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, 2017		$ 306,068		$ (929)	$ 325,762	$ (18,765)
Beginning Balance, unit at Sep. 30, 2017				326	55,888
Net income (loss)		76,955		$ 445	$ 76,510
Unrealized gain on pension plan obligation		1,344	[1]			1,344
Tax effect of unrealized gain on pension plan obligation		(422)				(422)
Unrealized gain (loss) on captive insurance collateral		(1,151)				(1,151)
Tax effect of unrealized gain (loss) on captive insurance collateral		242				242
Distributions		(19,139)		(499)	(18,640)
Retirement of units	[2]	(22,538)			$ (22,538)
Retirement of units, shares	[2]				(2,370)
Ending Balance at Jun. 30, 2018		341,359		$ (983)	$ 361,094	(18,752)
Ending Balance, Unit at Jun. 30, 2018				326	53,518
Beginning Balance at Mar. 31, 2018		366,260		$ (743)	$ 385,909	(18,906)
Beginning Balance, unit at Mar. 31, 2018				326	54,607
Net income (loss)		(8,005)		$ (49)	$ (7,956)
Unrealized gain on pension plan obligation		448	[1]			448
Tax effect of unrealized gain on pension plan obligation		(120)				(120)
Unrealized gain (loss) on captive insurance collateral		(220)				(220)
Tax effect of unrealized gain (loss) on captive insurance collateral		46				46
Distributions		(6,535)		(191)	(6,344)
Retirement of units	[2]	(10,515)			$ (10,515)
Retirement of units, shares	[2]				(1,089)
Ending Balance at Jun. 30, 2018		341,359		$ (983)	$ 361,094	(18,752)
Ending Balance, Unit at Jun. 30, 2018				326	53,518
Beginning Balance at Sep. 30, 2018		309,785		$ (1,303)	$ 329,129	(18,041)
Beginning Balance, unit at Sep. 30, 2018				326	53,088
Impact from adoption of ASU No. 2014-09		9,224		$ 60	$ 9,164
Net income (loss)		51,542		319	51,223
Unrealized gain on pension plan obligation		1,366	[1]			1,366
Tax effect of unrealized gain on pension plan obligation		(373)				(373)
Unrealized gain (loss) on captive insurance collateral		1,960				1,960
Tax effect of unrealized gain (loss) on captive insurance collateral		(416)				(416)
Unrealized loss on interest rate hedges		(1,845)				(1,845)
Tax effect of unrealized loss on interest rate hedges		488				488
Distributions		(19,208)		(598)	(18,610)
Retirement of units	[2]	(34,948)			$ (34,948)
Retirement of units, shares	[2]				(3,671)
Ending Balance at Jun. 30, 2019		317,575		$ (1,522)	$ 335,958	(16,861)
Ending Balance, Unit at Jun. 30, 2019				326	49,417
Beginning Balance at Mar. 31, 2019		355,421		$ (1,146)	$ 373,748	(17,181)
Beginning Balance, unit at Mar. 31, 2019				326	50,302
Net income (loss)		(23,098)		$ (150)	$ (22,948)
Unrealized gain on pension plan obligation		455	[1]			455
Tax effect of unrealized gain on pension plan obligation		(124)				(124)
Unrealized gain (loss) on captive insurance collateral		666				666
Tax effect of unrealized gain (loss) on captive insurance collateral		(140)				(140)
Unrealized loss on interest rate hedges		(733)				(733)
Tax effect of unrealized loss on interest rate hedges		196				196
Distributions		(6,491)		(226)	(6,265)
Retirement of units	[2]	(8,577)			$ (8,577)
Retirement of units, shares	[2]				(885)
Ending Balance at Jun. 30, 2019		$ 317,575		$ (1,522)	$ 335,958	$ (16,861)
Ending Balance, Unit at Jun. 30, 2019				326	49,417

[1] This item is included in the computation of net periodic pension cost.

[2] See Note 4 – Common Unit Repurchase and Retirement.