XML 25 R11.htm IDEA: XBRL DOCUMENT

Self-Insurance	9 Months Ended
Self-Insurance	Sep. 30, 2017
Self-Insurance [Abstract]
Self-Insurance	(5)Self-Insurance We self-insure our underground mining equipment. Such equipment is allocated among ten mining units spread out over 18 miles. The historical cost of such equipment is approximately $256 million. Restricted cash of $3.4 million represents cash held and controlled by a third party and is restricted for future workers’ compensation claim payments.