INCOME TAXES - DEFERRED TAXES (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant components of deferred tax assets
Net operating loss carryforwards	$ 276,100,000	$ 281,300,000
Research credits	25,000,000	23,400,000
Capitalized research and development	1,400,000	2,100,000
License fees	300,000	500,000
Other - net	9,800,000	7,600,000
Total deferred tax assets	312,600,000	314,900,000
Valuation allowance for deferred tax assets	(312,600,000)	(314,900,000)
Valuation allowance
Decrease in valuation allowance	2,300,000	$ 3,300,000	$ 5,500,000
Valuation allowance for deferred tax assets related to benefits of stock option deductions	$ 4,900,000