ACQUISITIONS (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Asset acquisition [Line Items]
Asset acquisition upfront payment		$ 185	$ 1,014
Upfront payment allocated to research and development expenses		174	967
Deferred tax assets related to asset acquisition		11	47
Contingent and regulatory milestone payments		938	2,325
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	2,020
Upfront payment for future negotiation rights	25
Asset acquisition subsequent milestone payment	555
Cormorant [Member]
Asset acquisition [Line Items]
Asset acquisition upfront payment		35
Upfront payment allocated to research and development expenses		35
Contingent and regulatory milestone payments		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]
Asset acquisition upfront payment			200
Upfront payment allocated to research and development expenses			167
Deferred tax assets related to asset acquisition			33
Contingent and regulatory milestone payments	100		1,875
Flexus Biosciences, Inc. [Member]
Asset acquisition [Line Items]
Asset acquisition upfront payment			814
Upfront payment allocated to research and development expenses			800
Deferred tax assets related to asset acquisition			14
Contingent and regulatory milestone payments	$ 350	$ 100	450
Acquisition costs			$ 14