(1) Summary of Significant Accounting Policies (Detail)	12 Months Ended		48 Months Ended	60 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2015 T	Dec. 31, 2015
EquityInterestinSavoyEnergyLP	45.00%
Interest in Sunrise Energ LLC	50.00%
Estimated Minimum Useful Equip Life	five
Estimated Maximum Useful Equip Life	twenty
Asset Retirement Discount Rate	6.00%
Number of Customers With Supply Commitments			three
Tons of Coal Commitment for Three Years (in US Ton)			4,900,000
Sales Accounted For By Three Customers				90.00%
Percent Sales To One Customer	46.00%	43.00%
Percent Sales To Second Customer	31.00%	29.00%
Percent Sales To Third Customer	16.00%	17.00%