ACQUISITIONS, DIVESTITURES AND LICENSING ARRANGEMENTS (Licensing Arrangements) (Details) - Licensing Agreements [Member] $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($)
Halozyme [Member]
Licensing Arrangements [Line Items]
Number of original targets	11
License arrangement upfront payment	$ 105
Potential contingent milestones	$ 160
CytomX [Member]
Licensing Arrangements [Line Items]
Number of original targets	4
Number of potential additional collaboration targets	8
R&D payments prior to 2017	$ 75
License arrangement upfront payment	200
Potential contingent milestones	448
Biogen [Member]
Licensing Arrangements [Line Items]
Proceeds from out-licensed arrangements	300
Potential milestone receipts	410
Roche [Member]
Licensing Arrangements [Line Items]
Proceeds from out-licensed arrangements	170
Potential milestone receipts	$ 205