Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Sep. 30, 2024		Jun. 30, 2024		Mar. 31, 2024		Dec. 31, 2023		Sep. 30, 2023		Jun. 30, 2023		Mar. 31, 2023		Dec. 31, 2022		Sep. 30, 2024		Sep. 30, 2023		Sep. 30, 2022
Quarterly Financial Information Disclosure [Abstract]
Sales	$ 240,331		$ 331,640		$ 666,032		$ 528,096		$ 266,937		$ 300,121		$ 737,617		$ 648,187		$ 1,766,099		$ 1,952,862		$ 2,006,558
Gross profit for product, installations and services	57,880		88,247		206,046		149,651		50,733		64,428		203,039		152,551		501,824		470,751
Operating income (loss)	(48,559)		(12,291)		100,331		21,621		(22,989)		(29,586)		91,515		23,605		61,102		62,545		60,453
Income (loss) before income taxes	(50,642)		(15,201)		96,244		18,153		(26,171)		(33,196)		86,294		19,002		48,554		45,929		49,026
Net income (loss)	(35,086)		(11,044)		68,374		12,979		(19,729)		(23,906)		62,041		13,539		35,223		31,945		35,288
Limited Partners’ interest in net income	$ (34,760)		$ (10,943)		$ 67,754		$ 12,861		$ (19,549)		$ (23,690)		$ 61,479		$ 13,417		$ 34,912		$ 31,657		$ 35,007
Net income (loss) per Limited Partner unit:
Basic and diluted income per Limited Partner Unit:	$ (1.00)	[1]	$ (0.31)	[1]	$ 1.56	[1]	$ 0.32	[1]	$ (0.55)	[1]	$ (0.67)	[1]	$ 1.42	[1]	$ 0.33	[1]	$ 0.90	[1],[2]	$ 0.81	[1],[2]	$ 0.85	[2]

[1] The sum of the quarters do not add-up to the total due to the weighting of Limited Partner Units outstanding, rounding or the theoretical effects of FASB ASC 260-10-45-60 to Master Limited Partners earnings per unit.

[2] See Note 19 - Earnings Per Limited Partner Units.