Significant Accounting Policies - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) $ / shares	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) agency $ / shares	Jun. 30, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of government agencies | agency				3
Change in allowance for doubtful accounts | $				$ 200
Capitalized contract cost, amortization period	5 years	5 years		5 years
Commission expense | $		$ 5,800	$ 3,600	$ 11,100	$ 6,600
Customer Concentration Risk | Sales Revenue, Net | Foreign Customers
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage		36.80%	32.90%	35.00%	32.40%
Customer Concentration Risk | Sales Revenue, Net | Government Agencies
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage		19.00%	16.80%	16.80%	17.30%
Customer Concentration Risk | Sales Revenue, Net | Federal Government Agencies
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage		7.60%	6.40%	6.70%	7.30%
Class A Common Stock | Underwritten Public Offering
Summary Of Significant Accounting Policies [Line Items]
Number of shares issued in public offering (in shares) | shares	2,500,000
Number of shares issued by the company in public offering (in shares) | shares	1,931,206
Number of shares issued by sharesholders in public offering (in shares) | shares	568,794
Sale of stock, offering price (in usd per share) | $ / shares	$ 56.50	$ 56.50		$ 56.50
Net proceeds from public offering | $	$ 107,900