Overview and Basis of Presentation - Schedule of Total Advertising Costs Included in Direct Salaries and Related Costs in Condensed Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Direct Salaries and Related Costs [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Customer-acquisition advertising costs	$ 10,182	$ 12,104