Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities (Narrative) (Details)

Marketable Securities (Narrative) (Details) - Corporate Bonds [Member]
Jun. 30, 2018
USD ($)
Schedule of Available-for-sale Securities [Line Items]  
Securities in a loss position, less than one year | item 7
Fair value, less than one year $ 6,451,770
Unrealized losses, less than one year $ 51,358
Securities in a loss position, greater than one year | item 5
Fair value, greater than one year $ 5,195,598
Unrealized losses, greater than one year $ 13,597