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Other Long-Term Liabilities
 9 Months Ended
Sep. 30, 2020
Other Liabilities Disclosure [Abstract]  
Other Long-Term Liabilities Other Long-Term Liabilities
Other long-term liabilities are summarized as follows (in thousands):
 September 30, 2020December 31, 2019
Black lung obligations$30,013 $30,233 
Other2,263 1,197 
Total other long-term liabilities$32,276 $31,430