Other Financial Data - Other Income (Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Interest income (expense), net:
Interest expense	$ (60,000)	$ (59,000)	$ (114,000)	$ (119,000)
Interest income	2,000	3,000	5,000	8,000
Interest income (expense), net	(58,000)	(56,000)	(109,000)	(111,000)
Other, net:
Net periodic pension and postretirement benefit (Note 8)	19,000	17,000	39,000	33,000
Loss from the extinguishment of long-term debt (Note 5)	0	(43,000)	0	(43,000)
Investment impairments	0	(3,000)	0	(11,000)
Foreign currency loss	(21,000)	(7,000)	(3,000)	(11,000)
Gain (loss) on derivative instruments	12,000	(3,000)	(4,000)	(7,000)
Gain on equity method investments	0	0	0	1,000
Fair value adjustments to equity investments	4,000	16,000	5,000	15,000
Other	2,000	2,000	(3,000)	11,000
Total other income (expense)	$ 16,000	$ (21,000)	$ 34,000	$ (12,000)