Principles of consolidation and basis of presentation (Policies)	9 Months Ended
Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
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.
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 consolidated 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.

- Definition

Disclosure of accounting policy for environmental remediation costs that are expensed during the period that resulted from improper or other than normal operation of a long-lived asset. This accounting policy may address (1) whether the obligation is measured on a discounted basis, (2) the event, situation, or set of circumstances that generally triggers recognition of loss contingencies arising from the entity's environmental remediation-related obligations, and (3) the timing of recognition of any recoveries. This accounting policy does not address: (1) accounting for pollution control costs of current operations or for costs of future site restoration or closure that are required upon the cessation of operations or sale of facilities (2) environmental remediation actions that are undertaken at the sole discretion of management and that are not induced by the threat, by governments or other parties, of litigation or of assertion of a claim or an assessment (3) recognition of liabilities of insurance companies for unpaid claims or (4) asset impairment issues.

+ References + Details