CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 24, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 76,534	$ 37,995	$ 14,440
Other comprehensive income:
Net unrealized (losses) gains on cash flow hedges		(10)	6
Reclassification of realized losses on cash flow hedges into earnings		215	1,100
Amortization of net actuarial losses and prior service credits into earnings and net change in funded status of benefit plans	4,142	10,715	(55)
Recognition in earnings of net actuarial loss for pension settlement	0	6,100	2,000
Other comprehensive income	4,142	17,020	3,051
Total comprehensive income	$ 80,676	$ 55,015	$ 17,491