Consolidated Statements Of Partners' Capital (USD $) In Thousands		Total	Common Stock	General Partner	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Sep. 30, 2010		$ 279,911	$ 307,092	$ 290	$ (27,471)
Beginning Balance, unit at Sep. 30, 2010			67,078	326
Net income		24,344	24,229	115
Unrealized gain on pension plan obligation	[1]	171			171
Tax effect of unrealized gain on pension plan obligation		(167)			(167)
Distributions	[2]	(20,677)	(20,459)	(218)
Retirement of units, in units	[3]		(2,108)
Retirement of units	[3]	(10,949)	(10,949)
Ending Balance at Sep. 30, 2011		272,633	299,913	187	(27,467)
Ending Balance, Unit at Sep. 30, 2011			64,970	326
Net income		25,989	25,853	136
Unrealized gain on pension plan obligation	[1]	1,176			1,176
Tax effect of unrealized gain on pension plan obligation		(480)			(480)
Distributions	[2]	(19,525)	(19,299)	(226)
Retirement of units, in units	[3]		(3,968)
Retirement of units	[3]	(19,648)	(19,648)
Ending Balance at Sep. 30, 2012		260,145	286,819	97	(26,771)
Ending Balance, Unit at Sep. 30, 2012			61,002	326
Net income		29,906	29,747	159
Unrealized gain on pension plan obligation	[1]	6,337			6,337
Tax effect of unrealized gain on pension plan obligation		(2,577)			(2,577)
Distributions	[2]	(19,313)	(19,060)	(253)
Retirement of units, in units	[3]		(3,284)
Retirement of units	[3]	(15,217)	(15,217)
Ending Balance at Sep. 30, 2013		$ 259,281	$ 282,289	$ 3	$ (23,011)
Ending Balance, Unit at Sep. 30, 2013			57,718	326

[1] These items are included in the computation of net periodic pension cost. See Note 12-Employee Benefit Plan.

[2] See Note 3-Quarterly Distributions of Available Cash.

[3] See Note 4-Common Unit Repurchase and Retirement.