| Discontinued operations | The following is a reconciliation of the loss recorded on the sale: 
|  |  |  |  |  |  |  |  |  |  
|  |  |  |  
|  |  |  |  
| Net proceeds received from the sale of Performance Materials |  | $ | 624,256 |  |  
| Transaction costs |  | (13,161) |  |  
| Net assets derecognized |  | (681,973) |  |  
| Loss on sale of Performance Materials |  | $ | (70,878) |  |  
|  |  |  |  
|  |  |  |  The following table summarizes the results of discontinued operations for the periods presented: 
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|  | Years ended December 31,
 |  
|  | 2020 |  | 2019 |  | 2018 |  
| Sales | $ | 342,738 |  |  | $ | 373,686 |  |  | $ | 386,921 |  |  
| Cost of goods sold | 251,917 |  |  | 281,566 |  |  | 308,679 |  |  
| Selling, general and administrative expenses | 33,195 |  |  | 37,364 |  |  | 37,226 |  |  
| Other operating expense, net | 18,289 |  |  | 14,462 |  |  | 13,023 |  |  
| Operating income | 39,337 |  |  | 40,294 |  |  | 27,993 |  |  
| Equity in net income from affiliated companies | (37) |  |  | (12) |  |  | (42) |  |  
| 
Interest expense, net (1) 
 | 16,210 |  |  | 24,453 |  |  | 22,965 |  |  
| Other (income) expense, net | (3,481) |  |  | 274 |  |  | 474 |  |  
| Loss on sale of Performance Materials | 70,878 |  |  | — |  |  | — |  |  
| (Loss) Income from discontinued operations before income tax | (44,233) |  |  | 15,579 |  |  | 4,596 |  |  
| Provision (benefit) for income taxes | 58,008 |  |  | 1,022 |  |  | (4,646) |  |  
| (Loss) income from discontinued operations, net of tax | $ | (102,241) |  |  | $ | 14,557 |  |  | $ | 9,242 |  | The following table summarizes the assets and liabilities of discontinued operations at December 31, 2019: 
|  |  |  |  |  |  |  |  |  |  
|  |  | December 31, 2019
 |  
| ASSETS |  |  |  
| Cash and cash equivalents |  | $ | 18,423 |  |  
| Accounts receivables, net |  | 40,484 |  |  
| Inventories, net |  | 143,323 |  |  
| Prepaid and other current assets |  | 4,139 |  |  
| Investments in affiliated companies |  | 115 |  |  
| Property, plant and equipment, net |  | 175,614 |  |  
| Goodwill |  | 286,227 |  |  
| Other intangible assets, net |  | 121,113 |  |  
| Right-of-use lease assets |  | 8,878 |  |  
| Other long-term assets |  | 71,697 |  |  
| Total assets held for sale |  | $ | 870,013 |  |  
| LIABILITIES |  |  |  
| Notes payable and current maturities of long-term debt |  | $ | 7,766 |  |  
| Accounts payable |  | 30,267 |  |  
| Operating lease liabilities—current |  | 3,326 |  |  
| Accrued liabilities |  | 16,744 |  |  
| Long-term debt, excluding current portion |  | 55,972 |  |  
| Deferred income taxes |  | 8,612 |  |  
| Operating lease liabilities—noncurrent |  | 5,248 |  |  
| Other long-term liabilities |  | 17,366 |  |  
| Total liabilities held for sale |  | $ | 145,301 |  |  |