Restructuring and Severance - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost And Reserve [Line Items]
Restructuring and severance	$ 3,088	$ 1,266
General and Administrative Expense
Restructuring Cost And Reserve [Line Items]
Severance costs		$ 100