CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 26, 2015	Dec. 27, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 12,266	$ 55,807
Other comprehensive income:
Net unrealized gains (losses) on cash flow hedges	177	(227)
Reclassification of realized losses on cash flow hedges into earnings	333	357
Amortization of net actuarial losses and prior service credits into earnings	959	959
Other comprehensive income	1,469	1,089
Total comprehensive income	$ 13,735	$ 56,896