CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Total
Balance, Value at Dec. 31, 2020	$ 50	$ 641,195	$ (392,317)	$ 73	$ 249,001
Balance, Shares at Dec. 31, 2020	49,872,213
Sale of common stock under license agreement with Vifor International, value	$ 3	44,966			44,969
Sale of common stock under license agreement with Vifor International, shares	3,282,391
Stock-based compensation expense		17,850			17,850
Shares issued upon exercise of stock options, value		1,639			1,639
Shares issued upon exercise of stock options, shares	136,787
Shares issued upon vesting of restricted stock units, value		2,935			2,935
Shares issued upon vesting of restricted stock units, shares	189,421
Net loss			(88,441)		(88,441)
Other comprehensive income (loss)				(431)	(431)
Balance, Value at Dec. 31, 2021	$ 53	708,585	(480,758)	(358)	227,522
Balance, Shares at Dec. 31, 2021	53,480,812
Stock-based compensation expense		14,345			14,345
Shares issued upon exercise of stock options, value		311			311
Shares issued upon exercise of stock options, shares	48,307
Shares issued upon vesting of restricted stock units, value		3,389			3,389
Shares issued upon vesting of restricted stock units, shares	268,222
Net loss			(85,474)		(85,474)
Other comprehensive income (loss)				(1,314)	(1,314)
Balance, Value at Dec. 31, 2022	$ 53	726,630	(566,232)	(1,672)	158,779
Balance, Shares at Dec. 31, 2022	53,797,341
Net proceeds from sales of common stock under open market sales agreement		1,117			1,117
Net proceeds from sales of common stock under open market sales agreement (shares)	386,881
Stock-based compensation expense		12,710			12,710
Shares issued upon exercise of stock options, value	$ 1	559			$ 560
Shares issued upon exercise of stock options, shares	93,218				93,218
Shares issued upon vesting of restricted stock units, value		1,020			$ 1,020
Shares issued upon vesting of restricted stock units, shares	203,264
Net loss			(118,513)		(118,513)
Other comprehensive income (loss)				1,412	1,412
Balance, Value at Dec. 31, 2023	$ 54	$ 742,036	$ (684,745)	$ (260)	$ 57,085
Balance, Shares at Dec. 31, 2023	54,480,704