Basis of Presentation and Summary of Significant Accounting Policies (Details) (USD $)																										3 Months Ended
	Jun. 30, 2013 Recurring basis	Jun. 30, 2013 Recurring basis Total	Dec. 31, 2012 Recurring basis Total	Jun. 30, 2013 Recurring basis Total Acquisition-related contingent consideration	Jun. 30, 2013 Recurring basis Total Money market funds	Dec. 31, 2012 Recurring basis Total Money market funds	Jun. 30, 2013 Recurring basis Total Corporate debt securities	Dec. 31, 2012 Recurring basis Total Corporate debt securities	Jun. 30, 2013 Recurring basis Total U.S. treasury and government agency securities	Dec. 31, 2012 Recurring basis Total U.S. treasury and government agency securities	Jun. 30, 2013 Recurring basis Total Commercial paper	Dec. 31, 2012 Recurring basis Total Commercial paper	Jun. 30, 2013 Recurring basis Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2012 Recurring basis Quoted Prices in Active Markets for Identical Assets (Level 1)	Jun. 30, 2013 Recurring basis Quoted Prices in Active Markets for Identical Assets (Level 1) Money market funds	Dec. 31, 2012 Recurring basis Quoted Prices in Active Markets for Identical Assets (Level 1) Money market funds	Jun. 30, 2013 Recurring basis Significant Other Observable Inputs (Level 2)	Dec. 31, 2012 Recurring basis Significant Other Observable Inputs (Level 2)	Jun. 30, 2013 Recurring basis Significant Other Observable Inputs (Level 2) Corporate debt securities	Dec. 31, 2012 Recurring basis Significant Other Observable Inputs (Level 2) Corporate debt securities	Jun. 30, 2013 Recurring basis Significant Other Observable Inputs (Level 2) U.S. treasury and government agency securities	Dec. 31, 2012 Recurring basis Significant Other Observable Inputs (Level 2) U.S. treasury and government agency securities	Jun. 30, 2013 Recurring basis Significant Other Observable Inputs (Level 2) Commercial paper	Dec. 31, 2012 Recurring basis Significant Other Observable Inputs (Level 2) Commercial paper	Jun. 30, 2013 Recurring basis Significant Unobservable Inputs (Level 3)	Jun. 30, 2013 Recurring basis Significant Unobservable Inputs (Level 3) Acquisition-related contingent consideration	Jun. 30, 2013 Non-recurring basis Significant Unobservable Inputs (Level 3)
Fair value of assets measured on a recurring basis
Fair value of assets		$ 218,545,000	$ 204,808,000		$ 19,934,000	$ 24,058,000	$ 127,419,000	$ 111,690,000	$ 54,691,000	$ 59,569,000	$ 2,501,000	$ 9,491,000	$ 19,934,000	$ 24,058,000	$ 19,934,000	$ 24,058,000	$ 184,611,000	$ 180,750,000	$ 127,419,000	$ 111,690,000	$ 54,691,000	$ 59,569,000	$ 2,501,000	$ 9,491,000
Fair value of liabilities				14,000,000																					14,000,000	14,000,000
Intangible assets																											17,200,000
Discount rate																										15.00%	19.00%
Transfers or reclassifications of securities from Level 1 to Level 2	0
Transfers or reclassifications of securities from Level 2 to Level 1	$ 0