Basis of presentation and summary of significant accounting policies (Policies)	3 Months Ended
Mar. 31, 2022
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Principles of consolidation	Principles of consolidation: The accompanying condensed consolidated financial statements include the accounts and transactions of the Company. All significant intercompany accounts and transactions have been eliminated in consolidation. The accompanying condensed consolidated balance sheet as of December 31, 2021 has been derived from audited financial statements. The unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and note disclosures normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) have been condensed or omitted pursuant to those rules and regulations, although the Company believes that the disclosures made are adequate to make the information not misleading. It is suggested that these condensed consolidated financial statements be read in conjunction with the consolidated financial statements and the notes thereto included in the Company’s latest Form 10-K for the year ended December 31, 2021. In the opinion of management, the accompanying condensed consolidated financial statements contain all adjustments (consisting solely of normal recurring adjustments) necessary to present fairly the financial position as of March 31, 2022 and the results of operations for the three months ended March 31, 2022 and 2021, and cash flows for the three months ended March 31, 2022 and 2021. The results of operations for interim periods are not necessarily indicative of the results to be expected for the full year.
Use of estimates	Use of estimates: The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. Estimates also affect the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates.
Environmental incidents	Environmental incidents: The Company accrues a liability when an environmental incident has occurred and the costs are estimable. The Company does not record a receivable for recoveries from third parties for environmental matters until it has determined that the amount of the collection is reasonably assured. The accrued liability is relieved when the Company pays the liability or a third party assumes the liability. Upon determination that collection is reasonably assured or a third party assumes the liability, the Company records the amount as a reduction of expense.
Fair value of financial instruments	The Company believes that the fair values of its financial instruments, including cash and cash equivalents, receivables and payables, approximate their respective book values because of their short-term nature. The fair values described herein were determined using significant other observable inputs (Level 2) as defined by GAAP.

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Use of estimates:

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

Fair value of financial instruments

The Company believes that the fair values of its financial instruments, including cash and cash equivalents, receivables and payables, approximate their respective book values because of their short-term nature. The fair values described herein were determined using significant other observable inputs (Level 2) as defined by GAAP.