Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Narrative (Details)

v3.19.1
Summary of Significant Accounting Policies - Narrative (Details) - USD ($)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Accounting Policies [Abstract]    
Realized gains (losses) recognized on available-for-sale investments $ 0 $ (200,000)