Subsequent Events - Additional Information (Details) - Subsequent Event - Mitsubishi Tanabe Pharma Corporation $ in Thousands	Oct. 08, 2019 USD ($)
Subsequent Event [Line Items]
Upfront licensing fees receivable	$ 30,000
Supply agreement description	The Company will be responsible for supplying inebilizumab to MTPC pursuant to a supply agreement that it expects to enter into. On a country-by-country and product-by-product basis, the licenses will become perpetual, non-exclusive and fully paid-up upon the later of (a) the expiration of the last valid claim of a Company patent covering the product; (b) the expiration of any regulatory exclusivity with respect to the product; or (c) 10 years after the first commercial sale of the product in such country.
Number of years considered after first commercial sale of product in country	10 years
License agreement termination period	180 days