EMPLOYEE BENEFIT PLANS - NET PENSION EXPENSE (Details) - Qualified Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 13	$ 11
Interest cost	19	22
Expected return on assets	(28)	(24)
Recognized actuarial loss (gain)	9	9
Wages and Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net pension expense	13	11
Nonoperating Income (Expense) [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net pension expense	$ 0	$ 7