Fair Value Measurement (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Money Market Funds [Member]
Schedule of assets and liabilities measured at fair value on a recurring basis
Total assets at fair value on a recurring basis	$ 101	$ 113
Deferred payments [Member]
Liabilities:
Total liabilities at fair value on a recurring basis	4,556	4,514
Quoted Prices In Active Markets For Identical Assets/Liabilities (Level 1) [Member] | Money Market Funds [Member]
Schedule of assets and liabilities measured at fair value on a recurring basis
Total assets at fair value on a recurring basis	101	113
Significant Unobservable Inputs (Level 3) [Member] | Deferred payments [Member]
Liabilities:
Total liabilities at fair value on a recurring basis	$ 4,556	$ 4,514