Prepaid Expenses and Other Assets - Summary of Prepaid Expenses and Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Prepaid Expense and Other Assets [Abstract]
Revenues in excess of billings	$ 7,987	$ 4,841
Prepaid expenses	3,390	7,494
Contract retainage	2,469	1,449
Income tax receivable	471	2,230
Other	1,245	864
Total prepaid expenses and other assets	$ 15,562	$ 16,878