CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 28, 2020	Mar. 30, 2019	Mar. 28, 2020	Mar. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 77,361	$ 121,016	$ 117,524	$ 148,735
Other comprehensive income:
Amortization of net actuarial losses and prior service credits into earnings	541	552	1,082	1,104
Other comprehensive income	541	552	1,082	1,104
Total comprehensive income	$ 77,902	$ 121,568	$ 118,606	$ 149,839