FAIR VALUE MEASUREMENTS - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity investments not measured at fair value	$ 93		$ 93			$ 58
Equity investments without readily determinable fair values	221		221			204
Net gains (losses) from equity securities	174	$ 201	(525)	$ (82)
Equity Securities Donation | Gilead Foundation
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Donation expense		$ 212		$ 212
Level 2 | MYR GmbH | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Liability for MYR GmbH contingent consideration	0		0			0
Level 3 | MYR GmbH | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Liability for MYR GmbH contingent consideration	334		334		$ 341	0
Market value | MYR GmbH | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Liability for MYR GmbH contingent consideration	334		334			0
Market value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term and long-term debt	32,300		32,300			34,600
Carrying value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term and long-term debt, carrying values	$ 29,100		$ 29,100			$ 30,300