Goodwill, In-Process Research and Development and Intellectual Property - Summary of Estimated Future Amortization Expense of Intangible Assets (Detail) - Intellectual Property [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
2018	$ 10,552
2019	10,552
2020	10,552
2021	10,552
2022	10,210
Thereafter	220
Total	$ 52,638	$ 37,090