Goodwill and Other Intangible Assets (Schedule of Identifiable Intangible Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 11,650	$ 12,130
Accumulated Amortization	(5,536)	(5,589)
Intangible Assets, Net	6,114	6,541
Proprietary adjuvant technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,026	8,357
Accumulated Amortization	(2,274)	(2,263)
Intangible Assets, Net	5,752	6,094
Collaboration agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	3,624	3,773
Accumulated Amortization	(3,262)	(3,326)
Intangible Assets, Net	$ 362	$ 447