Segment Reporting (Detail) - Revenue By Location (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Total revenue (in dollars)	$ 57,481	$ 55,238	$ 118,675	$ 99,087
Total revenue	100.00%	100.00%	100.00%	100.00%
United States [Member]
United States (in dollars)	37,537	30,671	75,403	55,092
United States	65.00%	56.00%	64.00%	55.00%
Japan [Member]
Other foreign country (in dollars)	9,432	9,765	19,792	19,374
Other foreign country	17.00%	18.00%	17.00%	20.00%
Taiwan [Member]
Other foreign country (in dollars)	2,865	7,429	8,882	9,959
Other foreign country	5.00%	13.00%	7.00%	10.00%
Other [Member]
Other foreign country (in dollars)	$ 7,647	$ 7,373	$ 14,598	$ 14,662
Other foreign country	13.00%	13.00%	12.00%	15.00%