Segment Information (Revenue by Geographic Region) (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	[1]	$ 33,112	$ 29,734	$ 63,687	$ 57,964
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue		10,889	10,354	20,629	20,737
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue		3,205	3,330	6,399	6,714
Republic of Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue		12,119	10,411	24,972	19,645
Rest of the World
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue		$ 6,899	$ 5,639	$ 11,687	$ 10,868

[1] Quarters ended June 30, Components of Revenue2017 2016License Fees9,084 6,678Service Revenue24,028 23,056Net Revenue33,112 29,734 Six Months Ended June 30, Components of Revenue2017 2016License Fees$15,677 $12,455Service Revenue48,010 45,509Net Revenue$63,687 $57,964