CONSOLIDATED STATEMENTS OF CASH FLOWS Non-Cash Activities - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Other Significant Noncash Transactions [Line Items]
Unrealized loss on available-for-sale securities	$ 131	$ 8
Common Stock Issued to Board of Directors and Scientific Advisory Board that was Earned and Accrued for in Previous Period [Member]
Other Significant Noncash Transactions [Line Items]
Other significant noncash transaction, value of consideration received	300	300
Common Stock Issued to Employees that was Earned and Accrued for in Previous Period Net of Shares Withheld for Taxes [Member]
Other Significant Noncash Transactions [Line Items]
Other significant noncash transaction, value of consideration received	1,105	967
Other Capitalized Property Plant and Equipment [Member]
Other Significant Noncash Transactions [Line Items]
Net change in accounts payable and accrued expenses related to purchases of property and equipment	$ (120)	$ (725)