Intangible Assets (Details 2) (USD $)	6 Months Ended	12 Months Ended		6 Months Ended		12 Months Ended		6 Months Ended		12 Months Ended		6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended		6 Months Ended
	Mar. 31, 2011	Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2010 NGL Supply	Mar. 31, 2011 Depreciation and amortization	Mar. 31, 2013 Depreciation and amortization	Mar. 31, 2012 Depreciation and amortization	Sep. 30, 2010 Depreciation and amortization NGL Supply	Mar. 31, 2011 Interest expense	Mar. 31, 2013 Interest expense	Mar. 31, 2012 Interest expense	Sep. 30, 2010 Interest expense NGL Supply	Mar. 31, 2013 Loss on early extinguishment of debt	Mar. 31, 2011 Cost of sales - natural gas liquids logistics	Mar. 31, 2013 Cost of sales - natural gas liquids logistics	Mar. 31, 2012 Cost of sales - natural gas liquids logistics	Sep. 30, 2010 Cost of sales - natural gas liquids logistics NGL Supply
Amortization related to intangible assets
Amortization expense	$ 1,558,000	$ 44,086,000	$ 6,615,000	$ 827,000	$ 593,000	$ 29,657,000	$ 4,538,000	$ 391,000	$ 565,000	$ 3,375,000	$ 1,277,000	$ 36,000	$ 5,769,000	$ 400,000	$ 5,285,000	$ 800,000	$ 400,000
Future amortization expense of intangible assets
2014		44,485,000
2015		43,137,000
2016		41,396,000
2017		39,567,000
2018		34,234,000
Thereafter		210,204,000
Total		$ 413,023,000