Intangible Assets - Summary of Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Acquired Finite-Lived Intangible Assets [Line Items]
Less: accumulated amortization	$ (45,003)	$ (36,984)
Goodwill	3,218
Intangible assets, net	16,684	16,787
Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	23,949	21,126
Customer relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	27,778	26,777
Intellectual property assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	$ 6,742	$ 5,868