DEBT - Debt Outstanding (Details) - USD ($)	Sep. 30, 2021	Aug. 31, 2021	May 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total short-term debt	$ 795,000,000			$ 600,000,000
Total long-term debt	11,466,000,000			6,060,000,000
Commercial paper
Debt Instrument [Line Items]
Short-term debt	795,000,000			600,000,000
Senior notes | $600 million, 3.15% due December 1, 2022
Debt Instrument [Line Items]
Aggregate principal	$ 600,000,000
Stated interest rate (percent)	3.15%
Total long-term debt	$ 599,000,000			598,000,000
Senior notes | $400 million, 2.90% due December 15, 2022
Debt Instrument [Line Items]
Aggregate principal	$ 400,000,000
Stated interest rate (percent)	2.90%
Total long-term debt	$ 399,000,000			398,000,000
Senior notes | $1,500 million, 0.650% due August 3, 2023
Debt Instrument [Line Items]
Aggregate principal	$ 1,500,000,000	$ 1,500,000,000
Stated interest rate (percent)	0.65%	0.65%
Total long-term debt	$ 1,491,000,000			0
Senior notes | $600 million, 3.85% due October 1, 2024
Debt Instrument [Line Items]
Aggregate principal	$ 600,000,000
Stated interest rate (percent)	3.85%
Total long-term debt	$ 598,000,000			598,000,000
Senior notes | $600 million, 4.50% due April 1, 2025
Debt Instrument [Line Items]
Aggregate principal	$ 600,000,000
Stated interest rate (percent)	4.50%
Total long-term debt	$ 596,000,000			595,000,000
Senior notes | $750 million, 1.350% due February 3, 2027
Debt Instrument [Line Items]
Aggregate principal	$ 750,000,000	$ 750,000,000
Stated interest rate (percent)	1.35%	1.35%
Total long-term debt	$ 742,000,000			0
Senior notes | $600 million, 3.95% due March 15, 2027
Debt Instrument [Line Items]
Aggregate principal	$ 600,000,000
Stated interest rate (percent)	3.95%
Total long-term debt	$ 596,000,000			596,000,000
Senior notes | $500 million, 3.125% due August 15, 2029
Debt Instrument [Line Items]
Aggregate principal	$ 500,000,000
Stated interest rate (percent)	3.125%
Total long-term debt	$ 496,000,000			495,000,000
Senior notes | $500 million, 4.875% due April 1, 2030
Debt Instrument [Line Items]
Aggregate principal	$ 500,000,000
Stated interest rate (percent)	4.875%
Total long-term debt	$ 495,000,000			494,000,000
Senior notes | $750 million, 2.150% due February 3, 2032
Debt Instrument [Line Items]
Aggregate principal	$ 750,000,000	$ 750,000,000
Stated interest rate (percent)	2.15%	2.15%
Total long-term debt	$ 741,000,000			0
Senior notes | $250 million, 8.15% due June 15, 2038
Debt Instrument [Line Items]
Aggregate principal	$ 250,000,000
Stated interest rate (percent)	8.15%
Total long-term debt	$ 262,000,000			262,000,000
Senior notes | $400 million, 4.625% due December 1, 2042
Debt Instrument [Line Items]
Aggregate principal	$ 400,000,000
Stated interest rate (percent)	4.625%
Total long-term debt	$ 396,000,000			396,000,000
Senior notes | $750 million, 4.95% due October 1, 2044
Debt Instrument [Line Items]
Aggregate principal	$ 750,000,000
Stated interest rate (percent)	4.95%
Total long-term debt	$ 740,000,000			739,000,000
Senior notes | $400 million, 4.80% due March 15, 2047
Debt Instrument [Line Items]
Aggregate principal	$ 400,000,000
Stated interest rate (percent)	4.80%
Total long-term debt	$ 395,000,000			396,000,000
Senior notes | $500 million, 3.95% due August 15, 2049
Debt Instrument [Line Items]
Aggregate principal	$ 500,000,000
Stated interest rate (percent)	3.95%
Total long-term debt	$ 492,000,000			493,000,000
Term loan | Gentiva term loan, due July 2, 2025
Debt Instrument [Line Items]
Total long-term debt	1,928,000,000			0
Term loan | Delayed draw term loan, due May 28, 2024
Debt Instrument [Line Items]
Aggregate principal			$ 500,000,000
Total long-term debt	$ 500,000,000			$ 0