Segments and Geographic Information - Selected Information by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$ 11,790	$ 12,986	$ 13,956	$ 11,247	$ 20,930	$ 11,556	$ 11,610	$ 10,477	$ 49,979	$ 54,573	$ 38,287
Total assets	61,220				57,571				61,220	57,571
Total Long-lived assets	16,124				14,502				16,124	14,502
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues									10,464	19,955	7,677
Total assets	21,683				21,423				21,683	21,423
Total Long-lived assets	523				663				523	663
Switzerland [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues									33,264	27,302	23,139
Total assets	1,366				4,673				1,366	4,673
Total Long-lived assets	535				369				535	369
Nottingham, UK Facility [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues									3,559	4,632	4,422
Total assets	38,129				31,288				38,129	31,288
Total Long-lived assets	15,064				13,468				15,064	13,468
Other Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues									2,692	2,684	3,049
Total assets	42				187				42	187
Total Long-lived assets	$ 2				$ 2				2	2
International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues									$ 39,515	$ 34,618	$ 30,610