Inventories - Additional Information (Detail)	12 Months Ended
	Sep. 30, 2014 gal	Sep. 30, 2013 gal
Inventory [Line Items]
Heating oil and other fuel inventories	14,300,000	17,100,000
Maximum product supply by other supplier	10.00%	10.00%
Home heating oil and Propane
Inventory [Line Items]
Market price based product supply contracts for next twelve months	285,700,000
Diesel and gasoline
Inventory [Line Items]
Market price based product supply contracts for next twelve months	24,800,000
Global Companies LLC
Inventory [Line Items]
Product purchases	17.00%	19.00%
J P Morgan Ventures Energy Corp
Inventory [Line Items]
Product purchases		11.00%
Nic Holding Corp
Inventory [Line Items]
Product purchases	11.00%