Partnership's Repurchase Activities (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	1 Months Ended				3 Months Ended		36 Months Ended
	Dec. 31, 2014		Oct. 31, 2014		Dec. 31, 2014		Sep. 30, 2014		Nov. 30, 2014
Capital Unit [Line Items]
Partnership's common units authorized for repurchase	6,044				6,044
Private Transaction
Capital Unit [Line Items]
Partnership's common units authorized for repurchase	1,150				1,150		1,450
Plan III Common Units Repurchase Program
Capital Unit [Line Items]
Partnership's common units authorized for repurchase	4,894				4,894
Total Number of Units Purchased	1	[1]	122	[1]	123	[1]	3,619	[1],[2]
Average Price Paid per Unit	$ 5.72	[3]	$ 5.64	[3]	$ 5.64	[3]	$ 4.69	[2],[3]
Maximum Number of Units that May Yet Be Purchased	2,302		2,303		2,302		2,425	[2]	2,303

[1] Units were repurchased as part of a publicly announced program, except as noted in a private transaction.

[2] Includes 1.45 million common units acquired in a private transaction.

[3] Amounts include repurchase costs.