Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended
	Oct. 15, 2020	May 17, 2018	Oct. 31, 2021
Regulatory Milestones [Member]
Subsequent Event [Line Items]
Proceeds from the sale of stock			$ 50,000
Vifor International Ltd. [Member] | Regulatory Milestones [Member]
Subsequent Event [Line Items]
Proceeds from the sale of stock	$ 50,000		$ 50,000
Common stock, shares issued			3,282,391
Shares Issued Price Per Share			$ 15.23
Vifor Fresenius Medical Care Renal Pharma Ltd. [Member]
Subsequent Event [Line Items]
Common stock, shares issued		1,174,827
Shares Issued Price Per Share		$ 17.024
Subsequent Event [Member] | Vifor International Ltd. [Member] | Regulatory Milestones [Member]
Subsequent Event [Line Items]
Proceeds from the sale of stock			$ 50,000
Common stock, shares issued			3,282,391
Shares Issued Price Per Share			$ 15.23
Subsequent Event [Member] | Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] | Regulatory Milestones [Member]
Subsequent Event [Line Items]
Proceeds from milestone payments			$ 15,000