POSTRETIREMENT BENEFIT PLANS - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Defined Benefit Plan Disclosure [Line Items]
Recognition of previously deferred postretirement benefit plan amounts, before tax	$ 140,000,000	$ 290,000,000	$ 420,000,000	$ 867,000,000
Recognition of previously deferred postretirement benefit plan amounts, net of tax	110,000,000	227,000,000	330,000,000	681,000,000
Retiree medical and life insurance plans
Defined Benefit Plan Disclosure [Line Items]
Recognition of previously deferred postretirement benefit plan amounts, before tax	4,000,000	11,000,000	14,000,000	31,000,000
Qualified defined benefit pension plans
Defined Benefit Plan Disclosure [Line Items]
Material contributions to qualified defined benefit pension plans	$ 0	$ 0	$ 0	$ 0