EMPLOYEE BENEFIT PLANS - Pension and Retirements Expenses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Multiemployer Plans [Line Items]
Service cost	$ 7	$ 8	$ 15	$ 16
Non-service pension benefit	(14)	(38)	(31)	(77)
Total net periodic benefit (income) cost	(9)	(11)	(16)	(22)
UTC Sponsored Defined Benefit Plans
Multiemployer Plans [Line Items]
Service cost	0	5	0	9
Non-service pension benefit	0	(19)	(2)	(39)
Total net periodic benefit (income) cost	$ 0	$ (14)	$ (2)	$ (30)