Inventories (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Inventory Disclosure [Abstract]
Coal - NACoal	$ 25,749	$ 24,710	$ 21,048
Mining supplies - NACoal	18,641	17,406	17,131
Total inventories at weighted average cost	44,390	42,116	38,179
Sourced inventories - HBB	130,012	90,713	112,250
Retail inventories - KC	46,205	51,616	56,920
Total inventories at FIFO	176,217	142,329	169,170
Inventories, net	$ 220,607	$ 184,445	$ 207,349