Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Summary of Components of Marketable Securities (Details)

v3.8.0.1
Summary of Significant Accounting Policies - Summary of Components of Marketable Securities (Details) - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Amortized Cost $ 18,448 $ 18,843
Unrealized Gains
Unrealized Losses (121) (78)
Market Value 18,327 18,765
U.S. Treasuries [Member]    
Amortized Cost 2,496 1,744
Unrealized Gains
Unrealized Losses (1)
Market Value 2,495 1,744
Corporate Bonds [Member]    
Amortized Cost 15,952 17,099
Unrealized Gains
Unrealized Losses (120) (78)
Market Value $ 15,832 $ 17,021