Business Segment Reporting (Narrative) (Details) $ in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2020 USD ($) segment	Dec. 31, 2019 segment
Business Segment Reporting [Abstract]
Number of reportable segments \| segment	1	2
Maximum percentage of revenue from customers and franchisees generated in foreign market	5.00%
Investment in minority interest \| $	$ 4

Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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