During the threesix months ended March 31,June 30, 2020, we committed $458$687 for expenditures related to tenant improvements and leasing costs for leases executed during the period for approximately 49,000363,000 square feet. Committed but unspent tenant related obligations based on existing leases as of March 31,June 30, 2020 were $807.$561.

Certain of our industrial lands in Hawaii may require environmental remediation, especially if the use of those lands is changed; however, we do not have any present plans to change the use of those lands. As of both March 31,June 30, 2020 and December 31, 2019, accrued environmental remediation costs of $6,940 were included in accounts payable and other liabilities in our condensed consolidated balance sheets. These accrued environmental remediation costs relate to maintenance of our properties for current uses, and, because of the indeterminable timing of the remediation, these amounts have not been discounted to present value. In general, we do not have any insurance designated to limit any losses that we may incur as a result of known or unknown environmental conditions which are not caused by an insured event, such as fire or flood, although some of our tenants may maintain such insurance that may benefit us. Although we do not believe that there are environmental conditions at any of our properties that will have a material adverse effect on us, we cannot be sure that such conditions are not present at our properties or that costs we incur to remediate contamination will not have a material adverse effect on our business or financial condition. Charges for environmental remediation costs, if any, are included in other operating expenses in our condensed consolidated statements of comprehensive income.

We are a lessor of industrial and logistics properties. Our leases provide our tenants with the contractual right to use and economically benefit from all the physical space specified in the leases; therefore, we have determined to evaluate our leases as lease arrangements.

Our leases provide for base rent payments and in addition may include variable payments. Rental income from operating leases, including any payments derived by index or market-based indices, is recognized on a straight line basis over the lease term when we have determined that the collectability of substantially all of the lease payments is probable. Some of our leases have options to extend or terminate the lease exercisable at the option of our tenants, which are considered when determining the lease term. We do not include in our measurement of our lease receivables certain variable payments, including payments determined by changes in the index or market-based indices after the inception of the lease, certain tenant reimbursements and other income until the specific events that trigger the variable payments have occurred. Such payments totaled $11,520$11,640 and $8,281$9,483 for the three months ended March 31,June 30, 2020 and 2019, respectively, of which tenant reimbursements totaled $11,275$11,395 and $7,119,$9,483, respectively, and $23,160 and $17,764 for the six months ended June 30, 2020 and 2019, respectively, of which tenant reimbursements totaled $22,670 and $16,602, respectively.

We increased rental income to record revenue on a straight line basis by $1,967$2,096 and $979$2,002 for the three months ended March 31,June 30, 2020 and 2019, respectively, and $4,063 and $2,981 for the six months ended June 30, 2020 and 2019, respectively. Rents receivable include $60,303$62,399 and $58,336 of straight line rents at March 31,June 30, 2020 and December 31, 2019, respectively.

Certain of our tenants have requested relief from their obligations to pay rent due to us in response to the current economic conditions resulting from the COVID-19 pandemic. As of AprilJuly 27, 2020, we granted requests for certain of our tenants to defer rent payments totaling $2,132.$2,799. These tenants will be obligated to pay, in most cases, the deferred rents in 12 equal monthly installments commencing in September 2020. We have elected to use the FASB relief package regarding the application of lease accounting guidance to lease concessions provided as a result of the COVID-19 pandemic. The FASB relief package provides entities with the option to account for lease concessions resulting from the COVID-19 pandemic outside of the existing lease modification guidance if the resulting cash flows from the modified lease are substantially the same as the original lease. Because the deferred rents referenced above will be repaid over a 12-month period, the cash flows from the respective leases are substantially the same as before the rent deferrals. These deferred amounts did not impact our results for the three and six months ended June 30, 2020 and as of June 30, 2020, we recognized an increase in our accounts receivable related to these deferred amounts of $2,317.

We have a $750,000 unsecured revolving credit facility that is available for our general business purposes, including acquisitions. The maturity date of our revolving credit facility is December 29, 2021. We may borrow, repay and reborrow funds under our revolving credit facility until maturity, and no principal repayment is due until maturity. Interest on borrowings under our revolving credit facility is calculated at floating rates based on LIBOR plus a premium that varies based on our leverage ratio. We have the option to extend the maturity date of our revolving credit facility for 2, six month periods, subject to payment of extension fees and satisfaction of other conditions. We are also required to pay a commitment fee on the unused portion of our revolving credit facility. The agreement governing our revolving credit facility, or our credit agreement, also includes a feature under which the maximum borrowing availability under our revolving credit facility may be increased to up to $1,500,000 in certain circumstances. As of March 31,June 30, 2020, interest payable on the amount outstanding under our revolving credit facility was LIBOR plus 155140 basis points and our commitment fee was 25 basis points. As of March 31,June 30, 2020 and December 31, 2019, the interest rate payable on borrowings under our revolving credit facility was 2.50%1.59% and 3.26%, respectively. The weighted average interest rate for borrowings under our revolving credit facility was 3.23%2.04% and 3.80%3.76% for the three months ended March 31,June 30, 2020 and 2019, respectively, and 2.80% and 3.77% for the six months ended June 30, 2020 and June 30, 2019, respectively. As of March 31,June 30, 2020 and April 29,July 27, 2020, we had $265,000$320,000 outstanding under our revolving credit facility, and $485,000$430,000 available to borrow under our revolving credit facility.

Our credit agreement provides for acceleration of payment of all amounts due thereunder upon the occurrence and continuation of certain events of default, such as a change of control of us, which includes The RMR Group LLC, or RMR LLC, ceasing to act as our business manager and property manager. Our credit agreement also contains a number of covenants, including covenants that restrict our ability to incur debts or to make distributions in certain circumstances, and generally requires us to maintain certain financial ratios. We believe we were in compliance with the terms and conditions of the covenants under our credit agreement at March 31,June 30, 2020.

We estimate the fair value of our mortgage notes payable using discounted cash flow analyses and currently prevailing market rates as of the measurement date (Level 3 inputs). Because Level 3 inputs are unobservable, our estimated fair value may differ materially from the actual fair value.

We have 0 employees. The personnel and various services we require to operate our business are provided to us by RMR LLC. We have 2 agreements with RMR LLC to provide management services to us: (1) a business management agreement, which relates to our business generally; and (2) a property management agreement, which relates to our property level operations.

Pursuant to our property management agreement with RMR LLC, we recognized aggregate property management and construction supervision fees of $1,923$1,860 and $1,347$3,783 for the three and six months ended March 31,June 30, 2020, respectively, and $1,922 and $3,269 for the three and six months ended June 30, 2019, respectively. These amounts are included in other operating expenses or have been capitalized, as appropriate, in our condensed consolidated financial statements.

We have relationships and historical and continuing transactions with RMR LLC, The RMR Group Inc., or RMR Inc., and others related to them, including other companies to which RMR LLC or its subsidiaries provide management services and some of which have trustees, directors or officers who are also our Trustees or officers. RMR LLC is a majority owned subsidiary of RMR Inc. The Chair of our Board of Trustees and one of our Managing Trustees, Adam Portnoy, is the sole trustee, an officer and the controlling shareholder of ABP Trust, which is the controlling shareholder of RMR Inc., a managing director and the president and chief executive officer of RMR Inc. and an officer and employee of RMR LLC. John Murray, our other Managing Trustee and our President and Chief Executive Officer, also serves as an executive officer of RMR LLC, and each of our other officers is also an officer and employee of RMR LLC. Some of our Independent Trustees also serve as independent trustees or independent directors of other public companies to which RMR LLC or its subsidiaries provide management services. Adam Portnoy serves as chair of the boards of trustees or boards of directors of several of these public companies and as a managing director or managing trustee of these public companies. Other officers of RMR LLC, including Mr. Murray and certain of our other officers, serve as managing trustees, managing directors or officers of certain of these companies.

We and the other AIC shareholders historically participated in a combined property insurance program arranged and insured or reinsured in part by AIC. The policies under that program expired on June 30, 2019, and we and the other AIC shareholders elected not to renew the AIC property insurance program; we have instead purchased standalone property insurance coverage with unrelated third party insurance providers.

As of March 31,June 30, 2020 and December 31, 2019, our investment in AIC had a carrying value of $298. This amount is$11 and $298, respectively. These amounts are included in other assets in our condensed consolidated balance sheets. In June 2020, we received an additional liquidating distribution of approximately $287 from AIC in connection with its dissolution. We did 0t recognize any income related to our investment in AIC for the three and six months ended March 31,June 30, 2020, respectively, and recognized $404$130 and $534 related to our investment in AIC for the three and six months ended March 31,June 30, 2019, respectively, which amount isamounts are presented as equity in earnings of an investee in our condensed consolidated statements of comprehensive income. Our other comprehensive income included our proportionate share of unrealized gains on securities, if any, which were owned by AIC, related to our investment in AIC.

For further information about these and other such relationships and certain other related person transactions, see our 2019 Annual Report.

In February and March 2020, we entered into agreements related to a joint venture for 12 of our Mainland Properties with an Asian institutional investor. We contributed to the joint venture 11 of these properties in February 2020 and the remaining property in March 2020. We received from the investor $82,035 and $26,231 in February and March 2020, respectively, for a 39% equity interest in the joint venture, and we retained the remaining 61% equity interest. The joint venture assumed $406,980 of then existing mortgage debts on the properties we contributed. We incurred transaction costs of $626 in connection with the formation of this joint venture.

We recognized a noncontrolling interest in our condensed consolidated balance sheets of $100,668 as of the completion of this transaction, which was equal to 39% of our aggregate carrying value of the total equity of the properties immediately prior to our respective contributions of the properties to the joint venture. The difference between the net proceeds received from this transaction and the noncontrolling interest recognized, which was $6,972, has been reflected as an increase in additional paid in capital in our condensed consolidated balance sheets. The portion of the joint venture's net loss not attributable to us, or $152$264 and $416 for the three and six months ended March 31,June 30, 2020, respectively, is reported as noncontrolling interest in our condensed consolidated statements of comprehensive income. During the three and six months ended March 31,June 30, 2020, the joint venture did not make anymade aggregate cash distributions of $1,898 to itsthe other joint venture investor, which are reflected as a decrease in total equity attributable to noncontrolling interest holders.in our condensed consolidated balance sheets. As of March 31,June 30, 2020, the joint venture held real estate assets with an aggregate net book value of $667,054,$660,958, including restricted cash of $11,302$13,703, and subject to non-recoursehad liabilities of $408,212.$408,181.

We are continuing to closely monitoringmonitor the impact of the COVID-19 pandemic on all aspects of our business, including:

We believe that our current financial resources and our expectations as to the future performance of the industrial and logistics industrysector and our tenants will enable us to withstand the COVID-19 pandemic and its aftermath. As of April 29,July 27, 2020, we had:

In light of the above resources, expectations and conditions, we believe that we are well positioned to weather the present disruptions facing the real estate industry. However, as a result of the COVID-19 pandemic and its aftermath, certain of our tenants have requested relief from their obligations to pay rent due to us. We are evaluatingevaluate these requests on a tenant by tenant basis. As of AprilJuly 27, 2020, we granted requests for certain of our tenants to defer rent payments totaling $2,132$2,799 with respect to leases that represent, as of March 31,June 30, 2020, approximately 6.5%8.2% of our annualized rental revenues. As of June 30, 2020, we recognized an increase in our accounts receivable balance related to these deferred rent payments of $2,317. These tenants will be obligated to pay, in most cases, the deferred rents in 12 equal monthly installments commencing in September 2020. For the three months ended June 30, 2020, we collected approximately 97% of our contractual rents due after giving effect to such rent deferrals. These deferred amounts did not negatively impact our financial results, and we did not record any revenue reserves for these amounts, for the three and six months ended March 31,June 30, 2020, and will continue to be reflected in our financial results in the applicable future reporting periods.periods, assuming these tenants will pay the deferred rents due to us.

We do not have any employees and the personnel and various services we require to operate our business are provided to us by RMR LLC pursuant to our business and property management agreements with RMR LLC. RMR LLC has implemented enhanced cleaning protocols and social distancing guidelines at its corporate headquarters and its regional offices, as well as business continuity plans to ensure that RMR LLC employees remain safe and able to support ILPTus and other companies managed by RMR LLC or its subsidiaries, including providing appropriate information technology such as notebook computers, smart phones, computer applications, information technology security applications and technology support.

All RMR LLC property management and engineering personnel have been trained on COVID-19 precaution procedures. As states and local communities across the United States have moved to shelter in placestay at home orders, RMR LLC has worked to reduce and optimize our operating costs at our properties by:

RMR LLC’s property management teams have also established business continuity plans to ensure operational stability at our properties. RMR LLC regional management offices limit walk-in visitors and maintain maximum office occupancy limits as required by state and local guidelines, including weekly rotations of employees as needed.

As stay at home orders are lifted or loosened across the United States, RMR LLC has suspended allimplemented additional procedures at our properties based on recommended guidelines from the U.S. Centers for Disease Control and Prevention and other regulatory agencies. For example:

RMR LLC has significantly reduced non-essential work travel and its regional leadership personnel have not been allowed to work in the same locations at the same time. RMR LLC also requires its employees who work at our properties to use personal protective equipment and business continuity bonus payments arehave been provided to those individuals.certain essential workers at our properties.

There are extensive uncertainties surrounding the COVID-19 pandemic and its aftermath. These uncertainties include, among others:

As a result of these uncertainties, we are unable to determine what the ultimate impact will be on our, our tenants’ and other stakeholders’ businesses, operations, financial results and financial position. For further information and risks relating to the COVID-19 pandemic and its aftermath on us and our business, see Part II, Item 1A, “Risk Factors” ofin this Quarterly Report on Form 10-Q.