Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) Segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments | Segment	1
Government receivables unbilled amount	$ 4.0	$ 2.4
Deferred revenue	3.3
Rent expense and occupancy costs	$ 5.2	4.4	$ 3.4
Employee Stock Purchase Plan [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of closing price of common stock	85.00%
Percentage of discount recognized on graded-vesting based on stock-based compensation expense over the purchase period	15.00%
Patents [Member]
Summary Of Significant Accounting Policies [Line Items]
Initial term of patents	20 years
Patent amortization expense	$ 0.5	0.5	0.4
Patents [Member] | Research and Development Expenses [Member]
Summary Of Significant Accounting Policies [Line Items]
Book value of patent abandoned	$ 0.2	$ 0.1	$ 0.5