Fair Value Measurements (Details) (EUR €)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Percentage of net royalties receivable as contingent consideration (in hundredths)	50.00%
Royalties for RSV [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Percentage of net royalties receivable as contingent consideration (in hundredths)	10.00%	2.00%
Acquisition-related Contingent Consideration [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1	€ 5,753	€ 3,212
Change in fair value recorded in earnings	780	2,541
Balance at December 31	€ 6,533	€ 5,753