Business - Additional Information (Detail) $ in Thousands	1 Months Ended		3 Months Ended						9 Months Ended
	Oct. 31, 2020	May 31, 2018	Sep. 30, 2023 USD ($) item	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Sep. 30, 2023 USD ($) item	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Nature Of Business [Line Items]
Date of formation									Jul. 02, 2004
Proceeds from equity and debt financing			$ 520,700						$ 520,700
Number of follow-on public offerings | item			4						4
Payments received in connection with license and supply agreements			$ 284,800						$ 284,800
Unrestricted cash and cash equivalents and marketable securities			83,288						83,288
Accumulated deficit			652,408						652,408		$ 566,232
Net loss			(28,032)	$ (31,479)	$ (26,665)	$ (23,180)	$ (4,206)	$ (27,749)	(86,176)	$ (55,135)
Net cash used in operating activities									(74,708)	$ (55,220)
Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 2 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing		50.00%
License Agreement with Maruishi Pharmaceutical Co. Ltd [Member]
Nature Of Business [Line Items]
Earned milestone payment			$ 1,449						$ 1,449
Minimum [Member]
Nature Of Business [Line Items]
Expected approvals and commercial launches period									12 months
Maximum [Member]
Nature Of Business [Line Items]
Expected approvals and commercial launches period									18 months
CSL Vifor [Member] | Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 1 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing	40.00%
Affiliated Entity [Member] | Vifor International Ltd. [Member]
Nature Of Business [Line Items]
Proceeds from the sale of common stock under license agreement with Vifor International									$ 98,000
Affiliated Entity [Member] | Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] | Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 2 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing		50.00%
Affiliated Entity [Member] | CSL Vifor [Member] | Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 1 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing	60.00%