Common Unit Repurchase and Retirement - Additional Information (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified		1 Months Ended	6 Months Ended
	Mar. 31, 2014	Jan. 14, 2014 Second Amendment	Mar. 31, 2014 Second Amendment	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]
Partnership's common units authorized for repurchase	6,044			3,000	1,900
Availability required to repurchase common units		$ 45	$ 45
Percentage of the maximum facility size on a historical proforma and forward-looking basis		15.00%	15.00%
Non Seasonal maximum borrowing capacity under revolving credit facility		$ 300	$ 300
Minimum fixed charge coverage ratio for distributions to unit holders or to repurchase common units		1.15	1.15