Description of Business and Summary of Significant Accounting Policies - Goodwill (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Goodwill [Line Items]
Amortization of Acquired Intangible Assets	$ 1,400,000	$ 1,200,000	$ 2,500,000	$ 2,400,000
Goodwill [Roll Forward]
Goodwill, beginning balance			259,218,000
Goodwill, Acquired During Period			61,421,000
Foreign currency translation adjustments			(401,000)
Goodwill, ending balance	$ 320,238,000		$ 320,238,000