Other Long-Term Liabilities - Summary of Other Long-Term Liabilites (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other Long Term Liabilities Disclosure [Abstract]
Other long term liabilities	$ 19,059	$ 13,862
Income taxes payable	99,200	4,993
Total other long-term liabilities	$ 118,259	$ 18,855