XML 64 R53.htm IDEA: XBRL DOCUMENT v3.10.0.1
East Tennessee Materials and Energy Corporation (M&EC) - Schedule of Change in Asset Retirement Obligation (Details)
$ in Thousands
6 Months Ended
Jun. 30, 2018
USD ($)
Asset Retirement Obligation Disclosure [Abstract]  
Balance as of December 31, 2017 $ 2,791
Accretion expense 19
Adjustment to closure liabilities 1,215
Payments (3,101)
Balance as of June 30, 2018 $ 924