INCOME TAXES - Provision for income taxes (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
INCOME. TAXES.
Loss before income taxes, as reported in the consolidated statements of operations	$ (172,871,000)	$ (173,482,000)	$ (118,476)
Computed "expected" tax benefit	(36,303,000)	(36,431,000)	(40,282)
Increase (decrease) in income taxes resulting from:
Expected benefit from state and local taxes	(2,128,000)	(2,243,000)	(1,106)
Research and development credits	(7,266,000)	(4,726,000)	(3,697)
Other	641,000	639,000	1,563
Stock awards	1,292,000	(473,000)	8,213
Enactment of federal tax reform	0	0	51,768
Change in the balance of the valuation allowance for deferred tax assets	43,764,000	43,234,000	(16,459)
Income Tax Expense (Benefit)	$ 0	$ 0	$ 0

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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