Long-Term Debt and Bank Facility Borrowings - Additional Information (Detail) (USD $)					0 Months Ended	12 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Revolving Credit Facility	Sep. 30, 2013 Revolving Credit Facility	Jan. 14, 2014 Second Amendment	Sep. 30, 2014 Second Amendment	Jan. 14, 2014 Second Amendment	Sep. 30, 2014 8.875% Senior Notes	Sep. 30, 2014 8.875% Senior Notes Second Amendment
Debt Instrument [Line Items]
Non Seasonal maximum borrowing capacity under revolving credit facility						$ 300,000,000	$ 300,000,000
Maximum borrowing capacity (heating season December to April) under revolving credit facility						450,000,000
Issuance of line of credit for working capital purposes						100,000,000
Alternate revolving credit facility expiry						Jan. 14, 2019
Revolving credit facility expiry						Jun. 01, 2017
Additional revolving credit						100,000,000
Facility size that can be increased without consulting bank group						100,000,000
Line of credit facility description						All outstanding amounts owed under the second amended and restated credit facility become due and payable on the facility termination date of June 1, 2017. If the Partnership has repaid, prepaid or otherwise defeased at least $100 million of our 8.875% Senior Notes and Availability is equal to or greater than the aggregate amount required to repay the remaining outstanding 8.875% Senior Notes ("Payoff Amount"), then the facility termination date is January 14, 2019.
Amount required to repaid, prepaid or defeased									100,000,000
Description of variable rate						The interest rate on the second amended and restated credit facility is LIBOR plus (i) 1.75% (if Availability, as defined in the agreement is greater than or equal to $150 million), or (ii) 2.00% (if Availability is greater than $75 million but less than $150 million), or (iii) 2.25% (if Availability is less than or equal to $75 million). The Commitment Fee on the unused portion of the facility is 0.30% per annum.
Condition one, additional interest rate based on LIBOR						1.75%
Condition two, additional interest rate based on LIBOR						2.00%
Condition three, additional interest rate based on LIBOR						2.25%
Minimum availability, condition one						150,000,000
Maximum availability, condition two						150,000,000
Minimum availability, condition two						75,000,000
Maximum availability, condition three						75,000,000
Commitment fee on the unused portion of the facility						0.30%
Availability percentage to maximum facility size						12.50%
Minimum fixed charge coverage ratio						110.00%
Availability required to make acquisition						40,000,000
Availability required to pay distributions					45,000,000	45,000,000
Percentage of the maximum facility size on a historical proforma and forward-looking basis					15.00%	15.00%
Minimum fixed charge coverage ratio for distributions to unit holders or to repurchase common units					115.00%	115.00%
Interest accrued by public notes for each year								8.875%	8.875%
Hedging positions and payable amounts secured under credit facility	14,900,000	10,500,000
Letters of credit issued	52,800,000	44,700,000
Revolving credit facility outstanding			0	0
Availability in compliance with the fixed charge coverage ratio	149,600,000	164,300,000
Total restricted net assets	$ 389,000,000	$ 375,000,000