Summary of Significant Accounting Policies - Additional Information (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Customer shares	Dec. 31, 2015 USD ($) Customer shares	Dec. 31, 2014 USD ($) Customer
Summary Of Significant Accounting Policies [Line Items]
Estimated salvage value	70.00%
Capitalized software development costs, net	$ 8,497,000	$ 15,855,000
Capitalized computer software, amortization	7,400,000	7,200,000	$ 5,200,000
Additions to capitalized software development costs	$ 0	9,600,000	8,400,000
Variance below minimum VSOE rate	10.00%
Advertising costs	$ 1,300,000	500,000	3,000,000
Prepaid advertising costs	$ 0	$ 0
Common stock, conversion ratio	One
Preferred stock, shares outstanding | shares	0	0
Reclassification of foreign currency translation adjustment from other comprehensive income	$ 0	$ 280,000	0
Cumulative foreign currency translation amount	(10,800,000)	(7,400,000)	(4,400,000)
Foreign currency translation adjustments, tax	0	0	0
Transaction gains (losses) arising from transactions denominated in foreign currencies	$ 3,000,000	$ 2,400,000	$ 5,300,000
Customer Concentration Risk | Sales Revenue, Goods, Net
Summary Of Significant Accounting Policies [Line Items]
Number of individual customer accounted for 10% or more of net accounts receivable | Customer	0	0
Number of individual customer accounted for 10% or more of total revenues | Customer	0	0	0
Class A
Summary Of Significant Accounting Policies [Line Items]
Common stock, voting rights, per share	One
Class B Convertible
Summary Of Significant Accounting Policies [Line Items]
Common stock, voting rights, per share	Ten
Computer Equipment And Purchased Software
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, years	3 years
Office Equipment And Automobiles
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, years	5 years
Office Furniture And Corporate Aircraft
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, years	10 years
Software Development
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets, years	3 years