EQUITY AND LONG-TERM INVESTMENTS AND FAIR VALUE MEASUREMENTS - Convertible Promissory Note in Gate Neurosciences (Details) - Gate Neurosciences Member - USD ($) $ in Millions		12 Months Ended
	Nov. 24, 2021	Dec. 31, 2022	Dec. 31, 2021
Equity Investment
Number of common stock issued description	The number of common stock shares to be issued in a qualified event shall be equal to the amount due on the conversion date divided by the lesser of a capped conversion price (the “Capped Conversion Price”) and the qualified event price (the “Qualified Event Price”). The Capped Conversion Price is calculated as $50.0 million divided by the number of common stock outstanding at such time on a fully diluted basis. The Qualified Event Price is the price per share determined by the qualified event. A qualified financing is a sale or series of sales of preferred stock where (i) at least 50 percent of counterparties are not existing shareholders, (ii) net proceeds to Gate are at least $35.0 million, and (iii) the stated or implied equity valuation of Gate is at least $80.0 million.
Equity and long-term investments at fair value		$ 15.7	$ 15.1
Unrealized gain from fair value changes in equity investments		$ 0.6
Unrealized loss from fair value changes in equity investments			$ 0.8
Convertible Promissory Note Purchase Agreement
Equity Investment
Debt Instrument, Principal Payment	$ 15.0
Debt Instrument, annual interest rate	8.00%