Summary of Amortization Expense of Acquired Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Expected Amortization Expense [Line Items]
Amortization of acquired intangible assets in cost of net revenues	$ 213	$ 267	$ 706	$ 450
Amortization of acquired intangible assets in operating expenses	870	868	2,624	1,460
Total amortization of acquired intangible assets	$ 1,083	$ 1,135	$ 3,330	$ 1,910