INVENTORIES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Inventory [Line Items]
Write-down of inventory			$ 2,403	$ 1,327
Benefit in cost of goods sold related to previously written down as excess inventory	$ 3,700		12,300
Pre-launch inventory costs	28,400		28,400		$ 28,400
Auryxia Drug Substance
Inventory [Line Items]
Write-down of inventory	$ 1,300	$ 700	$ 2,400	$ 1,300