License, Collaboration and Other Significant Agreements - Deferred Revenue (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Deferred Revenue:
Short-Term	$ 18,034	$ 39,830
Long-Term	33,660	$ 33,120
Total	51,694
Otsuka Pharmaceutical Company. Ltd. | Otsuka U.S. Agreement
Deferred Revenue:
Short-Term	10,672
Long-Term	20,777
Total	31,449
Otsuka Pharmaceutical Company. Ltd. | Otsuka International Agreement
Deferred Revenue:
Short-Term	7,362
Long-Term	8,204
Total	15,566
Vifor Pharma
Deferred Revenue:
Short-Term	0
Long-Term	4,679
Total	$ 4,679