CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Sep. 25, 2021	Sep. 26, 2020	Sep. 28, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 122,793	$ 60,758	$ 68,632
Other comprehensive income (loss):
Amortization of net actuarial gains (losses) and prior service credits into earnings and net change in funded status of benefit plans	7,234	(641)	(1,516)
Recognition in earnings of net actuarial loss for pension settlement	958	1,051	0
Other comprehensive income (loss)	8,192	410	(1,516)
Total comprehensive income	$ 130,985	$ 61,168	$ 67,116