Senior Credit Facility - Credit Agreement (Details) - USD ($)					12 Months Ended
	Dec. 30, 2017	Jun. 15, 2017	Dec. 31, 2016	Feb. 19, 2016	Dec. 30, 2017
Line of Credit Facility
Senior Credit Facility, Maximum Borrowing Capacity	$ 500,000,000			$ 500,000,000	$ 500,000,000
Swingline Loan, Maximum Borrowing Capacity			$ 50,000,000		50,000,000
Debt Issuance Costs, Net	(1,400,000)		(1,100,000)		(1,400,000)
Unsecured debt, net of debt issuance costs	426,100,000		273,900,000		426,100,000
Unsecured Debt, Current	(25,000,000)		(10,000,000)		(25,000,000)
Long-term Debt, Excluding Current Maturities	401,069,000		263,850,000		401,069,000
Term Loan, Maximum Borrowing Capacity		$ 100,000,000		200,000,000
Unsecured Debt	427,500,000		275,000,000		427,500,000
Letters of Credit Outstanding, Amount	$ 39,600,000		44,300,000		$ 39,600,000
Debt Instrument, Interest Rate, Stated Percentage	1.00%				1.00%
Debt Instrument, Basis Spread on Variable Rate	0.75%
Commitment fee for unused capacity	0.125%
Compensating Balance, Amount	$ 0				$ 0
Debt Instrument, Covenant Compliance					all
Base Rate
Line of Credit Facility
Line of Credit Facility, Interest Rate at Period End	4.50%				4.50%
London Interbank Offered Rate (LIBOR)
Line of Credit Facility
Line of Credit Facility, Interest Rate at Period End	1.56%				1.56%
Minimum
Line of Credit Facility
Debt Instrument, Basis Spread on Variable Rate					0.50%
Commitment fee for unused capacity					0.075%
Maximum
Line of Credit Facility
Debt Instrument, Basis Spread on Variable Rate					1.125%
Commitment fee for unused capacity					0.20%
February 2016 Term Loan
Line of Credit Facility
Term loan, Maximum Month End Outstanding Amount	$ 180,000,000		190,000,000		$ 180,000,000
Term Loan, Maximum Borrowing Capacity				$ 200,000,000
Debt Instrument, Maturity Date	Feb. 19, 2022
Due in years three through five February 2016 Term Loan
Line of Credit Facility
Debt Instrument, Frequency of Periodic Payment					20
Due in years one and two February 2016 Term Loan
Line of Credit Facility
Debt Instrument, Frequency of Periodic Payment					10
June 2017 Term Loan
Line of Credit Facility
Term loan, Maximum Month End Outstanding Amount	$ 97,500,000		0		$ 97,500,000
Term Loan, Maximum Borrowing Capacity		$ 100,000,000
Debt Instrument, Maturity Date	Jun. 15, 2022
Due in years three through five June 2017 Term Loan
Line of Credit Facility
Debt Instrument, Frequency of Periodic Payment					10
Due in years one and two June 2017 Term Loan
Line of Credit Facility
Debt Instrument, Frequency of Periodic Payment					5
2016 Senior Credit Facility
Line of Credit Facility
Line of Credit Facility, Maximum Month-end Outstanding Amount	$ 0		$ 85,000,000
Number of Financial Covenants
Line of Credit Facility
Debt Instrument, Covenant Description					2
Fixed Charge Coverage Ratio Minimum Requirement
Line of Credit Facility
Debt Instrument, Covenant Description					2.00
Leverage Ratio Maximum Requirement
Line of Credit Facility
Debt Instrument, Covenant Description					4.00