Financial Instruments and Other Guarantees	6 Months Ended
Financial Instruments and Other Guarantees	Jun. 30, 2022
Financial Instruments And Guarantees [Abstract]
Financial Instruments and Other Guarantees	Financial Instruments and Other Guarantees The Company is a party to various guarantees and financial instruments that carry off-balance-sheet risk and are not reflected in the accompanying condensed consolidated balance sheets. At June 30, 2022, such instruments included $1,453.5 million of surety bonds and $475.1 million of letters of credit. Such financial instruments provide support for the Company’s reclamation bonding requirements, lease obligations, insurance policies and various other performance guarantees. The Company periodically evaluates the instruments for on-balance sheet treatment based on the amount of exposure under the instrument and the likelihood of required performance. The Company does not expect any material losses to result from these guarantees or off-balance-sheet instruments in excess of liabilities provided for in the accompanying condensed consolidated balance sheets. Reclamation Bonding The Company is required to provide various forms of financial assurance in support of its mining reclamation obligations in the jurisdictions in which it operates. Such requirements are typically established by statute or under mining permits. In November 2020, the Company entered into an agreement with the providers of its surety bond portfolio to resolve previous collateral demands. In accordance with the agreement, the Company initially provided $75.0 million of collateral, in the form of letters of credit. The Company subsequently granted second liens on $200.0 million of certain mining equipment and is further required to post an additional $25.0 million of collateral per year from 2021 through 2024 for the benefit of the surety providers. The collateral postings further increase to the extent the Company generates more than $100.0 million of free cash flow (as defined in the surety agreement) in any twelve-month period or has cumulative asset sales in excess of $10.0 million, as of the last quarter end during the term of the agreement. Based upon the Company’s free cash flow through June 30, 2022, additional collateral of $13.0 million was posted during the three months ended March 31, 2022 and $25.7 million was posted subsequent to June 30, 2022, in the form of cash-collateralized letters of credit. At June 30, 2022, the Company’s asset retirement obligations of $725.1 million were supported by surety bonds of $1,276.9 million, as well as letters of credit issued under the Company’s receivables securitization program and the Company LC Agreement. Letters of credit issued at June 30, 2022 which served as collateral for surety bonds in support of asset retirement obligations amounted to $346.4 million. Accounts Receivable Securitization The Company entered into the Sixth Amended and Restated Receivables Purchase Agreement, as amended, dated as of April 3, 2017 (the Receivables Purchase Agreement) to extend the Company’s receivables securitization facility previously in place and expand that facility to include certain receivables from the Company’s Australian operations. The receivables securitization program (Securitization Program) is subject to customary events of default set forth in the Receivables Purchase Agreement. The Receivables Purchase Agreement was amended in January 2022 to extend the Securitization Program to January 2025, reduce the available funding capacity from $250.0 million to $175.0 million, and amend the relevant borrowing rate from a LIBOR-based rate to one based on Bloomberg’s Short-Term Bank Yield Index (BSBY). Such funding is accounted for as a secured borrowing, limited to the availability of eligible receivables, and may be secured by a combination of collateral and the trade receivables underlying the program, from time to time. Funding capacity under the Securitization Program may also be utilized for letters of credit in support of other obligations. Borrowings under the Securitization Program bear interest at BSBY plus 2.1% per annum and remain outstanding throughout the term of the agreement, subject to the Company maintaining sufficient eligible receivables. At June 30, 2022, the Company had no outstanding borrowings and $161.5 million of letters of credit outstanding under the Securitization Program. The letters of credit were primarily in support of reclamation obligations. Availability under the Securitization Program, which is adjusted for certain ineligible receivables, was $13.5 million at June 30, 2022. The Company was not required to post cash collateral under the Securitization Program at June 30, 2022. The Company incurred interest and fees associated with the Securitization Program of $0.9 million and $0.7 million during the three months ended June 30, 2022 and 2021, respectively, and $1.8 million and $1.4 million during the six months ended June 30, 2022 and 2021, respectively, which have been recorded as “Interest expense” in the accompanying unaudited condensed consolidated statements of operations. Collateralized Letter of Credit Agreement In February 2022, the Company entered into a new agreement, which provides up to $250.0 million of capacity for irrevocable standby letters of credit, expected to primarily support reclamation bonding requirements. The agreement requires the Company to provide cash collateral at a level of 103% of the aggregate amount of letters of credit outstanding under the arrangement (limited to $5.0 million total excess collateralization.) Outstanding letters of credit bear a fixed fee in the amount of 0.75% per annum. The Company receives a deposit rate of 0.35% per annum on the amount of cash collateral posted in support of letters of credit, with the rate subject to variation over time. The agreement has an initial expiration date of December 31, 2025. At June 30, 2022, collateralized letters of credit of $12.3 million were outstanding under the agreement