PENSION BENEFITS - Pension Assumptions (Details) - Pension Plan $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Effect of .25% decrease in discount rate on pension expense	$ 2
Effect of .25% decrease in discount rate on pension benefit obligation	69
Effect of .25% increase in discount rate on pension expense	(5)
Effect of .25% increase in discount rate on pension benefit obligation	(64)
Effect of .25% decrease in long-term return on assets on pension expense	2
Effect of .25% increase in long-term return on assets on pension expense	$ (2)