Property and Equipment by Geographic Area (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	$ 57,160	$ 54,677
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	45,521	43,810
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	5,193	4,753
India
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	3,685	3,033
Other international
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	$ 2,761	$ 3,081