Collaborative and Other Agreements (Narrative) (Details) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cash Paid For Channel Collaboration Agreement		$ 32,000
Intrexon Corporation [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payments For Services Under Collaborative Agreement			$ 941,000	$ 357,000
Fees Payable Upon Commencement Of The First Phase 2 Trial	$ 2,500,000	2,500,000
Fees Payable Upon First Regulatory Approval	5,000,000	5,000,000
Expenses Incurred Under Channel Collaborative Agreement	22,000
Cash Paid For Channel Collaboration Agreement	3,000
University Of Leicester [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payments For Services Under Collaborative Agreement	$ 50,000	115,000	182,000	168,000
Collaborative Agreement Expiration Date	Nov. 12, 2015
University Of Glasgow [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payments For Services Under Collaborative Agreement	$ 0	61,000
Walter Reed Army Institute Of Research [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Payments For Services Under Collaborative Agreement	$ 0	$ 0	$ 207,000	309,000
Common Stock [Member] | Intrexon Corporation [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Stock Issued During Period, Value, Issued for Services				$ 3,000,000