DEBT - Debt Outstanding (Details) - USD ($)	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total short-term debt	$ 1,724,000,000		$ 699,000,000
Long-term debt	6,058,000,000		4,967,000,000
Commercial paper
Debt Instrument [Line Items]
Short-term debt	325,000,000		300,000,000
Term note
Debt Instrument [Line Items]
Short-term debt	1,000,000,000		0
Senior notes | $400 million, 2.50% due December 15, 2020
Debt Instrument [Line Items]
Face amount	$ 400,000,000
Stated interest rate (percent)	2.50%
Long-term debt, current maturities	$ 399,000,000		399,000,000
Senior notes | $600 million, 3.15% due December 1, 2022
Debt Instrument [Line Items]
Face amount	$ 600,000,000
Stated interest rate (percent)	3.15%
Long-term debt	$ 598,000,000		598,000,000
Senior notes | $400 million, 2.90% due December 15, 2022
Debt Instrument [Line Items]
Face amount	$ 400,000,000
Stated interest rate (percent)	2.90%
Long-term debt	$ 398,000,000		397,000,000
Senior notes | $600 million, 3.85% due October 1, 2024
Debt Instrument [Line Items]
Face amount	$ 600,000,000
Stated interest rate (percent)	3.85%
Long-term debt	$ 597,000,000		597,000,000
Senior notes | $600 million, 4.50% due April 1, 2025
Debt Instrument [Line Items]
Face amount	$ 600,000,000	$ 600,000,000
Stated interest rate (percent)	4.50%	4.50%
Long-term debt	$ 594,000,000		0
Senior notes | $600 million, 3.95% due March 15, 2027
Debt Instrument [Line Items]
Face amount	$ 600,000,000
Stated interest rate (percent)	3.95%
Long-term debt	$ 596,000,000		595,000,000
Senior notes | $500 million, 3.125% due August 15, 2029
Debt Instrument [Line Items]
Face amount	$ 500,000,000
Stated interest rate (percent)	3.125%
Long-term debt	$ 495,000,000		495,000,000
Senior notes | $500 million, 4.875% due April 1, 2030]
Debt Instrument [Line Items]
Face amount	$ 500,000,000	$ 500,000,000
Stated interest rate (percent)	4.875%	4.875%
Long-term debt	$ 494,000,000		0
Senior notes | $250 million, 8.15% due June 15, 2038
Debt Instrument [Line Items]
Face amount	$ 250,000,000
Stated interest rate (percent)	8.15%
Long-term debt	$ 262,000,000		262,000,000
Senior notes | $400 million, 4.625% due December 1, 2042
Debt Instrument [Line Items]
Face amount	$ 400,000,000
Stated interest rate (percent)	4.625%
Long-term debt	$ 396,000,000		396,000,000
Senior notes | $750 million, 4.95% due October 1, 2044
Debt Instrument [Line Items]
Face amount	$ 750,000,000
Stated interest rate (percent)	4.95%
Long-term debt	$ 739,000,000		739,000,000
Senior notes | $400 million, 4.80% due March 15, 2047
Debt Instrument [Line Items]
Face amount	$ 400,000,000
Stated interest rate (percent)	4.80%
Long-term debt	$ 396,000,000		396,000,000
Senior notes | $500 million, 3.95% due August 15, 2049
Debt Instrument [Line Items]
Face amount	$ 500,000,000
Stated interest rate (percent)	3.95%
Long-term debt	$ 493,000,000		$ 492,000,000