XML 56 R45.htm IDEA: XBRL DOCUMENT v3.20.2
Business Segments (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Segment Reporting Information [Line Items]        
Revenues $ 32,295 $ 32,603 $ 105,294 $ 114,052
Operating profit (loss) 9,398 8,663 21,460 34,197
Expenditures for property, plant and equipment 7,003 7,297 19,802 13,264
Depreciation, depletion and amortization 4,876 4,044 14,044 12,095
Operating segments | Coal Mining        
Segment Reporting Information [Line Items]        
Revenues 20,395 18,799 62,896 58,119
Operating profit (loss) 11,174 10,492 25,857 27,761
Expenditures for property, plant and equipment 3,150 2,291 7,817 6,542
Depreciation, depletion and amortization 3,793 3,102 10,951 9,252
Operating segments | NAMining        
Segment Reporting Information [Line Items]        
Revenues 9,443 8,993 33,115 30,496
Operating profit (loss) 244 (358) 1,519 (743)
Expenditures for property, plant and equipment 3,220 4,971 10,406 6,213
Depreciation, depletion and amortization 723 588 2,021 1,699
Operating segments | Minerals Management        
Segment Reporting Information [Line Items]        
Revenues 2,722 5,022 9,950 25,950
Operating profit (loss) 1,673 3,900 6,450 22,358
Expenditures for property, plant and equipment 633 0 1,372 291
Depreciation, depletion and amortization 327 324 981 1,057
Unallocated Items        
Segment Reporting Information [Line Items]        
Revenues 904 52 1,257 726
Operating profit (loss) (3,623) (5,470) (12,341) (15,336)
Expenditures for property, plant and equipment 0 35 207 218
Depreciation, depletion and amortization 33 30 91 87
Eliminations        
Segment Reporting Information [Line Items]        
Revenues (1,169) (263) (1,924) (1,239)
Operating profit (loss) $ (70) $ 99 $ (25) $ 157