Common Stock and Stock-Based Compensation Plans (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Equity-based compensation expense included in interim condensed consolidated statements of comprehensive income
Total equity-based compensation expense	$ 1,366	$ 1,415	$ 3,688	$ 3,540
Cost of revenue [Member]
Equity-based compensation expense included in interim condensed consolidated statements of comprehensive income
Total equity-based compensation expense	73	61	177	171
Research and development, net [Member]
Equity-based compensation expense included in interim condensed consolidated statements of comprehensive income
Total equity-based compensation expense	468	510	1,327	1,372
Sales and marketing [Member]
Equity-based compensation expense included in interim condensed consolidated statements of comprehensive income
Total equity-based compensation expense	284	291	723	747
General and administrative [Member]
Equity-based compensation expense included in interim condensed consolidated statements of comprehensive income
Total equity-based compensation expense	$ 541	$ 553	$ 1,461	$ 1,250