LEASES (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
	Jan. 01, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Operating Lease Cost		$ 5	$ 6
Short-term Lease Cost		6	7
Variable Lease, Cost		2	0
Lease, Cost		13	13
Operating cash flows for operating leases		5	$ 6
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 99	3		$ 105
Operating lease right-of-use assets		86		89
Finance Lease, Right-of-Use Asset		12		12
Less accumulated depreciation		5,922		5,878
Total Lease Assets		91		95
Operating lease liabilities - current		15		16
Finance Lease, Liability, Current		1		1
Operating lease liabilities - noncurrent		72		74
Finance Lease, Liability, Noncurrent		4		5
Total Lease Liabilities		$ 92		$ 96
Operating Lease, Weighted Average Remaining Lease Term		6 years 4 months 24 days		6 years 3 months 18 days
Finance Lease, Weighted Average Remaining Lease Term		4 years 3 months 18 days		4 years 6 months
Operating Lease, Weighted Average Discount Rate, Percent		4.13%		4.13%
Finance Lease, Weighted Average Discount Rate, Percent		4.22%		4.22%
Lessee, Operating Lease, Liability, Payments, Remainder of 2020		$ 13
Finance Lease, Liability, Payments, Due 2020		1
Lessee, Operating Lease, Liability, Payments, Due 2021		16
Finance Lease, Liability, Payments, Due 2021		2
Lessee, Operating Lease, Liability, Payments, Due 2022		16
Finance Lease, Liability, Payments, Due 2022		1
Lessee, Operating Lease, Liability, Payments, Due 2023		14
Finance Lease, Liability, Payments, Due 2023		1
Lessee, Operating Lease, Liability, Payments, Due 2024		13
Finance Lease, Liability, Payments, Due 2024		1
Lessee, Operating Lease, Liability, Payments, Due 2025 and thereafter		27
Finance Lease, Liability, Payments, Due 2025 and thereafter		0
Lessee, Operating Lease, Liability, Payments, Due		99
Finance Lease, Liability, Payment, Due		6
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		12
Finance Lease, Liability, Undiscounted Excess Amount		1
Operating Lease, Liability		87
Finance Lease, Liability		5
Lessee, Additional Leases Not yet Commenced, Assumptions and Judgment, Amount		$ 16
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract		20 years
finance leases [Member]
Less accumulated depreciation		$ 7		$ 6