Other Comprehensive Earnings (Loss), Tax Effects on Changes in Other Comprehensive Earnings (loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2016	Sep. 27, 2015	Sep. 25, 2016	Sep. 27, 2015
Other Comprehensive Earnings (Loss) [Abstract]
Tax benefit (expense) on cash flow hedging activities	$ 1,420	$ (7,400)	$ 9,423	$ (11,362)
Tax benefit (expense) on unrealized holding gains	221	700	(547)	164
Tax expense on changes in unrecognized pension and postretirement amounts	0	(660)	0	(660)
Reclassification Adjustment from AOCE, Tax expense (benefit) on cash flow hedging activities	2,456	1,487	5,274	2,537
Reclassification Adjustment from AOCE, Tax expense (benefit) on amortization of unrecognized pension and postretirement amounts	(666)	338	(1,999)	(942)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent, Total	3,431	$ (5,535)	$ 12,151	$ (10,263)
Cash Flow Hedge gains to be Reclassified within Twelve Months	$ 11,699