Other Receivables and Current Assets - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other receivables and current assets	$ 263,820	$ 239,349
Receivables related to unrecognized revenue
Other receivables and current assets	215,155	199,119
Income taxes receivable, including overpayments and refunds
Other receivables and current assets	21,663	15,718
Prepaid expenses and other current assets
Other receivables and current assets	$ 27,002	$ 24,512