LICENSING ARRANGEMENTS (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Promedior [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Warrant upfront payment				$ 84
Upfront payment capitalized				66
Upfront payments for licensing and alliance arrangements				$ 150
Halozyme [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payments for licensing and alliance arrangements		$ 105
Number of Collaboration Targets		11
Collaborative Arrangement Contingent Payments Maximum Exposure	$ 160
CytomX [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payments for licensing and alliance arrangements		$ 75
Number of Collaboration Targets		8
Collaborative Arrangement Contingent Payments Maximum Exposure	448
Number of Initial Collaboration Targets		4
Payment for Additional Targets Made To Collaborative Partner		$ 200
Biogen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from out-licensed arrangements		300
Potential Milestone Receipts	410
Roche [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from out-licensed arrangements		170
Potential Milestone Receipts	205
Nitto Denko [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payments for licensing and alliance arrangements			$ 100
Collaborative Arrangement Contingent Payments Maximum Exposure	$ 898
F-Star [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		75
In Process Research and Development [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		$ 75