Summary of Significant Accounting Policies (Details 4) (USD $) In Thousands, unless otherwise specified			12 Months Ended	6 Months Ended		12 Months Ended		6 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Consolidated total revenues Customer concentration risk Crude oil and natural gas liquids Largest customer	Mar. 31, 2011 Consolidated total revenues Customer concentration risk Wholesale supply and marketing item	Sep. 30, 2010 Consolidated total revenues Customer concentration risk Natural gas liquids logistics NGL Supply item	Mar. 31, 2012 Consolidated accounts receivable Customer concentration risk Wholesale supply and marketing item	Mar. 31, 2013 Consolidated accounts receivable Customer concentration risk Crude oil logistics item	Sep. 30, 2010 Cost of sales Supplier concentration risk NGL Supply item	Mar. 31, 2010 Cost of sales Supplier concentration risk NGL Supply item
Concentration of Credit Risk
Number of customers or suppliers				1	2	1	1	3	3
Percentage of concentration risk			10.00%	10.00%	28.00%	21.00%	10.00%
Inventories
Crude oil	$ 46,156
Propane	45,428	78,993
Other natural gas liquids	24,090	9,259
Other	11,221	6,252
Total	$ 126,895	$ 94,504