Business Combination (Details) (USD $)	6 Months Ended	1 Months Ended
	Jun. 30, 2011	Apr. 30, 2011 Privately-held company	Apr. 04, 2011 Privately-held company	Apr. 04, 2011 Privately-held company Core technology
Business combination
Cash paid to acquire a privately -held company	$ 28,273,000	$ 28,300,000
Definite-lived intangibles			16,400,000	13,600,000
Goodwill	$ 15,104,000	$ 15,100,000