Common Unit Repurchase Plans and Retirement - Additional Information (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended			12 Months Ended
	Sep. 30, 2013		Jun. 30, 2013	Sep. 30, 2010 Plan I Common Units Repurchase Program	Sep. 30, 2012 Plan II Common Units Repurchase Program	Jul. 31, 2012 Initial Common Units Authorized Plan III Common Units Repurchase Program	Jul. 31, 2013 Additional Common Units Authorized Plan III Common Units Repurchase Program
Capital Unit [Line Items]
Average Price Paid per Unit				$ 4.04	$ 4.94
Partnership's common units authorized for repurchase				7,500	7,250	3,000	1,900
Partnership's common units authorized for repurchase in a private transaction	1,150	[1]	1,150
Availability required to repurchase common units	$ 61.3
Percentage of the maximum facility size on a historical proforma and forward-looking basis	17.50%
Maximum borrowing capacity under revolving credit facility	350
Seasonal advance amount included in maximum borrowing capacity under revolving credit facility	$ 100
Minimum fixed charge coverage ratio to repurchase common units	1.15

[1] Third quarter fiscal 2013 common unit repurchases include 1.15 million common units acquired in a private transaction.