Major Customers (Tables)

3 Months Ended

Mar. 31, 2013

Major Customers [Abstract]

Major Customers

	March 31,	Three months	Three months
	2013	ended	ended
	Receivable	March 31,	March 31,
	Balance	2013 Sales	2012 Sales
	(in thousands)
NRG Energy, Inc. (fka GenOn Energy, Inc.)	$                   4,011	$                 12,431	$                 10,523
Indiana Harbor Coke Company, L.P	4,891	7,981	9,328
PPL Corporation	n/a	n/a	10,527
American Electric Power Company, Inc.	3,427	9,598	n/a