Consolidated Statements of Partners' Capital and Comprehensive Income (Loss) (USD $) In Thousands		Total	Common	General Partner	Accumulated Other Comprehensive Income (Loss)
Balance at Sep. 30, 2009		$ 306,334	$ 332,340	$ 309	$ (26,315)
Balance, Units at Sep. 30, 2009			75,137	326
Net income		28,320	28,192	128
Unrealized gain (loss) on pension plan obligation		(1,977)			(1,977)
Tax effect of unrealized gain (loss) on pension plan obligation		821			821
Total comprehensive income		27,164	28,192	128	(1,156)
Distributions (1)	[1]	(20,353)	(20,206)	(147)
Retirement of units (2)	[2]	(33,234)	(33,234)
Retirement of units (2), Units	[2]		(8,059)
Balance at Sep. 30, 2010		279,911	307,092	290	(27,471)
Balance, Units at Sep. 30, 2010			67,078	326
Net income		24,344	24,229	115
Unrealized gain (loss) on pension plan obligation		171			171
Tax effect of unrealized gain (loss) on pension plan obligation		(167)			(167)
Total comprehensive income		24,348	24,229	115	4
Distributions (1)	[1]	(20,677)	(20,459)	(218)
Retirement of units (2)	[2]	(10,949)	(10,949)
Retirement of units (2), Units	[2]		(2,108)
Balance at Sep. 30, 2011		272,633	299,913	187	(27,467)
Balance, Units at Sep. 30, 2011			64,970	326
Net income		25,989	25,853	136
Unrealized gain (loss) on pension plan obligation		1,176			1,176
Tax effect of unrealized gain (loss) on pension plan obligation		(480)			(480)
Total comprehensive income		26,685	25,853	136	696
Distributions (1)		(19,525)	(19,299)	(226)
Retirement of units (2)	[2]	(19,648)	(19,648)
Retirement of units (2), Units	[2]		(3,968)
Balance at Sep. 30, 2012		$ 260,145	$ 286,819	$ 97	$ (26,771)
Balance, Units at Sep. 30, 2012			61,002	326

[1] See Note 4 - Quarterly Distributions of Available Cash

[2] See Note 2 - Common Unit Repurchase and Retirement