Discontinued Operations (Details) (USD $)	12 Months Ended							2 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2012 Coal cleaning business item	Sep. 30, 2011 Coal cleaning business	Sep. 30, 2010 Coal cleaning business	Mar. 31, 2011 Coal cleaning business	Nov. 16, 2012 Coal cleaning business Subsequent Event item
Discontinued operations
Revenue				$ 22,268,000	$ 48,476,000	$ 56,486,000
Loss from operations of discontinued operations before income taxes				(36,210,000)	(91,615,000)	(52,954,000)
Gain on disposal				267,000	0	0
Income tax benefit (provision)				124,000	(4,374,000)	24,552,000
Loss from discontinued operations, net of income taxes	(35,819,000)	(95,989,000)	(28,402,000)	(35,819,000)	(95,989,000)	(28,402,000)
Impairment of coal cleaning assets held for sale				13,000,000	35,000,000	34,500,000	37,000,000
Book value for the coal cleaning assets, net of liabilities				(4,900,000)
Property, plant and equipment, held for sale				1,900,000	16,100,000
Other assets, held for sale				5,900,000	8,300,000
Number of facilities sold				1				2
Cash proceeds from sale of asset				2,000,000
Potential future consideration				$ 8,400,000				$ 10,000,000
Number of facilities under contract for sale				8