ACQUISITIONS (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Asset acquisition [Line Items]
Asset acquisition upfront payment	$ 510
Upfront payment allocated to research and development expenses	485
Deferred tax assets related to asset acquisition	25
Contingent and regulatory milestone payments	2,958
IFM [Member]
Asset acquisition [Line Items]
Asset acquisition upfront payment		$ 325
Upfront payment allocated to research and development expenses		311
Deferred tax assets related to asset acquisition		14
Contingent and regulatory milestone payments	25	2,020
Total Contingent Development and Regulatory Milestone Payments	555
Upfront payment for future negotiation rights		25
Cormorant [Member]
Asset acquisition [Line Items]
Asset acquisition upfront payment			$ 35
Upfront payment allocated to research and development expenses			35
Deferred tax assets related to asset acquisition		0
Contingent and regulatory milestone payments	$ 60		485
Padlock Therapeutics, Inc. [Member]
Asset acquisition [Line Items]
Asset acquisition upfront payment			150
Upfront payment allocated to research and development expenses			139
Deferred tax assets related to asset acquisition			11
Contingent and regulatory milestone payments			453
Cardioxyl Pharmaceuticals, Inc. [Member]
Asset acquisition [Line Items]
Contingent and regulatory milestone payments		100
Flexus Biosciences, Inc. [Member]
Asset acquisition [Line Items]
Contingent and regulatory milestone payments		$ 350	$ 100