- Schedule of revenue by major customers (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Revenue, Major Customer [Line Items]
Percentage of revenue generated by customer	100.00%	100.00%
Restaurant/Retail | McDonald’s Corporation | Reportable Segments
Revenue, Major Customer [Line Items]
Percentage of revenue generated by customer	33.00%	25.00%
Restaurant/Retail | Yum! Brands, Inc. | Reportable Segments
Revenue, Major Customer [Line Items]
Percentage of revenue generated by customer	14.00%	11.00%
Government | U.S. Department of Defense | Reportable Segments
Revenue, Major Customer [Line Items]
Percentage of revenue generated by customer	26.00%	35.00%
Other
Revenue, Major Customer [Line Items]
Percentage of revenue generated by customer	27.00%	29.00%