EMPLOYEE BENEFIT PLANS - Pension and Retirements Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Multiemployer Plans [Line Items]
Service cost	$ 7	$ 7	$ 22	$ 23
Non-service pension benefit	(16)	(47)	(47)	(124)
Total net periodic benefit (income) cost	(9)	(11)	(25)	(33)
UTC Sponsored Defined Benefit Plans
Multiemployer Plans [Line Items]
Service cost	0	4	0	13
Non-service pension benefit	0	(20)	(2)	(59)
Total net periodic benefit (income) cost	$ 0	$ (16)	$ (2)	$ (46)