Business - Additional Information (Detail) $ in Thousands	1 Months Ended		3 Months Ended
	Oct. 31, 2020	May 31, 2018	Mar. 31, 2023 USD ($) item	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Nature Of Business [Line Items]
Date of formation			Jul. 02, 2004
Proceeds from equity and debt financing			$ 519,600
Number of follow-on public offerings | item			4
Payments received in connection with license and supply agreements			$ 273,000
Unrestricted cash and cash equivalents and marketable securities			123,357
Accumulated deficit			592,897		$ 566,232
Net (loss) income			(26,665)	$ (27,749)
Net cash used in operating activities			(34,618)	$ (25,525)
Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 1 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing	60.00%
Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 2 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing		50.00%
Vifor International Ltd. [Member]
Nature Of Business [Line Items]
Proceeds from the sale of common stock under license agreement with Vifor International			$ 98,000
Vifor International Ltd. [Member] | Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 1 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing	40.00%
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%