Inventories - Additional Information (Detail)	12 Months Ended
	Sep. 30, 2013 gal	Sep. 30, 2012 gal
Inventory [Line Items]
Heating oil and other fuel inventories	17,100,000	10,000,000
Market price based product supply contracts for next twelve months	221,000,000
Maximum product supply by other supplier	10.00%	10.00%
Global Companies LLC
Inventory [Line Items]
Product purchases	19.00%
JPMorgan Ventures Energy Corporation
Inventory [Line Items]
Product purchases	11.00%
NIC Holding Corp
Inventory [Line Items]
Product purchases	9.00%
Phillips 66
Inventory [Line Items]
Product purchases	9.00%
Global Companies LLC
Inventory [Line Items]
Product purchases		24.00%
J P Morgan Ventures Energy Corp
Inventory [Line Items]
Product purchases		9.00%
Nic Holding Corp
Inventory [Line Items]
Product purchases		9.00%