CONDENSED CONSOLIDATED STATEMENT OF PARTNERS' CAPITAL (unaudited) - 6 months ended Mar. 31, 2018 - USD ($) shares in Thousands, $ in Thousands	Total	Common Unitholders [Member]	Accumulated Other Comprehensive (Loss) [Member]
Balance at Sep. 30, 2017	$ 552,982	$ 581,794	$ (28,812)
Balance (in units) at Sep. 30, 2017		61,105
Net income	143,955	$ 143,955
Other comprehensive income	1,514		1,514
Partnership distributions	(73,499)	$ (73,499)
Common Units issued under Restricted Unit Plans (in units)		299
Compensation cost recognized under Restricted Unit Plans, net of forfeitures	4,301	$ 4,301
Balance at Mar. 31, 2018	$ 629,253	$ 656,551	$ (27,298)
Balance (in units) at Mar. 31, 2018		61,404