Debt (Details)					1 Months Ended	9 Months Ended	12 Months Ended
		Dec. 10, 2015 USD ($)	Jun. 19, 2014 USD ($)	Dec. 28, 2011 USD ($)	Jan. 31, 2012 USD ($)	Sep. 28, 2018	Dec. 26, 2017	Dec. 27, 2016 USD ($)	Dec. 29, 2015 USD ($)	Dec. 30, 2014 USD ($)	Dec. 31, 2013 USD ($)	Jul. 14, 2014 BusinessUnit
Line Of Credit Facility [Line Items]
Line of credit facility borrowings									$ 591,263,000	$ 595,421,000
Quarterly amortization of term loan									$ 1,000,000
Commitment fee percentage									0.50%
Issuance of debt			$ 40,000,000						$ 0	$ 40,000,000	$ 0
Number of restaurants acquired | BusinessUnit												56
Interest is paid at base rate										4.00%
Notional amount of interest rate derivatives					$ 150,000,000.0
Derivatives interest rate payable					2.50%
Senior note redemption percentage one									105.25%
Senior note redemption percentage two									102.625%
Credit agreement period									95 days
Scenario, Forecast
Line Of Credit Facility [Line Items]
Maximum leverage ratio						525.00%	575.00%	600.00%
Credit agreement, prepayment amount								$ 3,300,000
Revolving Credit Facility
Line Of Credit Facility [Line Items]
Borrowing capacity available under our revolving line of credit				$ 110,000,000
Increase to borrowing capacity of Revolving Facility				110,000,000.0
Weighted average interest rate									4.17%
Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Line Of Credit Facility [Line Items]
Interest is paid at base rate		3.75%							3.75%
Basis of spread on base rate change									0.50%
Revolving Credit Facility
Line Of Credit Facility [Line Items]
Borrowing capacity available under our revolving line of credit									$ 80,900,000	$ 90,900,000
Outstanding letters of credit									(29,100,000)	(19,100,000)
Line of credit facility borrowings	[1]								0	0
Term Loan
Line Of Credit Facility [Line Items]
Line of credit facility borrowings									$ 401,263,000	405,421,000
Term loan borrowings				$ 375,000,000.0
Issuance of debt			40,000,000
Interest is paid at base rate									0.00%
Weighted average interest rate									4.75%
Term Loan | London Interbank Offered Rate (LIBOR)
Line Of Credit Facility [Line Items]
Interest is paid at base rate		0.75%
Basis of spread on base rate change		3.75%
Term Loan Debt
Line Of Credit Facility [Line Items]
Issuance of debt			40,000,000.0
Increase to borrowing capacity of Revolving Facility			125,000,000.0
Line of credit facility, remaining borrowing capacity			85,000,000.0
Line of Credit
Line Of Credit Facility [Line Items]
Debt issuance cost		$ 1,800,000	$ 700,000
Senior Notes
Line Of Credit Facility [Line Items]
Line of credit facility borrowings									$ 190,000,000	$ 190,000,000
Interest on senior notes									10.50%

[1] At December 29, 2015, the Company had $80.9 million of borrowing capacity available under its Revolving Facility, net of $29.1 million of outstanding letters of credit. At December 30, 2014, the Company had $90.9 million of borrowing capacity available under its Revolving Facility, net of $19.1 million of outstanding letters of credit.