Discontinued Operations (Details) (USD $)	1 Months Ended	3 Months Ended			6 Months Ended
	Jan. 31, 2013 item	Mar. 31, 2013 item T	Dec. 31, 2012 item	Mar. 31, 2012	Mar. 31, 2013 T	Mar. 31, 2012	Sep. 30, 2012
Discontinued operations
Remaining assets held for sale		$ 0			$ 0		$ 5,864,000
Income (loss) from discontinued operations, net of income taxes		2,023,000		(2,330,000)	25,000	(12,798,000)
Coal cleaning business
Discontinued operations
Remaining assets held for sale		0			0
Revenue		137,000		4,507,000	4,386,000	9,798,000
Loss from operations of discontinued operations before income taxes		(1,087,000)		(2,330,000)	(3,085,000)	(12,798,000)
Gain on disposal		3,110,000	0	0	3,110,000	0
Income tax provision		0		0	0	0
Income (loss) from discontinued operations, net of income taxes		2,023,000		(2,330,000)	25,000	(12,798,000)
Property, plant and equipment, held for sale							1,900,000
Other assets, held for sale							5,900,000
Number of facilities sold	8	8	2
Number of purchasers involved in the sale of discontinued operations		1
Period over which a majority of the consideration from the sale of discontinued operations is to be received		8 years
Maximum potential future consideration		53,400,000			53,400,000
Feedstock agreed to be identified by the entity under the obligation (in tons)		1,000,000			1,000,000
Number of facilities sold with which the entity has an agreement to identify feedstock		1
Extension period for identification of feedstock supply if a specified quantity is identified in a specified period		6 months
Minimum quantity of feedstock supply to be identified by the entity in a specified period to qualify for extension period (in tons)		500,000			500,000
Liability for unidentified feedstock supply guaranteed under obligation (in dollars per ton)		7			7
Accrued liability for unidentified feedstock supply guaranteed under obligation		$ 5,700,000			$ 5,700,000