Leases Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2019	Dec. 27, 2018	Dec. 26, 2018
Lessee, Lease, Description [Line Items]
Operating Lease, Lease Income	$ 100
Finance Lease, Liability, Payments, Remainder of Fiscal Year	52
Capital Leases, Future Minimum Payments Due, Next Twelve Months			$ 95
Operating Lease, Payments	6,526
Property held under operating leases, net (ROU Asset)	200,726	$ 205,200	0
Operating Lease, Cost	6,931
Short-term Lease, Cost	8
Variable Lease, Cost	170
Sublease Income	(27)
Lease, Cost	7,096
Operating Lease, Liability	218,140	$ 222,300
Finance Lease, Principal Payments	35
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	205,223
Operating Leases, Future Minimum Payments Due, Next Twelve Months	19,893		25,388
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Next Twelve Months	954		1,443
Finance Lease, Liability, Payments, Due Year Two	54
Capital Leases, Future Minimum Payments Due in Two Years			54
Operating Leases, Future Minimum Payments, Due in Two Years	26,411		24,437
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Two Years	1,108		1,108
Finance Lease, Liability, Payments, Due Year Three	54
Capital Leases, Future Minimum Payments Due in Three Years			54
Operating Leases, Future Minimum Payments, Due in Three Years	26,062		23,342
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Three Years	1,078		1,078
Finance Lease, Liability, Payments, Due Year Four	45
Capital Leases, Future Minimum Payments Due in Four Years			45
Operating Leases, Future Minimum Payments, Due in Four Years	25,028		22,338
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Four Years	1,001		1,001
Finance Lease, Liability, Payments, Due Year Five	0
Capital Leases, Future Minimum Payments Due in Five Years			0
Operating Leases, Future Minimum Payments, Due in Five Years	22,500		20,634
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, within Five Years	989		989
Finance Lease, Liability, Payments, Due after Year Five	0
Capital Leases, Future Minimum Payments Due Thereafter			0
Operating Leases, Future Minimum Payments, Due Thereafter	153,141		150,342
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Thereafter	2,612		2,612
Finance Lease, Liability, Payments, Due	205
Capital Leases, Future Minimum Payments Due			248
Operating Leases, Future Minimum Payments Due	273,035		266,481
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals	7,742		8,231
Finance Lease, Liability, Undiscounted Excess Amount	(55)
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(54,895)
Finance Lease, Liability	150
Capital Leases, Future Minimum Payments, Interest Included in Payments			(64)
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments			184
Capital Lease Obligations, Current	(41)		(68)
Obligations under finance leases, net of current portion	109		116
Finance Lease, Liability, Current	(41)
Current portion of obligations under operating leases	(17,697)		0
Finance Lease, Liability, Noncurrent	109
Finance Lease, Right-of-Use Asset, Amortization	6
Finance Lease, Interest Expense	8
Operating Lease, Liability, Noncurrent	200,443		$ 0
Property Lease [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Payments	6,196
Operating Lease, Cost	6,604
Short-term Lease, Cost	0
Variable Lease, Cost	97
Sublease Income	(27)
Lease, Cost	6,688
Finance Lease, Principal Payments	35
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 200,555
Finance Lease, Weighted Average Remaining Lease Term	3 years 4 months 25 days
Operating Lease, Weighted Average Discount Rate, Percent	4.38%
Operating Lease, Weighted Average Remaining Lease Term	12 years 4 months 14 days
Finance Lease, Weighted Average Discount Rate, Percent	11.09%
Finance Lease, Right-of-Use Asset, Amortization	$ 6
Finance Lease, Interest Expense	8
Equipment Lease [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Payments	330
Operating Lease, Cost	327
Short-term Lease, Cost	8
Variable Lease, Cost	73
Sublease Income	0
Lease, Cost	408
Finance Lease, Principal Payments	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 4,668
Operating Lease, Weighted Average Discount Rate, Percent	3.98%
Operating Lease, Weighted Average Remaining Lease Term	3 years 9 months 10 days
Finance Lease, Weighted Average Discount Rate, Percent	0.00%
Operating Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	$ 6,770
General and Administrative Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	119
Depreciation and amortization [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	6
Interest Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	8
Restructuring Charges [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	$ 193