%
Amount Outstanding	$ 30,033,000	$ 30,033,000	30,670,000
Face amount of debt instrument	$ 35,000,000	$ 35,000,000
Secured Debt | $160 Million Fixed Rate Loan
Debt Instrument [Line Items]
Stated Rate	3.48%	3.48%
Effective interest rate	3.58%	3.58%
Amount Outstanding	$ 160,000,000	$ 160,000,000	160,000,000
Face amount of debt instrument	$ 160,000,000	$ 160,000,000
Unsecured Debt
Debt Instrument [Line Items]
Weighted average rate	3.69%	3.69%
Amount Outstanding	$ 1,524,618,000	$ 1,524,618,000	1,535,311,000
Discounts and unamortized debt issuance costs	$ (10,382,000)	$ (10,382,000)	(7,689,000)
Unsecured Debt | $170 Million Unsecured 2015 Term Loan
Debt Instrument [Line Items]
Effective interest rate	2.54%	2.54%
Amount Outstanding	$ 0	$ 0	170,000,000
Face amount of debt instrument	170,000,000	$ 170,000,000
Unsecured Debt | $170 Million Unsecured 2015 Term Loan | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		1.125%
Unsecured Debt | $300 Million Unsecured 2013 Term Loan
Debt Instrument [Line Items]
Amount Outstanding	0	$ 0	300,000,000
Face amount of debt instrument	$ 300,000,000	$ 300,000,000
Unsecured Debt | $300 Million Unsecured 2013 Term Loan | Interest rate swaps
Debt Instrument [Line Items]
Effective interest rate	2.78%	2.78%
Unsecured Debt | $300 Million Unsecured 2013 Term Loan | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		1.20%
Unsecured Debt | $500 Million Unsecured 2015 Line of Credit | Line of Credit
Debt Instrument [Line Items]
Effective interest rate	3.17%	3.17%
Amount Outstanding	$ 0	$ 0	$ 23,000,000
Face amount of debt instrument	500,000,000	500,000,000
Unsecured Debt | $500 Million Unsecured 2015 Line of Credit | Line of Credit | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Unsecured Debt | $500 Million Unsecured 2018 Line of Credit
Debt Instrument [Line Items]
Face amount of debt instrument	$ 500,000,000	$ 500,000,000
Unsecured Debt | $500 Million Unsecured 2018 Line of Credit | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		0.90%
Unsecured Debt | $500 Million Unsecured 2018 Line of Credit | Line of Credit
Debt Instrument [Line Items]
Effective interest rate	3.15%	3.15%
Amount Outstanding	$ 235,000,000	$ 235,000,000	$ 0
Maximum extension period		1 year
Number of extension periods | period		2
Extension period		6 months
Unsecured Debt | $500 Million Unsecured 2018 Line of Credit | Line of Credit | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate	0.90%	1.00%
Unsecured Debt | Amended and Restated $300 Million Unsecured 2011 Term Loan
Debt Instrument [Line Items]
Amount Outstanding	$ 300,000,000	$ 300,000,000	$ 300,000,000
Face amount of debt instrument	$ 300,000,000	$ 300,000,000
Maximum extension period		22 months
Unsecured Debt | Amended and Restated $300 Million Unsecured 2011 Term Loan | Interest rate swaps
Debt Instrument [Line Items]
Effective interest rate	3.20%	3.20%
Unsecured Debt | Amended and Restated $300 Million Unsecured 2011 Term Loan | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%
Unsecured Debt | Amended and Restated $300 Million Unsecured 2011 Term Loan | Line of Credit | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%	1.15%
Unsecured Debt | $350 Million Senior Notes
Debt Instrument [Line Items]
Stated Rate	3.40%	3.40%
Effective interest rate	3.43%	3.43%
Amount Outstanding	$ 350,000,000	$ 350,000,000	$ 350,000,000
Face amount of debt instrument	$ 350,000,000	$ 350,000,000
Unsecured Debt | $400 Million Senior Notes
Debt Instrument [Line Items]
Stated Rate	4.45%	4.45%
Effective interest rate	4.10%	4.10%
Amount Outstanding	$ 400,000,000	$ 400,000,000	400,000,000
Face amount of debt instrument	$ 400,000,000	$ 400,000,000
Unsecured Debt | $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Effective interest rate	4.00%	4.00%
Amount Outstanding	$ 250,000,000	$ 250,000,000	$ 0
Face amount of debt instrument	250,000,000	250,000,000
Notional amount of interest rate swap agreements	$ 150,000,000	$ 150,000,000
Unsecured Debt | $250 Million Unsecured 2018 Term Loan | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		1.60%
Through March 29, 2020 | Unsecured Debt | $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Interest rate on derivative instrument	4.11%	4.11%
From March 30, 2020 through March 31, 2025 | Unsecured Debt | $250 Million Unsecured 2018 Term Loan
Debt Instrument [Line Items]
Interest rate on derivative instrument	4.21%	4.21%

Variable Interest Entities (Det

Variable Interest Entities (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Eye Street 1201 N.W. Associates LLC
Variable Interest Entity [Line Items]
Piedmont's %	98.60%
Net Carrying Amount	$ 89.2	$ 81.1
Percent of cash flow entitled to entity	100.00%
Eye Street 1225 N.W. Associates LLC
Variable Interest Entity [Line Items]
Piedmont's %	98.10%
Net Carrying Amount	$ 64.8	65.2
Percent of cash flow entitled to entity	100.00%
Piedmont 500 W. Monroe Fee LLC
Variable Interest Entity [Line Items]
Piedmont's %	100.00%
Net Carrying Amount	$ 256.2	$ 263.2
Percent of cash flow entitled to entity	100.00%

Derivative Instruments (Details

Derivative Instruments (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)contract	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)contract	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Derivative [Line Items]
Maximum period of extension term			78 months
Interest Rate Cash Flow Hedge Derivative at Fair Value, Net [Abstract]
Gross derivative assets	$ 4,069,000		$ 4,069,000		$ 688,000
Gross derivative liabilities	0		0		(1,478,000)
Net derivative asset/(liability)	4,069,000		4,069,000		$ (790,000)
Amount of gain recognized in OCI	1,145,000	$ 175,000	4,408,000	$ 307,000
Total amount of Interest Expense presented in the consolidated statements of income	15,849,000	16,183,000	45,294,000	52,661,000
Total amount of Loss on Extinguishment of Debt presented in the consolidated statements of income	0	0	1,680,000	0
Loss on write off of discount and unamortized debt issuance costs			400,000
Gain (loss) to be reclassified	3,600,000		3,600,000
Gain (loss) from hedge ineffectiveness	0	0	0	0
Interest rate swaps
Derivative [Line Items]
Total Notional Amount (in millions)	450,000,000		450,000,000
Interest Rate Cash Flow Hedge Derivative at Fair Value, Net [Abstract]
Total amount of Interest Expense presented in the consolidated statements of income	15,849,000	16,183,000	45,294,000	52,661,000
Interest rate swaps | Interest Expense
Interest Rate Cash Flow Hedge Derivative at Fair Value, Net [Abstract]
Amount of gain recognized in OCI	1,145,000	175,000	4,408,000	307,000
Amount of gain/(loss) reclassified from OCI	434,000	(653,000)	885,000	(2,936,000)
Interest rate swaps | Gain (Loss) On Extinguishment Of Debt
Interest Rate Cash Flow Hedge Derivative at Fair Value, Net [Abstract]
Amount of gain/(loss) reclassified from OCI	$ 0	$ 0	$ (1,258,000)	$ 0
$250 Million Unsecured 2018 Term Loan | Interest rate swaps
Derivative [Line Items]
Number of Swap Agreements | contract	3		3
Total Notional Amount (in millions)	$ 150,000,000		$ 150,000,000
Unsecured Debt | Amended and Restated $300 Million Unsecured 2011 Term Loan
Derivative [Line Items]
Face amount of debt instrument	$ 300,000,000		$ 300,000,000
Unsecured Debt | Amended and Restated $300 Million Unsecured 2011 Term Loan | Interest rate swaps
Derivative [Line Items]
Number of Swap Agreements | contract	3		3
Total Notional Amount (in millions)	$ 300,000,000		$ 300,000,000
Unsecured Debt | $250 Million Unsecured 2018 Term Loan
Derivative [Line Items]
Face amount of debt instrument	250,000,000		250,000,000
Hedged portion of long-term debt	150,000,000		150,000,000
Total Notional Amount (in millions)	$ 150,000,000		$ 150,000,000
Unsecured Debt | $250 Million Unsecured 2018 Term Loan | Interest rate swaps
Derivative [Line Items]
Number of Swap Agreements | contract	2		2
Total Notional Amount (in millions)	$ 100,000,000		$ 100,000,000
Unsecured Debt | $250 Million Unsecured 2018 Term Loan Maturing 2020 | Interest rate swaps
Derivative [Line Items]
Number of Swap Agreements | contract	1		1
Total Notional Amount (in millions)	$ 50,000,000		$ 50,000,000

Fair Value Measurement of Fin_3

Fair Value Measurement of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps	$ 4,069	$ 688
Interest rate swaps	0	1,478
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	6,807	7,382
Restricted cash and escrows	1,374	1,373
Accounts payable and accrued expenses	14,584	126,429
Debt, net	1,715,371	1,726,927
Interest rate swaps | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps	4,069	688
Interest rate swaps	0	1,478
Tenant receivables, net | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Tenant receivables, net	10,522	12,139
Notes receivable | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Tenant receivables, net	3,200	0
Level 1 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	6,807	7,382
Restricted cash and escrows	1,374	1,373
Accounts payable and accrued expenses	14,584	126,429
Level 1 | Tenant receivables, net | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Tenant receivables, net	10,522	12,139
Level 1 | Notes receivable | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Tenant receivables, net	3,200	0
Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, net	1,714,923	1,759,905
Level 2 | Interest rate swaps | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps	4,069	688
Interest rate swaps	$ 0	$ 1,478

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)category	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)category	Sep. 30, 2017USD ($)
Loss Contingencies [Line Items]
Number of tenant and building improvement categories | category	2		2
Collectibility of Tenant Reimbursements
Loss Contingencies [Line Items]
Reductions in reimbursement revenues	$ 61	$ 0	$ 500	$ 300
Non-Incremental Capital Expenditures
Loss Contingencies [Line Items]
Period for commitments for funding non-incremental capital expenditures			5 years
Potential obligations for tenant improvements	47,000		$ 47,000
Non-Incremental Capital Expenditures | Maximum
Loss Contingencies [Line Items]
Period for commitments for funding non-incremental capital expenditures			3 years
Incremental Capital Expenditures
Loss Contingencies [Line Items]
Potential obligations for tenant improvements	$ 34,900		$ 34,900

Assets Held for Sale (Assets He

Assets Held for Sale (Assets Held-for-Sale) (Details) $ in Thousands	Sep. 30, 2018USD ($)property	Dec. 31, 2017USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties sold | property	14
Total other assets held for sale, net	$ 12,752	$ 61,193
Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total real estate assets held for sale, net	113,918	448,788
Straight-line rent receivables	7,607	34,750
Prepaid expenses and other assets	1,157	1,624
Deferred lease costs, less accumulated amortization of $2,364 and $18,710 as of September 30, 2018 and December 31, 2017, respectively	3,988	24,819
Total other assets held for sale, net	12,752	61,193
Intangible lease liabilities, less accumulated amortization of $0 and $935 as of September 30, 2018 and December 31, 2017, respectively	0	380
Accumulated amortization on deferred lease costs	2,364	18,710
Accumulated amortization on Intangible lease liabilities	0	935
Disposal Group, Held-for-sale, Not Discontinued Operations | Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:	23,608	98,106
Disposal Group, Held-for-sale, Not Discontinued Operations | Building and building improvements
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:	90,281	348,374
Accumulated depreciation (building improvements)	60,434	226,188
Disposal Group, Held-for-sale, Not Discontinued Operations | Construction in progress
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:	$ 29	$ 2,308

Stock Based Compensation (Narra

Stock Based Compensation (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense related to stock awards	$ 1.7	$ 1.3	$ 6.7	$ 7
Compensation expense, non-vested awards			$ 5.6	$ 5.4
Total shares issued to employees, directors, and officers (in shares)			355,055
Unrecognized compensation cost related to nonvested	$ 5.1		$ 5.1
Weighted Average
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to nonvested, weighted-average vesting period			1 year
Stock Awards | Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			1 year

Stock Based Compensation (Rollf

Stock Based Compensation (Rollforward of Stock Awards) (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested and Potential Stock Awards, End of period (in shares)	1,034,995		1,034,995
Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested and Potential Stock Awards, Beginning of period (in shares)			868,437
Unvested and Potential Stock Awards, End of period (in shares)	1,034,995		1,034,995
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Unvested and Potential Stock Awards, Weighted-Average Grant Date Fair Value, Beginning of period (in dollars per share)			$ 21.69
Unvested and Potential Stock Awards, Weighted-Average Grant Date Fair Value, End of period (in dollars per share)	$ 22.36		$ 22.36
Deferred Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Deferred Stock Awards Granted (in shares)			354,236
Performance Stock Awards and Deferred Stock Awards Vested (in shares)			(332,019)
Deferred Stock Awards Forfeited (in shares)			(8,481)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Deferred Stock Awards Granted (in dollars per share)	$ 0	$ 0	$ 17.84	$ 21.38
Performance Stock Awards and Deferred Stock Awards Vested, Weighted-Average Grant Date Fair Value (in dollars per share)			19.21
Deferred Stock Awards Forfeited, Weighted-Average Grant Date Fair Value (in dollars per share)			$ 19.77
Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Increase in Estimated Potential Share Award, net of forfeitures (in shares)			313,827
Performance Stock Awards and Deferred Stock Awards Vested (in shares)			(161,005)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Increase in Estimated Potential Share Award, net of forfeitures, Weighted-Average Grant Date Fair Value (in dollars per share)			$ 23.80
Performance Stock Awards and Deferred Stock Awards Vested, Weighted-Average Grant Date Fair Value (in dollars per share)			$ 18.47

Stock Based Compensation (Addit

Stock Based Compensation (Additional Information Regarding Stock Award Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Deferred Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value of Deferred Stock Granted During the Period (in dollars per share)	$ 0	$ 0	$ 17.84	$ 21.38
Total Grant Date Fair Value of Deferred Stock Vested During the Period	$ 16	$ 11	$ 6,378	$ 5,852
Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Liability Awards Paid During the Period	$ 0	$ 0	$ 2,947	$ 2,877

Stock Based Compensation (Outst

Stock Based Compensation (Outstanding Employee Stock Awards) (Details) - $ / shares	May 17, 2018	May 18, 2017	May 24, 2016	Jan. 03, 2014	Sep. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested Shares (in shares)					1,034,995
Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date Fair Value (in dollars per share)					$ 22.36	$ 21.69
Unvested Shares (in shares)					1,034,995	868,437
Deferred Stock Awards | Deferred Stock Award, Granted January 3, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted (in shares)				72,969
Grant Date Fair Value (in dollars per share)				$ 16.45
Unvested Shares (in shares)					16,416
Deferred Stock Awards | Deferred Stock Award, Granted January 3, 2014 | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				20.00%
Deferred Stock Awards | Deferred Stock Award, Granted January 3, 2014 | Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				20.00%
Deferred Stock Awards | Deferred Stock Award, Granted January 3, 2014 | Share-based Compensation Award, Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				20.00%
Deferred Stock Awards | Deferred Stock Award, Granted January 3, 2014 | Share-based Compensation Award, Tranche Four
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				20.00%
Deferred Stock Awards | Deferred Stock Award, Granted January 3, 2014 | Share-based Compensation Award, Tranche Five
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage				20.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 24, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted (in shares)			208,003
Grant Date Fair Value (in dollars per share)			$ 19.91
Unvested Shares (in shares)					60,591
Deferred Stock Awards | Deferred Stock Award, Granted May 24, 2016 | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 24, 2016 | Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 24, 2016 | Share-based Compensation Award, Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 24, 2016 | Share-based Compensation Award, Tranche Four
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 18, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted (in shares)		219,863
Grant Date Fair Value (in dollars per share)		$ 21.38
Unvested Shares (in shares)					123,507
Deferred Stock Awards | Deferred Stock Award, Granted May 18, 2017 | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 18, 2017 | Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 18, 2017 | Share-based Compensation Award, Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 18, 2017 | Share-based Compensation Award, Tranche Four
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage		25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 17, 2018 Deferred Stock Award Independent Directors | Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted (in shares)	31,388
Grant Date Fair Value (in dollars per share)	$ 17.84
Unvested Shares (in shares)					31,388
Deferred Stock Awards | Deferred Stock Award, Granted May 17, 2018 Deferred Stock Award Independent Directors | Share-based Compensation Award, Tranche One | Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	100.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 17, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted (in shares)	302,706
Grant Date Fair Value (in dollars per share)	$ 17.84
Unvested Shares (in shares)					239,777
Deferred Stock Awards | Deferred Stock Award, Granted May 17, 2018 | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 17, 2018 | Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 17, 2018 | Share-based Compensation Award, Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	25.00%
Deferred Stock Awards | Deferred Stock Award, Granted May 17, 2018 | Share-based Compensation Award, Tranche Four
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	25.00%
Performance Share Awards | Performance Share Program Award, Granted May 24, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted (in shares)			0
Grant Date Fair Value (in dollars per share)			$ 23.02
Unvested Shares (in shares)					99,337
Performance Share Awards | Performance Share Program Award, Granted May 18, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted (in shares)		0
Grant Date Fair Value (in dollars per share)		$ 30.45
Unvested Shares (in shares)					143,335
Performance Share Awards | Performance Share Program Award, Granted May 17, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net Shares Granted (in shares)	0
Grant Date Fair Value (in dollars per share)	$ 23.52
Unvested Shares (in shares)					320,644

Supplemental Disclosures for _3

Supplemental Disclosures for the Statement of Consolidated Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Accrued capital expenditures and deferred lease costs	$ 21,784	$ 8,590
Change in accrued dividends and discount on dividend reinvestments	(101,794)	(30,531)
Change in accrued share repurchases as part of an announced plan	(1,277)	0
Investment in consolidated joint venture	0	63,026
Cash and cash equivalents	6,807	36,108	$ 7,382	$ 6,992
Restricted cash and escrows	1,374	1,260	1,373	1,212
Total cash, cash equivalents, and restricted cash and escrows shown in the consolidated statement of cash flows	$ 8,181	$ 37,368	$ 8,755	$ 8,204

Earnings Per Share (Details)

Earnings Per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Earnings Per Share [Abstract]
Weighted-average common shares outstanding – basic (in shares)	128,371,062	145,415,678	130,837,223	145,372,182
Plus: Incremental weighted-average shares from time-vested deferred and performance stock awards (in shares)	448,000	303,000	350,000	308,000
Weighted-average common shares outstanding – diluted (in shares)	128,818,658	145,719,431	131,187,127	145,679,582
Common stock, shares issued (in shares)	128,371,442	145,295,000	128,371,442	145,295,000	142,358,940
Common stock, shares outstanding (in shares)	128,371,442	145,295,000	128,371,442	145,295,000	142,358,940

Guarantor and Non-Guarantor F_3

Guarantor and Non-Guarantor Financial Information (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Assets:
Land	$ 523,994	$ 521,186
Buildings and improvements, less accumulated depreciation	2,309,803	2,325,282
Intangible lease assets, less accumulated amortization	65,527	77,805
Construction in progress	22,753	11,681
Real estate assets held for sale, net	113,918	448,788
Total real estate assets	3,035,995	3,384,742
Cash and cash equivalents	6,807	7,382	$ 36,108	$ 6,992
Tenant and straight-line rent receivables, net	179,267	166,533
Advances to affiliates		0
Investment in subsidiaries	0	0
Notes receivable	3,200	0
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	36,913	23,283
Goodwill	98,918	98,918
Deferred lease costs, net	250,038	257,916
Other assets held for sale, net	12,752	61,193
Total assets	3,623,890	3,999,967
Liabilities:
Debt, net	1,715,371	1,726,927
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	109,087	216,653
Advances from affiliates		0
Deferred income	27,450	29,582
Intangible lease liabilities, net	37,986	38,458
Interest rate swaps	0	1,478
Liabilities held for sale, net	0	380
Total liabilities	1,889,894	2,013,478
Equity:
Total stockholders’ equity	1,733,996	1,986,489		$ 2,097,703
Total liabilities and stockholders’ equity	3,623,890	3,999,967
Eliminations
Assets:
Land	0	0
Buildings and improvements, less accumulated depreciation	(300)	(300)
Intangible lease assets, less accumulated amortization	0	0
Construction in progress	0	0
Real estate assets held for sale, net	0	0
Total real estate assets	(300)	(300)
Cash and cash equivalents	0	0
Tenant and straight-line rent receivables, net	0	0
Advances to affiliates		(7,971,908)
Investment in subsidiaries	(4,523,936)	(3,437,471)
Notes receivable	(145,310)	(233,310)
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	(9)	(740)
Goodwill	0	0
Deferred lease costs, net	0	0
Other assets held for sale, net	0	0
Total assets	(4,669,555)	(11,643,729)
Liabilities:
Debt, net	(145,310)	(233,310)
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	(9)	(740)
Advances from affiliates		(8,070,163)
Deferred income	0	0
Intangible lease liabilities, net	0	0
Interest rate swaps		0
Liabilities held for sale, net		0
Total liabilities	(145,319)	(8,304,213)
Equity:
Total stockholders’ equity	(4,524,236)	(3,339,516)
Total liabilities and stockholders’ equity	(4,669,555)	(11,643,729)
Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Assets:
Land	0	0
Buildings and improvements, less accumulated depreciation	0	0
Intangible lease assets, less accumulated amortization	0	0
Construction in progress	0	0
Real estate assets held for sale, net	0	0
Total real estate assets	0	0
Cash and cash equivalents	150	150
Tenant and straight-line rent receivables, net	0	0
Advances to affiliates		1,674,276
Investment in subsidiaries	1,734,476	3,437,299
Notes receivable	0	0
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	80	2
Goodwill	0	0
Deferred lease costs, net	0	0
Other assets held for sale, net		0
Total assets	1,734,706	5,111,727
Liabilities:
Debt, net	0	0
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	710	104,028
Advances from affiliates		5,277,957
Deferred income	0	0
Intangible lease liabilities, net	0	0
Interest rate swaps		0
Liabilities held for sale, net		0
Total liabilities	710	5,381,985
Equity:
Total stockholders’ equity	1,733,996	(270,258)
Total liabilities and stockholders’ equity	1,734,706	5,111,727
Piedmont OP (the Issuer) | Reportable Legal Entities
Assets:
Land	36,094	36,094
Buildings and improvements, less accumulated depreciation	174,627	180,886
Intangible lease assets, less accumulated amortization	0	181
Construction in progress	2,915	85
Real estate assets held for sale, net	0	32,815
Total real estate assets	213,636	250,061
Cash and cash equivalents	3,024	3,890
Tenant and straight-line rent receivables, net	15,757	16,891
Advances to affiliates		6,297,632
Investment in subsidiaries	2,789,292	0
Notes receivable	810	88,810
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	8,971	5,094
Goodwill	98,918	98,918
Deferred lease costs, net	15,625	16,611
Other assets held for sale, net	0	2,266
Total assets	3,146,033	6,780,173
Liabilities:
Debt, net	1,524,558	1,535,239
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	14,321	20,279
Advances from affiliates		941,494
Deferred income	1,853	3,631
Intangible lease liabilities, net	0	0
Interest rate swaps		1,478
Liabilities held for sale, net		0
Total liabilities	1,540,732	2,502,121
Equity:
Total stockholders’ equity	1,605,301	4,278,052
Total liabilities and stockholders’ equity	3,146,033	6,780,173
Non-Guarantors | Reportable Legal Entities
Assets:
Land	487,900	485,092
Buildings and improvements, less accumulated depreciation	2,135,476	2,144,696
Intangible lease assets, less accumulated amortization	65,527	77,624
Construction in progress	19,838	11,596
Real estate assets held for sale, net	113,918	415,973
Total real estate assets	2,822,659	3,134,981
Cash and cash equivalents	3,633	3,342
Tenant and straight-line rent receivables, net	163,510	149,642
Advances to affiliates		0
Investment in subsidiaries	168	172
Notes receivable	147,700	144,500
Prepaid expenses, restricted cash, escrows, interest rate swaps, and other assets	27,871	18,927
Goodwill	0	0
Deferred lease costs, net	234,413	241,305
Other assets held for sale, net	12,752	58,927
Total assets	3,412,706	3,751,796
Liabilities:
Debt, net	336,123	424,998
Accounts payable, accrued expenses, dividends payable, and accrued capital expenditures	94,065	93,086
Advances from affiliates		1,850,712
Deferred income	25,597	25,951
Intangible lease liabilities, net	37,986	38,458
Interest rate swaps		0
Liabilities held for sale, net		380
Total liabilities	493,771	2,433,585
Equity:
Total stockholders’ equity	2,918,935	1,318,211
Total liabilities and stockholders’ equity	$ 3,412,706	$ 3,751,796

Guarantor and Non-Guarantor F_4

Guarantor and Non-Guarantor Financial Information (Consolidating Statements of Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Revenues:
Rental income	$ 101,348	$ 108,868	$ 304,280	$ 345,399
Tenant reimbursements	23,170	24,253	68,211	73,375
Total revenues	129,708	137,587	388,782	434,729
Expenses:
Property operating costs	49,679	54,518	154,175	166,635
Depreciation	26,852	30,000	81,112	90,827
Amortization	14,840	18,123	46,818	57,852
General and administrative	6,677	6,190	21,487	21,868
Operating expenses	98,048	108,831	303,592	337,182
Real estate operating income	31,660	28,756	85,190	97,547
Other income (expense):
Interest expense	(15,849)	(16,183)	(45,294)	(52,661)
Other income/(expense)	303	290	1,480	228
Equity in income of unconsolidated joint ventures	0	3,754	0	3,872
Loss on extinguishment of debt	0	0	(1,680)	0
Gain/(loss) on sale of real estate assets, net	0	109,512	45,186	115,951
Other income (expense)	(15,546)		(308)
Income/(loss) before consolidated subsidiaries	16,114		84,882
Income from subsidiaries	0		0
Net income	16,114	126,129	84,882	164,937
Plus: Net loss applicable to noncontrolling interest	0	4	4	10	$ (15)
Net income applicable to Piedmont	16,114	126,133	84,886	164,947	$ 133,564
Eliminations
Revenues:
Rental income	(553)	(426)	(1,468)	(1,370)
Tenant reimbursements	(141)	(142)	(334)	(373)
Total revenues	(4,622)	(4,680)	(13,368)	(14,155)
Expenses:
Property operating costs	(4,622)	(4,680)	(13,368)	(14,155)
Depreciation	0	0	0	0
Amortization	0	0	0	0
General and administrative	0	0	0	0
Operating expenses	(4,622)	(4,680)	(13,368)	(14,155)
Real estate operating income	0	0	0	0
Other income (expense):
Interest expense	1,894	3,966	5,736	11,256
Other income/(expense)	(1,894)	(3,966)	(5,736)	(11,256)
Equity in income of unconsolidated joint ventures		0		0
Loss on extinguishment of debt			0
Gain/(loss) on sale of real estate assets, net		0	0	0
Other income (expense)	0		0
Income/(loss) before consolidated subsidiaries	0		0
Income from subsidiaries	(42,943)		(204,127)
Net income	(42,943)	0	(204,127)	0
Plus: Net loss applicable to noncontrolling interest	0	0	0	0
Net income applicable to Piedmont	(42,943)	0	(204,127)	0
Reportable Legal Entities
Other income (expense):
Other income (expense)	0
Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Revenues:
Rental income	0	0	0	0
Tenant reimbursements	0	0	0	0
Total revenues	0	0	0	0
Expenses:
Property operating costs	0	0	0	0
Depreciation	0	0	0	0
Amortization	0	0	0	0
General and administrative	42	77	228	261
Operating expenses	42	77	228	261
Real estate operating income	(42)	(77)	(228)	(261)
Other income (expense):
Interest expense	0	0	0	0
Other income/(expense)	0	0	0	0
Equity in income of unconsolidated joint ventures		0		0
Loss on extinguishment of debt			0
Gain/(loss) on sale of real estate assets, net		0	0	0
Other income (expense)			0
Income/(loss) before consolidated subsidiaries	(42)		(228)
Income from subsidiaries	16,156		85,114
Net income	16,114	(77)	84,886	(261)
Plus: Net loss applicable to noncontrolling interest	0	0	0	0
Net income applicable to Piedmont	16,114	(77)	84,886	(261)
Piedmont OP (the Issuer) | Reportable Legal Entities
Revenues:
Rental income	8,403	10,185	26,456	32,641
Tenant reimbursements	2,458	2,381	7,298	8,352
Total revenues	10,896	12,608	33,846	41,090
Expenses:
Property operating costs	4,973	5,372	14,614	17,027
Depreciation	2,816	3,199	8,527	9,943
Amortization	446	740	1,520	2,399
General and administrative	1,424	1,539	4,849	4,798
Operating expenses	9,659	10,850	29,510	34,167
Real estate operating income	1,237	1,758	4,336	6,923
Other income (expense):
Interest expense	(14,119)	(13,795)	(40,093)	(43,049)
Other income/(expense)	40	2,404	200	6,873
Equity in income of unconsolidated joint ventures		3,754		3,872
Loss on extinguishment of debt			(1,680)
Gain/(loss) on sale of real estate assets, net		(4)	1,417	6,430
Other income (expense)	(14,079)		(40,156)
Income/(loss) before consolidated subsidiaries	(12,842)		(35,820)
Income from subsidiaries	26,787		119,013
Net income	13,945	(5,883)	83,193	(18,951)
Plus: Net loss applicable to noncontrolling interest	0	0	0	0
Net income applicable to Piedmont	13,945	(5,883)	83,193	(18,951)
Non-Guarantors | Reportable Legal Entities
Revenues:
Rental income	93,498	99,109	279,292	314,128
Tenant reimbursements	20,853	22,014	61,247	65,396
Total revenues	123,434	129,659	368,304	407,794
Expenses:
Property operating costs	49,328	53,826	152,929	163,763
Depreciation	24,036	26,801	72,585	80,884
Amortization	14,394	17,383	45,298	55,453
General and administrative	5,211	4,574	16,410	16,809
Operating expenses	92,969	102,584	287,222	316,909
Real estate operating income	30,465	27,075	81,082	90,885
Other income (expense):
Interest expense	(3,624)	(6,354)	(10,937)	(20,868)
Other income/(expense)	2,157	1,852	7,016	4,611
Equity in income of unconsolidated joint ventures		0		0
Loss on extinguishment of debt			0
Gain/(loss) on sale of real estate assets, net		109,516	43,769	109,521
Other income (expense)	(1,467)		39,848
Income/(loss) before consolidated subsidiaries	28,998		120,930
Income from subsidiaries	0		0
Net income	28,998	132,089	120,930	184,149
Plus: Net loss applicable to noncontrolling interest	0	4	4	10
Net income applicable to Piedmont	28,998	132,093	120,934	184,159
Property management fee revenue
Revenues:
Property management and other property related revenue	368	454	1,059	1,379
Property management fee revenue | Eliminations
Revenues:
Property management and other property related revenue	(3,928)	(4,112)	(11,566)	(12,412)
Property management fee revenue | Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Revenues:
Property management and other property related revenue	0	0	0	0
Property management fee revenue | Piedmont OP (the Issuer) | Reportable Legal Entities
Revenues:
Property management and other property related revenue	0	0	0	0
Property management fee revenue | Non-Guarantors | Reportable Legal Entities
Revenues:
Property management and other property related revenue	4,296	4,566	12,625	13,791
Other property related income
Revenues:
Property management and other property related revenue	4,822	4,012	15,232	14,576
Other property related income | Eliminations
Revenues:
Property management and other property related revenue	0	0	0	0
Other property related income | Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Revenues:
Property management and other property related revenue	0	0	0	0
Other property related income | Piedmont OP (the Issuer) | Reportable Legal Entities
Revenues:
Property management and other property related revenue	35	42	92	97
Other property related income | Non-Guarantors | Reportable Legal Entities
Revenues:
Property management and other property related revenue	$ 4,787	$ 3,970	$ 15,140	$ 14,479

Guarantor and Non-Guarantor F_5

Guarantor and Non-Guarantor Financial Information (Consolidating Statements of Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont	$ 16,114	$ 126,133	$ 84,886	$ 164,947	$ 133,564
Effective portion of gain on derivative instruments that are designated and qualify as cash flow hedges (See Note 6)	1,145	175	4,408	307
Plus: Reclassification of gain included in net income	(434)	653	373	2,936
Other comprehensive income	711	853	4,781	3,296	$ 6,060
Comprehensive income applicable to Piedmont	16,825	126,986	89,667	168,243
Reportable Legal Entities | Piedmont (Parent) (Guarantor)
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont	16,114	(77)	84,886	(261)
Effective portion of gain on derivative instruments that are designated and qualify as cash flow hedges (See Note 6)	1,145		4,408
Plus: Reclassification of gain included in net income	(434)		373
Other comprehensive income	711		4,781
Comprehensive income applicable to Piedmont	16,825		89,667
Reportable Legal Entities | Piedmont OP (the Issuer)
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont	13,945	(5,883)	83,193	(18,951)
Effective portion of gain on derivative instruments that are designated and qualify as cash flow hedges (See Note 6)	1,145		4,408
Plus: Reclassification of gain included in net income	(434)		373
Other comprehensive income	711		4,781
Comprehensive income applicable to Piedmont	14,656		87,974
Reportable Legal Entities | Non-Guarantors
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont	28,998	132,093	120,934	184,159
Effective portion of gain on derivative instruments that are designated and qualify as cash flow hedges (See Note 6)	0		0
Plus: Reclassification of gain included in net income	0		0
Other comprehensive income	0		0
Comprehensive income applicable to Piedmont	28,998		120,934
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income applicable to Piedmont	(42,943)	$ 0	(204,127)	$ 0
Effective portion of gain on derivative instruments that are designated and qualify as cash flow hedges (See Note 6)	(1,145)		(4,408)
Plus: Reclassification of gain included in net income	434		(373)
Other comprehensive income	(711)		(4,781)
Comprehensive income applicable to Piedmont	$ (43,654)		$ (208,908)

Guarantor and Non-Guarantor F_6

Guarantor and Non-Guarantor Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	$ 138,322	$ 176,380
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles	(73,174)	(65,407)
Intercompany note receivable	0	0
Investments in unconsolidated joint ventures		(1,162)
Net sales proceeds from wholly-owned properties	419,554	375,199
Net sales proceeds from unconsolidated joint ventures	0	12,334
Note receivable issuance	(3,200)	0
Deferred lease costs paid	(15,831)	(19,419)
Distributions from subsidiaries	0
Net cash provided by investing activities	327,349	301,545
Cash Flows from Financing Activities:
Debt issuance and other costs paid	(947)	(101)
Proceeds from debt	820,061	147,000
Repayments of debt	(833,005)	(466,046)
Intercompany note payable	0	0
Costs of issuance of common stock	0	(97)
Value of shares withheld for payment of taxes related to employee stock compensation	(2,219)	(3,385)
Repurchases of common stock as part of announced plan	(266,062)	(3,895)
(Distributions to)/repayments from affiliates		0
Dividends paid and discount on dividend reinvestments	(184,073)	(122,237)
Net cash used in financing activities	(466,245)	(448,761)
Net (decrease)/increase in cash, cash equivalents, and restricted cash and escrows	(574)	29,164
Cash, cash equivalents, and restricted cash and escrows, beginning of period	8,755	8,204
Cash, cash equivalents, and restricted cash and escrows, end of period	8,181	37,368
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	(204,920)	0
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles	0	0
Intercompany note receivable	(88,000)	48,710
Investments in unconsolidated joint ventures		0
Net sales proceeds from wholly-owned properties	0	0
Net sales proceeds from unconsolidated joint ventures		0
Note receivable issuance	0
Deferred lease costs paid	0	0
Distributions from subsidiaries	(427,417)
Net cash provided by investing activities	(515,417)	48,710
Cash Flows from Financing Activities:
Debt issuance and other costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	0	0
Intercompany note payable	88,000	(48,710)
Costs of issuance of common stock		0
Value of shares withheld for payment of taxes related to employee stock compensation	0	0
Repurchases of common stock as part of announced plan	0	0
(Distributions to)/repayments from affiliates		0
Dividends paid and discount on dividend reinvestments	632,337	0
Net cash used in financing activities	720,337	(48,710)
Net (decrease)/increase in cash, cash equivalents, and restricted cash and escrows	0	0
Cash, cash equivalents, and restricted cash and escrows, beginning of period	0	0
Cash, cash equivalents, and restricted cash and escrows, end of period	0	0
Piedmont (Parent) (Guarantor) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	89,540	4,335
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles	0	0
Intercompany note receivable	0	0
Investments in unconsolidated joint ventures		0
Net sales proceeds from wholly-owned properties	0	0
Net sales proceeds from unconsolidated joint ventures		0
Note receivable issuance	0
Deferred lease costs paid	0	0
Distributions from subsidiaries	362,784
Net cash provided by investing activities	362,784	0
Cash Flows from Financing Activities:
Debt issuance and other costs paid	0	0
Proceeds from debt	0	0
Repayments of debt	0	0
Intercompany note payable	0	0
Costs of issuance of common stock		(97)
Value of shares withheld for payment of taxes related to employee stock compensation	(2,219)	(3,385)
Repurchases of common stock as part of announced plan	(266,062)	(3,895)
(Distributions to)/repayments from affiliates		125,271
Dividends paid and discount on dividend reinvestments	(184,043)	(122,229)
Net cash used in financing activities	(452,324)	(4,335)
Net (decrease)/increase in cash, cash equivalents, and restricted cash and escrows	0	0
Cash, cash equivalents, and restricted cash and escrows, beginning of period	150	150
Cash, cash equivalents, and restricted cash and escrows, end of period	150	150
Piedmont OP (the Issuer) | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	89,639	(15,468)
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles	(6,074)	(793)
Intercompany note receivable	88,000	0
Investments in unconsolidated joint ventures		(1,162)
Net sales proceeds from wholly-owned properties	36,572	23,028
Net sales proceeds from unconsolidated joint ventures		12,334
Note receivable issuance	0
Deferred lease costs paid	(1,826)	(858)
Distributions from subsidiaries	64,633
Net cash provided by investing activities	181,305	32,549
Cash Flows from Financing Activities:
Debt issuance and other costs paid	(947)	(102)
Proceeds from debt	820,061	147,000
Repayments of debt	(832,000)	(325,000)
Intercompany note payable	0	(14,289)
Costs of issuance of common stock		0
Value of shares withheld for payment of taxes related to employee stock compensation	0	0
Repurchases of common stock as part of announced plan	0	0
(Distributions to)/repayments from affiliates		197,519
Dividends paid and discount on dividend reinvestments	(258,907)	0
Net cash used in financing activities	(271,793)	5,128
Net (decrease)/increase in cash, cash equivalents, and restricted cash and escrows	(849)	22,209
Cash, cash equivalents, and restricted cash and escrows, beginning of period	3,906	3,693
Cash, cash equivalents, and restricted cash and escrows, end of period	3,057	25,902
Non-Guarantors | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	164,063	187,513
Cash Flows from Investing Activities:
Investment in real estate assets and real estate related intangibles	(67,100)	(64,614)
Intercompany note receivable	0	(48,710)
Investments in unconsolidated joint ventures		0
Net sales proceeds from wholly-owned properties	382,982	352,171
Net sales proceeds from unconsolidated joint ventures		0
Note receivable issuance	(3,200)
Deferred lease costs paid	(14,005)	(18,561)
Distributions from subsidiaries	0
Net cash provided by investing activities	298,677	220,286
Cash Flows from Financing Activities:
Debt issuance and other costs paid	0	1
Proceeds from debt	0	0
Repayments of debt	(1,005)	(141,046)
Intercompany note payable	(88,000)	62,999
Costs of issuance of common stock		0
Value of shares withheld for payment of taxes related to employee stock compensation	0	0
Repurchases of common stock as part of announced plan	0	0
(Distributions to)/repayments from affiliates		(322,790)
Dividends paid and discount on dividend reinvestments	(373,460)	(8)
Net cash used in financing activities	(462,465)	(400,844)
Net (decrease)/increase in cash, cash equivalents, and restricted cash and escrows	275	6,955
Cash, cash equivalents, and restricted cash and escrows, beginning of period	4,699	4,361
Cash, cash equivalents, and restricted cash and escrows, end of period	$ 4,974	$ 11,316

Subsequent Events (Details)

Subsequent Events (Details) $ / shares in Units, ft² in Thousands, $ in Thousands	Oct. 30, 2018$ / shares	Oct. 25, 2018USD ($)ft²a	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)
Subsequent Event [Line Items]
Payments to acquire real estate			$ 28,176	$ 0
Subsequent Event
Subsequent Event [Line Items]
Dividends declared (in dollars per share) | $ / shares	$ 0.21
9320 Excelsior Boulevard | Subsequent Event
Subsequent Event [Line Items]
Payments to acquire real estate		$ 49,400
Square footage of real estate property | ft²		268
Acreage of real estate acquired | a		5.84
Percent of real estate acquired leased		100.00%