SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Accounting	Basis of Accounting—The accompanying consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and include the accounts of us and our subsidiaries.
Principles of Consolidation	Principles of Consolidation—We consolidate all entities in which we have a controlling financial interest and control over significant operating decisions, as well as variable interest entities (“VIEs”) in which we are the primary beneficiary. All significant intercompany transactions and balances have been eliminated. All adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. The ownership interest of other investors in consolidated subsidiaries is recorded as non-controlling interest. We use the equity method of accounting for investments in entities in which we exercise significant influence but which do not meet the requirements for consolidation. Under the equity method, we record our proportionate share of the underlying net income (loss) of these entities as well as the proportionate interest in adjustments to other comprehensive income (loss).
Use of Estimates	Use of Estimates—The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Risks and Uncertainties	Risks and Uncertainties—In the normal course of business, we encounter several significant types of economic risk including credit, market, and capital market risks. Credit risk is the risk of the inability or unwillingness of a lessee, customer, or derivative counterparty to make contractually required payments or to fulfill its other contractual obligations. Market risk reflects the risk of a downturn or volatility in the underlying industry segments in which we operate, which could adversely impact the pricing of the services offered by us or a lessee’s or customer’s ability to make payments, increase the risk of unscheduled lease terminations and depress lease rates and the value of our leasing equipment or operating assets. Capital market risk is the risk that we are unable to obtain capital at reasonable rates to fund the growth of our business or to refinance existing debt facilities. We, through our subsidiaries, also conduct operations outside of the United States; such international operations are subject to the same risks as those associated with our United States operations as well as additional risks, including unexpected changes in regulatory requirements, heightened risk of political and economic instability, potentially adverse tax consequences and the burden of complying with foreign laws. We do not have significant exposure to foreign currency risk as all of our leasing arrangements and the majority of terminal services revenue are denominated in U.S. dollars.
Variable Interest Entities	Variable Interest Entities—The assessment of whether an entity is a VIE and the determination of whether to consolidate a VIE requires judgment. VIEs are defined as entities in which equity investors do not have the characteristics of a controlling financial interest or do not have sufficient equity at risk for the entity to finance its activities without additional subordinated financial support from other parties. A VIE is required to be consolidated by its primary beneficiary, and only by its primary beneficiary, which is defined as the party who has the power to direct the activities of a VIE that most significantly impact its economic performance and who has the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents—We consider all highly liquid short-term investments with a maturity of 90 days or less when purchased to be cash equivalents.Restricted Cash—Restricted cash consists of prepaid interest and principal pursuant to the requirements of certain of our debt agreements (see Note 7) and other qualifying construction projects at Jefferson Terminal.
Inventory	Inventory—We hold aircraft engine modules, spare parts and used material inventory for trading and to support operations within our Aviation Leasing segment. Aviation inventory is carried at the lower of cost or net realizable value on our balance sheet. We had Aviation inventory of $109.2 million and $100.3 million as of March 31, 2022 and December 31, 2021, respectively, which is included in Other assets in the Consolidated Balance Sheets.Commodities inventory is carried at the lower of cost or net realizable value on our balance sheet. Commodities are removed from inventory based on the average cost at the time of sale.
Deferred Financing Costs	Deferred Financing Costs—Costs incurred in connection with obtaining long term financing are capitalized and amortized to interest expense over the term of the underlying loans.
Operating Leases	Operating Leases—We lease equipment pursuant to operating leases. Operating leases with fixed rentals and step rentals are recognized on a straight-line basis over the term of the lease, assuming no renewals. Revenue is not recognized when collection is not reasonably assured. When collectability is not reasonably assured, the customer is placed on non-accrual status and revenue is recognized when cash payments are received. Generally, under our aircraft lease and engine agreements, the lessee is required to make periodic maintenance payments calculated based on the lessee’s utilization of the leased asset or at the end of the lease. Typically, under our aircraft lease agreements, the lessee is responsible for maintenance, repairs and other operating expenses throughout the term of the lease. These periodic maintenance payments accumulate over the term of the lease to fund major maintenance events, and we are contractually obligated to return maintenance payments to the lessee up to the cost of maintenance events paid by the lessee. In the event the total cost of maintenance events over the term of a lease is less than the cumulative maintenance payments, we are not required to return any unused or excess maintenance payments to the lessee. Maintenance payments received for which we expect to repay to the lessee are presented as Maintenance Deposits in our Consolidated Balance Sheets. All excess maintenance payments received that we do not expect to repay to the lessee are recorded as Maintenance revenues. Estimates in recognizing revenue include mean time between removal, projected costs for engine maintenance and forecasted utilization of aircraft which are affected by historical usage patterns and overall industry, market and economic conditions. Significant changes to these estimates could have a material effect on the amount of revenue recognized in the period. For purchase and lease back transactions, we account for the transaction as a single arrangement. We allocate the consideration paid based on the relative fair value of the aircraft and lease. The fair value of the lease may include a lease premium or discount, which is recorded as a favorable or unfavorable lease intangible. In April 2020, the FASB Staff issued a question-and-answer document (the “Q&A”) regarding accounting for lease concessions related to the effects of the COVID-19 pandemic. The Q&A permits an entity to elect to forgo the evaluation of the enforceable rights and obligations of a lease contract required under ASC 842, Leases, as long as the total rent payments after the lease concessions are substantially the same, or less than, the total rent payments in the existing lease. The impact of the COVID-19 related lease concessions granted above did not have a material impact on our results of operations during the three months ended March 31, 2022. Finance Leases—From time to time we enter into finance lease arrangements that include a lessee obligation to purchase the leased equipment at the end of the lease term, a bargain purchase option, or provides for minimum lease payments with a present value that equals or exceeds substantially all of the fair value of the leased equipment at the date of lease inception. Net investment in finance leases represents the minimum lease payments due from lessee, net of unearned income. The lease payments are segregated into principal and interest components similar to a loan. Unearned income is recognized on an effective interest method over the lease term and is recorded as finance lease income. The principal component of the lease payment is reflected as a reduction to the net investment in finance leases. Revenue is not recognized when collection is not reasonably assured. When collectability is not reasonably assured, the customer is placed on non-accrual status and revenue is recognized when cash payments are received. Other Revenue—Other revenue primarily consists of revenue related to the sale of engine modules, spare parts and used material inventory and other income. Revenues for the sale of engine modules, spare parts and used material inventory are recognized when a performance obligation is satisfied by transferring control of inventory to a customer.
Infrastructure Revenues	Infrastructure Revenues Terminal Services Revenues—Terminal services are provided to customers for the receipt and redelivery of various commodities. These revenues relate to performance obligations that are recognized over time using the right to invoice practical expedient, i.e., invoiced as the services are rendered and the customer simultaneously receives and consumes the benefit over the contract term. The Company’s performance of service and right to invoice corresponds with the value delivered to our customers. Revenues are typically invoiced and paid on a monthly basis. Rail Revenues—Rail revenues generally consist of the following performance obligations: industrial switching, interline services, demurrage and storage. Switching revenues are derived from the performance of switching services, which involve the movement of cars from one point to another within the limits of an individual plant, industrial area, or a rail yard. Switching revenues are recognized as the services are performed, and the services are generally completed on the same day they are initiated. Interline revenues are derived from transportation services for railcars that originate or terminate at our railroads and involve one or more other carriers. For interline traffic, one railroad typically invoices a customer on behalf of all railroads participating in the route directed by the customer. The invoicing railroad then pays the other railroads its portion of the total amount invoiced on a monthly basis. We record revenue related to interline traffic for transportation service segments provided by carriers along railroads that are not owned or controlled by us on a net basis. Interline revenues are recognized as the transportation movements occur. Our ancillary services revenue primarily relates to demurrage and storage services. Demurrage represents charges assessed by railroads for the detention of cars by shippers or receivers of freight beyond a specified free time and is recognized on a per day basis. Storage services revenue is earned for the provision of storage of shippers’ railcars and is generally recognized on a per day, per car basis, as the storage services are provided. Lease Income—Lease income consists of rental income from tenants for storage space. Lease income is recognized on a straight-line basis over the terms of the relevant lease agreement. Other Revenue—Other revenue primarily consists of revenue related to the handling, storage and sale of raw materials. Revenues for the handling and storage of raw materials relate to performance obligations that are recognized over time using the right to invoice practical expedient, i.e., invoiced as the services are rendered and the customer simultaneously receives and consumes the benefit over the contract term. Our performance of service and right to invoice corresponds with the value delivered to our customers. Revenues for the sale of raw materials relate to contracts that contain performance obligations to deliver the product over the term of the contract. The revenues are recognized when the control of the product is transferred to the customer, based on the volume delivered and the price within the contract. Other revenues are typically invoiced and paid on a monthly basis. Additionally, other revenue consists of revenue related to derivative trading activities. See Commodity Derivatives below for additional information. Payment terms for Infrastructure Revenues are generally short term in nature.
Leasing Arrangements	Leasing Arrangements—At contract inception, we evaluate whether an arrangement is or contains a lease for which we are the lessee (that is, arrangements which provide us with the right to control a physical asset for a period of time). Operating lease right-of-use (“ROU”) assets and lease liabilities are recognized in Operating lease right-of-use assets, net and Operating lease liabilities in our Consolidated Balance Sheets, respectively. Finance lease ROU assets are recognized in Property, plant and equipment, net and lease liabilities are recognized in Other liabilities in our Consolidated Balance Sheets. All lease liabilities are measured at the present value of the unpaid lease payments, discounted using our incremental borrowing rate based on the information available at commencement date of the lease. ROU assets, for both operating and finance leases, are initially measured based on the lease liability, adjusted for prepaid rent and lease incentives. ROU assets are subsequently measured at the carrying amount of the lease liability adjusted for prepaid or accrued lease payments and lease incentives. The finance lease ROU assets are subsequently amortized using the straight-line method. Operating lease expenses are recognized on a straight-line basis over the lease term. With respect to finance leases, amortization of the ROU asset is presented separately from interest expense related to the finance lease liability. Variable lease payments, which are primarily based on usage, are recognized when the associated activity occurs. We have elected to combine lease and non-lease components for all lease contracts where we are the lessee. Additionally, for arrangements with lease terms of 12 months or less, we do not recognize ROU assets, and lease liabilities and lease payments are recognized on a straight-line basis over the lease term with variable lease payments recognized in the period in which the obligation is incurred.
Concentration of Credit Risk	Concentration of Credit Risk—We are subject to concentrations of credit risk with respect to amounts due from customers on our finance leases and operating leases. We attempt to limit our credit risk by performing ongoing credit evaluations and, when deemed necessary, enter into collateral arrangements. During the three months ended March 31, 2021, one customer in the Aviation Leasing segment accounted for approximately 11% of total revenue. During the three months ended March 31, 2022, one customer in the Transtar segment accounted for approximately 23% of total revenue. As of March 31, 2022, there were two customers in the Aviation Leasing segment that represented 19% and 10% of total Accounts receivable, net, respectively, and one customer in the Transtar segment that represented 14% of total Accounts receivable, net. As of December 31, 2021, Accounts receivable from two customers in the Aviation Leasing segment represented 36% and 13% of total Accounts receivable, net, respectively. We maintain cash and restricted cash balances, which generally exceed federally insured limits, and subject us to credit risk, in high credit quality financial institutions. We monitor the financial condition of these institutions and have not experienced any losses associated with these accounts.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts—We determine the allowance for doubtful accounts based on our assessment of the collectability of our receivables on a customer-by-customer basis.
Comprehensive Income (Loss)	Comprehensive Income (Loss)—Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances, excluding those resulting from investments by and distributions to owners. Our comprehensive income (loss) represents net income (loss), as presented in the Consolidated Statements of Operations, adjusted for fair value changes recorded in other comprehensive income related to cash flow hedges of our equity method investees and pension and other postretirement benefits.
Derivative Financial Instruments	Derivative Financial Instruments Electricity Derivatives—Through our equity method investment in Long Ridge, we enter into derivative contracts as part of a risk management program to mitigate price risk associated with certain electricity price exposures. We primarily use swap derivative contracts, which are agreements to buy or sell a quantity of electricity at a predetermined future date and at a predetermined price. Cash Flow Hedges Certain of these derivative instruments are designated and qualify as cash flow hedges. Our share of the derivative's gain or loss is reported as Other comprehensive income (loss) related to equity method investees, net in our Consolidated Statements of Comprehensive Loss and recorded in Accumulated other comprehensive income in our Consolidated Balance Sheets. Derivatives Not Designated As Hedging Instruments Certain of these derivative instruments are not designated as hedging instruments for accounting purposes. Our share of the change in fair value of these contracts is recognized in Equity in earnings (losses) in unconsolidated entities in the Consolidated Statements of Operations. The cash flow impact of derivative contracts that are not designated as hedging instruments is recognized in Equity in losses (earnings) in unconsolidated entities in our Consolidated Statements of Cash Flows. Commodity Derivatives—Depending on market conditions, we enter into short-term forward purchase and sales contracts for butane. Gains and losses related to our butane derivatives are recorded on a net basis and are included in Other revenue in our Consolidated Statements of Operations, as these contracts are considered part of central operating activities. The cash flow impact of these derivatives is recognized in Change in fair value of non-hedge derivatives in our Consolidated Statements of Cash Flows. We record all derivative assets and liabilities on a gross basis at fair value, which are included in Other assets and Other liabilities, respectively, in our Consolidated Balance Sheets.
Recent Accounting Pronouncements	Recent Accounting Pronouncements—In July 2021, the FASB issued ASU 2021-05, Leases (Topic 842): Lessors—Certain Leases with Variable Lease Payments. This ASU requires lessors to classify and account for a lease with variable lease payments that do not depend on a reference index or a rate as an operating lease if (i) the lease would have been classified as a sales-type lease or a direct financing lease under Topic 842 and (ii) the lessor would have otherwise recognized a day-one loss. This standard is effective for all reporting periods beginning after December 15, 2021. We adopted this guidance in the first quarter of 2022, which did not have a material impact on our consolidated financial statements.
Fair Value Measurement	Fair value measurements and disclosures require the use of valuation techniques to measure fair value that maximize the use of observable inputs and minimize use of unobservable inputs. These inputs are prioritized as follows: •Level 1: Observable inputs such as quoted prices in active markets for identical assets or liabilities. •Level 2: Inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities or market corroborated inputs. •Level 3: Unobservable inputs for which there is little or no market data and which require us to develop our own assumptions about how market participants price the asset or liability. The valuation techniques that may be used to measure fair value are as follows: •Market approach—Uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities. •Income approach—Uses valuation techniques to convert future amounts to a single present amount based on current market expectations about those future amounts. •Cost approach—Based on the amount that currently would be required to replace the service capacity of an asset (replacement cost).

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

3 Months Ended

Mar. 31, 2022

Basis of Accounting—The accompanying consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and include the accounts of us and our subsidiaries.

Principles of Consolidation

Principles of Consolidation—We consolidate all entities in which we have a controlling financial interest and control over significant operating decisions, as well as variable interest entities (“VIEs”) in which we are the primary beneficiary. All significant intercompany transactions and balances have been eliminated. All adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. The ownership interest of other investors in consolidated subsidiaries is recorded as non-controlling interest.

We use the equity method of accounting for investments in entities in which we exercise significant influence but which do not meet the requirements for consolidation. Under the equity method, we record our proportionate share of the underlying net income (loss) of these entities as well as the proportionate interest in adjustments to other comprehensive income (loss).

Use of Estimates

Use of Estimates—The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Risks and Uncertainties

Risks and Uncertainties—In the normal course of business, we encounter several significant types of economic risk including credit, market, and capital market risks. Credit risk is the risk of the inability or unwillingness of a lessee, customer, or derivative counterparty to make contractually required payments or to fulfill its other contractual obligations. Market risk reflects the risk of a downturn or volatility in the underlying industry segments in which we operate, which could adversely impact the pricing of the services offered by us or a lessee’s or customer’s ability to make payments, increase the risk of unscheduled lease terminations and depress lease rates and the value of our leasing equipment or operating assets. Capital market risk is the risk that we are unable to obtain capital at reasonable rates to fund the growth of our business or to refinance existing debt facilities. We, through our subsidiaries, also conduct operations outside of the United States; such international operations are subject to the same risks as those associated with our United States operations as well as additional risks, including unexpected changes in regulatory requirements, heightened risk of political and economic instability, potentially adverse tax consequences and the burden of complying with foreign laws. We do not have significant exposure to foreign currency risk as all of our leasing arrangements and the majority of terminal services revenue are denominated in U.S. dollars.

Variable Interest Entities

Variable Interest Entities—The assessment of whether an entity is a VIE and the determination of whether to consolidate a VIE requires judgment. VIEs are defined as entities in which equity investors do not have the characteristics of a controlling financial interest or do not have sufficient equity at risk for the entity to finance its activities without additional subordinated financial support from other parties. A VIE is required to be consolidated by its primary beneficiary, and only by its primary beneficiary, which is defined as the party who has the power to direct the activities of a VIE that most significantly impact its economic performance and who has the obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE.

Cash and Cash Equivalents and Restricted Cash

Cash and Cash Equivalents—We consider all highly liquid short-term investments with a maturity of 90 days or less when purchased to be cash equivalents.Restricted Cash—Restricted cash consists of prepaid interest and principal pursuant to the requirements of certain of our debt agreements (see Note 7) and other qualifying construction projects at Jefferson Terminal.

Inventory

Inventory—We hold aircraft engine modules, spare parts and used material inventory for trading and to support operations within our Aviation Leasing segment. Aviation inventory is carried at the lower of cost or net realizable value on our balance sheet. We had Aviation inventory of $109.2 million and $100.3 million as of March 31, 2022 and December 31, 2021, respectively, which is included in Other assets in the Consolidated Balance Sheets.Commodities inventory is carried at the lower of cost or net realizable value on our balance sheet. Commodities are removed from inventory based on the average cost at the time of sale.

Deferred Financing Costs

Deferred Financing Costs—Costs incurred in connection with obtaining long term financing are capitalized and amortized to interest expense over the term of the underlying loans.

Operating Leases

Operating Leases—We lease equipment pursuant to operating leases. Operating leases with fixed rentals and step rentals are recognized on a straight-line basis over the term of the lease, assuming no renewals. Revenue is not recognized when collection is not reasonably assured. When collectability is not reasonably assured, the customer is placed on non-accrual status and revenue is recognized when cash payments are received.

Generally, under our aircraft lease and engine agreements, the lessee is required to make periodic maintenance payments calculated based on the lessee’s utilization of the leased asset or at the end of the lease. Typically, under our aircraft lease agreements, the lessee is responsible for maintenance, repairs and other operating expenses throughout the term of the lease. These periodic maintenance payments accumulate over the term of the lease to fund major maintenance events, and we are contractually obligated to return maintenance payments to the lessee up to the cost of maintenance events paid by the lessee. In the event the total cost of maintenance events over the term of a lease is less than the cumulative maintenance payments, we are not required to return any unused or excess maintenance payments to the lessee.

Maintenance payments received for which we expect to repay to the lessee are presented as Maintenance Deposits in our Consolidated Balance Sheets. All excess maintenance payments received that we do not expect to repay to the lessee are recorded as Maintenance revenues. Estimates in recognizing revenue include mean time between removal, projected costs for engine maintenance and forecasted utilization of aircraft which are affected by historical usage patterns and overall industry, market and economic conditions. Significant changes to these estimates could have a material effect on the amount of revenue recognized in the period.

For purchase and lease back transactions, we account for the transaction as a single arrangement. We allocate the consideration paid based on the relative fair value of the aircraft and lease. The fair value of the lease may include a lease premium or discount, which is recorded as a favorable or unfavorable lease intangible.

In April 2020, the FASB Staff issued a question-and-answer document (the “Q&A”) regarding accounting for lease concessions related to the effects of the COVID-19 pandemic. The Q&A permits an entity to elect to forgo the evaluation of the enforceable rights and obligations of a lease contract required under ASC 842, Leases, as long as the total rent payments after the lease concessions are substantially the same, or less than, the total rent payments in the existing lease. The impact of the COVID-19 related lease concessions granted above did not have a material impact on our results of operations during the three months ended March 31, 2022.

Finance Leases—From time to time we enter into finance lease arrangements that include a lessee obligation to purchase the leased equipment at the end of the lease term, a bargain purchase option, or provides for minimum lease payments with a present value that equals or exceeds substantially all of the fair value of the leased equipment at the date of lease inception. Net investment in finance leases represents the minimum lease payments due from lessee, net of unearned income. The lease payments are segregated into principal and interest components similar to a loan. Unearned income is recognized on an effective interest method over the lease term and is recorded as finance lease income. The principal component of the lease payment is reflected as a reduction to the net investment in finance leases. Revenue is not recognized when collection is not reasonably assured. When collectability is not reasonably assured, the customer is placed on non-accrual status and revenue is recognized when cash payments are received.

Other Revenue—Other revenue primarily consists of revenue related to the sale of engine modules, spare parts and used material inventory and other income. Revenues for the sale of engine modules, spare parts and used material inventory are recognized when a performance obligation is satisfied by transferring control of inventory to a customer.

Infrastructure Revenues

Terminal Services Revenues—Terminal services are provided to customers for the receipt and redelivery of various commodities. These revenues relate to performance obligations that are recognized over time using the right to invoice practical expedient, i.e., invoiced as the services are rendered and the customer simultaneously receives and consumes the benefit over the contract term. The Company’s performance of service and right to invoice corresponds with the value delivered to our customers. Revenues are typically invoiced and paid on a monthly basis.

Rail Revenues—Rail revenues generally consist of the following performance obligations: industrial switching, interline services, demurrage and storage. Switching revenues are derived from the performance of switching services, which involve the movement of cars from one point to another within the limits of an individual plant, industrial area, or a rail yard. Switching revenues are recognized as the services are performed, and the services are generally completed on the same day they are initiated.

Interline revenues are derived from transportation services for railcars that originate or terminate at our railroads and involve one or more other carriers. For interline traffic, one railroad typically invoices a customer on behalf of all railroads participating in the route directed by the customer. The invoicing railroad then pays the other railroads its portion of the total amount invoiced on a monthly basis. We record revenue related to interline traffic for transportation service segments provided by carriers along railroads that are not owned or controlled by us on a net basis. Interline revenues are recognized as the transportation movements occur.

Our ancillary services revenue primarily relates to demurrage and storage services. Demurrage represents charges assessed by railroads for the detention of cars by shippers or receivers of freight beyond a specified free time and is recognized on a per day basis. Storage services revenue is earned for the provision of storage of shippers’ railcars and is generally recognized on a per day, per car basis, as the storage services are provided.

Lease Income—Lease income consists of rental income from tenants for storage space. Lease income is recognized on a straight-line basis over the terms of the relevant lease agreement.

Other Revenue—Other revenue primarily consists of revenue related to the handling, storage and sale of raw materials. Revenues for the handling and storage of raw materials relate to performance obligations that are recognized over time using the right to invoice practical expedient, i.e., invoiced as the services are rendered and the customer simultaneously receives and consumes the benefit over the contract term. Our performance of service and right to invoice corresponds with the value delivered to our customers. Revenues for the sale of raw materials relate to contracts that contain performance obligations to deliver the product over the term of the contract. The revenues are recognized when the control of the product is transferred to the customer, based on the volume delivered and the price within the contract. Other revenues are typically invoiced and paid on a monthly basis.

Additionally, other revenue consists of revenue related to derivative trading activities. See Commodity Derivatives below for additional information.

Payment terms for Infrastructure Revenues are generally short term in nature.

Leasing Arrangements

Leasing Arrangements—At contract inception, we evaluate whether an arrangement is or contains a lease for which we are the lessee (that is, arrangements which provide us with the right to control a physical asset for a period of time). Operating lease right-of-use (“ROU”) assets and lease liabilities are recognized in Operating lease right-of-use assets, net and Operating lease liabilities in our Consolidated Balance Sheets, respectively. Finance lease ROU assets are recognized in Property, plant and equipment, net and lease liabilities are recognized in Other liabilities in our Consolidated Balance Sheets.

All lease liabilities are measured at the present value of the unpaid lease payments, discounted using our incremental borrowing rate based on the information available at commencement date of the lease. ROU assets, for both operating and finance leases, are initially measured based on the lease liability, adjusted for prepaid rent and lease incentives. ROU assets are subsequently measured at the carrying amount of the lease liability adjusted for prepaid or accrued lease payments and lease incentives. The finance lease ROU assets are subsequently amortized using the straight-line method.

Operating lease expenses are recognized on a straight-line basis over the lease term. With respect to finance leases, amortization of the ROU asset is presented separately from interest expense related to the finance lease liability. Variable lease payments, which are primarily based on usage, are recognized when the associated activity occurs.

We have elected to combine lease and non-lease components for all lease contracts where we are the lessee. Additionally, for arrangements with lease terms of 12 months or less, we do not recognize ROU assets, and lease liabilities and lease payments are recognized on a straight-line basis over the lease term with variable lease payments recognized in the period in which the obligation is incurred.

Concentration of Credit Risk

Concentration of Credit Risk—We are subject to concentrations of credit risk with respect to amounts due from customers on our finance leases and operating leases. We attempt to limit our credit risk by performing ongoing credit evaluations and, when deemed necessary, enter into collateral arrangements. During the three months ended March 31, 2021, one customer in the Aviation Leasing segment accounted for approximately 11% of total revenue. During the three months ended March 31, 2022, one customer in the Transtar segment accounted for approximately 23% of total revenue.

As of March 31, 2022, there were two customers in the Aviation Leasing segment that represented 19% and 10% of total Accounts receivable, net, respectively, and one customer in the Transtar segment that represented 14% of total Accounts receivable, net. As of December 31, 2021, Accounts receivable from two customers in the Aviation Leasing segment represented 36% and 13% of total Accounts receivable, net, respectively.

We maintain cash and restricted cash balances, which generally exceed federally insured limits, and subject us to credit risk, in high credit quality financial institutions. We monitor the financial condition of these institutions and have not experienced any losses associated with these accounts.

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts—We determine the allowance for doubtful accounts based on our assessment of the collectability of our receivables on a customer-by-customer basis.

Comprehensive Income (Loss)

Comprehensive Income (Loss)—Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances, excluding those resulting from investments by and distributions to owners. Our comprehensive income (loss) represents net income (loss), as presented in the Consolidated Statements of Operations, adjusted for fair value changes recorded in other comprehensive income related to cash flow hedges of our equity method investees and pension and other postretirement benefits.

Derivative Financial Instruments

Electricity Derivatives—Through our equity method investment in Long Ridge, we enter into derivative contracts as part of a risk management program to mitigate price risk associated with certain electricity price exposures. We primarily use swap derivative contracts, which are agreements to buy or sell a quantity of electricity at a predetermined future date and at a predetermined price.

Cash Flow Hedges

Certain of these derivative instruments are designated and qualify as cash flow hedges. Our share of the derivative's gain or loss is reported as Other comprehensive income (loss) related to equity method investees, net in our Consolidated Statements of Comprehensive Loss and recorded in Accumulated other comprehensive income in our Consolidated Balance Sheets.

Derivatives Not Designated As Hedging Instruments

Certain of these derivative instruments are not designated as hedging instruments for accounting purposes. Our share of the change in fair value of these contracts is recognized in Equity in earnings (losses) in unconsolidated entities in the Consolidated Statements of Operations. The cash flow impact of derivative contracts that are not designated as hedging instruments is recognized in Equity in losses (earnings) in unconsolidated entities in our Consolidated Statements of Cash Flows.

Commodity Derivatives—Depending on market conditions, we enter into short-term forward purchase and sales contracts for butane. Gains and losses related to our butane derivatives are recorded on a net basis and are included in Other revenue in our Consolidated Statements of Operations, as these contracts are considered part of central operating activities. The cash flow impact of these derivatives is recognized in Change in fair value of non-hedge derivatives in our Consolidated Statements of Cash Flows.

We record all derivative assets and liabilities on a gross basis at fair value, which are included in Other assets and Other liabilities, respectively, in our Consolidated Balance Sheets.

Recent Accounting Pronouncements

Recent Accounting Pronouncements—In July 2021, the FASB issued ASU 2021-05, Leases (Topic 842): Lessors—Certain Leases with Variable Lease Payments. This ASU requires lessors to classify and account for a lease with variable lease payments that do not depend on a reference index or a rate as an operating lease if (i) the lease would have been classified as a sales-type lease or a direct financing lease under Topic 842 and (ii) the lessor would have otherwise recognized a day-one loss. This standard is effective for all reporting periods beginning after December 15, 2021. We adopted this guidance in the first quarter of 2022, which did not have a material impact on our consolidated financial statements.

Fair Value Measurement

Fair value measurements and disclosures require the use of valuation techniques to measure fair value that maximize the use of observable inputs and minimize use of unobservable inputs. These inputs are prioritized as follows:

•Level 1: Observable inputs such as quoted prices in active markets for identical assets or liabilities.

•Level 2: Inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities or market corroborated inputs.

•Level 3: Unobservable inputs for which there is little or no market data and which require us to develop our own assumptions about how market participants price the asset or liability.

The valuation techniques that may be used to measure fair value are as follows:

•Market approach—Uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities.

•Income approach—Uses valuation techniques to convert future amounts to a single present amount based on current market expectations about those future amounts. •Cost approach—Based on the amount that currently would be required to replace the service capacity of an asset (replacement cost).