FAIR VALUE MEASUREMENTS - Book Values and Fair Values of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Book Values
Fair Value And Carrying Value By Balance Sheet Grouping [Line Items]
Short-term debt	$ 226	$ 2
Current maturities of long-term debt and finance lease obligations	315	2
Long-term debt and finance lease obligations	4,809	3,481
Fair values
Fair Value And Carrying Value By Balance Sheet Grouping [Line Items]
Short-term debt	226	2
Current maturities of long-term debt and finance lease obligations	315	2
Long-term debt and finance lease obligations	$ 5,156	$ 3,469