Basis of Presentation and Recent Accounting Pronouncements (Policies)	6 Months Ended
Jun. 30, 2021
Accounting Policies [Abstract]
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation. The accompanying unaudited consolidated financial statements include the accounts of our wholly owned subsidiaries and are prepared in accordance with United States generally accepted accounting principles (“GAAP”) and the rules and regulations of the Securities and Exchange Commission (“SEC”) applicable for interim periods and, therefore, do not include all information and footnotes required by GAAP for complete financial statements. In management’s opinion, all adjustments (which include normal recurring adjustments) considered necessary for a fair presentation have been included. The results of operations for our interim periods are not necessarily indicative of the results of operations that may be achieved for the entire 2021 fiscal year. The financial information as of December 31, 2020 is derived from our audited consolidated financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2020. We have reclassified certain amounts in prior-period financial statements to conform to the current period's presentation. On the Consolidated Balance Sheets, prior period presentation of the Canadian pension plan in Long-term liabilities is now reflected in Pension and other postretirement benefits. On the Statements of Consolidated Cash Flows, prior period presentation of Other non-cash changes in assets and liabilities is now reflected in Changes in operating assets and liabilities within the following categories: (i) Prepaid expenses and other current assets; (ii) Accrued liabilities; and (iii) Long-term assets and liabilities, net.
Use of Estimates in the Preparation of Financial Statements	Use of Estimates in the Preparation of Financial Statements. The preparation of financial statements in accordance with GAAP requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities known to exist as of the date the financial statements are published and the reported amounts of revenues and expenses during the reporting period. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of our consolidated financial statements; accordingly, it is possible that the actual results could differ from these estimates and assumptions, which could have a material effect on the reported amounts of our consolidated financial position and results of operations.
Supply Chain Financing	Supply Chain Financing. Upon our acquisition of Warrick (as defined in Note 4 below), we became party to several supply chain financing arrangements, in which we may sell certain of our customers’ trade accounts receivable to such customers’ financial institutions without recourse. We sell our undivided interests in certain of these receivables at our discretion when we determine that the cost of these arrangements is less than the cost of servicing our receivables with existing debt. Under the terms of the agreements, we retain no rights or interest, have no obligations with respect to the sold receivables and do not service the receivables after the sale. As such, these transactions are being accounted for as a sale. During both the quarter and six months ended June 30, 2021, we sold trade accounts receivable totaling $316.0 million related to these supply chain financing arrangements, of which our customers’ financial institutions applied discount fees totaling $1.9 million. To the extent discount fees related to the sale of trade accounts receivable under supply chain financing arrangements are not reimbursed by our customers, they are included in Other (expense) income, net. As of June 30, 2021, we had been and/or expected to be fully reimbursed by our customers for these discount fees.
Fair Value of Goodwill and Intangible Assets	Fair Value of Goodwill and Intangible Assets. Fair values and useful lives are determined based on, among other factors, the expected future period of benefit of the asset, the various characteristics of the asset, long‑term forecasts of the business, market prices, projected cash flows and the rate used in discounting those cash flows. As the determination of an asset’s fair value and useful life involves management making certain estimates and because these estimates form the basis for the determination of whether or not an impairment charge should be recorded, these estimates are considered to be critical accounting estimates.
New Accounting Pronouncements	Adoption of New Accounting Pronouncements In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify the accounting for income taxes by eliminating certain exceptions and implementing additional requirements which result in a more consistent application of Accounting Standards Codification (“ASC”) 740 Income Taxes. Most amendments within ASU 2019-12 are required to be applied on a prospective basis, while certain amendments must be applied on a retrospective or modified retrospective basis. Our adoption of ASU 2019-12 during the quarter ended March 31, 2021 did not result in a material impact on our consolidated financial statements. Accounting Pronouncements Issued But Not Yet Adopted In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”) and also issued subsequent amendments to the initial guidance (collectively, “Topic 848”). Topic 848 is effective for all entities as of March 12, 2020 through December 31, 2022 and provides optional guidance for contract modifications and certain hedging relationships associated with the transition from reference rates that are expected to be discontinued. We will adopt Topic 848 when our relevant contracts are modified upon transition to alternative reference rates. We do not expect our adoption of Topic 848 to have a material impact on our consolidated financial statements.
Leases	We determine whether an agreement is a lease at inception. We have operating and finance leases for equipment and real estate that primarily have fixed lease payments. Our leases have remaining lease terms of approximately one to 60 years, some of which may include options to extend the lease for up to 60 years and some of which may include options to terminate the lease within one year. For purposes of calculating lease liabilities, these options are included within the lease term when it has become reasonably certain that we will exercise such options. Short-term leases with an initial term of 12 months or less are not recorded on our Consolidated Balance Sheets. As most of our leases do not provide an implicit rate, we use information available at the lease commencement date in determining an incremental borrowing rate when calculating our right-of-use lease assets and liabilities. In determining the inputs to the incremental borrowing rate calculation, we make judgments about the value of the leased asset, our credit rating and the lease term, including the probability of our exercising options to extend or terminate the underlying lease. Additionally, we make judgments around contractual asset substitution rights in determining whether a contract contains a lease. We have lease agreements with lease and non-lease components, which are generally accounted for separately. These non-lease components include items such as common area maintenance, taxes and insurance for our real estate leases, as well as maintenance charges related to our equipment leases. We have, however, applied the practical expedient within ASU No. 2016-02, Leases (Topic 842): Amendments to the Financial Accounting Standards Board Accounting Standards Codification (“ASU 2016-02”), to not separate lease and non-lease components to our embedded supply system equipment leases and have therefore accounted for both lease and non‑lease components in determining the lease assets and liabilities. Many of our equipment leases contain clauses that require us to return the equipment with certain functionality intact. We account for these costs as residual value guarantees when the guarantee becomes probable of being owed. Our lease agreements do not contain any material restrictive covenants.

Basis of Presentation and Recent Accounting Pronouncements (Policies)

6 Months Ended

Jun. 30, 2021

Principles of Consolidation and Basis of Presentation

Principles of Consolidation and Basis of Presentation. The accompanying unaudited consolidated financial statements include the accounts of our wholly owned subsidiaries and are prepared in accordance with United States generally accepted accounting principles (“GAAP”) and the rules and regulations of the Securities and Exchange Commission (“SEC”) applicable for interim periods and, therefore, do not include all information and footnotes required by GAAP for complete financial statements. In management’s opinion, all adjustments (which include normal recurring adjustments) considered necessary for a fair presentation have been included. The results of operations for our interim periods are not necessarily indicative of the results of operations that may be achieved for the entire 2021 fiscal year. The financial information as of December 31, 2020 is derived from our audited consolidated financial statements and footnotes included in our Annual Report on Form 10-K for the year ended December 31, 2020. We have reclassified certain amounts in prior-period financial statements to conform to the current period's presentation. On the Consolidated Balance Sheets, prior period presentation of the Canadian pension plan in Long-term liabilities is now reflected in Pension and other postretirement benefits. On the Statements of Consolidated Cash Flows, prior period presentation of Other non-cash changes in assets and liabilities is now reflected in Changes in operating assets and liabilities within the following categories: (i) Prepaid expenses and other current assets; (ii) Accrued liabilities; and (iii) Long-term assets and liabilities, net.

Use of Estimates in the Preparation of Financial Statements

Use of Estimates in the Preparation of Financial Statements. The preparation of financial statements in accordance with GAAP requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities known to exist as of the date the financial statements are published and the reported amounts of revenues and expenses during the reporting period. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of our consolidated financial statements; accordingly, it is possible that the actual results could differ from these estimates and assumptions, which could have a material effect on the reported amounts of our consolidated financial position and results of operations.

Supply Chain Financing

Supply Chain Financing. Upon our acquisition of Warrick (as defined in Note 4 below), we became party to several supply chain financing arrangements, in which we may sell certain of our customers’ trade accounts receivable to such customers’ financial institutions without recourse. We sell our undivided interests in certain of these receivables at our discretion when we determine that the cost of these arrangements is less than the cost of servicing our receivables with existing debt. Under the terms of the agreements, we retain no rights or interest, have no obligations with respect to the sold receivables and do not service the receivables after the sale. As such, these transactions are being accounted for as a sale. During both the quarter and six months ended June 30, 2021, we sold trade accounts receivable totaling $316.0 million related to these supply chain financing arrangements, of which our customers’ financial institutions applied discount fees totaling $1.9 million. To the extent discount fees related to the sale of trade accounts receivable under supply chain financing arrangements are not reimbursed by our customers, they are included in Other (expense) income, net. As of June 30, 2021, we had been and/or expected to be fully reimbursed by our customers for these discount fees.

Fair Value of Goodwill and Intangible Assets

Fair Value of Goodwill and Intangible Assets. Fair values and useful lives are determined based on, among other factors, the expected future period of benefit of the asset, the various characteristics of the asset, long‑term forecasts of the business, market prices, projected cash flows and the rate used in discounting those cash flows. As the determination of an asset’s fair value and useful life involves management making certain estimates and because these estimates form the basis for the determination of whether or not an impairment charge should be recorded, these estimates are considered to be critical accounting estimates.

New Accounting Pronouncements

Adoption of New Accounting Pronouncements

In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify the accounting for income taxes by eliminating certain exceptions and implementing additional requirements which result in a more consistent application of Accounting Standards Codification (“ASC”) 740 Income Taxes. Most amendments within ASU 2019-12 are required to be applied on a prospective basis, while certain amendments must be applied on a retrospective or modified retrospective basis. Our adoption of ASU 2019-12 during the quarter ended March 31, 2021 did not result in a material impact on our consolidated financial statements.

Accounting Pronouncements Issued But Not Yet Adopted

In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”) and also issued subsequent amendments to the initial guidance (collectively, “Topic 848”). Topic 848 is effective for all entities as of March 12, 2020 through December 31, 2022 and provides optional guidance for contract modifications and certain hedging relationships associated with the transition from reference rates that are expected to be discontinued. We will adopt Topic 848 when our relevant contracts are modified upon transition to alternative reference rates. We do not expect our adoption of Topic 848 to have a material impact on our consolidated financial statements.

Leases

We determine whether an agreement is a lease at inception. We have operating and finance leases for equipment and real estate that primarily have fixed lease payments. Our leases have remaining lease terms of approximately one to 60 years, some of which may include options to extend the lease for up to 60 years and some of which may include options to terminate the lease within one year. For purposes of calculating lease liabilities, these options are included within the lease term when it has become reasonably certain that we will exercise such options. Short-term leases with an initial term of 12 months or less are not recorded on our Consolidated Balance Sheets.

As most of our leases do not provide an implicit rate, we use information available at the lease commencement date in determining an incremental borrowing rate when calculating our right-of-use lease assets and liabilities. In determining the inputs to the incremental borrowing rate calculation, we make judgments about the value of the leased asset, our credit rating and the lease term, including the probability of our exercising options to extend or terminate the underlying lease. Additionally, we make judgments around contractual asset substitution rights in determining whether a contract contains a lease.

We have lease agreements with lease and non-lease components, which are generally accounted for separately. These non-lease components include items such as common area maintenance, taxes and insurance for our real estate leases, as well as maintenance charges related to our equipment leases. We have, however, applied the practical expedient within ASU No. 2016-02, Leases (Topic 842): Amendments to the Financial Accounting Standards Board Accounting Standards Codification (“ASU 2016-02”), to not separate lease and non-lease components to our embedded supply system equipment leases and have therefore accounted for both lease and non‑lease components in determining the lease assets and liabilities.

Many of our equipment leases contain clauses that require us to return the equipment with certain functionality intact. We account for these costs as residual value guarantees when the guarantee becomes probable of being owed. Our lease agreements do not contain any material restrictive covenants.