Goodwill and Intangible Assets, Net (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Changes in the carrying amount of goodwill
Balance at the beginning of the period			$ 99,849
Acquisitions			29,607
Foreign exchange			(1,473)
Balance at the end of the period	127,983	72,111	127,983	72,111
Changes in the carrying amount of intangible assets
Balance at the beginning of the period			27,856
Acquisitions	17,667		17,667
Amortization	(1,900)	(1,100)	(3,714)	(2,200)
Foreign exchange			(280)
Balance at the end of the period	$ 41,529	$ 22,051	$ 41,529	$ 22,051