DEBT - Narrative (Details) $ / shares in Units, € in Millions		1 Months Ended					3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2021 USD ($)	Apr. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Apr. 30, 2020 USD ($) day $ / shares	Aug. 31, 2019 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2021 EUR (€)	Mar. 31, 2021 EUR (€)	Aug. 31, 2014 USD ($)	May 31, 2013 USD ($)
Debt Instrument
Payments of debt issuance costs									$ 10,000,000	$ 38,000,000
Loss on early extinguishment of debt	[1]						$ 0	$ 0	242,000,000	0
Level 2
Debt Instrument
Estimated market value of outstanding debt		$ 12,300,000,000					$ 12,300,000,000		$ 12,300,000,000		$ 14,000,000,000
Convertible Debt | 0.9% Convertible Senior Notes due September 2021
Debt Instrument
Aggregate principal amount														$ 1,000,000,000
Stated interest rate														0.90%
Payments related to principal amount		1,000,000,000
Payments related to conversion value in excess of the principal amount of senior notes		$ 86,000,000
Effective interest rate at debt origination														3.18%
Debt discount related to convertible notes, net of tax														$ 83,000,000
Debt discount related to convertible notes, before tax														$ 143,000,000
Convertible Debt | 0.75% Convertible Senior Notes due May 2025
Debt Instrument
Aggregate principal amount					$ 863,000,000
Stated interest rate		0.75%			0.75%		0.75%		0.75%		0.75%	0.75%
Payments of debt issuance costs											$ 19,000,000
Conversion price | $ / shares					$ 1,886.44
Ratio of closing share price to conversion price as a condition for conversion of the convertible notes, minimum (Percentage)					130.00%
If-converted value in excess of principal									$ 215,000,000
Effective interest rate at debt origination					4.10%
Debt discount related to convertible notes, net of tax					$ 100,000,000
Debt discount related to convertible notes, before tax					$ 130,000,000
Aggregate principal amount		$ 863,000,000					$ 863,000,000		863,000,000		863,000,000
Convertible Debt | 0.35% Convertible Senior Notes due June 2020
Debt Instrument
Aggregate principal amount															$ 1,000,000,000
Stated interest rate															0.35%
Payments related to principal amount				$ 1,000,000,000
Payments related to conversion value in excess of the principal amount of senior notes				$ 245,000,000
Senior Notes
Debt Instrument
Payments to redeem debt			$ 2,000,000,000
Carrying value of long-term debt		$ 10,300,000,000					$ 10,300,000,000		$ 10,300,000,000		$ 10,300,000,000
Senior Notes | 0.1% (€950 million) Senior Notes due March 2025
Debt Instrument
Aggregate principal amount | €												€ 950
Stated interest rate		0.10%					0.10%		0.10%			0.10%	0.10%
Effective interest rate at debt origination	[2]												0.30%
Aggregate principal amount		$ 1,101,000,000					$ 1,101,000,000		$ 1,101,000,000				€ 950
Senior Notes | 0.5% (€750 million) Senior Notes due March 2028
Debt Instrument
Aggregate principal amount | €												€ 750
Stated interest rate		0.50%					0.50%		0.50%			0.50%	0.50%
Effective interest rate at debt origination	[2]												0.63%
Aggregate principal amount		$ 869,000,000					$ 869,000,000		$ 869,000,000				€ 750
Senior Notes | 4.1% Senior Notes due April 2025 and 4.5% Senior Notes due April 2027
Debt Instrument
Loss on early extinguishment of debt									242,000,000
Senior Notes | 4.1% Senior Notes due April 2025
Debt Instrument
Stated interest rate											4.10%
Aggregate principal amount											$ 1,000,000,000
Payments to redeem debt			1,100,000,000
Senior Notes | 4.5% Senior Notes due April 2027
Debt Instrument
Stated interest rate											4.50%
Aggregate principal amount											$ 750,000,000
Payments to redeem debt			$ 868,000,000
Minimum | Euro-Denominated Debt | Designated as Hedging Instrument
Debt Instrument
Carrying value of the portions of euro-denominated debt designated as a net investment hedge									2,500,000,000	1,800,000,000
Minimum | Convertible Debt | 0.75% Convertible Senior Notes due May 2025
Debt Instrument
Minimum and maximum consecutive days the closing sales price of common stock must exceed a specified percentage of conversion price to trigger conversion feature of note (in days) | day					20
Additional payment to debt holder, settled In shares, aggregate value					$ 0
Maximum | Euro-Denominated Debt | Designated as Hedging Instrument
Debt Instrument
Carrying value of the portions of euro-denominated debt designated as a net investment hedge									4,300,000,000	$ 3,200,000,000
Maximum | Convertible Debt | 0.75% Convertible Senior Notes due May 2025
Debt Instrument
Minimum and maximum consecutive days the closing sales price of common stock must exceed a specified percentage of conversion price to trigger conversion feature of note (in days) | day					30
Additional payment to debt holder, settled In shares, aggregate value					$ 235,000,000
Revolving Credit Facility
Debt Instrument
Revolving credit facility, maximum borrowing capacity						$ 2,000,000,000
Revolving credit facility, term						5 years
Line of credit, current		0					0		0		0
Debt instrument, covenant, minimum liquidity amount											4,500,000,000
Debt instrument, covenant, pro forma liquidity required for distribution and share repurchases											6,000,000,000
Revolving Credit Facility | Minimum
Debt Instrument
Commitment fee rate						0.07%
Revolving Credit Facility | Maximum
Debt Instrument
Commitment fee rate						0.20%
Revolving Credit Facility | Rate 1 | Minimum | London Interbank Offered Rate (LIBOR)
Debt Instrument
Reference rate						0.00%
Basis spread on variable rate						0.875%
Revolving Credit Facility | Rate 1 | Maximum | London Interbank Offered Rate (LIBOR)
Debt Instrument
Basis spread on variable rate						1.50%
Revolving Credit Facility | Rate 2B | Federal Funds Purchased
Debt Instrument
Basis spread on variable rate						0.50%
Revolving Credit Facility | Rate 2C | One Month LIBOR
Debt Instrument
Basis spread on variable rate						1.00%
Revolving Credit Facility | Rate 2C | Minimum
Debt Instrument
Basis spread on variable rate						0.00%
Revolving Credit Facility | Rate 2C | Minimum | One Month LIBOR
Debt Instrument
Reference rate						0.00%
Revolving Credit Facility | Rate 2C | Maximum
Debt Instrument
Basis spread on variable rate						0.50%
Letter of Credit
Debt Instrument
Revolving credit facility, maximum borrowing capacity						$ 80,000,000
Letters of credit issued		$ 4,000,000					$ 4,000,000		$ 4,000,000		$ 4,000,000
Swingline Loans
Debt Instrument
Revolving credit facility, maximum borrowing capacity						$ 100,000,000

[1] See Note 9 for additional information related to the loss on early extinguishment of debt.

[2] Represents the coupon interest rate adjusted for deferred debt issuance costs, premiums or discounts existing at the origination of the debt.