Description of Business and Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation Our Consolidated Financial Statements are prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). The Company’s Consolidated Financial Statements include the Operating Partnership, wholly owned subsidiaries and those entities in which the Company has the controlling interest. The Operating Partnership’s Consolidated Financial Statements include wholly owned subsidiaries and those entities in which the Operating Partnership has the controlling interest. We consolidate joint venture investments, such as interests in partnerships and limited liability companies, when we control the major operating and financial policies of the investment through majority ownership, in our capacity as a general partner or managing member or through some other contractual right. At December 31, 2020, three properties owned through a joint venture investment were consolidated. We also consolidate those entities deemed to be variable interest entities in which we are determined to be the primary beneficiary. At December 31, 2020, we have involvement with, and are the primary beneficiary in, an entity that we concluded to be a variable interest entity (see Note 4). In addition, during 2019, we acquired a building using a special purpose entity owned by a qualified intermediary to facilitate a potential Section 1031 reverse exchange under the Internal Revenue Code. We determined that this entity was a variable interest entity of which we were the primary beneficiary and therefore, we consolidated this entity as of December 31, 2019. During 2020, we completed the exchange by acquiring 100% of the special purpose entity. All intercompany transactions and accounts have been eliminated. Certain amounts within the Consolidated Statements of Income for the year ended December 31, 2018 were removed and/or combined to conform to the current year presentation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in accordance with GAAP requires us to make estimates and assumptions that affect the amounts reported in our Consolidated Financial Statements and accompanying notes. Actual results could differ from those estimates.
Insurance	Insurance We are primarily self-insured for health care claims for participating employees. We have stop-loss coverage to limit our exposure to significant claims on a per claim and annual aggregate basis. We determine our liabilities for claims, including incurred but not reported losses, based on all relevant information, including actuarial estimates of claim liabilities. At December 31, 2020, a reserve of $0.5 million was recorded to cover estimated reported and unreported claims.
Real Estate and Related Assets	Real Estate and Related Assets Real estate and related assets are recorded at cost and stated at cost less accumulated depreciation. Renovations, replacements and other expenditures that improve or extend the life of assets are capitalized and depreciated over their estimated useful lives. Expenditures for ordinary maintenance and repairs are charged to expense as incurred. Depreciation is computed using the straight-line method over the estimated useful life of 40 years for buildings and depreciable land infrastructure costs, 15 years for building improvements and five to seven years for furniture, fixtures and equipment. Tenant improvements are amortized using the straight-line method over the initial fixed terms of the respective leases, which generally are from three to 10 years. Depreciation expense for real estate assets was $204.6 million, $214.7 million and $191.0 million for the years ended December 31, 2020, 2019 and 2018, respectively. Expenditures directly related to the development and construction of real estate assets are included in net real estate assets and are stated at depreciated cost. Development expenditures include pre-construction costs essential to the development of properties, development and construction costs, interest costs on qualifying assets, real estate taxes, development personnel salaries and related costs and other costs incurred during the period of development. Interest and other carrying costs are capitalized until the building is ready for its intended use, but not later than a year from cessation of major construction activity. We consider a construction project as substantially completed and ready for its intended use upon the completion of tenant improvements. We cease capitalization on the portion that is substantially completed and occupied or held available for occupancy and capitalize only those costs associated with the portion under construction. We record liabilities for the performance of asset retirement activities when the obligation to perform such activities is probable even when uncertainty exists about the timing and/or method of settlement. Upon the acquisition of real estate assets accounted for as asset acquisitions, we assess the fair value of acquired tangible assets such as land, buildings and tenant improvements, intangible assets and liabilities such as above and below market leases, acquired in-place leases and other identifiable intangible assets and assumed liabilities. We allocate fair value on a relative basis based on estimated cash flow projections that utilize discount and/or capitalization rates as well as available market information. The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant. The above and below market rate portions of leases acquired in connection with property acquisitions are recorded in deferred leasing costs and in accounts payable, accrued expenses and other liabilities, respectively, at fair value and amortized into rental revenue over the remaining term of the respective leases as described below. Fair value is calculated as the present value of the difference between (1) the contractual amounts to be paid pursuant to each in-place lease and (2) our estimate of fair market lease rates for each corresponding in-place lease, using a discount rate that reflects the risks associated with the leases acquired and measured over a period equal to the remaining initial term of the lease for above-market leases and the remaining initial term plus the term of any renewal option that the customer would be economically compelled to exercise for below-market leases. In-place leases acquired are recorded at fair value in deferred leasing costs and amortized to depreciation and amortization expense over the remaining term of the respective lease. The value of in-place leases is based on our evaluation of the specific characteristics of each customer’s lease. Factors considered include estimates of carrying costs during hypothetical expected lease-up periods, current market conditions, the customer’s credit quality and costs to execute similar leases. In estimating carrying costs, we include real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, we consider tenant improvements, leasing commissions and legal and other related expenses. Real estate and other assets are classified as long-lived assets held for use or as long-lived assets held for sale. Real estate is classified as held for sale when the sale of the asset is probable, has been duly approved by the Company, a legally enforceable contract has been executed and the buyer’s due diligence period, if any, has expired.
Impairments of Real Estate Assets and Investments in Unconsolidated Affiliates	Impairments of Real Estate Assets and Investments in Unconsolidated Affiliates With respect to assets classified as held for use, we perform an impairment analysis if our evaluation of events or changes in circumstances indicate that the carrying value may not be recoverable, such as a significant decline in occupancy, identification of materially adverse legal or environmental factors, change in our designation of an asset from core to non-core, which may impact the anticipated holding period, or a decline in market value to an amount less than cost. This analysis is generally performed at the property level, except when an asset is part of an interdependent group such as an office park, and consists of determining whether the asset’s carrying amount will be recovered from its undiscounted estimated future operating and residual cash flows. These cash flows are estimated based on a number of assumptions that are subject to economic and market uncertainties including, among others, demand for space, competition for customers, changes in market rental rates, costs to operate each property and expected ownership periods. For properties under development, the cash flows are based on expected service potential of the asset or asset group when development is substantially complete. If the carrying amount of a held for use asset exceeds the sum of its undiscounted future operating and residual cash flows, an impairment loss is recorded for the difference between estimated fair value of the asset and the carrying amount. We generally estimate the fair value of assets held for use by using discounted cash flow analyses. In some instances, appraisal information may be available and is used in addition to a discounted cash flow analysis. As the factors used in generating these cash flows are difficult to predict and are subject to future events that may alter our assumptions, the discounted and/or undiscounted future operating and residual cash flows estimated by us in our impairment analyses or those established by appraisal may not be achieved and we may be required to recognize future impairment losses on properties held for use. We record assets held for sale at the lower of the carrying amount or estimated fair value. Fair value of assets held for sale is equal to the estimated or contracted sales price with a potential buyer, less costs to sell. The impairment loss is the amount by which the carrying amount exceeds the estimated fair value. We also analyze our investments in unconsolidated affiliates for impairment. This analysis consists of determining whether an expected loss in market value of an investment is other than temporary by evaluating the length of time and the extent to which the market value has been less than cost, the financial condition and near-term prospects of the investment, and our intent and ability to retain our investment for a period of time sufficient to allow for any anticipated recovery in market value. As the factors used in this analysis are difficult to predict and are subject to future events that may alter our assumptions, we may be required to recognize future impairment losses on our investments in unconsolidated affiliates.
Sales of Real Estate	Sales of Real Estate For sales of real estate where we have collected the consideration to which we are entitled in exchange for transferring the real estate, the related assets and liabilities are removed from the balance sheet and the resultant gain or loss is recorded in the period the transaction closes. Any post-sale involvement is accounted for as separate performance obligations and when the separate performance obligations are satisfied, the sales price allocated to each is recognized.
Discontinued Operations	Discontinued OperationsProperties that are sold or classified as held for sale are classified as discontinued operations provided that the disposal represents a strategic shift that has (or will have) a major effect on our operations and financial results. Interest expense is included in discontinued operations if a related loan securing the sold property is to be paid off or assumed by the buyer in connection with the sale.
Investments in Unconsolidated Affiliates	Investments in Unconsolidated Affiliates We account for our joint venture investments using the equity method of accounting when our interests represent a general partnership interest but substantive participating rights or substantive kick out rights have been granted to the limited partners or when our interests do not represent a general partnership interest and we do not control the major operating and financial policies of the investment. These investments are initially recorded at cost as investments in unconsolidated affiliates and are subsequently adjusted for our share of earnings and cash contributions and distributions. To the extent our cost basis at formation of the joint venture is different than the basis reflected at the joint venture level, the basis difference is amortized over the life of the related assets and included in our share of equity in earnings of unconsolidated affiliates.
Cash Equivalents	Cash Equivalents We consider highly liquid investments with an original maturity of three months or less when purchased to be cash equivalents.
Restricted Cash	Restricted Cash Restricted cash represents cash deposits that are legally restricted or held by third parties on our behalf, such as construction-related escrows, property disposition proceeds set aside and designated or intended to fund future tax-deferred exchanges of qualifying real estate investments and escrows and reserves for debt service, real estate taxes and property insurance established pursuant to certain mortgage financing arrangements.
Redeemable Common Units and Preferred Units	Redeemable Common Units and Preferred Units Limited partners holding Common Units other than the Company (“Redeemable Common Units”) have the right to put any and all of the Common Units to the Operating Partnership and the Company has the right to put any and all of the Preferred Units to the Operating Partnership in exchange for their liquidation preference plus accrued and unpaid distributions in the event of a corresponding redemption by the Company of the underlying Preferred Stock. Consequently, these Redeemable Common Units and Preferred Units are classified outside of permanent partners’ capital in the Operating Partnership’s accompanying balance sheets. The recorded value of the Redeemable Common Units is based on fair value at the balance sheet date as measured by the closing price of Common Stock on that date multiplied by the total number of Redeemable Common Units outstanding. The recorded value of the Preferred Units is based on their redemption value.
Income Tax	Income Taxes The Company has elected and expects to continue to qualify as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the “Code”). A corporate REIT is a legal entity that holds real estate assets and, through the payment of dividends to stockholders, is generally permitted to reduce or avoid the payment of federal and state income taxes at the corporate level. To maintain qualification as a REIT, the Company is required to pay dividends to its stockholders equal to at least 90.0% of its annual REIT taxable income, excluding net capital gains. The partnership agreement requires the Operating Partnership to pay economically equivalent distributions on outstanding Common Units at the same time that the Company pays dividends on its outstanding Common Stock. Other than income taxes related to its taxable REIT subsidiary, the Operating Partnership does not reflect any federal income taxes in its financial statements, since as a partnership the taxable effects of its operations are attributed to its partners. The Operating Partnership does record state income tax for states that tax partnership income directly. We conduct certain business activities through a taxable REIT subsidiary, as permitted under the Code. The taxable REIT subsidiary is subject to federal, state and local income taxes on its taxable income. We record provisions for income taxes based on its income recognized for financial statement purposes, including the effects of differences between such income and the amount recognized for tax purposes.
Concentration of Credit Risk	Concentration of Credit Risk At December 31, 2020, properties that we wholly own were leased to 1,378 customers. The geographic locations that comprise greater than 10.0% of our rental and other revenues are Atlanta, Nashville, Raleigh and Tampa. Our customers engage in a wide variety of businesses. No single customer generated more than 5% of our consolidated revenues during 2020. We maintain our cash and cash equivalents and our restricted cash at financial or other intermediary institutions. The combined account balances at each institution may exceed FDIC insurance coverage and, as a result, there is a concentration of credit risk related to amounts on deposit in excess of FDIC insurance coverage. Additionally, from time to time in connection with tax-deferred 1031 transactions, our restricted cash balances may be commingled with other funds being held by any such intermediary institution, which would subject our balance to the credit risk of the institution.
Derivative Financial Instruments	Derivative Financial Instruments We borrow funds at a combination of fixed and variable rates. Borrowings under our revolving credit facility and bank term loans bear interest at variable rates. Our long-term debt, which consists of secured and unsecured long-term financings, typically bears interest at fixed rates. Our interest rate risk management objectives are to limit generally the impact of interest rate changes on earnings and cash flows and lower our overall borrowing costs. To achieve these objectives, from time to time, we enter into interest rate hedge contracts such as collars, swaps, caps and treasury lock agreements in order to mitigate our interest rate risk with respect to existing and prospective debt instruments. We generally do not hold or issue these derivative contracts for trading or speculative purposes. The interest rate on all of our variable rate debt is generally adjusted at one or three month intervals, subject to settlements under these interest rate hedge contracts. Interest rate swaps involve the receipt of variable rate amounts from a counterparty in exchange for making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. Changes in the fair value of derivatives designated and that qualify as cash flow hedges are recorded in accumulated other comprehensive income/(loss) and are subsequently reclassified into interest expense as interest payments are made on our debt. We account for terminated derivative instruments by recognizing the related accumulated other comprehensive income/(loss) balance in current earnings, unless the hedged forecasted transaction continues as originally planned, in which case we continue to amortize the accumulated other comprehensive income/(loss) into earnings over the originally designated hedge period.
Earnings Per Share and Per Unit	Earnings Per Share and Per Unit Basic earnings per share of the Company is computed by dividing net income available for common stockholders by the weighted Common Shares outstanding - basic. Diluted earnings per share is computed by dividing net income available for common stockholders (inclusive of noncontrolling interests in the Operating Partnership) by the weighted Common Shares outstanding - basic plus the dilutive effect of options, warrants and convertible securities outstanding, including Common Units, using the treasury stock method. Weighted Common Shares outstanding - basic includes all unvested restricted stock where dividends received on such restricted stock are non-forfeitable. Basic earnings per unit of the Operating Partnership is computed by dividing net income available for common unitholders by the weighted Common Units outstanding - basic. Diluted earnings per unit is computed by dividing net income available for common unitholders by the weighted Common Units outstanding - basic plus the dilutive effect of options and warrants, using the treasury stock method. Weighted Common Units outstanding - basic includes all of the Company’s unvested restricted stock where distributions received on such restricted stock are non-forfeitable.
Recently Issued Accounting Standards	Recently Issued Accounting Standards The Financial Accounting Standards Board (“FASB”) issued an accounting standards update (“ASU”) that changes certain disclosure requirements for fair value measurements. We adopted the ASU as of January 1, 2020 with no material effect on our Notes to Consolidated Financial Statements. The FASB issued an ASU that provides temporary optional expedients and exceptions to the guidance on contract modifications and hedge accounting to ease the financial reporting burdens related to the expected market transition from LIBOR and other interbank offered rates to alternative reference rates, such as the Secured Overnight Financing Rate (“SOFR”). Entities can elect not to apply certain modification accounting requirements to contracts affected by reference rate reform, if certain criteria are met. An entity that makes this election would not have to remeasure the contracts at the modification date or reassess a previous accounting determination. Entities can also elect various optional expedients that would allow them to continue applying hedge accounting for hedging relationships affected by reference rate reform, if certain criteria are met. The guidance in this ASU is optional and may be elected over the period March 12, 2020 through December 31, 2022 as reference rate reform activities occur. We will continue to evaluate the impact of this ASU; however, we currently expect to avail ourselves of such optional expedients and exceptions should our modified contracts meet the required criteria. Due to the business disruptions and challenges severely affecting the global economy caused by the COVID-19 pandemic, lessors may provide rent deferrals and other lease concessions to lessees. In April 2020, the FASB staff issued a question and answer document (the “Lease Modification Q&A”) focused on the application of lease accounting guidance to lease concessions provided as a result of the COVID-19 pandemic. Under existing lease guidance, we would have to determine, on a lease by lease basis, if a lease concession was the result of a new arrangement reached with the tenant (treated within the lease modification accounting framework) or if a lease concession was under the enforceable rights and obligations within the existing lease agreement (precluded from applying the lease modification accounting framework). The Lease Modification Q&A allows us, if certain criteria have been met, to bypass the lease by lease analysis, and instead elect to either apply the lease modification accounting framework or not, with such election applied consistently to leases with similar characteristics and similar circumstances. We have elected the practical expedient and will not apply lease modification accounting on a lease by lease basis where applicable. As a result, $3.7 million of deferred rent is included in accounts receivable on our Consolidated Balance Sheets at December 31, 2020.

Description of Business and Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Our Consolidated Financial Statements are prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”).

The Company’s Consolidated Financial Statements include the Operating Partnership, wholly owned subsidiaries and those entities in which the Company has the controlling interest. The Operating Partnership’s Consolidated Financial Statements include wholly owned subsidiaries and those entities in which the Operating Partnership has the controlling interest. We consolidate joint venture investments, such as interests in partnerships and limited liability companies, when we control the major operating and financial policies of the investment through majority ownership, in our capacity as a general partner or managing member or through some other contractual right. At December 31, 2020, three properties owned through a joint venture investment were consolidated. We also consolidate those entities deemed to be variable interest entities in which we are determined to be the primary beneficiary. At December 31, 2020, we have involvement with, and are the primary beneficiary in, an entity that we concluded to be a variable interest entity (see Note 4).

In addition, during 2019, we acquired a building using a special purpose entity owned by a qualified intermediary to facilitate a potential Section 1031 reverse exchange under the Internal Revenue Code. We determined that this entity was a variable interest entity of which we were the primary beneficiary and therefore, we consolidated this entity as of December 31, 2019. During 2020, we completed the exchange by acquiring 100% of the special purpose entity.

All intercompany transactions and accounts have been eliminated.

Certain amounts within the Consolidated Statements of Income for the year ended December 31, 2018 were removed and/or combined to conform to the current year presentation.

Use of Estimates

The preparation of consolidated financial statements in accordance with GAAP requires us to make estimates and assumptions that affect the amounts reported in our Consolidated Financial Statements and accompanying notes. Actual results could differ from those estimates.

Insurance

We are primarily self-insured for health care claims for participating employees. We have stop-loss coverage to limit our exposure to significant claims on a per claim and annual aggregate basis. We determine our liabilities for claims, including incurred but not reported losses, based on all relevant information, including actuarial estimates of claim liabilities. At December 31, 2020, a reserve of $0.5 million was recorded to cover estimated reported and unreported claims.

Real Estate and Related Assets

Real estate and related assets are recorded at cost and stated at cost less accumulated depreciation. Renovations, replacements and other expenditures that improve or extend the life of assets are capitalized and depreciated over their estimated useful lives. Expenditures for ordinary maintenance and repairs are charged to expense as incurred. Depreciation is computed using the straight-line method over the estimated useful life of 40 years for buildings and depreciable land infrastructure costs, 15 years for building improvements and five to seven years for furniture, fixtures and equipment. Tenant improvements are amortized using the straight-line method over the initial fixed terms of the respective leases, which generally are from three to 10 years. Depreciation expense for real estate assets was $204.6 million, $214.7 million and $191.0 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Expenditures directly related to the development and construction of real estate assets are included in net real estate assets and are stated at depreciated cost. Development expenditures include pre-construction costs essential to the development of properties, development and construction costs, interest costs on qualifying assets, real estate taxes, development personnel salaries and related costs and other costs incurred during the period of development. Interest and other carrying costs are capitalized until the building is ready for its intended use, but not later than a year from cessation of major construction activity. We consider a construction project as substantially completed and ready for its intended use upon the completion of tenant improvements. We cease capitalization on the portion that is substantially completed and occupied or held available for occupancy and capitalize only those costs associated with the portion under construction.

We record liabilities for the performance of asset retirement activities when the obligation to perform such activities is probable even when uncertainty exists about the timing and/or method of settlement.

Upon the acquisition of real estate assets accounted for as asset acquisitions, we assess the fair value of acquired tangible assets such as land, buildings and tenant improvements, intangible assets and liabilities such as above and below market leases, acquired in-place leases and other identifiable intangible assets and assumed liabilities. We allocate fair value on a relative basis based on estimated cash flow projections that utilize discount and/or capitalization rates as well as available market information. The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant.

The above and below market rate portions of leases acquired in connection with property acquisitions are recorded in deferred leasing costs and in accounts payable, accrued expenses and other liabilities, respectively, at fair value and amortized into rental revenue over the remaining term of the respective leases as described below. Fair value is calculated as the present value of the difference between (1) the contractual amounts to be paid pursuant to each in-place lease and (2) our estimate of fair market lease rates for each corresponding in-place lease, using a discount rate that reflects the risks associated with the leases acquired and measured over a period equal to the remaining initial term of the lease for above-market leases and the remaining initial term plus the term of any renewal option that the customer would be economically compelled to exercise for below-market leases.

In-place leases acquired are recorded at fair value in deferred leasing costs and amortized to depreciation and amortization expense over the remaining term of the respective lease. The value of in-place leases is based on our evaluation of the specific characteristics of each customer’s lease. Factors considered include estimates of carrying costs during hypothetical expected lease-up periods, current market conditions, the customer’s credit quality and costs to execute similar leases. In estimating carrying costs, we include real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, we consider tenant improvements, leasing commissions and legal and other related expenses.

Real estate and other assets are classified as long-lived assets held for use or as long-lived assets held for sale. Real estate is classified as held for sale when the sale of the asset is probable, has been duly approved by the Company, a legally enforceable contract has been executed and the buyer’s due diligence period, if any, has expired.

Impairments of Real Estate Assets and Investments in Unconsolidated Affiliates

With respect to assets classified as held for use, we perform an impairment analysis if our evaluation of events or changes in circumstances indicate that the carrying value may not be recoverable, such as a significant decline in occupancy, identification of materially adverse legal or environmental factors, change in our designation of an asset from core to non-core, which may impact the anticipated holding period, or a decline in market value to an amount less than cost. This analysis is generally performed at the property level, except when an asset is part of an interdependent group such as an office park, and consists of determining whether the asset’s carrying amount will be recovered from its undiscounted estimated future operating and residual cash flows. These cash flows are estimated based on a number of assumptions that are subject to economic and market uncertainties including, among others, demand for space, competition for customers, changes in market rental rates, costs to operate each property and expected ownership periods. For properties under development, the cash flows are based on expected service potential of the asset or asset group when development is substantially complete.

If the carrying amount of a held for use asset exceeds the sum of its undiscounted future operating and residual cash flows, an impairment loss is recorded for the difference between estimated fair value of the asset and the carrying amount. We generally estimate the fair value of assets held for use by using discounted cash flow analyses. In some instances, appraisal information may be available and is used in addition to a discounted cash flow analysis. As the factors used in generating these cash flows are difficult to predict and are subject to future events that may alter our assumptions, the discounted and/or undiscounted future operating and residual cash flows estimated by us in our impairment analyses or those established by appraisal may not be achieved and we may be required to recognize future impairment losses on properties held for use.

We record assets held for sale at the lower of the carrying amount or estimated fair value. Fair value of assets held for sale is equal to the estimated or contracted sales price with a potential buyer, less costs to sell. The impairment loss is the amount by which the carrying amount exceeds the estimated fair value.

We also analyze our investments in unconsolidated affiliates for impairment. This analysis consists of determining whether an expected loss in market value of an investment is other than temporary by evaluating the length of time and the extent to which the market value has been less than cost, the financial condition and near-term prospects of the investment, and our intent and ability to retain our investment for a period of time sufficient to allow for any anticipated recovery in market value. As the factors used in this analysis are difficult to predict and are subject to future events that may alter our assumptions, we may be required to recognize future impairment losses on our investments in unconsolidated affiliates.

Sales of Real Estate

For sales of real estate where we have collected the consideration to which we are entitled in exchange for transferring the real estate, the related assets and liabilities are removed from the balance sheet and the resultant gain or loss is recorded in the period the transaction closes. Any post-sale involvement is accounted for as separate performance obligations and when the separate performance obligations are satisfied, the sales price allocated to each is recognized.

Discontinued Operations

Discontinued OperationsProperties that are sold or classified as held for sale are classified as discontinued operations provided that the disposal represents a strategic shift that has (or will have) a major effect on our operations and financial results. Interest expense is included in discontinued operations if a related loan securing the sold property is to be paid off or assumed by the buyer in connection with the sale.

Investments in Unconsolidated Affiliates

We account for our joint venture investments using the equity method of accounting when our interests represent a general partnership interest but substantive participating rights or substantive kick out rights have been granted to the limited partners or when our interests do not represent a general partnership interest and we do not control the major operating and financial policies of the investment. These investments are initially recorded at cost as investments in unconsolidated affiliates and are

subsequently adjusted for our share of earnings and cash contributions and distributions. To the extent our cost basis at formation of the joint venture is different than the basis reflected at the joint venture level, the basis difference is amortized over the life of the related assets and included in our share of equity in earnings of unconsolidated affiliates.

Cash Equivalents

We consider highly liquid investments with an original maturity of three months or less when purchased to be cash equivalents.

Restricted Cash

Restricted cash represents cash deposits that are legally restricted or held by third parties on our behalf, such as construction-related escrows, property disposition proceeds set aside and designated or intended to fund future tax-deferred exchanges of qualifying real estate investments and escrows and reserves for debt service, real estate taxes and property insurance established pursuant to certain mortgage financing arrangements.

Redeemable Common Units and Preferred Units

Limited partners holding Common Units other than the Company (“Redeemable Common Units”) have the right to put any and all of the Common Units to the Operating Partnership and the Company has the right to put any and all of the Preferred Units to the Operating Partnership in exchange for their liquidation preference plus accrued and unpaid distributions in the event of a corresponding redemption by the Company of the underlying Preferred Stock. Consequently, these Redeemable Common Units and Preferred Units are classified outside of permanent partners’ capital in the Operating Partnership’s accompanying balance sheets. The recorded value of the Redeemable Common Units is based on fair value at the balance sheet date as measured by the closing price of Common Stock on that date multiplied by the total number of Redeemable Common Units outstanding. The recorded value of the Preferred Units is based on their redemption value.

Income Tax

Income Taxes

The Company has elected and expects to continue to qualify as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the “Code”). A corporate REIT is a legal entity that holds real estate assets and, through the payment of dividends to stockholders, is generally permitted to reduce or avoid the payment of federal and state income taxes at the corporate level. To maintain qualification as a REIT, the Company is required to pay dividends to its stockholders equal to at least 90.0% of its annual REIT taxable income, excluding net capital gains. The partnership agreement requires the Operating Partnership to pay economically equivalent distributions on outstanding Common Units at the same time that the Company pays dividends on its outstanding Common Stock.

Other than income taxes related to its taxable REIT subsidiary, the Operating Partnership does not reflect any federal income taxes in its financial statements, since as a partnership the taxable effects of its operations are attributed to its partners. The Operating Partnership does record state income tax for states that tax partnership income directly.

We conduct certain business activities through a taxable REIT subsidiary, as permitted under the Code. The taxable REIT subsidiary is subject to federal, state and local income taxes on its taxable income. We record provisions for income taxes based on its income recognized for financial statement purposes, including the effects of differences between such income and the amount recognized for tax purposes.

Concentration of Credit Risk

At December 31, 2020, properties that we wholly own were leased to 1,378 customers. The geographic locations that comprise greater than 10.0% of our rental and other revenues are Atlanta, Nashville, Raleigh and Tampa. Our customers engage in a wide variety of businesses. No single customer generated more than 5% of our consolidated revenues during 2020.

We maintain our cash and cash equivalents and our restricted cash at financial or other intermediary institutions. The combined account balances at each institution may exceed FDIC insurance coverage and, as a result, there is a concentration of credit risk related to amounts on deposit in excess of FDIC insurance coverage. Additionally, from time to time in connection with tax-deferred 1031 transactions, our restricted cash balances may be commingled with other funds being held by any such intermediary institution, which would subject our balance to the credit risk of the institution.

Derivative Financial Instruments

We borrow funds at a combination of fixed and variable rates. Borrowings under our revolving credit facility and bank term loans bear interest at variable rates. Our long-term debt, which consists of secured and unsecured long-term financings, typically bears interest at fixed rates. Our interest rate risk management objectives are to limit generally the impact of interest rate changes on earnings and cash flows and lower our overall borrowing costs. To achieve these objectives, from time to time, we enter into interest rate hedge contracts such as collars, swaps, caps and treasury lock agreements in order to mitigate our interest rate risk with respect to existing and prospective debt instruments. We generally do not hold or issue these derivative contracts for trading or speculative purposes. The interest rate on all of our variable rate debt is generally adjusted at one or three month intervals, subject to settlements under these interest rate hedge contracts.

Interest rate swaps involve the receipt of variable rate amounts from a counterparty in exchange for making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. Changes in the fair value of derivatives designated and that qualify as cash flow hedges are recorded in accumulated other comprehensive income/(loss) and are subsequently reclassified into interest expense as interest payments are made on our debt.

We account for terminated derivative instruments by recognizing the related accumulated other comprehensive income/(loss) balance in current earnings, unless the hedged forecasted transaction continues as originally planned, in which case we continue to amortize the accumulated other comprehensive income/(loss) into earnings over the originally designated hedge period.

Earnings Per Share and Per Unit

Basic earnings per share of the Company is computed by dividing net income available for common stockholders by the weighted Common Shares outstanding - basic. Diluted earnings per share is computed by dividing net income available for common stockholders (inclusive of noncontrolling interests in the Operating Partnership) by the weighted Common Shares outstanding - basic plus the dilutive effect of options, warrants and convertible securities outstanding, including Common Units, using the treasury stock method. Weighted Common Shares outstanding - basic includes all unvested restricted stock where dividends received on such restricted stock are non-forfeitable.

Basic earnings per unit of the Operating Partnership is computed by dividing net income available for common unitholders by the weighted Common Units outstanding - basic. Diluted earnings per unit is computed by dividing net income available for common unitholders by the weighted Common Units outstanding - basic plus the dilutive effect of options and warrants, using the treasury stock method. Weighted Common Units outstanding - basic includes all of the Company’s unvested restricted stock where distributions received on such restricted stock are non-forfeitable.

Recently Issued Accounting Standards

The Financial Accounting Standards Board (“FASB”) issued an accounting standards update (“ASU”) that changes certain disclosure requirements for fair value measurements. We adopted the ASU as of January 1, 2020 with no material effect on our Notes to Consolidated Financial Statements.

The FASB issued an ASU that provides temporary optional expedients and exceptions to the guidance on contract modifications and hedge accounting to ease the financial reporting burdens related to the expected market transition from LIBOR and other interbank offered rates to alternative reference rates, such as the Secured Overnight Financing Rate (“SOFR”). Entities can elect not to apply certain modification accounting requirements to contracts affected by reference rate reform, if certain criteria are met. An entity that makes this election would not have to remeasure the contracts at the modification date or reassess a previous accounting determination. Entities can also elect various optional expedients that would allow them to continue applying hedge accounting for hedging relationships affected by reference rate reform, if certain criteria are met. The guidance in this ASU is optional and may be elected over the period March 12, 2020 through December 31, 2022 as reference rate reform activities occur. We will continue to evaluate the impact of this ASU; however, we currently expect to avail ourselves of such optional expedients and exceptions should our modified contracts meet the required criteria.

Due to the business disruptions and challenges severely affecting the global economy caused by the COVID-19 pandemic, lessors may provide rent deferrals and other lease concessions to lessees. In April 2020, the FASB staff issued a question and answer document (the “Lease Modification Q&A”) focused on the application of lease accounting guidance to lease concessions provided as a result of the COVID-19 pandemic. Under existing lease guidance, we would have to determine, on a lease by lease basis, if a lease concession was the result of a new arrangement reached with the tenant (treated within the lease modification accounting framework) or if a lease concession was under the enforceable rights and obligations within the existing lease agreement (precluded from applying the lease modification accounting framework). The Lease Modification

Q&A allows us, if certain criteria have been met, to bypass the lease by lease analysis, and instead elect to either apply the lease modification accounting framework or not, with such election applied consistently to leases with similar characteristics and similar circumstances. We have elected the practical expedient and will not apply lease modification accounting on a lease by lease basis where applicable. As a result, $3.7 million of deferred rent is included in accounts receivable on our Consolidated Balance Sheets at December 31, 2020.