Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Feb. 28, 2017
ASU No. 2016-09
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect of differed tax assets	$ 14.0
HealthCare Royalty Partners and its Affiliates (“HCR”) | Andexanet Alfa
Summary Of Significant Accounting Policies [Line Items]
Payment receivable contingent upon FDA's approval	$ 100.0	$ 100.0