CONDENSED CONSOLIDATED STATEMENT OF PARTNERS' CAPITAL - USD ($) shares in Thousands, $ in Thousands	Total	General Partner	Common Stock	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Sep. 30, 2023	$ 263,724	$ (4,615)	$ 281,862	$ (13,523)
Beginning Balance, unit at Sep. 30, 2023		326	35,603
Net Income (Loss)	70,309	$ 637	$ 69,672
Unrealized gain on pension plan obligation	955			955
Tax effect of unrealized gain on pension plan obligation	(240)			(240)
Unrealized gain on captive insurance collateral	1,596			1,596
Tax effect of unrealized gain on captive insurance collateral	(336)			(336)
Unrealized loss on interest rate hedges	(1,007)			(1,007)
Tax effect of unrealized loss on interest rate hedges	270			270
Distributions	(18,689)	(1,041)	(17,648)
Retirement of units	(9,029)		$ (9,029)
Retirement of units, shares			(829)
Ending Balance at Jun. 30, 2024	307,553	$ (5,019)	$ 324,857	(12,285)
Ending Balance, Unit at Jun. 30, 2024		326	34,774
Beginning Balance at Mar. 31, 2024	331,135	$ (4,544)	$ 348,382	(12,703)
Beginning Balance, unit at Mar. 31, 2024		326	35,372
Net Income (Loss)	(11,044)	$ (101)	$ (10,943)
Unrealized gain on pension plan obligation	317			317
Tax effect of unrealized gain on pension plan obligation	(80)			(80)
Unrealized gain on captive insurance collateral	401			401
Tax effect of unrealized gain on captive insurance collateral	(84)			(84)
Unrealized loss on interest rate hedges	(186)			(186)
Tax effect of unrealized loss on interest rate hedges	50			50
Distributions	(6,455)	(374)	(6,081)
Retirement of units	(6,501)		$ (6,501)
Retirement of units, shares			(598)
Ending Balance at Jun. 30, 2024	307,553	$ (5,019)	$ 324,857	(12,285)
Ending Balance, Unit at Jun. 30, 2024		326	34,774
Beginning Balance at Sep. 30, 2024	263,893	$ (5,714)	$ 282,058	(12,451)
Beginning Balance, unit at Sep. 30, 2024		326	34,587
Net Income (Loss)	102,166	$ 952	$ 101,214
Unrealized gain on pension plan obligation	1,298			1,298
Tax effect of unrealized gain on pension plan obligation	(344)			(344)
Unrealized gain on captive insurance collateral	373			373
Tax effect of unrealized gain on captive insurance collateral	(78)			(78)
Unrealized loss on interest rate hedges	(319)			(319)
Tax effect of unrealized loss on interest rate hedges	83			83
Distributions	(19,481)	(1,157)	(18,324)
Retirement of units	(10,023)		$ (10,023)
Retirement of units, shares			(836)
Ending Balance at Jun. 30, 2025	337,568	$ (5,919)	$ 354,925	(11,438)
Ending Balance, Unit at Jun. 30, 2025		326	33,751
Beginning Balance at Mar. 31, 2025	370,581	$ (5,340)	$ 387,603	(11,682)
Beginning Balance, unit at Mar. 31, 2025		326	34,568
Net Income (Loss)	(16,629)	$ (157)	$ (16,472)
Unrealized gain on pension plan obligation	434			434
Tax effect of unrealized gain on pension plan obligation	(116)			(116)
Unrealized gain on captive insurance collateral	202			202
Tax effect of unrealized gain on captive insurance collateral	(42)			(42)
Unrealized loss on interest rate hedges	(316)			(316)
Tax effect of unrealized loss on interest rate hedges	82			82
Distributions	(6,817)	(422)	(6,395)
Retirement of units	(9,811)		$ (9,811)
Retirement of units, shares			(817)
Ending Balance at Jun. 30, 2025	$ 337,568	$ (5,919)	$ 354,925	$ (11,438)
Ending Balance, Unit at Jun. 30, 2025		326	33,751