Discontinued Operations (Details) (USD $)	1 Months Ended	3 Months Ended
	Jan. 31, 2013 item T	Dec. 31, 2012 item	Dec. 31, 2011	Sep. 30, 2012
Discontinued operations
Loss from discontinued operations, net of income taxes		$ (1,998,000)	$ (10,468,000)
Coal cleaning business
Discontinued operations
Revenue		4,249,000	5,291,000
Loss from operations of discontinued operations before income taxes		(1,998,000)	(10,468,000)
Income tax provision		0	0
Loss from discontinued operations, net of income taxes		(1,998,000)	(10,468,000)
Property, plant and equipment, held for sale		2,000,000		1,900,000
Other assets, held for sale		5,900,000		5,900,000
Number of facilities sold	8	2
Potential future consideration	48,000,000	10,000,000
Cash proceeds from sale of asset	$ 3,800,000
Feedstock agreed to be identified by the entity under the obligation (in tons)	1,000,000
Period during which the entity agreed to identify a specified quantity of feedstock	30 months
Liability for unidentified feedstock supply guaranteed under obligation (in dollars per ton)	7