ACQUISITIONS AND LICENSING AGREEMENTS - Narrative (Details) business in Thousands			10 Months Ended	12 Months Ended			34 Months Ended
	Mar. 06, 2019 USD ($)	Oct. 16, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) business	Dec. 31, 2018 USD ($) business	Dec. 31, 2017 USD ($) business	Dec. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2017 USD ($)	Feb. 21, 2017 USD ($)
Business Combinations
Other expense				$ 1,414,000,000	$ (20,000,000)	$ (348,000,000)
Reduction of additional paid-in capital					$ 18,000,000	$ 9,000,000
Number of other material business combinations | business				0
Number of material business combinations | business					0	0
Payment for contingent consideration liability				$ 35,000,000	$ 37,000,000	$ 45,000,000
Additional Paid-In Capital
Business Combinations
Reduction of additional paid-in capital					15,000,000	$ 2,000,000
Synergy
Business Combinations
Cash payments to acquire certain assets and assumed liabilities	$ 180,000,000
Revenue of acquiree since acquisition date			$ 55,000,000
Operating results of acquiree since acquisition			$ 0
Pro-forma revenue				0	0
Pro-forma operating results				0	$ 0
Other expense				$ 8,000,000
Medpharma
Business Combinations
Cash payments to acquire certain assets and assumed liabilities		$ 18,000,000
Percentage interest acquired		40.00%
Medpharma | Additional Paid-In Capital
Business Combinations
Reduction of additional paid-in capital		$ 15,000,000
EyeGate | Development and Regulatory Milestones
Business Combinations
Upfront payment									$ 4,000,000
Possible contingent consideration (up to)										$ 34,000,000
Payment for contingent consideration liability							$ 3,000,000
Carrying value, contingent consideration, liability								$ 0
EyeGate | Sales Based Milestone Payments
Business Combinations
Possible contingent consideration (up to)										$ 65,000,000