License, Collaboration and Other Significant Agreements - Deferred Revenues Balance (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Deferred Revenue:
Short-Term	$ 34,886	$ 39,830
Long-Term	42,799	$ 33,120
Total	77,685
Otsuka Pharmaceutical Company. Ltd. | U.S.
Deferred Revenue:
Short-Term	19,090
Long-Term	26,854
Total	45,944
Otsuka Pharmaceutical Company. Ltd. | International
Deferred Revenue:
Short-Term	11,807
Long-Term	11,266
Total	23,073
MTPC | Supply of Validation Drug Product
Deferred Revenue:
Short-Term	3,989
Total	3,989
Vifor Pharma
Deferred Revenue:
Long-Term	4,679
Total	$ 4,679