Organization and Capitalization - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended
	Dec. 18, 2017	Dec. 31, 2017	Mar. 31, 2018	Dec. 06, 2013
Organization And Capitalization [Line Items]
Common stock, shares authorized		750,000,000	750,000,000
Preferred stock, shares authorized				25,000,000
Preferred stock, par value (in dollars per share)				$ 0.01
Minimum [Member]
Organization And Capitalization [Line Items]
Common stock, shares authorized				225,000,000
Maximum [Member]
Organization And Capitalization [Line Items]
Common stock, shares authorized				750,000,000
China National Scientific and Instruments and Materials Company [Member]
Organization And Capitalization [Line Items]
Proceeds from distribution agreement		$ 7,500,000
Proceeds from distribution agreement including equity investment			$ 7,500,000
Distribution agreement, equity investment			$ 3,000,000
Distribution agreement, equity investment per share	$ 2.33
Distribution minimum royalties payment	$ 14,000,000
Distribution minimum royalties payment term	5 years
China National Scientific and Instruments and Materials Company [Member] | Minimum [Member]
Organization And Capitalization [Line Items]
Expected proceeds from distribution agreement	$ 29,000,000