Total Revenues Gross Profit and Long Lived Assets Excluding Long Term Deferred Tax Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets
Total revenues	$ 125,212	$ 129,896	$ 366,398	$ 372,053
Gross profit	100,823	106,961	294,502	302,194
Long-lived assets	64,810		64,810		$ 71,628
Domestic
Revenues from External Customers and Long-Lived Assets
Total revenues	72,439	82,513	220,177	228,427
Gross profit	57,716	68,084	175,814	185,052
Long-lived assets	59,728		59,728		67,031
EMEA
Revenues from External Customers and Long-Lived Assets
Total revenues	40,018	34,636	107,761	106,833
Gross profit	32,716	28,183	86,936	86,131
Long-lived assets	3,542		3,542		3,256
Other Regions
Revenues from External Customers and Long-Lived Assets
Total revenues	12,755	12,747	38,460	36,793
Gross profit	10,391	$ 10,694	31,752	$ 31,011
Long-lived assets	$ 1,540		$ 1,540		$ 1,341