LEASES Supplemental Information Related to Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 326
Operating Lease, Payments	164	$ 79
Incentive from Lessor	33
Lessee, Operating Leases Not Yet Commenced, Amount	750
Operating Lease, Impairment Loss	$ 31
Operating Lease, Weighted Average Remaining Lease Term	9 years	9 years
Operating Lease, Weighted Average Discount Rate, Percent	3.00%	4.00%
MyoKardia Acquisition [Member]
Lessee, Lease, Description [Line Items]
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 82