Revolving credit line Revolving credit line (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of Revolving Credit Line

The following table summarizes our revolving credit line balance:

	December 31, 2017		December 31, 2016
Revolving credit line - 5.25 percent at December 31, 2017 (prime plus 0.75 percent), due September 29, 2018 - current portion	$	4,900,000	$	—
Total	$	4,900,000	$	—