Segment and Related Information - Revenue by Major Customers (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue, Major Customer [Line Items]
Concentration risk, percentage	100.00%	100.00%	100.00%	100.00%
Operating segments | Restaurant/Retail | McDonald’s Corporation
Revenue, Major Customer [Line Items]
Concentration risk, percentage	10.00%	22.00%	10.00%	25.00%
Operating segments | Restaurant/Retail | Yum! Brands, Inc.
Revenue, Major Customer [Line Items]
Concentration risk, percentage	13.00%	12.00%	13.00%	12.00%
Operating segments | Government | U.S. Department of Defense
Revenue, Major Customer [Line Items]
Concentration risk, percentage	36.00%	34.00%	35.00%	31.00%
Other
Revenue, Major Customer [Line Items]
Concentration risk, percentage	41.00%	32.00%	42.00%	32.00%