Tier Reit (TIER) 10-Q 9 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - $ / shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	TIER REIT INC
Entity Central Index Key	0001176373
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Par Value Per Share (in dollar per share)	$ 0.0001
Entity Common Stock, Shares Outstanding		55,520,525
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Emerging Growth Company	false
Entity Small Business	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Real estate
Land	$ 148,122	$ 154,422
Land held for development	50,240	36,830
Buildings and improvements, net	1,062,177	1,132,428
Real estate under development	71,412	41,404
Total real estate	1,331,951	1,365,084
Cash and cash equivalents	9,805	30,741
Restricted cash	3,327	6,141
Accounts receivable, net	61,237	67,335
Prepaid expenses and other assets	9,072	11,376
Investments in unconsolidated entities	30,187	32,746
Deferred financing fees, net	2,526	2,756
Lease intangibles, net	95,980	101,372
Total assets	1,544,085	1,617,551
Liabilities
Notes payable, net	661,550	714,755
Accounts payable and accrued liabilities	63,350	91,548
Acquired below-market leases, net	21,165	22,651
Other liabilities	15,795	11,116
Total liabilities	761,860	840,070
Commitments and contingencies
Equity
Preferred stock, $.0001 par value per share; 17,500,000 shares authorized, none outstanding	0	0
Convertible stock, $.0001 par value per share; 1,000 shares authorized, none outstanding	0	0
Common stock, $.0001 par value per share; 382,499,000 shares authorized, 55,298,782 and 53,839,766 shares issued and outstanding at March 31, 2019, and December 31, 2018, respectively	6	5
Additional paid-in capital	2,784,317	2,749,106
Cumulative distributions and net loss attributable to common stockholders	(2,002,087)	(1,977,969)
Accumulated other comprehensive income (loss)	(3,617)	3,409
Stockholders’ equity	778,619	774,551
Noncontrolling interests	3,606	2,930
Total equity	782,225	777,481
Total liabilities and equity	$ 1,544,085	$ 1,617,551

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (shares)	17,500,000	17,500,000
Preferred stock, shares outstanding (shares)	0	0
Convertible stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible stock, shares authorized (shares)	1,000	1,000
Convertible stock, shares outstanding (shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (shares)	382,499,000	382,499,000
Common stock, shares issued (shares)	55,298,782	53,839,766
Common stock, shares outstanding (shares)	55,298,782	53,839,766

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Rental revenue	$ 50,092,000	$ 54,143,000
Expenses
Property operating expenses	11,050,000	13,155,000
Real estate taxes	8,101,000	8,754,000
Property management fees	63,000	85,000
Interest expense	5,759,000	8,109,000
Asset impairment losses	937,000	0
General and administrative	8,945,000	5,503,000
Depreciation and amortization	22,903,000	24,616,000
Total expenses	57,758,000	60,222,000
Interest and other income	154,000	45,000
Loss on early extinguishment of debt	(6,025,000)	(8,988,000)
Gain on sale of assets	0	12,014,000
Loss before income taxes, equity in operations of investments, and gain on remeasurement of investment in unconsolidated entities	(13,537,000)	(3,008,000)
Provision for income taxes	(234,000)	(195,000)
Equity in operations of investments	(446,000)	287,000
Gain on remeasurement of investment in unconsolidated entities	0	11,242,000
Net income (loss)	(14,217,000)	8,326,000
Noncontrolling interests	93,000	64,000
Net income (loss) attributable to common stockholders	$ (14,124,000)	$ 8,390,000
Weighted average common shares outstanding - basic (in shares)	54,319,635	47,645,050
Weighted average common shares outstanding - diluted (in shares)	54,319,635	48,299,882
Basic net income (loss) per common share (in dollars per share)	$ (0.26)	$ 0.18
Diluted net income (loss) per common share (in dollars per share)	(0.26)	0.17
Distributions declared per common share (in dollars per share)	$ 0.18	$ 0.18
Comprehensive income (loss):
Net income (loss)	$ (14,217,000)	$ 8,326,000
Other comprehensive income (loss): unrealized gain (loss) on interest rate derivatives	(7,027,000)	5,438,000
Comprehensive income (loss)	(21,244,000)	13,764,000
Comprehensive loss attributable to noncontrolling interests	94,000	62,000
Comprehensive income (loss) attributable to common stockholders	$ (21,150,000)	$ 13,826,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Changes in Equity (unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Cumulative Distributions and Net Loss Attributable to Common Stockholders	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2017		47,623
Beginning balance at Dec. 31, 2017	$ 677,571	$ 5	$ 2,609,540	$ (1,936,960)	$ 4,218	$ 768
Increase (Decrease) in Equity
Net income (loss)	8,326			8,390		(64)
Unrealized loss on interest rate derivatives	5,438				5,436	2
Share-based compensation, net (in shares)		33
Share based compensation, net	791		748			43
Contributions by noncontrolling interests	2,603					2,603
Common stock ($0.18 per share)	(8,626)			(8,626)
Distributions declared, Noncontrolling interests	(3)					(3)
Ending balance (in shares) at Mar. 31, 2018		47,656
Ending balance at Mar. 31, 2018	687,560	$ 5	2,610,288	(1,936,561)	10,479	3,349
Beginning balance (in shares) at Dec. 31, 2018		53,840
Beginning balance at Dec. 31, 2018	777,481	$ 5	2,749,106	(1,977,969)	3,409	2,930
Increase (Decrease) in Equity
Net income (loss)	(14,217)			(14,124)		(93)
Issuance of common stock, net (in shares)		1,442
Issuance of common stock, net	34,481	$ 1	34,480
Unrealized loss on interest rate derivatives	(7,027)				(7,026)	(1)
Share-based compensation, net (in shares)		17
Share based compensation, net	782		731			51
Contributions by noncontrolling interests	721					721
Common stock ($0.18 per share)	(9,994)			(9,994)
Distributions declared, Noncontrolling interests	(2)					(2)
Ending balance (in shares) at Mar. 31, 2019		55,299
Ending balance at Mar. 31, 2019	$ 782,225	$ 6	$ 2,784,317	$ (2,002,087)	$ (3,617)	$ 3,606

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Equity (unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Distributions declared per common share (in dollars per share)	$ 0.18	$ 0.18

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities
Net income (loss)	$ (14,217)	$ 8,326
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Asset impairment losses	937	0
Gain on sale of assets	0	(12,014)
Gain on remeasurement of investment in unconsolidated entities	0	(11,242)
Loss on early extinguishment of debt	6,025	8,988
Amortization of restricted shares and units	1,020	1,000
Depreciation and amortization	22,903	24,616
Amortization of lease intangibles	(171)	(63)
Amortization of above- and below-market rent	(1,486)	(1,276)
Amortization of deferred financing fees	348	404
Equity in operations of investments	446	(287)
Ownership portion of fees from unconsolidated entities	15	48
Distributions from investments	0	10
Change in accounts receivable	1,492	644
Change in prepaid expenses and other assets	843	911
Change in lease commissions	(1,478)	(1,130)
Change in other lease intangibles	(22)	4
Change in accounts payable and accrued liabilities	(27,416)	(21,510)
Change in other liabilities	(285)	508
Cash used in operating activities	(11,046)	(2,063)
Cash flows from investing activities
Escrow deposits	0	(3,000)
Return of investments	0	1,711
Purchases of real estate	(18,691)	(98,875)
Investments in unconsolidated entities	2,098	(409)
Capital expenditures for real estate	(14,474)	(8,526)
Capital expenditures for real estate under development	(20,384)	(18,211)
Proceeds from sales of assets	71,522	141,391
Insurance proceeds for capital expenditures	1,605	0
Cash provided by investing activities	21,676	14,081
Cash flows from financing activities
Financing costs	0	(3,178)
Proceeds from notes payable	65,000	702,000
Payments on notes payable	(118,654)	(700,384)
Payments for early extinguishment of debt	(5,694)	(3,632)
Issuance of common stock	35,003	0
Costs associated with issuance of common stock	(522)	0
Transfer of common stock	(238)	(210)
Distributions paid to common stockholders	(9,994)	(8,626)
Distributions paid to noncontrolling interests	(2)	(3)
Contributions from noncontrolling interests	721	2,453
Cash used in financing activities	(34,380)	(11,580)
Net change in cash, cash equivalents, and restricted cash	(23,750)	438
Cash, cash equivalents, and restricted cash at beginning of period	36,882	22,310
Cash, cash equivalents, and restricted cash at end of period	$ 13,132	$ 22,748

Business

Business	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business	Business Organization TIER REIT, Inc. is a publicly traded (NYSE: TIER), self-managed, Dallas-based real estate investment trust focused on owning quality, well-managed commercial office properties in dynamic markets throughout the U.S. As used herein, “TIER REIT,” “TIER,” the “Company,” “we,” “us,” or “our” refers to TIER REIT, Inc. and its subsidiaries unless the context otherwise requires. TIER REIT’s vision is to be the premier owner and operator of best-in-class office properties in TIER 1 submarkets, which are primarily higher density and amenity-rich locations within select, high-growth metropolitan areas that offer a walkable experience to various amenities. Our mission is to provide unparalleled, TIER ONE Property Services to our tenants and outsized total return through stock price appreciation and dividend growth to our stockholders. TIER REIT was incorporated in June 2002 as a Maryland corporation and has elected to be treated, and currently qualifies, as a real estate investment trust, or REIT, for federal income tax purposes. As of March 31, 2019 , we owned interests in 17 operating office properties and two development properties. Our operating properties are located in five markets throughout the United States. Substantially all of our business is conducted through Tier Operating Partnership LP (“Tier OP”), a Texas limited partnership. Our wholly-owned subsidiary, Tier GP, Inc., a Delaware corporation, is the sole general partner of Tier OP. Our direct and indirect wholly-owned subsidiaries, Tier Business Trust, a Maryland business trust, and Tier Partners, LLC, a Delaware limited liability company, are limited partners that together with Tier GP, Inc. own all of Tier OP.

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies Interim Unaudited Financial Information The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and should be read in conjunction with the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2018 , which was filed with the Securities and Exchange Commission (“SEC”) on February 11, 2019. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been omitted from this report on Form 10-Q pursuant to the rules and regulations of the SEC. The results for the interim periods shown in this report are not necessarily indicative of future financial results. The accompanying condensed consolidated balance sheets as of March 31, 2019 , and December 31, 2018 , and condensed consolidated statements of operations and comprehensive income (loss), changes in equity, and cash flows for the periods ended March 31, 2019 and 2018 , have not been audited by our independent registered public accounting firm. In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments necessary to present fairly our financial position as of March 31, 2019 , and December 31, 2018 , and our results of operations and our cash flows for the periods ended March 31, 2019 and 2018 . These adjustments are of a normal recurring nature. We have evaluated subsequent events for recognition or disclosure in our condensed consolidated financial statements. Proposed Merger On March 25, 2019, we announced our entry into a definitive merger agreement (the “Merger Agreement”) with Cousins Properties Incorporated (“Cousins”), and Murphy Subsidiary Holdings Corporation, a wholly-owned subsidiary of Cousins (“Merger Sub”), to combine in a 100% stock-for-stock transaction (the “Merger”). Under the terms of the agreement, Cousins will issue 2.98 shares of newly issued common stock in exchange for each share of TIER common stock. The all-stock merger is intended to qualify as a tax-free “reorganization” for U.S. federal income tax purposes. Upon closing, Cousins and TIER stockholders will own approximately 72% and 28% of the combined company’s stock, respectively. The transaction is subject to customary closing conditions, including receipt of the approval of both Cousins and TIER stockholders. There can be no assurance that the Merger will be completed on the terms or timeline currently contemplated or at all. Summary of Significant Accounting Policies Described below are certain of our significant accounting policies. The disclosures regarding several of the policies have been condensed or omitted in accordance with interim reporting regulations specified by Form 10-Q pursuant to the rules and regulations of the SEC. Please see our consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for a complete listing of our significant accounting policies. Real Estate The following is a summary of our buildings and improvements and related lease intangibles as of March 31, 2019 , and December 31, 2018 (in thousands): Lease Intangibles Assets Liabilities Acquired Below-Market Leases Buildings and Improvements Other Lease Intangibles as of March 31, 2019 Cost $ 1,500,620 $ 162,091 $ (60,043 ) Less: accumulated depreciation and amortization (438,443 ) (66,111 ) 38,878 Net $ 1,062,177 $ 95,980 $ (21,165 ) Lease Intangibles Assets Liabilities Acquired Below-Market Leases Buildings and Improvements Other Lease Intangibles as of December 31, 2018 Cost $ 1,574,653 $ 170,824 $ (60,509 ) Less: accumulated depreciation and amortization (442,225 ) (69,452 ) 37,858 Net $ 1,132,428 $ 101,372 $ (22,651 ) We amortize the value of in-place leases, in-place tenant improvements, and in-place leasing commissions to expense over the initial term of the respective leases. The tenant relationship values are amortized to expense over the tenants’ respective initial lease terms and any anticipated renewal periods, but in no event does the amortization period for intangible assets or liabilities exceed the remaining depreciable life of the building. Should a tenant terminate its lease, the unamortized portion of the acquired lease intangibles related to that tenant would be charged to expense. The estimated remaining average useful lives for acquired lease intangibles range from an ending date of April 2019 to an ending date of November 2027. Anticipated amortization associated with acquired lease intangibles for each of the following five years is as follows (in thousands): April 2019 - December 2019 $ 5,386 2020 $ 6,141 2021 $ 4,899 2022 $ 4,197 2023 $ 3,634 Impairment of Real Estate-Related Assets For our consolidated real estate assets, we monitor events and changes in circumstances indicating that the carrying amounts of the real estate assets may not be recoverable. When such events or changes in circumstances are present, we assess potential impairment by comparing estimated future undiscounted cash flows expected to be generated over the life of the asset, including its eventual disposition, to the carrying amount of the asset. In the event that the carrying amount exceeds the estimated future undiscounted cash flows, we recognize an impairment loss to adjust the carrying amount of the asset to its estimated fair value. Our process to estimate the fair value of an asset involves using bona fide purchase offers or the expected sales price of an executed sales agreement, which would be considered Level 1 or Level 2 assumptions within the fair value hierarchy. To the extent that this type of third-party information is unavailable, we estimate projected cash flows and a risk-adjusted rate of return that we believe would be used by a third party market participant in estimating the fair value of an asset. This is considered a Level 3 assumption within the fair value hierarchy. These projected cash flows are prepared internally by the Company’s asset management professionals and are updated quarterly to reflect in-place and projected leasing activity, market revenue and expense growth rates, market capitalization rates, discount rates, and changes in economic and other relevant conditions. The Company’s Chief Financial Officer, Chief Accounting Officer, and Managing Director - Asset Management review these projected cash flows to assure that the valuation is prepared using reasonable inputs and assumptions, which are consistent with market data or with assumptions that would be used by a third party market participant and assume the highest and best use of the real estate investment. We recorded an impairment charge of approximately $0.9 million for the three months ended March 31, 2019 , related to final closing costs for properties that were impaired in 2018, and sold in 2019. We had no impairment charges for the three months ended March 31, 2018 . For our unconsolidated real estate assets, at each reporting date we compare the estimated fair value of our investment to the carrying amount. An impairment charge is recorded to the extent the fair value of our investment is less than the carrying amount and the decline in value is determined to be other an other-than-temporary decline. We had no impairment charges related to our investments in unconsolidated entities for the three months ended March 31, 2019 or 2018 . In evaluating our investments for impairment, management makes several estimates and assumptions, including, but not limited to, the projected date of disposition (the intended hold period) and sales price for each property, the estimated future cash flows of each property during our estimated ownership period, and for unconsolidated investments, the estimated future distributions from the investment. A change in these estimates and assumptions could result in understating or overstating the carrying amount of our investments, which could be material to our financial statements. We undergo continuous evaluations of property level performance, credit market conditions, and financing options. If our assumptions regarding the cash flows expected to result from the use and eventual disposition of our properties decrease or our expected hold periods decrease, we may incur future impairment charges on our real estate-related assets. In addition, we may incur impairment charges on assets classified as held for sale in the future if the carrying amount of the asset upon classification as held for sale exceeds the estimated fair value, less costs to sell. Hurricane Harvey In August 2017, One & Two Eldridge Place and Three Eldridge Place (collectively known as the “Eldridge Properties”), located in Houston, Texas, experienced flood-related damage as a result of Hurricane Harvey and its aftermath. By early January 2018, all of the properties were fully operational. We carry comprehensive property, casualty, flood, and business interruption insurance that we anticipate will cover our losses at the properties, subject to a deductible. The Eldridge Properties were sold in January 2019. As of March 31, 2019 , we have an insurance recovery receivable of $4.4 million in “accounts receivable, net” on our condensed consolidated balance sheet for the estimated net book value of damaged assets and the restoration expenses incurred because we determined the insurance proceeds were probable of receipt. To the extent that insurance proceeds ultimately exceed the net book value of damaged assets plus the restoration expenses incurred, the excess (net of the deductible) will be reflected as income in the period insurance proceeds are received or when receipt is deemed probable to occur. Cash, Cash Equivalents, and Restricted Cash We consider investments in highly-liquid money market funds or investments with original maturities of three months or less to be cash equivalents. Restricted cash includes restricted money market accounts, as required by our lenders or by leases, for anticipated tenant improvements, property taxes and insurance, certain tenant security deposits, and additional loan security reserves. The following is a summary of our cash, cash equivalents, and restricted cash total as presented in our condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2018 (in thousands): March 31, March 31, Cash and cash equivalents $ 9,805 $ 10,183 Restricted cash 3,327 12,565 Total cash, cash equivalents, and restricted cash $ 13,132 $ 22,748 Accounts Receivable, net The following is a summary of our accounts receivable, net as of March 31, 2019 , and December 31, 2018 (in thousands): March 31, December 31, Straight-line rental revenue receivable $ 52,267 $ 51,912 Insurance receivable 4,358 9,680 Tenant receivables 2,767 5,572 Non-tenant receivables 1,845 821 Allowance for doubtful accounts — (650 ) Total $ 61,237 $ 67,335 As of March 31, 2019, our lease related receivables, which includes tenant receivables and straight-line rental revenue receivables, are reduced for credit losses as a reduction to rental revenue. Management assesses collectability based on its judgment of whether a tenant may or may not meet its financial obligations and reduces these receivables to an amount it believes is collectible. As of December 31, 2018, prior to the adoption of the leasing standard, our allowance for doubtful accounts was an estimate based on management’s evaluation of accounts where it determined that a tenant may not meet its financial obligations. In these situations, management used its judgment, based on the facts and circumstances, and recorded a reserve for that tenant against amounts due to reduce the receivable to an amount it believed was collectible. These reserves were reevaluated and adjusted as additional information became available. Investments in Unconsolidated Entities Investments in unconsolidated entities consist of our noncontrolling interests in properties. We account for these investments using the equity method of accounting in accordance with GAAP. We use the equity method of accounting when we have significant influence, but not control, of the operating and financial decisions of these investments and thereby have some responsibility to create a return on our investment. The equity method of accounting requires these investments to be initially recorded at cost and subsequently increased (decreased) for our share of net income (loss), including eliminations for our share of inter-company transactions, and increased (decreased) for contributions (distributions). To the extent that we contribute assets to an unconsolidated entity, our investment in the unconsolidated entity is recorded at our cost basis in the assets that were contributed to the entity. To the extent that our cost basis is different than the basis reflected at the entity level, the basis difference is generally amortized over the life of the related asset and included in our share of equity in operations of investments. For unconsolidated investments that have properties under development, we capitalize interest expense to our investment basis using our weighted average interest rate of consolidated debt. Capitalization begins when we are engaged in the activities necessary to get the property ready for its intended use. We cease capitalization when the development is completed and ready for its intended use or if the intended use changes such that capitalization is no longer appropriate. For the three months ended March 31, 2018, we capitalized interest incurred of approximately $0.3 million for unconsolidated entities with properties under development, which is included in our investments in unconsolidated entities on our condensed consolidated balance sheets. We had no unconsolidated properties under development in 2019. Noncontrolling Interests Noncontrolling interests consist of our third-party partners’ proportionate share of equity in certain consolidated real estate properties and restricted stock units issued to our independent directors. Lessee Accounting We have land that is subject to long-term ground leases, and we lease surface parking lots and parking spaces, all of which provides parking to our office tenants at certain properties. Additionally, we lease office equipment. In addition to evaluating whether a contractual arrangement contains or is a lease at lease inception, we evaluate lease classification at lease commencement. Our operating leases generally contain fixed payment terms. Right-of-use (“ROU”) assets and lease liabilities are recognized at the lease commencement date and calculated as the present value of lease payments over the respective lease term. Management utilizes significant judgment and assumptions in assessing whether a contract contains a lease as defined by the accounting standard and also in determining the amount of the ROU asset and lease liability. The discount rate used to calculate the present value of our lease liability is evaluated for each lease at commencement. Since the implicit rate is not readily determinable for our leases, we use our incremental borrowing rate based on the information available at the commencement date. Additionally, the lease term used in our determination of the lease liability is based on our assessment of whether we will exercise extension and termination options as provided by the leases. Revenue Recognition Our rental revenue primarily consists of revenue generated from leases. We recognize rental income generated from all leases of consolidated real estate assets on a straight-line basis over the terms of the respective leases, including the effect of rent holidays, if any. Certain of our leases are subject to variable payment terms in which payments are periodically increased on the basis of increases in the Consumer Price Index (“CPI”). Changes to the CPI are not estimated as part of the related straight-line rent revenue and are recognized in the period in which the revenue is generated. Additionally, certain of our tenant leases contain options to extend or terminate the lease term. We do not include these extensions or termination options in our assessment of lease terms unless we are reasonably certain the tenant will exercise these options. For contracts with customers (as defined by GAAP), we recognize revenue when we transfer promised goods or services to a customer in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. Our revenue from contracts with customers primarily consists of parking income and development fee income. Parking income - Parking income is primarily generated (1) through contractual arrangements with management companies that operate our parking garages and remit the monthly revenue collected to us or (2) directly through tenant leases. Revenue is recognized at a point in time upon the performance of services. Accounts receivable are recorded for services provided in advance of receiving payment. Management applies judgment in determining whether we are the principal or agent in those arrangements with management companies. We report revenue and expenses from these arrangements on a gross basis since we control the fulfillment of the promise to provide the service. Development fee income - We serve as a development manager for development projects owned by unconsolidated entities in which we have an ownership interest. Development fees are paid monthly and structured based on costs that approximate the percentage of construction completed. Our performance obligation is therefore satisfied over time, and we recognize development fee income based on progress of the developments. Sales of Real Estate Gain on sale of assets - Upon the disposition of a property, we recognize a gain or loss at a point in time when we determine control of the underlying asset has been transferred to the buyer. Our performance obligation is generally satisfied at closing of the transaction. Any continuing involvement is analyzed as a separate performance obligation in the contract and a portion of the sales price is allocated to each performance obligation. When the performance obligation related to the continuing involvement is satisfied, the sales price allocated to it is recognized. There is significant judgment applied to estimate the amount of any variable consideration identified within the sales price and assess its probability of occurrence based on current market information, historical transactions, and forecasted information that is reasonably available.

New Accounting Pronouncements

New Accounting Pronouncements	3 Months Ended
	Mar. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements New Accounting Pronouncements to be Adopted In June 2016, the Financial Accounting Standards Board (“FASB”) issued amended guidance that requires measurement and recognition of expected credit losses for financial assets, including trade and other receivables, held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. This is different from the current guidance as this will require immediate recognition of estimated credit losses expected to occur over the remaining life of many financial assets. Generally, the pronouncement requires a modified retrospective method of adoption. This guidance is effective for fiscal years and interim periods within those years beginning after December 15, 2019, with early adoption permitted. We are currently evaluating the impact this guidance will have on our financial statements when adopted. In August 2018, the FASB issued amended guidance that removes certain disclosure requirements related to the fair value hierarchy, modifies existing disclosure requirements related to measurement uncertainty, and adds new disclosure requirements, such as disclosing the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and disclosing the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. This guidance is effective for fiscal years and interim periods within those years beginning after December 15, 2019, with early adoption permitted. We are currently evaluating the impact this guidance will have on our financial statements when adopted. Recently Adopted Accounting Pronouncements In February 2016, FASB issued updated guidance that sets out revised principles for the recognition, measurement, presentation and disclosure of leases for both lessees and lessors. The guidance requires lessees to recognize assets and liabilities for operating leases with lease terms greater than twelve months on the balance sheet. The guidance modifies lessors’ classification criteria for leases and the accounting for sales-type and direct financing leases. The guidance also makes changes to lessor accounting and reporting, specifically the classification of lease components and non-lease components, such as services provided to tenants. The guidance is effective for fiscal years and interim periods within those years beginning after December 15, 2018. We adopted this guidance on January 1, 2019, using the cumulative effect method in the period of adoption under the transition option provided by the standard. The adoption did not result in a cumulative catch-up adjustment to our opening cumulative distributions and net loss attributable to common stockholders. Upon adoption, we elected the package of practical expedients for all existing leases as of January 1, 2019, which permits us not to reassess (1) whether any expired or existing contracts are or contain leases, (2) lease classification for any expired or existing leases, and (3) any initial direct costs for any existing leases as of the adoption date. We also elected, as a lessor, the practical expedient to not separate non-lease components from associated lease components. Our non-lease components include common area maintenance and utilities services provided to tenants. We met the criteria to elect this expedient since we concluded (1) the pattern and transfer of such services and the associated lease component (i.e., rent) are the same and (2) the lease component (i.e., rent), if accounted for separately, would be classified as an operating lease. Therefore, non-lease components are accounted as part of the related lease component, which is the predominant component, under the leasing standard. Upon adoption of the standard, as a lessee, we recognized right-of-use assets recorded within “prepaid expenses and other assets” of approximately $2.2 million and corresponding operating lease liabilities recorded within “other liabilities” of approximately $2.2 million on our condensed consolidated balance sheet related to our ground leases and surface parking lot operating leases. As a lessor, our recognition of rental income remained substantially the same with previous guidance; however, the treatment of initial direct costs has changed upon adoption. Certain external legal fees related to the successful execution of lease agreements that were previously capitalized are required to be expensed as incurred under the new accounting standard. In June 2018, the FASB issued updated guidance that is intended to simplify aspects of share-based compensation issued to non-employees by making the guidance consistent with the accounting for employee share-based compensation. This guidance is effective for annual reporting periods, and interim periods within those years, beginning after December 15, 2018. We adopted this guidance on January 1, 2019, and the adoption did not have a material impact on our financial statements.

Real Estate Activities

Real Estate Activities	3 Months Ended
	Mar. 31, 2019
Real Estate [Abstract]
Real Estate Activities	Real Estate Activities Dispositions of Real Estate The following table presents our sales of real estate for the three months ended March 31, 2019 (in thousands): Property Name Date of Disposition Location Rentable Square Footage Contract Sale Price Proceeds from Sale Eldridge Properties (1) 01/31/19 Houston, TX 824 $ 78,400 $ 71,522 _________________ (1) Consists of two properties, One & Two Eldridge Place and Three Eldridge Place. Properties that have been sold or disposed contributed net loss of approximately $0.8 million and net income of approximately $0.2 million to our net income (loss) for the three months ended March 31, 2019 and 2018, respectively. These amounts include impairment losses and exclude any gains related to the sales or other dispositions of these properties. Acquisition of Real Estate On February 27, 2019, we acquired a 95% interest in 3354 Peachtree Road, an approximate three -acre land site located in Atlanta, Georgia. The total purchase price of the joint venture transaction was approximately $14.2 million (at 100% ).

Real Estate Under Development

Real Estate Under Development	3 Months Ended
	Mar. 31, 2019
Real Estate Under Development [Abstract]
Real Estate Under Development	Real Estate Under Development When we are engaged in activities to get a potential development ready for its intended use, we capitalize interest, property taxes, insurance, ground lease payments, and direct construction costs. For the three months ended March 31, 2019 , we capitalized a total of approximately $30.5 million , including approximately $1.0 million of interest. For the three months ended March 31, 2018 , we capitalized a total of approximately $21.8 million , which included approximately $0.8 million of interest. These costs are classified as real estate under development on our condensed consolidated balance sheets until such time that the development is complete.

Investments in Unconsolidated E

Investments in Unconsolidated Entities	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Investments in Unconsolidated Entities	Investments in Unconsolidated Entities We participate in real estate ventures for the purpose of acquiring and developing office properties in which we may or may not have a controlling financial interest. Our investments in unconsolidated entities consist of our noncontrolling interests in certain properties that are accounted for using the equity method of accounting. The following is a summary of our investments in unconsolidated entities as of March 31, 2019 , and December 31, 2018 (dollar amounts in thousands): Ownership Interest Unconsolidated Investment Balance Entity Name Property March 31, December 31, March 31, December 31, 208 Nueces Street, LLC (1)(2) Third + Shoal 47.50 % 47.50 % $ 30,187 $ 32,746 _________________ (1) We evaluate our investments in unconsolidated entities in order to determine if they are variable interest entities (“VIEs”). Based on our assessment, we identified this entity as a VIE, but we are not the primary beneficiary, as we do not have the power to direct the activities that most significantly impact the economic performance of this entity. For VIEs in which we are not deemed to be the primary beneficiary, we continue to account for them using the equity method. The maximum amount of exposure to loss with respect to this VIE is the carrying amount of our investment and any debt guaranteed by us. As of March 31, 2019 , and December 31, 2018, Tier OP guaranteed 25% of the construction loan of 208 Nueces Street, LLC, as discussed below in “Guarantees.” At March 31, 2019 , our VIE had total assets of approximately $154.2 million and total liabilities of approximately $99.6 million . At December 31, 2018 , our VIE had total assets of approximately $140.6 million and total liabilities of approximately $85.2 million . (2) Our investments in unconsolidated entities at March 31, 2019 , and December 31, 2018 , include basis adjustments that total approximately $4.2 million and $6.4 million , respectively. Basis adjustments represent the aggregate difference between our historical cost basis and our equity basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differences occur from impairment of investments and upon the transfer of assets that were previously owned by us into a joint venture. In addition, capitalized interest and certain acquisition, transaction, and other costs may not be reflected in the net assets at the joint venture level. Our equity in operations of investments represents our proportionate share of the combined earnings and losses of our investment for the period of our ownership. For the three months ended March 31, 2019 and 2018 , we recorded approximately $0.4 million of loss and approximately $0.3 million of income, respectively, for our share of equity in operations from our investments in unconsolidated entities. Guarantees The unconsolidated entities in which we have investments generally finance their activities with a combination of partner equity and debt financing. In 2017, 208 Nueces Street, LLC entered into a construction loan for the development of Third + Shoal, in which Tier OP guaranteed up to 50% of the outstanding principal balance. This percentage is reduced when certain conditions in the guarantee agreement are met, and as of March 31, 2019 , this percentage was 25% . The guarantee, which extends to October 2021 when the loan matures, includes a project completion guarantee and a payment guarantee covering a percentage of the outstanding loan. Additionally, there is a recourse carve-out agreement in which Tier OP guarantees the entire outstanding balance of the loan in addition to any related losses that may arise from certain violations of the joint venture’s contractual agreements, including “bad boy acts.” In these situations, we have an indemnity and contribution agreement with our partners where each partner has indemnified the other for any recourse liability resulting from claims triggered by that partner. As of March 31, 2019 , 208 Nueces Street, LLC has a loan commitment of approximately $103.8 million , of which, if the full amount of the debt obligation was borrowed, we estimate approximately $26.0 million is our maximum exposure related to the payment guarantee. As of March 31, 2019 , the outstanding balance of the construction loan for 208 Nueces Street, LLC was approximately $73.5 million , of which we estimate approximately $18.4 million is our maximum exposure related to the payment guarantee. These maximum exposure estimates do not take into account any recoveries from the underlying collateral or any reimbursement from our partners. We believe that, as of March 31, 2019 , in the event we become legally obligated to perform under the payment guarantee, the collateral in 208 Nueces Street, LLC should be sufficient to repay the obligation. If it is not, we and our partners would need to contribute additional capital to the venture.

Notes Payable, net

Notes Payable, net	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Notes Payable, net	Notes Payable, net Our notes payable, net were approximately $661.6 million and $714.8 million as of March 31, 2019 , and December 31, 2018, respectively. As of March 31, 2019 , all of our outstanding debt was fixed rate debt (or effectively fixed rate debt, through the use of interest rate swaps), with the exception of approximately $72.0 million . As of March 31, 2019 , the stated annual interest rates on our outstanding debt, ranged from approximately 3.06% to 4.24% . As of March 31, 2019 , the effective weighted average interest rate for our debt is approximately 3.45% . Our loan agreements generally require us to comply with certain reporting and financial covenants. As of March 31, 2019 , we believe we were in compliance with the covenants under each of our loan agreements, including our credit facility. Our outstanding debt has maturity dates that range from January 2022 to January 2025. The following table provides information regarding the timing of principal payments of our notes payable, net, as of March 31, 2019 (in thousands): Principal payments due in: April 2019 - December 2019 $ — 2020 — 2021 — 2022 297,000 2023 66,000 2024 and Thereafter 300,000 Less: unamortized debt issuance costs (1) (1,450 ) Notes payable, net $ 661,550 ________________ (1) Excludes approximately $2.5 million of unamortized debt issuance costs associated with the revolving line of credit because these costs are presented as an asset on our condensed consolidated balance sheets. Credit Facility We have a credit agreement through our operating partnership, Tier OP, that provides for total unsecured borrowings of up to $900.0 million , subject to our compliance with certain financial covenants. The facility consists of a $300.0 million term loan, a $275.0 million term loan, and a $325.0 million revolving line of credit. The $300.0 million term loan matures on January 17, 2025. The $275.0 million term loan matures on June 30, 2022. The revolving line of credit matures on January 18, 2022, and can be extended one additional year subject to certain conditions and payment of an extension fee. The annual interest rate on the credit facility is equal to either, at our election, (1) the “base rate” (calculated as the greatest of (i) the agent’s “prime rate”; (ii) 0.5% above the Federal Funds Effective Rate; or (iii) the LIBOR Market Index Rate plus 1.0% ) plus the applicable margin or (2) LIBOR for an interest period of one , three , or six months plus the applicable margin. The applicable margin will be determined based on the ratio of total indebtedness to total asset value and ranges from 10 basis points to 235 basis points. We have entered into interest rate swap agreements to hedge interest rates on $525.0 million of these borrowings to manage our exposure to future interest rate movements. All amounts owed are guaranteed by us and certain subsidiaries of Tier OP. As of March 31, 2019 , we had approximately $575.0 million in borrowings outstanding under the term loans and $22.0 million in borrowings outstanding under the revolving line of credit with the ability, subject to our most restrictive financial covenants, to borrow an additional approximately $302.4 million under the facility as a whole. As of March 31, 2019 , the weighted average effective interest rate for borrowings under the credit facility as a whole, inclusive of our interest rate swaps, was approximately 3.36% .

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value, as defined by GAAP, is a market-based measurement, not an entity-specific measurement. Therefore, a fair value measurement should be determined based on the assumptions that market participants would use in pricing the asset or liability. As a basis for considering market participant assumptions in fair value measurements, a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the fair value hierarchy) and the reporting entity’s own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the fair value hierarchy) has been established. Assets and Liabilities Measured at Fair Value on a Recurring Basis Derivative financial instruments We use derivative financial instruments, such as interest rate swaps, to manage our interest rate risk. The valuation of these instruments is determined using widely accepted valuation techniques including discounted cash flow analysis of the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. We incorporate credit valuation adjustments (“CVAs”) to appropriately reflect both our own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of our derivative contracts for the effect of nonperformance risk, we have considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees. Although we have determined that the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy, the CVAs associated with our derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by us and our counterparties. However, we have assessed the significance of the impact of the CVAs on the overall valuation of our derivative positions and have determined that they are not significant. As a result, we have determined that our derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. Unrealized gains or losses on derivatives are recorded in accumulated other comprehensive income (loss) (“OCI”) within equity at each measurement date. Our derivative financial instruments are included in “prepaid expenses and other assets” and “other liabilities” on our condensed consolidated balance sheets. The following table sets forth our financial assets and liabilities measured at fair value on a recurring basis, which equals book value, by level within the fair value hierarchy as of March 31, 2019 , and December 31, 2018 (in thousands): Basis of Fair Value Measurements Quoted Prices In Active Markets for Identical Items (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Description March 31, 2019 Derivative financial instruments: Assets $ 4,434 $ — $ 4,434 $ — Liabilities $ (8,050 ) $ — $ (8,050 ) $ — December 31, 2018 Derivative financial instruments: Assets $ 7,751 $ — $ 7,751 $ — Liabilities $ (4,340 ) $ — $ (4,340 ) $ — Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Impairment of Real Estate Related Assets We have recorded non-cash impairment charges related to a reduction in the fair value of certain of our assets. The inputs used to calculate the fair value of these assets included projected cash flows and a risk-adjusted rate of return that we estimated would be used by a market participant in valuing these assets or by obtaining third-party broker valuation estimates, bona fide purchase offers, or the expected sales price of an executed sales agreement. During the three months ended March 31, 2019 , we recorded additional impairment loss of approximately $0.9 million for properties that were impaired in 2018, and sold in 2019. We had approximately $41.6 million in impairment losses during the year ended December 31, 2018, for properties assessed for impairment due to the disposition of a property and changes in management’s estimate of the intended hold periods of certain of our properties. The following table summarizes the assets that were measured at fair value and impaired during the three months ended March 31, 2019 , and the year ended December 31, 2018 (in thousands): Basis of Fair Value Measurements Description Fair Value of Assets at Impairment Quoted Prices In Active Markets for Identical Items (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Losses for the three months ended March 31, 2019 Real estate $ 69,544 $ — $ 69,544 $ — $ (937 ) for the year ended December 31, 2018 Real estate $ 97,544 $ — $ 97,544 $ — $ (41,564 ) Financial Instruments not Reported at Fair Value Financial instruments held at March 31, 2019 , and December 31, 2018 , but not measured at fair value on a recurring basis include cash and cash equivalents, restricted cash, accounts receivable, notes payable, accounts payable and accrued liabilities, and other liabilities. With the exception of notes payable, the financial statement carrying amounts of these items approximate their fair values due to their short-term nature. Estimated fair values for notes payable have been determined using recent trading activity and/or bid-ask spreads and are classified as Level 2 in the fair value hierarchy. Carrying amounts of our notes payable and the related estimated fair value as of March 31, 2019 , and December 31, 2018 , are as follows (in thousands): March 31, 2019 December 31, 2018 Carrying Amount Fair Value Carrying Amount Fair Value Notes payable $ 663,000 $ 663,135 $ 716,654 $ 718,505 Less: unamortized debt issuance costs (1,450 ) (1,899 ) Notes payable, net $ 661,550 $ 714,755

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities We may be exposed to the risk associated with variability of interest rates that might impact our cash flows and the results of our operations. Our objectives in using interest rate derivatives are to add stability to interest expense and to manage our exposure to interest rate movements. To accomplish this objective, we have used interest rate swaps as part of our interest rate risk management strategy. Our interest rate swaps involve the receipt of variable-rate amounts from counterparties in exchange for us making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. Our hedging strategy of entering into interest rate swaps, therefore, is to eliminate or reduce, to the extent possible, the volatility of cash flows. The following table summarizes the notional values of our derivative financial instruments (in thousands) as of March 31, 2019 . The notional values provide an indication of the extent of our involvement in these instruments at March 31, 2019 , but do not represent exposure to credit, interest rate, or market risks. Type/Description Notional Value Index Strike Rate Effective Date Maturity Date Interest rate swap - cash flow hedge $ 125,000 one-month LIBOR 1.6775 % 12/31/14 10/31/19 Interest rate swap - cash flow hedge $ 125,000 one-month LIBOR 1.6935 % 04/30/15 10/31/19 Interest rate swap - cash flow hedge $ 125,000 one-month LIBOR 1.7615 % 06/30/15 05/31/22 Interest rate swap - cash flow hedge $ 150,000 one-month LIBOR 1.7695 % 06/30/15 05/31/22 Interest rate swap - cash flow hedge $ 62,500 one-month LIBOR 2.8220 % 10/31/19 12/31/24 Interest rate swap - cash flow hedge $ 62,500 one-month LIBOR 2.8230 % 10/31/19 12/31/24 Interest rate swap - cash flow hedge $ 125,000 one-month LIBOR 2.8220 % 10/31/19 12/31/24 The table below presents the fair value of our derivative financial instruments, included in “prepaid expenses and other assets” and “other liabilities” on our condensed consolidated balance sheets, as of March 31, 2019 , and December 31, 2018 (in thousands): Derivatives Designated as Hedging Instruments: Derivative Assets Derivative Liabilities March 31, December 31, March 31, December 31, Interest rate swaps $ 4,434 $ 7,751 $ (8,050 ) $ (4,340 ) The tables below present the effect of the change in fair value of derivative financial instruments in our condensed consolidated statements of operations and comprehensive income (loss) for the three months ended March 31, 2019 and 2018 (in thousands): Derivatives in Cash Flow Hedging Relationship Gain (loss) recognized in OCI on derivatives For the Three Months Ended March 31, 2019 March 31, 2018 Interest rate swaps $ (7,027 ) $ 5,438 Loss reclassified from OCI into income For the Three Months Ended Location March 31, 2019 March 31, 2018 Interest expense (1) $ 1,020 $ 159 ______________ (1) Changes in fair value as a result of accrued interest associated with our swap transactions are recorded in accumulated OCI and subsequently reclassified into income. Such amounts are shown net in the condensed consolidated statements of changes in equity and offset dollar for dollar. Total interest expense presented in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) in which the effects of cash flow hedges are recorded For the Three Months Ended Location March 31, 2019 March 31, 2018 Interest expense $ 5,759 $ 8,109 Amounts reported in accumulated OCI related to derivatives will be reclassified to interest expense as interest payments and accruals are made on our variable-rate debt. We estimate that approximately $2.3 million will be reclassified as a decrease to interest expense over the next twelve months ending March 31, 2020. We have agreements with our derivative counterparties that contain provisions where if we default on any of our indebtedness for at least 30 days, during which time such default has not been remedied, and in all cases provided that the aggregate amount of all such defaults is not less than $10.0 million for recourse debt or $75.0 million for non-recourse debt, then we could also be declared in default on our derivative obligations.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies As of March 31, 2019 , we had commitments of approximately $29.4 million for future tenant improvements and leasing commissions. We have employment agreements with our five named executive officers. The term of each employment agreement ends on August 3, 2021, provided that the term will automatically continue for an additional one -year period unless either party provides 60 days written notice of non-renewal prior to the expiration of the initial term. The agreements provide for lump sum payments and an immediate lapse of restrictions on compensation received under the long-term incentive plan upon termination of employment without cause. As a result, in the event we terminated all of these agreements without cause as of March 31, 2019 , we would have recognized approximately $19.1 million in related compensation expense.

Equity

Equity	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Equity	Equity Stock Plans Our 2015 Equity Incentive Plan allows for, and our 2005 Incentive Award Plan allowed for, equity-based incentive awards to be granted to our employees, non-employee directors, and key persons as detailed below: Restricted stock units held by independent directors. We have outstanding restricted stock units (“RSUs”) held by our independent directors. These units vest 13 months after the grant date. Subsequent to vesting, the restricted stock units will be converted to an equivalent number of shares of common stock upon the earlier to occur of the following events or dates: (i) separation from service for any reason other than cause; (ii) a change in control of the Company; (iii) death; or (iv) a date ranging from July 2019 to February 2020, depending on the director. Expense is measured at the grant date based on the estimated fair value of the award and is recognized over the vesting period. Any forfeitures of awards are recognized as they occur. The following is a summary of the number of outstanding RSUs held by our independent directors as of March 31, 2019 and 2018 : March 31, 2019 March 31, 2018 Units Weighted Average Price per unit Units Weighted Average Price per unit Outstanding at the beginning of the year 12,910 $ 23.24 19,672 $ 17.03 Issued 891 $ 22.45 — $ — Converted (2,582 ) $ 23.24 (1,917 ) $ 18.27 Outstanding at the end of the period (1) 11,219 $ 23.18 17,755 $ 16.90 _____________ (1) As of March 31, 2019 , none of the RSUs held by our independent directors are vested. Restricted stock units held by employees. We have outstanding RSUs held by employees. These units vest from December 2019 to December 2021 at which time the units will be converted into a number of shares of common stock, which could range from zero shares to 200% of the issued number of units. The actual number of shares of common stock issued will be based on our total stockholder return (“TSR”) percentage as compared to three metrics: our annualized TSR on a predetermined absolute basis, the TSR of the constituent companies of the Nareit Office Index (unweighted), and the TSR of a select group of peer companies. The following is a summary of the number of outstanding RSUs held by our employees as of March 31, 2019 and 2018 : March 31, 2019 March 31, 2018 Units Weighted Average Price per unit Units Weighted Average Price per unit Outstanding at the beginning of the year 226,745 $ 17.61 208,620 $ 16.59 Issued 119,264 $ 23.76 129,188 $ 17.24 Outstanding at the end of the period 346,009 $ 19.73 337,808 $ 16.84 Compensation cost is measured at the grant date, based on the estimated fair value of the award (ranging from $16.80 per unit to $27.79 per unit) as determined by a Monte Carlo simulation-based model using the assumptions outlined in the table below. Any forfeitures of awards are recognized as they occur. Assumption Value Expected volatility 23% - 26% Risk-free interest rate 1.53% - 2.48% Expected term 35 months Expected dividend yield 3.6% - 4.3% Restricted stock. We have outstanding restricted stock held by employees. Restrictions on outstanding shares lapse based on various lapse schedules and range from December 2019 to December 2021. Compensation cost is measured at the grant date based on the estimated fair value of the award and is recognized as expense over the service period based on a tiered lapse schedule. Any forfeitures of awards are recognized as they occur. The following is a summary of the number of shares of restricted stock outstanding as of March 31, 2019 and 2018 : March 31, 2019 March 31, 2018 Shares Weighted Average Price per share Shares Weighted Average Price per share Outstanding at the beginning of the year 153,568 $ 18.93 180,791 $ 20.47 Issued 103,545 $ 23.76 125,558 $ 17.24 Forfeitures (10,205 ) $ 16.92 — $ — Restrictions lapsed (25,165 ) $ 26.88 (41,062 ) $ 26.23 Outstanding at the end of the period 221,743 $ 20.37 265,287 $ 18.05 For the three months ended March 31, 2019 and 2018 , we recognized a total of approximately $1.0 million , for compensation expense related to the amortization of all of the equity-based incentive awards outlined above. As of March 31, 2019 , the total remaining compensation cost on unvested awards was approximately $8.1 million , with a weighted average remaining contractual life of approximately 1.6 years . ATM Programs On May 10, 2017, we established an at-the-market equity offering program (the “May 2017 ATM Program”) pursuant to which we may issue and sell shares of our common stock having an aggregate offering price of up to $125.0 million in amounts and at times as we determine from time to time. On August 8, 2018, we established an additional ATM program (the “August 2018 ATM Program” and, together with the May 2017 ATM Program, the “ATM Programs”) pursuant to which we may issue and sell shares of our common stock having an additional aggregate offering price of up to $125.0 million , in amounts and at times as we determine from time to time. The following table provides certain details of sales under our ATM Programs for the three months ended March 31, 2019 (dollars in thousands). There were no sales for the three months ended March 31, 2018. Number of Shares Issued Gross Proceeds Commissions Issuance Costs Net Proceeds May 2017 ATM Program 316,969 $ 7,718 $ (96 ) $ (21 ) $ 7,601 August 2018 ATM Program 1,125,000 27,285 (341 ) (64 ) 26,880 Total 1,441,969 $ 35,003 $ (437 ) $ (85 ) $ 34,481 We have no obligation to sell any of such shares under our ATM Programs. Actual sales will depend on a variety of factors to be determined by the Company from time to time, including, among others, market conditions, the trading price of our common stock, our determinations of the appropriate sources of funding for the Company, and potential uses of funding available to us. We intend to use the net proceeds from the offering of such shares, if any, for general corporate purposes, which may include future acquisitions, development, and repayment of indebtedness, including borrowings under our credit facility.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2019
Revenues [Abstract]
Revenue	Revenue We recognize rental income generated from all leases of consolidated real estate assets on a straight-line basis over the terms of the respective leases, including the effect of rent holidays, if any. The total net increase to rental revenue due to straight-line rent adjustments for the three months ended March 31, 2019 and 2018 , was approximately $3.9 million and $0.5 million , respectively. When a tenant exceeds its tenant improvement allowance, this amount is reimbursed to us and recorded as a deferred rent liability, which is recognized as rental revenue over the life of the lease. The total net increase to rental revenue due to this deferred rent for the three months ended March 31, 2019 and 2018 , was approximately $0.4 million and $0.4 million , respectively. Our rental revenue also includes amortization of acquired above- and below-market leases. The total net increase to rental revenue due to the amortization of acquired above- and below-market leases for the three months ended March 31, 2019 and 2018 , was approximately $1.5 million and $1.3 million , respectively. Revenues relating to lease termination fees are recognized on a straight-line basis amortized from the time that a tenant’s right to occupy the leased space is modified through the end of the revised lease term. We recognized no lease termination fees for the three months ended March 31, 2019 . For the three months ended March 31, 2018 , we recognized lease termination fees of approximately $0.3 million . Included in our rental revenue is parking income of approximately $2.1 million and $2.2 million for the three months ended March 31, 2019 and 2018 , respectively, which represents revenue from contracts with customers. We had no significant development fee income for the three months ended March 31, 2019 or 2018 . Accounts receivables from contracts with customers were approximately $0.8 million and $0.7 million as of March 31, 2019 , and December 31, 2018 , respectively.

Leasing Activity

Leasing Activity	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leasing Activity	Leasing Activity As Lessor Our primary source of rental income is generated from our operating leases of office space and is included in “rental revenue” on our condensed consolidated statement of operations and comprehensive income (loss). Our leases with tenants are classified as operating leases. The weighted average remaining lease term for existing leases as of March 31, 2019 , was approximately 5.9 years . After the adoption of new accounting guidance related to leasing, future minimum base rental payments due to us under these non-cancelable operating leases in effect as of March 31, 2019 , are as follows (in thousands): as of March 31, 2019 Amount April 2019 - December 2019 $ 91,882 2020 122,165 2021 106,007 2022 97,046 2023 86,093 2024 and thereafter 284,895 Total $ 788,088 Prior to adoption of new accounting guidance related to leasing, future minimum base rental payments due to us under non-cancelable leases in effect as of December 31, 2018 , were as follows (in thousands): as of December 31, 2018 Amount 2019 $ 131,871 2020 127,275 2021 108,955 2022 99,782 2023 88,138 2024 and thereafter 294,965 Total $ 850,986 As Lessee We have land that is subject to long-term ground leases, and we lease surface parking lots and parking spaces, all of which provides parking to our office tenants at certain properties. Additionally, we lease office equipment. These leases are classified as operating leases under relevant accounting guidance. As of March 31, 2019 , we had operating lease ROU assets of approximately $2.0 million recorded within “prepaid expenses and other assets” and corresponding operating lease liabilities of approximately $2.0 million recorded within “other liabilities” on our condensed consolidated balance sheet. Total rent expense for our operating leases was approximately $0.2 million for the three months ended March 31, 2019 . Cash paid related to our operating lease liabilities totaled approximately $0.2 million for the three months ended March 31, 2019 , and is included in cash used in operating activities on our condensed consolidated statement of cash flows. The weighted average discount rate used to measure the ROU assets and lease liabilities for our operating leases was approximately 4.0% as of March 31, 2019 . Our surface parking lot and parking space leases provide extension options. We did not recognize these extension options in the ROU assets and lease liabilities related to these leases, since we determined it is not reasonably certain that we will exercise them as we consider other parking alternatives for those properties. The weighted average remaining lease term for our operating leases was approximately 3.0 years as of March 31, 2019 . Additionally, we have elected as an accounting policy not to recognize short-term leases (i.e., leases with a lease term of 12 months or less), on our condensed consolidated balance sheet. As of March 31, 2019 , we have no short-term leases and therefore no lease costs associated with short-term leases for the three months ended March 31, 2019 . After the adoption of new accounting guidance related to leasing, future minimum base rental payments payable by us under these non-cancelable operating leases in effect at March 31, 2019 , are as follows (in thousands): as of March 31, 2019 Amount April 2019 - December 2019 $ 623 2020 715 2021 462 2022 175 2023 117 2024 and thereafter — Total $ 2,092 Less: discount (135 ) Total operating lease liabilities $ 1,957 Prior to adoption of new accounting guidance related to leasing, future minimum base rental payments payable by us under these non-cancelable leases in effect as of December 31, 2018 , were as follows (in thousands): as of December 31, 2018 Amount 2019 $ 1,448 2020 1,279 2021 995 2022 683 2023 450 2024 and thereafter — Total $ 4,855

Net Income (Loss) per Common Sh

Net Income (Loss) per Common Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Net Income (Loss) per Common Share	Net Income (Loss) per Common Share Net income (loss) per common share is calculated using the two-class method, which requires the allocation of undistributed net income between common and participating stockholders. All outstanding restricted stock awards containing rights to non-forfeitable distributions are considered participating securities for this calculation. In periods of net loss, no loss is allocated to participating securities because our participating securities do not have a contractual obligation to share in our losses. The following table reflects the calculation of basic and diluted net income (loss) per common share for the three months ended March 31, 2019 and 2018 (in thousands, except per share data): For the Three Months Ended March 31, 2019 March 31, 2018 Numerator: Net income (loss) attributable to common stockholders $ (14,124 ) $ 8,390 Less: net income allocated to participating securities — — Numerator for basic net income (loss) per share $ (14,124 ) $ 8,390 Add: undistributed net income allocated to participating securities — — Less: undistributed net income re-allocated to participating securities — — Numerator for diluted net income (loss) per share (1) $ (14,124 ) $ 8,390 Denominator: Weighted average common shares outstanding - basic 54,320 47,645 Effect of dilutive securities — 655 Weighted average common shares outstanding - diluted 54,320 48,300 Basic net income (loss) per common share $ (0.26 ) $ 0.18 Diluted net income (loss) per common share $ (0.26 ) $ 0.17 Securities excluded from weighted average common shares outstanding - diluted because their effect would be anti-dilutive 826 19 _______________ (1) In periods where there is no undistributed net income to allocate to participating securities, the treasury stock method is used to calculate dilutive securities.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	3 Months Ended
	Mar. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Supplemental cash flow information is summarized below for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 March 31, 2018 Interest paid, net of amounts capitalized $ 5,301 $ 7,804 Income taxes paid $ — $ 2 Non-cash investing activities: Property and equipment additions in accounts payable and accrued liabilities $ 22,248 $ 17,712 Lease liabilities arising from obtaining right-of-use assets $ 2,153 $ — Liabilities assumed through the purchase of real estate $ — $ 7,028 Escrow deposits applied to purchase of real estate $ — $ 21,350 Escrow deposit applied to purchase of real estate from noncontrolling interest $ — $ 150 Acquisition of controlling interest in unconsolidated entity $ — $ 927 Non-cash financing activities: Mortgage notes assumed (1) $ — $ 89,733 Unrealized gain on interest rate derivatives $ — $ 5,438 Unrealized loss on interest rate derivatives $ 7,027 $ — _________________ (1) The approximately $89.7 million mortgage notes assumed during the three months ended March 31, 2018 , includes approximately $44.9 million of debt assumed when we acquired the remaining 50.00% interest in our Domain 8 property, and approximately $44.9 million of debt associated with our previously held 50.00% unconsolidated interest in the Domain 8 property. Domain 8 was consolidated during the three months ended March 31, 2018 .

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Real Estate	We amortize the value of in-place leases, in-place tenant improvements, and in-place leasing commissions to expense over the initial term of the respective leases. The tenant relationship values are amortized to expense over the tenants’ respective initial lease terms and any anticipated renewal periods, but in no event does the amortization period for intangible assets or liabilities exceed the remaining depreciable life of the building. Should a tenant terminate its lease, the unamortized portion of the acquired lease intangibles related to that tenant would be charged to expense. The estimated remaining average useful lives for acquired lease intangibles range from an ending date of April 2019 to an ending date of November 2027.
Impairment of Real Estate-Related Assets	Impairment of Real Estate-Related Assets For our consolidated real estate assets, we monitor events and changes in circumstances indicating that the carrying amounts of the real estate assets may not be recoverable. When such events or changes in circumstances are present, we assess potential impairment by comparing estimated future undiscounted cash flows expected to be generated over the life of the asset, including its eventual disposition, to the carrying amount of the asset. In the event that the carrying amount exceeds the estimated future undiscounted cash flows, we recognize an impairment loss to adjust the carrying amount of the asset to its estimated fair value. Our process to estimate the fair value of an asset involves using bona fide purchase offers or the expected sales price of an executed sales agreement, which would be considered Level 1 or Level 2 assumptions within the fair value hierarchy. To the extent that this type of third-party information is unavailable, we estimate projected cash flows and a risk-adjusted rate of return that we believe would be used by a third party market participant in estimating the fair value of an asset. This is considered a Level 3 assumption within the fair value hierarchy. These projected cash flows are prepared internally by the Company’s asset management professionals and are updated quarterly to reflect in-place and projected leasing activity, market revenue and expense growth rates, market capitalization rates, discount rates, and changes in economic and other relevant conditions. The Company’s Chief Financial Officer, Chief Accounting Officer, and Managing Director - Asset Management review these projected cash flows to assure that the valuation is prepared using reasonable inputs and assumptions, which are consistent with market data or with assumptions that would be used by a third party market participant and assume the highest and best use of the real estate investment. We recorded an impairment charge of approximately $0.9 million for the three months ended March 31, 2019 , related to final closing costs for properties that were impaired in 2018, and sold in 2019. We had no impairment charges for the three months ended March 31, 2018 . For our unconsolidated real estate assets, at each reporting date we compare the estimated fair value of our investment to the carrying amount. An impairment charge is recorded to the extent the fair value of our investment is less than the carrying amount and the decline in value is determined to be other an other-than-temporary decline. We had no impairment charges related to our investments in unconsolidated entities for the three months ended March 31, 2019 or 2018 . In evaluating our investments for impairment, management makes several estimates and assumptions, including, but not limited to, the projected date of disposition (the intended hold period) and sales price for each property, the estimated future cash flows of each property during our estimated ownership period, and for unconsolidated investments, the estimated future distributions from the investment. A change in these estimates and assumptions could result in understating or overstating the carrying amount of our investments, which could be material to our financial statements. We undergo continuous evaluations of property level performance, credit market conditions, and financing options. If our assumptions regarding the cash flows expected to result from the use and eventual disposition of our properties decrease or our expected hold periods decrease, we may incur future impairment charges on our real estate-related assets. In addition, we may incur impairment charges on assets classified as held for sale in the future if the carrying amount of the asset upon classification as held for sale exceeds the estimated fair value, less costs to sell.
Hurricane Harvey	Hurricane Harvey In August 2017, One & Two Eldridge Place and Three Eldridge Place (collectively known as the “Eldridge Properties”), located in Houston, Texas, experienced flood-related damage as a result of Hurricane Harvey and its aftermath. By early January 2018, all of the properties were fully operational. We carry comprehensive property, casualty, flood, and business interruption insurance that we anticipate will cover our losses at the properties, subject to a deductible. The Eldridge Properties were sold in January 2019. As of March 31, 2019 , we have an insurance recovery receivable of $4.4 million in “accounts receivable, net” on our condensed consolidated balance sheet for the estimated net book value of damaged assets and the restoration expenses incurred because we determined the insurance proceeds were probable of receipt. To the extent that insurance proceeds ultimately exceed the net book value of damaged assets plus the restoration expenses incurred, the excess (net of the deductible) will be reflected as income in the period insurance proceeds are received or when receipt is deemed probable to occur.
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents, and Restricted Cash We consider investments in highly-liquid money market funds or investments with original maturities of three months or less to be cash equivalents. Restricted cash includes restricted money market accounts, as required by our lenders or by leases, for anticipated tenant improvements, property taxes and insurance, certain tenant security deposits, and additional loan security reserves.
Accounts Receivable, net	As of March 31, 2019, our lease related receivables, which includes tenant receivables and straight-line rental revenue receivables, are reduced for credit losses as a reduction to rental revenue. Management assesses collectability based on its judgment of whether a tenant may or may not meet its financial obligations and reduces these receivables to an amount it believes is collectible. As of December 31, 2018, prior to the adoption of the leasing standard, our allowance for doubtful accounts was an estimate based on management’s evaluation of accounts where it determined that a tenant may not meet its financial obligations. In these situations, management used its judgment, based on the facts and circumstances, and recorded a reserve for that tenant against amounts due to reduce the receivable to an amount it believed was collectible. These reserves were reevaluated and adjusted as additional information became available.
Investments in Unconsolidated Entities	Investments in Unconsolidated Entities Investments in unconsolidated entities consist of our noncontrolling interests in properties. We account for these investments using the equity method of accounting in accordance with GAAP. We use the equity method of accounting when we have significant influence, but not control, of the operating and financial decisions of these investments and thereby have some responsibility to create a return on our investment. The equity method of accounting requires these investments to be initially recorded at cost and subsequently increased (decreased) for our share of net income (loss), including eliminations for our share of inter-company transactions, and increased (decreased) for contributions (distributions). To the extent that we contribute assets to an unconsolidated entity, our investment in the unconsolidated entity is recorded at our cost basis in the assets that were contributed to the entity. To the extent that our cost basis is different than the basis reflected at the entity level, the basis difference is generally amortized over the life of the related asset and included in our share of equity in operations of investments. For unconsolidated investments that have properties under development, we capitalize interest expense to our investment basis using our weighted average interest rate of consolidated debt. Capitalization begins when we are engaged in the activities necessary to get the property ready for its intended use. We cease capitalization when the development is completed and ready for its intended use or if the intended use changes such that capitalization is no longer appropriate.
Noncontrolling Interests	Noncontrolling Interests Noncontrolling interests consist of our third-party partners’ proportionate share of equity in certain consolidated real estate properties and restricted stock units issued to our independent directors.
Lessee Accounting	Lessee Accounting We have land that is subject to long-term ground leases, and we lease surface parking lots and parking spaces, all of which provides parking to our office tenants at certain properties. Additionally, we lease office equipment. In addition to evaluating whether a contractual arrangement contains or is a lease at lease inception, we evaluate lease classification at lease commencement. Our operating leases generally contain fixed payment terms. Right-of-use (“ROU”) assets and lease liabilities are recognized at the lease commencement date and calculated as the present value of lease payments over the respective lease term. Management utilizes significant judgment and assumptions in assessing whether a contract contains a lease as defined by the accounting standard and also in determining the amount of the ROU asset and lease liability. The discount rate used to calculate the present value of our lease liability is evaluated for each lease at commencement. Since the implicit rate is not readily determinable for our leases, we use our incremental borrowing rate based on the information available at the commencement date. Additionally, the lease term used in our determination of the lease liability is based on our assessment of whether we will exercise extension and termination options as provided by the leases.
Revenue Recognition	Revenue Recognition Our rental revenue primarily consists of revenue generated from leases. We recognize rental income generated from all leases of consolidated real estate assets on a straight-line basis over the terms of the respective leases, including the effect of rent holidays, if any. Certain of our leases are subject to variable payment terms in which payments are periodically increased on the basis of increases in the Consumer Price Index (“CPI”). Changes to the CPI are not estimated as part of the related straight-line rent revenue and are recognized in the period in which the revenue is generated. Additionally, certain of our tenant leases contain options to extend or terminate the lease term. We do not include these extensions or termination options in our assessment of lease terms unless we are reasonably certain the tenant will exercise these options. For contracts with customers (as defined by GAAP), we recognize revenue when we transfer promised goods or services to a customer in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. Our revenue from contracts with customers primarily consists of parking income and development fee income. Parking income - Parking income is primarily generated (1) through contractual arrangements with management companies that operate our parking garages and remit the monthly revenue collected to us or (2) directly through tenant leases. Revenue is recognized at a point in time upon the performance of services. Accounts receivable are recorded for services provided in advance of receiving payment. Management applies judgment in determining whether we are the principal or agent in those arrangements with management companies. We report revenue and expenses from these arrangements on a gross basis since we control the fulfillment of the promise to provide the service. Development fee income - We serve as a development manager for development projects owned by unconsolidated entities in which we have an ownership interest. Development fees are paid monthly and structured based on costs that approximate the percentage of construction completed. Our performance obligation is therefore satisfied over time, and we recognize development fee income based on progress of the developments.
Sales of Real Estate	Sales of Real Estate Gain on sale of assets - Upon the disposition of a property, we recognize a gain or loss at a point in time when we determine control of the underlying asset has been transferred to the buyer. Our performance obligation is generally satisfied at closing of the transaction. Any continuing involvement is analyzed as a separate performance obligation in the contract and a portion of the sales price is allocated to each performance obligation. When the performance obligation related to the continuing involvement is satisfied, the sales price allocated to it is recognized. There is significant judgment applied to estimate the amount of any variable consideration identified within the sales price and assess its probability of occurrence based on current market information, historical transactions, and forecasted information that is reasonably available.

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Schedule of cost basis, accumulated depreciation and amortization related to entity's consolidated real estate properties and related lease intangibles	The following is a summary of our buildings and improvements and related lease intangibles as of March 31, 2019 , and December 31, 2018 (in thousands): Lease Intangibles Assets Liabilities Acquired Below-Market Leases Buildings and Improvements Other Lease Intangibles as of March 31, 2019 Cost $ 1,500,620 $ 162,091 $ (60,043 ) Less: accumulated depreciation and amortization (438,443 ) (66,111 ) 38,878 Net $ 1,062,177 $ 95,980 $ (21,165 ) Lease Intangibles Assets Liabilities Acquired Below-Market Leases Buildings and Improvements Other Lease Intangibles as of December 31, 2018 Cost $ 1,574,653 $ 170,824 $ (60,509 ) Less: accumulated depreciation and amortization (442,225 ) (69,452 ) 37,858 Net $ 1,132,428 $ 101,372 $ (22,651 )
Anticipated amortization associated with the acquired lease intangibles for each of the five years	Anticipated amortization associated with acquired lease intangibles for each of the following five years is as follows (in thousands): April 2019 - December 2019 $ 5,386 2020 $ 6,141 2021 $ 4,899 2022 $ 4,197 2023 $ 3,634
Cash, cash equivalents and restricted cash	The following is a summary of our cash, cash equivalents, and restricted cash total as presented in our condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2018 (in thousands): March 31, March 31, Cash and cash equivalents $ 9,805 $ 10,183 Restricted cash 3,327 12,565 Total cash, cash equivalents, and restricted cash $ 13,132 $ 22,748
Cash, cash equivalents and restricted cash	The following is a summary of our cash, cash equivalents, and restricted cash total as presented in our condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2018 (in thousands): March 31, March 31, Cash and cash equivalents $ 9,805 $ 10,183 Restricted cash 3,327 12,565 Total cash, cash equivalents, and restricted cash $ 13,132 $ 22,748
Summary of net accounts receivable	The following is a summary of our accounts receivable, net as of March 31, 2019 , and December 31, 2018 (in thousands): March 31, December 31, Straight-line rental revenue receivable $ 52,267 $ 51,912 Insurance receivable 4,358 9,680 Tenant receivables 2,767 5,572 Non-tenant receivables 1,845 821 Allowance for doubtful accounts — (650 ) Total $ 61,237 $ 67,335

Real Estate Activities (Tables)

Real Estate Activities (Tables)	3 Months Ended
	Mar. 31, 2019
Real Estate [Abstract]
Sale of real estate	The following table presents our sales of real estate for the three months ended March 31, 2019 (in thousands): Property Name Date of Disposition Location Rentable Square Footage Contract Sale Price Proceeds from Sale Eldridge Properties (1) 01/31/19 Houston, TX 824 $ 78,400 $ 71,522 _________________ (1) Consists of two properties, One & Two Eldridge Place and Three Eldridge Place.

Investments in Unconsolidated_2

Investments in Unconsolidated Entities (Tables)	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Summary of the entity's investments in unconsolidated entities	The following is a summary of our investments in unconsolidated entities as of March 31, 2019 , and December 31, 2018 (dollar amounts in thousands): Ownership Interest Unconsolidated Investment Balance Entity Name Property March 31, December 31, March 31, December 31, 208 Nueces Street, LLC (1)(2) Third + Shoal 47.50 % 47.50 % $ 30,187 $ 32,746 _________________ (1) We evaluate our investments in unconsolidated entities in order to determine if they are variable interest entities (“VIEs”). Based on our assessment, we identified this entity as a VIE, but we are not the primary beneficiary, as we do not have the power to direct the activities that most significantly impact the economic performance of this entity. For VIEs in which we are not deemed to be the primary beneficiary, we continue to account for them using the equity method. The maximum amount of exposure to loss with respect to this VIE is the carrying amount of our investment and any debt guaranteed by us. As of March 31, 2019 , and December 31, 2018, Tier OP guaranteed 25% of the construction loan of 208 Nueces Street, LLC, as discussed below in “Guarantees.” At March 31, 2019 , our VIE had total assets of approximately $154.2 million and total liabilities of approximately $99.6 million . At December 31, 2018 , our VIE had total assets of approximately $140.6 million and total liabilities of approximately $85.2 million . (2) Our investments in unconsolidated entities at March 31, 2019 , and December 31, 2018 , include basis adjustments that total approximately $4.2 million and $6.4 million , respectively. Basis adjustments represent the aggregate difference between our historical cost basis and our equity basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differences occur from impairment of investments and upon the transfer of assets that were previously owned by us into a joint venture. In addition, capitalized interest and certain acquisition, transaction, and other costs may not be reflected in the net assets at the joint venture level.

Notes Payable, net (Tables)

Notes Payable, net (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Schedule of long-term debt maturities	The following table provides information regarding the timing of principal payments of our notes payable, net, as of March 31, 2019 (in thousands): Principal payments due in: April 2019 - December 2019 $ — 2020 — 2021 — 2022 297,000 2023 66,000 2024 and Thereafter 300,000 Less: unamortized debt issuance costs (1) (1,450 ) Notes payable, net $ 661,550 ________________ (1) Excludes approximately $2.5 million of unamortized debt issuance costs associated with the revolving line of credit because these costs are presented as an asset on our condensed consolidated balance sheets.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of financial assets and liabilities measured at fair value on a recurring basis	The following table sets forth our financial assets and liabilities measured at fair value on a recurring basis, which equals book value, by level within the fair value hierarchy as of March 31, 2019 , and December 31, 2018 (in thousands): Basis of Fair Value Measurements Quoted Prices In Active Markets for Identical Items (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Fair Value Description March 31, 2019 Derivative financial instruments: Assets $ 4,434 $ — $ 4,434 $ — Liabilities $ (8,050 ) $ — $ (8,050 ) $ — December 31, 2018 Derivative financial instruments: Assets $ 7,751 $ — $ 7,751 $ — Liabilities $ (4,340 ) $ — $ (4,340 ) $ —
Schedule of financial assets and liabilities measured at fair value on a nonrecurring basis	The following table summarizes the assets that were measured at fair value and impaired during the three months ended March 31, 2019 , and the year ended December 31, 2018 (in thousands): Basis of Fair Value Measurements Description Fair Value of Assets at Impairment Quoted Prices In Active Markets for Identical Items (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Losses for the three months ended March 31, 2019 Real estate $ 69,544 $ — $ 69,544 $ — $ (937 ) for the year ended December 31, 2018 Real estate $ 97,544 $ — $ 97,544 $ — $ (41,564 )
Schedule of carrying amounts and related estimated fair value of notes payable	Carrying amounts of our notes payable and the related estimated fair value as of March 31, 2019 , and December 31, 2018 , are as follows (in thousands): March 31, 2019 December 31, 2018 Carrying Amount Fair Value Carrying Amount Fair Value Notes payable $ 663,000 $ 663,135 $ 716,654 $ 718,505 Less: unamortized debt issuance costs (1,450 ) (1,899 ) Notes payable, net $ 661,550 $ 714,755

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of derivative instruments	The following table summarizes the notional values of our derivative financial instruments (in thousands) as of March 31, 2019 . The notional values provide an indication of the extent of our involvement in these instruments at March 31, 2019 , but do not represent exposure to credit, interest rate, or market risks. Type/Description Notional Value Index Strike Rate Effective Date Maturity Date Interest rate swap - cash flow hedge $ 125,000 one-month LIBOR 1.6775 % 12/31/14 10/31/19 Interest rate swap - cash flow hedge $ 125,000 one-month LIBOR 1.6935 % 04/30/15 10/31/19 Interest rate swap - cash flow hedge $ 125,000 one-month LIBOR 1.7615 % 06/30/15 05/31/22 Interest rate swap - cash flow hedge $ 150,000 one-month LIBOR 1.7695 % 06/30/15 05/31/22 Interest rate swap - cash flow hedge $ 62,500 one-month LIBOR 2.8220 % 10/31/19 12/31/24 Interest rate swap - cash flow hedge $ 62,500 one-month LIBOR 2.8230 % 10/31/19 12/31/24 Interest rate swap - cash flow hedge $ 125,000 one-month LIBOR 2.8220 % 10/31/19 12/31/24
Schedule of fair value of derivative financial instruments included in other liabilities	The table below presents the fair value of our derivative financial instruments, included in “prepaid expenses and other assets” and “other liabilities” on our condensed consolidated balance sheets, as of March 31, 2019 , and December 31, 2018 (in thousands): Derivatives Designated as Hedging Instruments: Derivative Assets Derivative Liabilities March 31, December 31, March 31, December 31, Interest rate swaps $ 4,434 $ 7,751 $ (8,050 ) $ (4,340 )
Schedule of effect of the change in fair value of derivative financial instruments in statement of operations and comprehensive income (loss)	The tables below present the effect of the change in fair value of derivative financial instruments in our condensed consolidated statements of operations and comprehensive income (loss) for the three months ended March 31, 2019 and 2018 (in thousands): Derivatives in Cash Flow Hedging Relationship Gain (loss) recognized in OCI on derivatives For the Three Months Ended March 31, 2019 March 31, 2018 Interest rate swaps $ (7,027 ) $ 5,438 Loss reclassified from OCI into income For the Three Months Ended Location March 31, 2019 March 31, 2018 Interest expense (1) $ 1,020 $ 159 ______________ (1) Changes in fair value as a result of accrued interest associated with our swap transactions are recorded in accumulated OCI and subsequently reclassified into income. Such amounts are shown net in the condensed consolidated statements of changes in equity and offset dollar for dollar. Total interest expense presented in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) in which the effects of cash flow hedges are recorded For the Three Months Ended Location March 31, 2019 March 31, 2018 Interest expense $ 5,759 $ 8,109

Equity (Tables)

Equity (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Schedule of restricted stock units	The following is a summary of the number of outstanding RSUs held by our independent directors as of March 31, 2019 and 2018 : March 31, 2019 March 31, 2018 Units Weighted Average Price per unit Units Weighted Average Price per unit Outstanding at the beginning of the year 12,910 $ 23.24 19,672 $ 17.03 Issued 891 $ 22.45 — $ — Converted (2,582 ) $ 23.24 (1,917 ) $ 18.27 Outstanding at the end of the period (1) 11,219 $ 23.18 17,755 $ 16.90 _____________ (1) As of March 31, 2019 , none of the RSUs held by our independent directors are vested. The following is a summary of the number of outstanding RSUs held by our employees as of March 31, 2019 and 2018 : March 31, 2019 March 31, 2018 Units Weighted Average Price per unit Units Weighted Average Price per unit Outstanding at the beginning of the year 226,745 $ 17.61 208,620 $ 16.59 Issued 119,264 $ 23.76 129,188 $ 17.24 Outstanding at the end of the period 346,009 $ 19.73 337,808 $ 16.84
Summary of restricted stock valuation assumptions	Compensation cost is measured at the grant date, based on the estimated fair value of the award (ranging from $16.80 per unit to $27.79 per unit) as determined by a Monte Carlo simulation-based model using the assumptions outlined in the table below. Any forfeitures of awards are recognized as they occur. Assumption Value Expected volatility 23% - 26% Risk-free interest rate 1.53% - 2.48% Expected term 35 months Expected dividend yield 3.6% - 4.3%
Summary of the number of shares of restricted stock outstanding	The following is a summary of the number of shares of restricted stock outstanding as of March 31, 2019 and 2018 : March 31, 2019 March 31, 2018 Shares Weighted Average Price per share Shares Weighted Average Price per share Outstanding at the beginning of the year 153,568 $ 18.93 180,791 $ 20.47 Issued 103,545 $ 23.76 125,558 $ 17.24 Forfeitures (10,205 ) $ 16.92 — $ — Restrictions lapsed (25,165 ) $ 26.88 (41,062 ) $ 26.23 Outstanding at the end of the period 221,743 $ 20.37 265,287 $ 18.05
Schedule of stock issuances	The following table provides certain details of sales under our ATM Programs for the three months ended March 31, 2019 (dollars in thousands). There were no sales for the three months ended March 31, 2018. Number of Shares Issued Gross Proceeds Commissions Issuance Costs Net Proceeds May 2017 ATM Program 316,969 $ 7,718 $ (96 ) $ (21 ) $ 7,601 August 2018 ATM Program 1,125,000 27,285 (341 ) (64 ) 26,880 Total 1,441,969 $ 35,003 $ (437 ) $ (85 ) $ 34,481

Leasing Activity (Tables)

Leasing Activity (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Schedule of future minimum base rental payments, lessor	After the adoption of new accounting guidance related to leasing, future minimum base rental payments due to us under these non-cancelable operating leases in effect as of March 31, 2019 , are as follows (in thousands): as of March 31, 2019 Amount April 2019 - December 2019 $ 91,882 2020 122,165 2021 106,007 2022 97,046 2023 86,093 2024 and thereafter 284,895 Total $ 788,088 Prior to adoption of new accounting guidance related to leasing, future minimum base rental payments due to us under non-cancelable leases in effect as of December 31, 2018 , were as follows (in thousands): as of December 31, 2018 Amount 2019 $ 131,871 2020 127,275 2021 108,955 2022 99,782 2023 88,138 2024 and thereafter 294,965 Total $ 850,986
Schedule of future minimum base rental payments, lessee	After the adoption of new accounting guidance related to leasing, future minimum base rental payments payable by us under these non-cancelable operating leases in effect at March 31, 2019 , are as follows (in thousands): as of March 31, 2019 Amount April 2019 - December 2019 $ 623 2020 715 2021 462 2022 175 2023 117 2024 and thereafter — Total $ 2,092 Less: discount (135 ) Total operating lease liabilities $ 1,957 Prior to adoption of new accounting guidance related to leasing, future minimum base rental payments payable by us under these non-cancelable leases in effect as of December 31, 2018 , were as follows (in thousands): as of December 31, 2018 Amount 2019 $ 1,448 2020 1,279 2021 995 2022 683 2023 450 2024 and thereafter — Total $ 4,855

Net Income (Loss) per Common _2

Net Income (Loss) per Common Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Basic and diluted net income (loss) per common share	The following table reflects the calculation of basic and diluted net income (loss) per common share for the three months ended March 31, 2019 and 2018 (in thousands, except per share data): For the Three Months Ended March 31, 2019 March 31, 2018 Numerator: Net income (loss) attributable to common stockholders $ (14,124 ) $ 8,390 Less: net income allocated to participating securities — — Numerator for basic net income (loss) per share $ (14,124 ) $ 8,390 Add: undistributed net income allocated to participating securities — — Less: undistributed net income re-allocated to participating securities — — Numerator for diluted net income (loss) per share (1) $ (14,124 ) $ 8,390 Denominator: Weighted average common shares outstanding - basic 54,320 47,645 Effect of dilutive securities — 655 Weighted average common shares outstanding - diluted 54,320 48,300 Basic net income (loss) per common share $ (0.26 ) $ 0.18 Diluted net income (loss) per common share $ (0.26 ) $ 0.17 Securities excluded from weighted average common shares outstanding - diluted because their effect would be anti-dilutive 826 19 _______________ (1) In periods where there is no undistributed net income to allocate to participating securities, the treasury stock method is used to calculate dilutive securities.

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	3 Months Ended
	Mar. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Schedule of supplemental cash flow information	Supplemental cash flow information is summarized below for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 March 31, 2018 Interest paid, net of amounts capitalized $ 5,301 $ 7,804 Income taxes paid $ — $ 2 Non-cash investing activities: Property and equipment additions in accounts payable and accrued liabilities $ 22,248 $ 17,712 Lease liabilities arising from obtaining right-of-use assets $ 2,153 $ — Liabilities assumed through the purchase of real estate $ — $ 7,028 Escrow deposits applied to purchase of real estate $ — $ 21,350 Escrow deposit applied to purchase of real estate from noncontrolling interest $ — $ 150 Acquisition of controlling interest in unconsolidated entity $ — $ 927 Non-cash financing activities: Mortgage notes assumed (1) $ — $ 89,733 Unrealized gain on interest rate derivatives $ — $ 5,438 Unrealized loss on interest rate derivatives $ 7,027 $ — _________________ (1) The approximately $89.7 million mortgage notes assumed during the three months ended March 31, 2018 , includes approximately $44.9 million of debt assumed when we acquired the remaining 50.00% interest in our Domain 8 property, and approximately $44.9 million of debt associated with our previously held 50.00% unconsolidated interest in the Domain 8 property. Domain 8 was consolidated during the three months ended March 31, 2018 .

Business (Details)

Business (Details)	3 Months Ended
	Mar. 31, 2019propertymarket
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating office properties	17
Number of development properties	2
Number of markets in which the entity operates interests in properties | market	5

Basis of Presentation and Sig_4

Basis of Presentation and Significant Accounting Policies (Proposed Merger) (Details) - Plan - Cousins Properties Incorporated and Murphy Subsidiary Holdings Corporation	Mar. 25, 2019shares
Business Acquisition [Line Items]
Ownership percentage	28.00%
Cousins Properties Incorporated
Business Acquisition [Line Items]
Number of shares issued of newly issued common stock in exchange for each share of TIER stock	2.98
Ownership percentage	72.00%

Basis of Presentation and Sig_5

Basis of Presentation and Significant Accounting Policies (Real Estate) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Real estate properties
Net	$ 1,062,177	$ 1,132,428
Intangible assets
Net	95,980	101,372
Intangible liabilities
Net	(21,165)	(22,651)
Other Lease Intangibles
Intangible assets
Cost	162,091	170,824
Less: accumulated depreciation and amortization	(66,111)	(69,452)
Net	95,980	101,372
Acquired Below-Market Leases
Intangible liabilities
Cost	(60,043)	(60,509)
Less: accumulated depreciation and amortization	(38,878)	(37,858)
Net	(21,165)	(22,651)
Anticipated amortization associated with acquired lease intangibles
Anticipated Amortization Associated with the Acquired Lease Intangibles for Each of the Following Five Years
April 2019 - December 2019	5,386
2020	6,141
2021	4,899
2022	4,197
2023	3,634
Buildings and Improvements
Real estate properties
Cost	1,500,620	1,574,653
Less: accumulated depreciation and amortization	(438,443)	(442,225)
Net	$ 1,062,177	$ 1,132,428

Basis of Presentation and Sig_6

Basis of Presentation and Significant Accounting Policies (Impairment of Real Estate Related Assets) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment losses	$ 937,000	$ 0	$ 41,600,000
Unconsolidated
Impaired Long-Lived Assets Held and Used [Line Items]
Asset impairment losses	$ 0	$ 0

Basis of Presentation and Sig_7

Basis of Presentation and Significant Accounting Policies (Hurricane Harvey) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Hurricane
Unusual or Infrequent Item, or Both [Line Items]
Insurance recoveries receivable	$ 4.4

Basis of Presentation and Sig_8

Basis of Presentation and Significant Accounting Policies (Cash, Cash Equivalents, and Restricted Cash) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 9,805	$ 30,741	$ 10,183
Restricted cash	3,327	6,141	12,565
Total cash, cash equivalents, and restricted cash	$ 13,132	$ 36,882	$ 22,748	$ 22,310

Basis of Presentation and Sig_9

Basis of Presentation and Significant Accounting Policies (Accounts Receivable, net) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accounts Receivable, Net [Abstract]
Straight-line rental revenue receivable	$ 52,267	$ 51,912
Insurance receivable	4,358	9,680
Tenant receivables	2,767	5,572
Non-tenant receivables	1,845	821
Allowance for doubtful accounts	0	(650)
Total	$ 61,237	$ 67,335

Basis of Presentation and Si_10

Basis of Presentation and Significant Accounting Policies (Investments in Unconsolidated Entities) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Investments in Unconsolidated Entities [Line Items]
Interest costs capitalized	$ 1	$ 0.8
Unconsolidated Entity
Investments in Unconsolidated Entities [Line Items]
Interest costs capitalized		$ 0.3

New Accounting Pronouncements -

New Accounting Pronouncements - Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset	$ 2,000
Total operating lease liabilities	$ 1,957
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset		$ 2,200
Total operating lease liabilities		$ 2,200

Real Estate Activities (Sales o

Real Estate Activities (Sales of Real Estate) (Details) ft² in Thousands, $ in Thousands	Jan. 31, 2019USD ($)ft²	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale		$ 71,522	$ 141,391
Contributed net income (loss)		$ (800)	$ 200
Eldridge Properties (1)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable square feet | ft²	824
Contract sale price	$ 78,400
Proceeds from sale	$ 71,522

Real Estate Activities (Acquisi

Real Estate Activities (Acquisitions of Real Estate) (Details) - 3354 Peachtree Road $ in Millions	Feb. 27, 2019USD ($)a
Business Acquisition [Line Items]
Acquisition of real estate, percent	95.00%
Land site acres | a	3
Contract purchase price | $	$ 14.2
Ownership Interest, total purchase price	100.00%

Real Estate Under Development (

Real Estate Under Development (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Real Estate Under Development [Abstract]
Development costs capitalized	$ 30.5	$ 21.8
Interest costs capitalized	$ 1	$ 0.8

Investments in Unconsolidated_3

Investments in Unconsolidated Entities (Summary of Investments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Investments in Unconsolidated Entities [Line Items]
Unconsolidated Investment Balance	$ 30,187		$ 32,746
Equity method investment, basis adjustment	4,200		6,400
Equity in operations of investments	(446)	$ 287
Variable Interest Entity, not primary beneficiary
Investments in Unconsolidated Entities [Line Items]
Total assets	154,200		140,600
Total liabilities	$ 99,600		$ 85,200
Third Shoal
Investments in Unconsolidated Entities [Line Items]
Ownership Interest	47.50%		47.50%
Unconsolidated Investment Balance	$ 30,187		$ 32,746
Third Shoal | TIER Operating Partnership
Investments in Unconsolidated Entities [Line Items]
Loan guarantee, percentage	25.00%	50.00%
Domain 8 and Third and Shoal [Member] | TIER Operating Partnership | Debt obligation
Investments in Unconsolidated Entities [Line Items]
Obligation, commitment	$ 103,800
Obligation, maximum exposure	26,000
Domain 8 and Third and Shoal [Member] | TIER Operating Partnership | Construction loan guarantee
Investments in Unconsolidated Entities [Line Items]
Obligation, commitment	73,500
Obligation, maximum exposure	$ 18,400

Notes Payable, net (Narrative)

Notes Payable, net (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Notes payable, net	$ 661,550,000	$ 714,755,000
Default interest rate	5.00%
Line of credit, maximum borrowing capacity	$ 900,000,000
Revolving loan extension period	1 year
LIBOR interest index period one	1 month
LIBOR interest index period two	3 months
LIBOR Interest Index period three	6 months
Amount of borrowings with risk managed by hedged interest rates	$ 525,000,000
Weighted average effective interest rate	3.36%
Line of credit | Federal Funds Effective Rate
Line of Credit Facility [Line Items]
Applicable margin	0.50%
Line of credit | Debt Instrument Variable Rate Base Libor
Line of Credit Facility [Line Items]
Applicable margin	1.00%
Term loan facility
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	$ 300,000,000
Second term loan facility
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	275,000,000
Revolving credit facility
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity	325,000,000
Borrowings outstanding	22,000,000
Available additional borrowings	302,400,000
Term loan facility and second term loan facility
Line of Credit Facility [Line Items]
Borrowings outstanding	$ 575,000,000
Minimum
Line of Credit Facility [Line Items]
Line of credit, applicable margin	0.10%
Maximum
Line of Credit Facility [Line Items]
Line of credit, applicable margin	2.35%
Notes payable
Line of Credit Facility [Line Items]
Notes payable, net	$ 661,550,000
Debt bearing interest at variable rates	$ 72,000,000
Weighted average interest rate for consolidated debt	3.45%
Notes payable | Minimum
Line of Credit Facility [Line Items]
Stated annual interest rate	3.06%
Notes payable | Maximum
Line of Credit Facility [Line Items]
Stated annual interest rate	4.24%

Notes Payable, net (Schedule of

Notes Payable, net (Schedule of Long-Term Debt Maturities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Principal payments due in:
Notes payable, net	$ 661,550	$ 714,755
Deferred financing fees, net	2,526	$ 2,756
Notes payable
Principal payments due in:
April 2019 - December 2019	0
2020	0
2021	0
2022	297,000
2023	66,000
2024 and Thereafter	300,000
Less: unamortized debt issuance costs	(1,450)
Notes payable, net	661,550
Revolving credit facility
Principal payments due in:
Deferred financing fees, net	$ 2,500

Fair Value Measurements (Financ

Fair Value Measurements (Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 4,434	$ 7,751
Liabilities	(8,050)	(4,340)
Quoted Prices In Active Markets for Identical Items (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Liabilities	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	4,434	7,751
Liabilities	(8,050)	(4,340)
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Liabilities	$ 0	$ 0

Fair Value Measurements (Impair

Fair Value Measurements (Impairment of Real Estate Related Assets) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset impairment charges	$ (937,000)	$ 0	$ (41,600,000)
Real Estate | Fair Value | Fair value measurements nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	69,544,000		97,544,000
Real Estate | Fair Value | Fair value measurements nonrecurring | Quoted Prices In Active Markets for Identical Items (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	0		0
Real Estate | Fair Value | Fair value measurements nonrecurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	69,544,000		97,544,000
Real Estate | Fair Value | Fair value measurements nonrecurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	0		0
Real Estate | Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset impairment charges	$ (937,000)		$ (41,564,000)

Fair Value Measurements (Fina_2

Fair Value Measurements (Financial Instruments not Reported at Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable, net	$ 661,550	$ 714,755
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	663,000	716,654
Less: unamortized debt issuance costs	(1,450)	(1,899)
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable	$ 663,135	$ 718,505

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities (Notional Values of Derivative Financial Instruments) (Details)	Mar. 31, 2019USD ($)
Derivative [Line Items]
Notional Value	$ 525,000,000
Swap Number One
Derivative [Line Items]
Notional Value	$ 125,000,000
Strike Rate	1.6775%
Swap Number Two
Derivative [Line Items]
Notional Value	$ 125,000,000
Strike Rate	1.6935%
Swap Number Three
Derivative [Line Items]
Notional Value	$ 125,000,000
Strike Rate	1.7615%
Swap Number Four
Derivative [Line Items]
Notional Value	$ 150,000,000
Strike Rate	1.7695%
Swap Number Five
Derivative [Line Items]
Notional Value	$ 62,500,000
Strike Rate	2.822%
Swap Number Six
Derivative [Line Items]
Notional Value	$ 62,500,000
Strike Rate	2.823%
Swap Number Seven
Derivative [Line Items]
Notional Value	$ 125,000,000
Strike Rate	2.822%

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities (Fair Value of Derivative Financial Instruments Included in Other Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative Assets	$ 4,434	$ 7,751
Derivative Liabilities	(8,050)	(4,340)
Designated as hedging instrument | Interest rate swaps
Derivative [Line Items]
Derivative Assets	4,434	7,751
Derivative Liabilities	$ (8,050)	$ (4,340)

Derivative Instruments and He_5

Derivative Instruments and Hedging Activities (Derivatives in Cash Flow Hedging Relationship) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in OCI on derivatives	$ (7,027)	$ 5,438
Interest expense	5,759	8,109
Cash flow hedging | Interest expense
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) reclassified from OCI into income	1,020	159
Interest expense	5,759	8,109
Cash flow hedging | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in OCI on derivatives	$ (7,027)	$ 5,438

Derivative Instruments and He_6

Derivative Instruments and Hedging Activities (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Debt Instrument, by Type [Line Items]
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	$ (2.3)
Period over which default must be remedied	30 days
Recourse debt
Debt Instrument, by Type [Line Items]
Minimum amount of debt default that could cause derivative obligations to also be in default	$ 10
Non-recourse debt
Debt Instrument, by Type [Line Items]
Minimum amount of debt default that could cause derivative obligations to also be in default	$ 75

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)executive
Commitments for future tenant improvements and leasing commissions
Commitments and contingencies
Future tenant improvements and leasing commissions	$ 29.4
Employment agreements
Commitments and contingencies
Number of executives | executive	5
Period of automatic continuation of term of employment	1 year
Notice period for non-renewal of term prior to the expiration of the initial term	60 days
Compensation expense if termination of employment without cause	$ 19.1

Equity (Restricted Stock Units)

Equity (Restricted Stock Units) (Details)	3 Months Ended		25 Months Ended
	Mar. 31, 2019metric$ / sharesshares	Mar. 31, 2018metric$ / sharesshares	Dec. 31, 2020
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted stock units held by independent directors, vested (in units) | shares	0
Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock Units, vesting period	13 months
Directors | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at the beginning of the year (in shares/units) | shares	12,910	19,672
Issued (in units) | shares	891	0
Converted (in units) | shares	(2,582)	(1,917)
Outstanding at the end of the year (in shares/units) | shares	11,219	17,755
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average price per unit, outstanding at the beginning of the year (in dollars per share/unit)	$ 23.24	$ 17.03
Weighted average price per unit, issued (in dollars per unit)	22.45	0
Weighted average price per unit, converted (in dollars per unit)	23.24	18.27
Weighted average price per unit, outstanding at the end of the year (in dollars per share/unit)	$ 23.18	$ 16.90
Employee | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at the beginning of the year (in shares/units) | shares	226,745	208,620
Issued (in units) | shares	119,264	129,188
Outstanding at the end of the year (in shares/units) | shares	346,009	337,808
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average price per unit, outstanding at the beginning of the year (in dollars per share/unit)	$ 17.61	$ 16.59
Weighted average price per unit, issued (in dollars per unit)	23.76	17.24
Weighted average price per unit, outstanding at the end of the year (in dollars per share/unit)	$ 19.73	$ 16.84
Number of metrics used to compare annualized total stockholder return to | metric	3	3
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected term	35 months	35 months
Employee | Restricted Stock Units (RSUs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Estimated fair value of award determined by Monte Carlo model (in dollars per unit)	$ 16.80
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility	23.00%	23.00%
Risk-free interest rate	1.53%	1.53%
Expected dividend yield	3.60%	3.60%
Employee | Restricted Stock Units (RSUs) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Estimated fair value of award determined by Monte Carlo model (in dollars per unit)	$ 27.79
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility	26.00%	26.00%
Risk-free interest rate	2.48%	2.48%
Expected dividend yield	4.30%	4.30%
Employee | Restricted Stock Units (RSUs) | Scenario, forecast | Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Number of common stock shares that restricted stock units can be converted to (in percent)			0.00%
Employee | Restricted Stock Units (RSUs) | Scenario, forecast | Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Number of common stock shares that restricted stock units can be converted to (in percent)			200.00%

Equity (Restricted Stock) (Deta

Equity (Restricted Stock) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Compensation expense related to the amortization of all equity-based incentive awards	$ 1
Total remaining compensation cost on unvested awards	$ 8.1
Compensation cost not yet recognized, unvested awards, period for recognition	1 year 7 months
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at the beginning of the year (in shares/units)	153,568	180,791
Issued (in shares)	103,545	125,558
Forfeiture (in shares)	(10,205)	0
Restrictions lapsed (in units)	(25,165)	(41,062)
Outstanding at the end of the year (in shares/units)	221,743	265,287
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average price per unit, outstanding at the beginning of the year (in dollars per share/unit)	$ 18.93	$ 20.47
Weighted average price per unit, issues (in dollars per share)	23.76	17.24
Weighted average price per unit, forfeited (in dollars per share)	16.92	0
Weighted average price per unit, restrictions lapsed (in dollars per share)	26.88	26.23
Weighted average price per unit, outstanding at the end of the year (in dollars per share/unit)	$ 20.37	$ 18.05

Equity (ATM Program) (Details)

Equity (ATM Program) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Aug. 08, 2018	May 10, 2017
Class of Stock [Line Items]
Issuance of common stock, issuance costs	$ (522,000)	$ 0
Issuance of common stock, value	$ 35,003,000	$ 0
ATM Program
Class of Stock [Line Items]
Common stock, shares issued (in shares)		1,441,969
Issuance of common stock, gross proceeds		$ 35,003,000
Issuance of common stock, commissions		(437,000)
Issuance of common stock, issuance costs		(85,000)
Issuance of common stock, value		$ 34,481,000
May 2017 ATM Program
Class of Stock [Line Items]
Common stock, authorized, value				$ 125,000,000
Common stock, shares issued (in shares)		316,969
Issuance of common stock, gross proceeds		$ 7,718,000
Issuance of common stock, commissions		(96,000)
Issuance of common stock, issuance costs		(21,000)
Issuance of common stock, value		$ 7,601,000
August 2018 ATM Program
Class of Stock [Line Items]
Common stock, authorized, value			$ 125,000,000
Common stock, shares issued (in shares)		1,125,000
Issuance of common stock, gross proceeds		$ 27,285,000
Issuance of common stock, commissions		(341,000)
Issuance of common stock, issuance costs		(64,000)
Issuance of common stock, value		$ 26,880,000

Revenue - Rental Income (Detail

Revenue - Rental Income (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 50,092,000	$ 54,143,000
Real estate, straight-line rent adjustments
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	3,900,000	500,000
Real estate, deferred rent
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	400,000	400,000
Real estate, acquired above- and below- market leases
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	1,500,000	1,300,000
Real estate, lease termination fees
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 0	$ 300,000

Revenue - Revenue form Contract

Revenue - Revenue form Contracts with Customers (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Accounts receivable
Rental Revenue [Line Items]
Accounts receivable, contracts with customers	$ 800,000		$ 700,000
Parking
Rental Revenue [Line Items]
Rental revenue	2,100,000	$ 2,200,000
Development fee
Rental Revenue [Line Items]
Rental revenue	$ 0	$ 0

Leasing Activity - Narrative (D

Leasing Activity - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Leases [Abstract]
Lease, weighted average remaining lease term	5 years 11 months
Operating lease, right-of-use asset	$ 2,000
Operating lease liability	1,957
Operating lease expense	200
Operating lease payments	$ 200
Operating lease, weighted average discount rate	4.00%
Operating lease, weighted average remaining lease term	3 years

Leasing Activity - Future Minim

Leasing Activity - Future Minimum (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
April 2019 - December 2019	$ 91,882
2020	122,165
2021	106,007
2022	97,046
2023	86,093
2024 and thereafter	284,895
Total	788,088
Operating Leases, Future Minimum Payments Receivable [Abstract]
2019		$ 131,871
2020		127,275
2021		108,955
2022		99,782
2023		88,138
2024 and thereafter		294,965
Total		850,986
Operating Lease Liabilities, Payments Due [Abstract]
April 2019 - December 2019	623
2020	715
2021	462
2022	175
2023	117
2024 and thereafter	0
Total	2,092
Less: discount	(135)
Total operating lease liabilities	$ 1,957
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019		1,448
2020		1,279
2021		995
2022		683
2023		450
2024 and thereafter		0
Total		$ 4,855

Net Income (Loss) per Common _3

Net Income (Loss) per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net income (loss) attributable to common stockholders	$ (14,124)	$ 8,390
Less: net income allocated to participating securities	0	0
Numerator for basic net income (loss) per share	(14,124)	8,390
Add: undistributed net income allocated to participating securities	0	0
Less: undistributed net income re-allocated to participating securities	0	0
Numerator for diluted net income (loss) per share (1)	$ (14,124)	$ 8,390
Denominator:
Weighted average common shares outstanding - basic (in shares)	54,319,635	47,645,050
Effect of dilutive securities (in shares)	0	655,000
Weighted average common shares outstanding - diluted (in shares)	54,319,635	48,299,882
Basic income (loss) per common share (in dollars per share)	$ (0.26)	$ 0.18
Diluted income (loss) per common share (in dollars per share)	$ (0.26)	$ 0.17
Securities excluded from weighted average common shares outstanding-diluted because their effect would be anti-dilutive (in shares)	826,000	19,000

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Mar. 29, 2018
Noncash or Part Noncash Acquisitions [Line Items]
Interest paid, net of amounts capitalized	$ 5,301	$ 7,804
Income taxes paid	0	2
Non-cash investing activities:
Property and equipment additions in accounts payable and accrued liabilities	22,248	17,712
Lease liabilities arising from obtaining right-of-use assets	2,153	0
Liabilities assumed through the purchase of real estate	0	7,028
Escrow deposits applied to purchase of real estate	0	21,350
Escrow deposit applied to purchase of real estate from noncontrolling interest	0	150
Acquisition of controlling interest in unconsolidated entity	0	927
Non-cash financing activities:
Mortgage notes assumed (1)	0	89,733
Unrealized gain (loss) on interest rate derivatives	$ 7,027	5,438
Domain 8
Non-cash financing activities:
Mortgage notes assumed (1)		89,700
Debt assumed at acquisition		44,900
Ownership Interest			50.00%	50.00%
Debt, previously held		$ 44,900

Uncategorized Items - tier-2019

Label	Element	Value
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	$ 679,031,000
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	1,460,000
Common Stock [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	$ 5,000
Shares, Outstanding	us-gaap_SharesOutstanding	47,623,000
Noncontrolling Interest [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	$ 768,000
Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	(1,936,325,000)
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	635,000
Additional Paid-in Capital [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	2,609,540,000
AOCI Attributable to Parent [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	5,043,000
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 825,000