Summary of Significant Accounting Policies - Additional Information (Detail) ¥ in Millions	1 Months Ended				9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2018 CNY (¥)	Jan. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Transfers between Levels 1, 2 and 3	$ 0			$ 0	$ 0
Restricted cash	100,000			100,000	100,000
Available for sale securities	0				0
MEDINET Co. [Member]
Summary Of Significant Accounting Policies [Line Items]
Upfront cash payment under license agreement			$ 10,000,000
Remaining performance obligations	$ 10,000,000				$ 10,000,000
Remaining performance obligation explanation					Expects to recognize revenue on approximately 75% and 100% of the remaining performance obligations over the next 12 months and the following 12 months, respectively.
Percentage of recognize revenue next 12 months					50.00%
Percentage of recognize revenue following 12 months					100.00%
Remaining performance obligation expected period	12 months				12 months
Royalties at percentage rates ranging					Low single digits to low double digits
Development milestone payments		¥ 330			$ 2,900,000
Regulatory payments	$ 1,000,000	720			7,400,000
Commercial Milestones Payment		¥ 7,300			64,100,000
Non-refundable upfront amount				10,000,000
Deferred license agreement cost	800,000				800,000
MEDINET Co. [Member] | License Agreement [Member]
Summary Of Significant Accounting Policies [Line Items]
Cost incurred related to license agreement					900,000
ASU 2014-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative impact	0				0
ASU 2016-02 [Member] | Minimum [Member] | Scenario, Forecast [Member]
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets						$ 8,000,000
ASU 2016-02 [Member] | Maximum [Member] | Scenario, Forecast [Member]
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets						$ 10,000,000
Significant Unobservable Inputs (Level 3) [Member] | Fair Value Measurement Recurring [Member]
Summary Of Significant Accounting Policies [Line Items]
Assets, fair value disclosure, recurring	0			0	0
Liabilities, fair value disclosure, recurring	$ 0			$ 0	$ 0