Business - Additional Information (Detail) $ in Thousands		1 Months Ended			12 Months Ended
	May 17, 2018 shares	Oct. 31, 2021 USD ($) shares	Oct. 31, 2020 USD ($) shares	May 31, 2018 USD ($) shares	Dec. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
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					$ 266,790
Proceeds from the sale of common stock under license agreement with Vifor International						$ 44,969	$ 38,449
Unrestricted cash and cash equivalents and marketable securities					156,749
Accumulated deficit					566,232	480,758
Net (loss) income					(85,474)	(88,441)	8,410
Net cash used in operating activities					$ (78,730)	$ (60,087)	$ (5,487)
Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 1 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing			60.00%				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			$ 38,449	$ 14,556
Proceeds from sale of common stock in connection with regulatory milestone		$ 44,969
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%				40.00%
Common stock, shares issued | shares		3,282,391	2,939,552
Vifor International Ltd. [Member] | Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 2 [Member]
Nature Of Business [Line Items]
Common stock, shares issued | shares	1,174,827
Vifor International Ltd. [Member] | Common Stock [Member]
Nature Of Business [Line Items]
Common stock, shares issued | shares		3,282,391	2,939,552	1,174,827
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%