ACQUISITIONS, DIVESTITURES, LICENSING AND OTHER ARRANGEMENTS - Schedule of Consideration Transferred - Asset Acquisition (Details) - MyoKardia Acquisition $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Business Acquisition [Line Items]
Cash consideration for outstanding shares	$ 12,030
Cash consideration for stock awards	1,059
Consideration paid	13,089
Charge for unvested stock awards	482
Transaction costs	53
Consideration to be allocated	12,660
Other intangible assets	11,553
Cash and cash equivalents	861
Deferred income taxes	295
Other assets	177
Other liabilities	(226)
Total assets acquired, net	12,660
IPRD
Business Acquisition [Line Items]
Identifiable assets acquired, indefinite-lived intangible assets	11,400
IPRD | Assets, Total | Product Concentration Risk
Business Acquisition [Line Items]
Identifiable assets acquired, indefinite-lived intangible assets	11,100
Licenses
Business Acquisition [Line Items]
Identifiable assets acquired, indefinite-lived intangible assets	115
Marketing, selling and administrative
Business Acquisition [Line Items]
Charge for unvested stock awards	241
Research and development
Business Acquisition [Line Items]
Charge for unvested stock awards	$ 241