Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Financial Assets and Liabilities Carried at Fair Value on Recurring Basis (Details)

v3.8.0.1
Fair Value Measurements - Financial Assets and Liabilities Carried at Fair Value on Recurring Basis (Details) - Recurring [Member] - Money Market Funds [Member] - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Assets:    
Money market funds [1] $ 34,907 $ 4,161
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]    
Assets:    
Money market funds [1] $ 34,907 $ 4,161
[1] Included in cash and cash equivalents