Acquisition 2012 Acquisition (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended				6 Months Ended	12 Months Ended
	Dec. 28, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 28, 2014	Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012	May 30, 2012
Business Acquisition [Line Items]
Restaurants Acquired	94	25	4		119	123		278
Equity ownership							28.90%	28.90%
Purchase price, cash on hand and inventory								$ 3.8
Purchase price, franchise fees								9.4
Purchase price, ROFR								3.6
Number of States for ROFR									20
Loan, Payment Period								5 years
Restaurants to be remodeled								455
Purchase price								74.5
Equity consideration								57.7
Purchase price, cash								16.8
Convertible Preferred Stock, Common Shares Issuable upon Conversion									9,414,580
Sale of Stock, Price Per Share									$ 6.13
Revenue of acquired restaurants since acquisition						34.0		174.3
Acquisition-related costs	$ 1.2	$ 0.4	$ 0.2	$ 0.1		$ 1.9		$ 1.2
Property Leases Owned in Fee by BKC [Member]
Business Acquisition [Line Items]
Restaurants Acquired								81
Property Leases Identical to BKC's Lease with Third Party [Member]
Business Acquisition [Line Items]
Restaurants Acquired								197