Subsequent Events (Details) $ / shares in Units, shares in Thousands, $ in Millions	Feb. 20, 2019 USD ($) restaurant director state $ / shares shares	Dec. 30, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017
Subsequent Event [Line Items]
Number of restaurants acquired		849	838	807	807	807	798	799	788
Number of states		20
Area Development and Remodeling Agreement | Subsequent Event
Subsequent Event [Line Items]
Number of states | state	16
Number of franchises	500
Quarterly payment amount | $	$ 3.0
Number of restaurants to be built	200
By September 30, 2019	7
By September 30, 2020	32
By September 30, 2021	41
By September 30, 2022	41
By September 30, 2023	40
By September 30, 2024	39
Number of restaurants to be remodeled or upgraded	748
By September 30, 2019	90
By September 30, 2020	130
By September 30, 2021	118
By September 30, 2022	131
By September 30, 2023	138
By September 30, 2024	141
Area Development and Remodeling Agreement | BKC | Minimum | Subsequent Event
Subsequent Event [Line Items]
Number of restaurants to be remodeled or upgraded	50
Contribution by counterparty | $	$ 10.0
Area Development and Remodeling Agreement | BKC | Maximum | Subsequent Event
Subsequent Event [Line Items]
Number of restaurants to be remodeled or upgraded	60
Contribution by counterparty | $	$ 12.0
Merger Agreement - Cambridge Holdings | Subsequent Event
Subsequent Event [Line Items]
Number of shares transferred in acquisition (in shares) | shares	7,360
Conversion price (in dollars per share) | $ / shares	$ 13.50
Term of restrictions on sale or transfer	2 years
Number of counterparty directors that may join board upon merger | director	2
Number of director nominees | director	2
Merger Agreement - Cambridge Holdings | Convertible Preferred Stock | Subsequent Event
Subsequent Event [Line Items]
Preferred stock dividend rate	9.00%
Shares issuable upon conversion of preferred stock (in shares) | shares	7,450
Merger Agreement - Cambridge Holdings | Cambridge Holdings | Subsequent Event
Subsequent Event [Line Items]
Percentage of outstanding common shares held	16.60%
Merger Agreement - Cambridge Holdings | Burger King | Subsequent Event
Subsequent Event [Line Items]
Number of restaurants acquired	166
Merger Agreement - Cambridge Holdings | Popeyes | Subsequent Event
Subsequent Event [Line Items]
Number of restaurants acquired	55