Business - Additional Information (Detail) $ in Thousands	1 Months Ended			12 Months Ended
	Oct. 31, 2021 USD ($) shares	Oct. 31, 2020 USD ($) shares	May 31, 2018 USD ($) shares	Dec. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) shares
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 agreements				$ 224,900
Proceeds from sale of common stock in connection with license agreement				44,969	$ 38,449
Unrestricted cash and cash equivalents and marketable securities				236,789
Accumulated deficit				480,758	392,317
Net (loss) income				(88,441)	8,410	$ (106,373)
Net cash used in operating activities				$ (60,087)	$ (5,487)	$ (109,225)
Vifor Agreement [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing		60.00%
Common Stock [Member]
Nature Of Business [Line Items]
Common stock, shares issued | shares						6,325,000
Vifor International Ltd. [Member]
Nature Of Business [Line Items]
Proceeds from sale of common stock in connection with license agreement		$ 38,449	$ 14,556
Proceeds from sale of common stock in connection with regulatory milestone	$ 44,969
Vifor International Ltd. [Member] | Vifor Agreement [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing		40.00%
Common stock, shares issued | shares		2,939,552
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