License, Collaboration and Other Significant Agreements - Deferred Revenues Balance (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Deferred Revenue:
Short-Term	$ 23,529	$ 39,830
Long-Term	34,542	$ 33,120
Total	58,071
Otsuka Pharmaceutical Company. Ltd. | Otsuka U.S. Agreement
Deferred Revenue:
Short-Term	15,378
Long-Term	20,557
Total	35,935
Otsuka Pharmaceutical Company. Ltd. | Otsuka International Agreement
Deferred Revenue:
Short-Term	8,151
Long-Term	9,306
Total	17,457
Vifor Pharma
Deferred Revenue:
Short-Term	0
Long-Term	4,679
Total	$ 4,679