Long-Term Debt and Bank Facility Borrowings - Additional Information (Detail) (USD $) In Millions, unless otherwise specified				3 Months Ended	1 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jul. 31, 2011	Dec. 31, 2012 First Amendment	Apr. 30, 2012 Second Amendment
Debt [Line Items]
Description of variable rate				The interest rate is LIBOR plus (i) 1.75% (if Availability, as defined in the revolving credit facility 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 0.375% 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
Maximum availability, condition two				150
Minimum availability, condition two				75
Maximum availability, condition three				75
Commitment fee on the unused portion of the facility				0.375%
Availability to maintain				43.8
Availability percentage to maximum facility size				12.50%
Minimum fixed charge coverage ratio				1.1
Availability required to make acquisition				40
Availability required to pay distributions for the period April 1, 2012 to December 31, 2012				61.3	50.0
Percentage of the maximum facility size on a historical proforma and forward-looking basis				17.50%
Minimum fixed charge coverage ratio for distributions to unit holders				1.15
Maximum payment of distributions per common unit for the period April 1, 2012 to December 31, 2012					0.2325
Amount outstanding under the revolving credit facility	36.7
Letters of credit issued	45.6	42.8
Availability in compliance with the fixed charge coverage ratio	154.2	179.2
Available sale of offering of common units under shelf registration			$ 250