Accrued expenses and other current liabilities - Summary of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Accrued goods and services	$ 24,193	$ 34,275
Employee compensation	12,339	11,296
Accrued license and milestone fees	3,367	2,464
Accrued professional service fees	1,391	1,492
Financing lease obligation, current portion	815
Contingent consideration, current portion		4,479
Other	490	654
Total accrued expenses and other current liabilities	$ 42,595	$ 54,660