Annual report pursuant to Section 13 and 15(d)

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

v3.10.0.1
Fair Value Measurements - Financial Assets and Liabilities Carried at Fair Value on Recurring Basis (Details) - Recurring [Member] - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Assets:    
Long-term equity securities $ 392  
Money Market Funds [Member]    
Assets:    
Money market funds [1]   $ 34,907
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money Market Funds [Member]    
Assets:    
Money market funds [1]   $ 34,907
Significant Unobservable Inputs (Level 3) [Member]    
Assets:    
Long-term equity securities $ 392  
[1] Included in cash and cash equivalents