SUPPLEMENTAL EQUITY INFORMATION - AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018
Changes in stockholders' equity
Balance at the beginning of the period			$ (604,289)
Other comprehensive income (loss) before reclassifications			17,745
Amounts reclassified from AOCL			15,689
Other comprehensive income	$ 5,441	$ 5,550	33,434	$ 16,649
Balance at the end of the period	(570,855)		(570,855)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Retirement benefit expense	4,330	2,778	19,386	8,335
Minimum Pension and Post-Retirement Liability
Changes in stockholders' equity
Balance at the beginning of the period			(595,820)
Other comprehensive income (loss) before reclassifications			17,745
Amounts reclassified from AOCL			15,689
Other comprehensive income			33,434
Balance at the end of the period	(562,386)		(562,386)
Minimum Pension and Post-Retirement Liability | Amount Reclassified from AOCI
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Retirement benefit expense	5,441	$ 5,550	15,689	$ 16,649
Other Comprehensive Loss Related to Equity Investments
Changes in stockholders' equity
Balance at the beginning of the period			(8,469)
Balance at the end of the period	$ (8,469)		$ (8,469)