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. 26, 2020	$ 362,381	$ 388,157	$ (25,776)
Balance (in units) at Sep. 26, 2020		62,146
Net income	165,193	$ 165,193
Other comprehensive income	1,186		1,186
Partnership distributions	(37,401)	(37,401)
Common Units issued under Restricted Unit Plans	(1,534)	$ (1,534)
Common Units issued under Restricted Unit Plans (in units)		383
Recognition in earnings of net actuarial loss for pension settlement	570		570
Compensation costs recognized under Restricted Unit Plans	4,953	$ 4,953
Balance, end of period at Mar. 27, 2021	495,348	$ 519,368	(24,020)
Balance (in units) at Mar. 27, 2021		62,529
Balance, beginning of period at Dec. 26, 2020	383,162	$ 408,345	(25,183)
Balance (in units) at Dec. 26, 2020		62,522
Net income	127,216	$ 127,216
Other comprehensive income	593		593
Partnership distributions	(18,757)	(18,757)
Common Units issued under Restricted Unit Plans	(31)	$ (31)
Common Units issued under Restricted Unit Plans (in units)		7
Recognition in earnings of net actuarial loss for pension settlement	570		570
Compensation costs recognized under Restricted Unit Plans	2,595	$ 2,595
Balance, end of period at Mar. 27, 2021	495,348	$ 519,368	(24,020)
Balance (in units) at Mar. 27, 2021		62,529
Balance, beginning of period at Sep. 25, 2021	425,421	$ 443,005	(17,584)
Balance (in units) at Sep. 25, 2021		62,538
Net income	196,400	$ 196,400
Other comprehensive income	588		588
Partnership distributions	(40,789)	(40,789)
Common Units issued under Restricted Unit Plans	(2,080)	$ (2,080)
Common Units issued under Restricted Unit Plans (in units)		430
Recognition in earnings of net actuarial loss for pension settlement	0
Compensation costs recognized under Restricted Unit Plans	5,609	$ 5,609
Balance, end of period at Mar. 26, 2022	585,149	$ 602,145	(16,996)
Balance (in units) at Mar. 26, 2022		62,968
Balance, beginning of period at Dec. 25, 2021	427,348	$ 444,638	(17,290)
Balance (in units) at Dec. 25, 2021		62,964
Net income	175,102	$ 175,102
Other comprehensive income	294		294
Partnership distributions	(20,464)	(20,464)
Common Units issued under Restricted Unit Plans	(31)	$ (31)
Common Units issued under Restricted Unit Plans (in units)		4
Recognition in earnings of net actuarial loss for pension settlement	0
Compensation costs recognized under Restricted Unit Plans	2,900	$ 2,900
Balance, end of period at Mar. 26, 2022	$ 585,149	$ 602,145	$ (16,996)
Balance (in units) at Mar. 26, 2022		62,968