Segment and Related Information - Schedule of revenue by major customers (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue, Major Customer [Line Items]
Percentage of revenue generated by customer	100.00%	100.00%
All Others
Revenue, Major Customer [Line Items]
Percentage of revenue generated by customer	35.00%	27.00%
Restaurant/Retail | McDonald’s Corporation | Reportable Segments
Revenue, Major Customer [Line Items]
Percentage of revenue generated by customer	19.00%	33.00%
Restaurant/Retail | Yum! Brands, Inc. | Reportable Segments
Revenue, Major Customer [Line Items]
Percentage of revenue generated by customer	13.00%	14.00%
Government | U.S. Department of Defense | Reportable Segments
Revenue, Major Customer [Line Items]
Percentage of revenue generated by customer	33.00%	26.00%