Intangible Assets and Goodwill - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 213,603	$ 213,603
Accumulated Amortization	(114,487)	(105,476)
Total	99,116	108,127
Developed product rights for Auryxia
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	213,603	213,603
Accumulated Amortization	(114,487)	(105,476)
Total	$ 99,116	$ 108,127
Finite-Lived Intangible Asset, Useful Life	6 years