Fair Value of Financial Assets and Liabilitiest (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets
Marketable securities -corporate bonds	$ 6,025
Marketable securities - mutual funds		$ 3,392
Liabilities
Fair value of warrant liabilities	702	2,959
Level 1 [Member]
Assets
Marketable securities -corporate bonds	211
Marketable securities - mutual funds		3,392
Fair Value, Inputs, Level 2 [Member]
Assets
Marketable securities -corporate bonds	5,814
Fair Value, Inputs, Level 3 [Member]
Assets
Marketable securities -corporate bonds
Liabilities
Fair value of warrant liabilities	$ 702	$ 2,959