CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 27,719	$ 37,168
Other comprehensive income:
Amortization of net actuarial losses and prior service credits into earnings	552	757
Other comprehensive income	552	757
Total comprehensive income	$ 28,271	$ 37,925