PRODUCT REVENUE AND PROVISIONS FOR VARIABLE CONSIDERATION - Schedule of Product Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Total revenues	$ 53,544	$ 57,336
Product revenue, net
Disaggregation of Revenue [Line Items]
Total revenues	51,992	55,791
Vafseo
Disaggregation of Revenue [Line Items]
Total revenues	15,802	12,034
Auryxia
Disaggregation of Revenue [Line Items]
Total revenues	$ 36,190	$ 43,757

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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