Revenues - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2018	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Percentage of revenue	100.00%	100.00%	100.00%	100.00%
Deferred revenue recognized in the period	$ 300	$ 300	$ 3,400	$ 4,200
Revenue remaining performance obligation expected timing of satisfaction explanation			The Company expects to recognize the majority of its deferred revenue as of June 30, 2019 over the next 180 days
Estimated refund liabilities timing of resolution explanation			Estimated refund liabilities are generally resolved in 180 days, once it is determined whether the requisite service levels and client requirements were achieved to settle the contingency.
Customer Engagement Solutions and Services [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue, performance obligation satisfied over time, method used, description			Revenues for customer engagement solutions and services are recognized over time using output methods such as a per minute, per hour, per call, per transaction or per time and materials basis
Other Revenues [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Percentage of revenue	2.60%	0.60%	2.20%	0.60%
Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings					$ 3,019
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings					$ 3,019	$ 3,000