Acquisition-Related Contingent Consideration (Details) (EUR €) In Thousands, unless otherwise specified	6 Months Ended			6 Months Ended
	Jun. 30, 2012		Apr. 01, 2009	Jun. 30, 2012 Royalties for Influenza Vaccines [Member]	Dec. 31, 2011 As recorded on December 31, 2011 [Member] Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 As recorded on December 31, 2011 [Member] Royalties for RSV [Member] Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 As recorded on December 31, 2011 [Member] Royalties for HSV [Member] Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 As recorded on December 31, 2011 [Member] Royalties for Influenza Vaccines [Member] Unobservable Inputs (Level 3) [Member]	Jun. 30, 2012 Measurement Adjustment [Member] Unobservable Inputs (Level 3) [Member]	Jun. 30, 2012 Measurement Adjustment [Member] Royalties for RSV [Member] Unobservable Inputs (Level 3) [Member]	Jun. 30, 2012 Measurement Adjustment [Member] Royalties for HSV [Member] Unobservable Inputs (Level 3) [Member]	Jun. 30, 2012 Measurement Adjustment [Member] Royalties for Influenza Vaccines [Member] Unobservable Inputs (Level 3) [Member]	Jun. 30, 2012 As adjusted on March 31, 2012 [Member] Unobservable Inputs (Level 3) [Member]	Jun. 30, 2012 As adjusted on March 31, 2012 [Member] Royalties for RSV [Member] Unobservable Inputs (Level 3) [Member]	Jun. 30, 2012 As adjusted on March 31, 2012 [Member] Royalties for HSV [Member] Unobservable Inputs (Level 3) [Member]	Jun. 30, 2012 As adjusted on March 31, 2012 [Member] Royalties for Influenza Vaccines [Member] Unobservable Inputs (Level 3) [Member]
Acquisition-Related Contingent Consideration [Abstract]
Contingent consideration cash payment from third party commence a Phase III clinical trial, maximum			€ 3,000
Percentage of net royalties receivable as contingent consideration (in hundredths)			50.00%
Percentage of amount received from third party for license receivable as contingent consideration (in hundredths)			25.00%
Discount rate of cash flows (in hundredths)	13.90%
Changes to the Company's acquisition-related contingent consideration [Abstract]
Fair value of the contingent consideration	6,291	[1]			5,753	3,216	2,537	0	538	349	189	0	6,291	3,565	2,726	0
Increase in fair value of contingent consideration	538
Decrease in the fair value of contingent consideration				€ 0

[1] Under the terms of the acquisition of Bestewil BV, as part of the consideration, the Company is committed to make further payments to NIL in the event that certain stated milestones for the development of vaccines are achieved. These have been considered on a risk probability basis.