Partnership's Repurchase Activities (Detail) - $ / shares shares in Thousands		3 Months Ended	12 Months Ended	36 Months Ended
		Dec. 31, 2014	Sep. 30, 2015	Sep. 30, 2014		Jun. 30, 2015	Mar. 31, 2015
Capital Unit [Line Items]
Partnership's common units authorized for repurchase			6,044
Private Transaction
Capital Unit [Line Items]
Partnership's common units authorized for repurchase			1,150	1,400
Plan III Common Units Repurchase Program
Capital Unit [Line Items]
Partnership's common units authorized for repurchase			4,894
Total Number of Units Purchased	[1]	123	123	3,619	[2]
Average Price Paid per Unit	[3]	$ 5.64	$ 5.64	$ 4.69	[2]
Maximum Number of Units that May Yet Be Purchased		2,302	2,302	2,425	[2]	2,302	2,302

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

[2] Includes 1.4 million common units acquired in a private transaction.

[3] Amounts include repurchase costs.