LICENSE, COLLABORATION AND OTHER REVENUE - CSL Vifor License Agreement (Details) $ / shares in Units, $ in Thousands				1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 22, 2022 USD ($) shares	Feb. 18, 2022 USD ($)	Apr. 08, 2019 USD ($)	May 31, 2017 USD ($) $ / shares shares	Jun. 30, 2023 USD ($) shares	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) performance_obligation shares	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) shares	May 12, 2017 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Common stock, issued (in shares) | shares					188,128,869		188,128,869		184,135,714
Deferred revenue, net of current portion					$ 43,296		$ 43,296		$ 43,296
Refund liability to customer, amortization of discount					900	$ 1,100	1,700	$ 1,100
Refund liability to customer, amortization of deferred gain					1,000	$ 800	2,000	$ 800
Vifor (International) Ltd.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract termination, prior written notice period		30 months
Private Placement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of shares sold in offering (in shares) | shares	4,000,000
Aggregate net proceeds from offering	$ 20,000
Aggregate net proceeds from offering, fair value in excess of carrying amount	$ 13,600
Vifor (International) Ltd.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract termination, prior written notice period		6 months
Refund liability to customer, gross					40,000		40,000
Refund liability to customer, net of deferred gain and discount					$ 40,600		$ 40,600
Vifor (International) Ltd. | License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue, remaining performance obligation, profit share percentage		66.00%
Upfront payment		$ 25,000
Number of performance obligations | performance_obligation							1
Refund liability to customer, purchase orders to total					50.00%		50.00%
Refund liability to customer, interest rate					15.00%		15.00%
Vifor (International) Ltd. | License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential milestone revenue			$ 25,000
Common stock, issued (in shares) | shares				3,571,429
Sale of stock, price per share (in dollars per share) | $ / shares				$ 14.00
Proceeds from common stock sold				$ 50,000
Premium over the closing stock price of common stock (in dollars per share) | $ / shares				$ 12.69
Premium amount over the closing stock price of common stock				$ 4,700						$ 4,700
CSL Vifor
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue, net of current portion					$ 43,300		$ 43,300