CONDENSED CONSOLIDATED STATEMENTS OF PARTNERS' CAPITAL (unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Unitholders [Member]	Accumulated Other Comprehensive Loss [Member]
Balance, beginning of period at Sep. 30, 2017	$ 552,982	$ 581,794	$ (28,812)
Balance (in units) at Sep. 30, 2017		61,105
Net (loss) income	127,360	$ 127,360
Other comprehensive income	2,271		2,271
Partnership distributions	(110,342)	(110,342)
Common Units issued under Restricted Unit Plans	(846)	$ (846)
Common Units issued under Restricted Unit Plans (in units)		300
Compensation costs recognized under Restricted Unit Plans	6,862	$ 6,862
Balance, end of period at Jun. 30, 2018	578,287	$ 604,828	(26,541)
Balance (in units) at Jun. 30, 2018		61,405
Balance, beginning of period at Mar. 31, 2018	629,253	$ 656,551	(27,298)
Balance (in units) at Mar. 31, 2018		61,404
Net (loss) income	(16,595)	$ (16,595)
Other comprehensive income	757		757
Partnership distributions	(36,843)	(36,843)
Common Units issued under Restricted Unit Plans	0	$ 0
Common Units issued under Restricted Unit Plans (in units)		1
Compensation costs recognized under Restricted Unit Plans	1,715	$ 1,715
Balance, end of period at Jun. 30, 2018	578,287	$ 604,828	(26,541)
Balance (in units) at Jun. 30, 2018		61,405
Balance, beginning of period at Sep. 29, 2018	493,824	$ 518,494	(24,670)
Balance (in units) at Sep. 29, 2018		61,405
Net (loss) income	119,694	$ 119,694
Other comprehensive income	1,656		1,656
Partnership distributions	(110,841)	(110,841)
Common Units issued under Restricted Unit Plans	(1,349)	$ (1,349)
Common Units issued under Restricted Unit Plans (in units)		261
Common Units issued for acquisition of business	1,600	$ 1,600
Common Units issued for acquisition of business (in units)		69
Compensation costs recognized under Restricted Unit Plans	8,855	$ 8,855
Balance, end of period at Jun. 29, 2019	513,439	$ 536,453	(23,014)
Balance (in units) at Jun. 29, 2019		61,735
Balance, beginning of period at Mar. 30, 2019	575,048	$ 598,614	(23,566)
Balance (in units) at Mar. 30, 2019		61,664
Net (loss) income	(29,041)	$ (29,041)
Other comprehensive income	552		552
Partnership distributions	(37,000)	(37,000)
Common Units issued under Restricted Unit Plans	0	$ 0
Common Units issued under Restricted Unit Plans (in units)		2
Common Units issued for acquisition of business	1,600	$ 1,600
Common Units issued for acquisition of business (in units)		69
Compensation costs recognized under Restricted Unit Plans	2,280	$ 2,280
Balance, end of period at Jun. 29, 2019	$ 513,439	$ 536,453	$ (23,014)
Balance (in units) at Jun. 29, 2019		61,735