LEASES - Components of Lease Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease costs	$ 60	$ 49
Amortization of right-of-use assets	15	17
Interest on lease liabilities	5	6
Total finance lease cost	20	23
Total lease cost	80	72
Short-term lease costs	17	13
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	44	29
Operating cash flows from finance leases	4	5
Finance cash flows from finance leases	15	25
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	67	83
Finance leases	0	3
Vehicles
Lessee, Lease, Description [Line Items]
Operating lease costs	35	28
Amortization of right-of-use assets	14	15
Interest on lease liabilities	2	3
Total finance lease cost	16	18
Total lease cost	51	46
Buildings
Lessee, Lease, Description [Line Items]
Operating lease costs	8	9
Amortization of right-of-use assets	0	1
Interest on lease liabilities	3	3
Total finance lease cost	3	4
Total lease cost	11	13
Other
Lessee, Lease, Description [Line Items]
Operating lease costs	17	12
Amortization of right-of-use assets	1	1
Interest on lease liabilities	0	0
Total finance lease cost	1	1
Total lease cost	$ 18	$ 13