Lease Commitments (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015
Operating Leased Assets [Line Items]
Percentage of facilities under operating lease	54.00%
Lease Expiration Date	Dec. 31, 2033
Accrued Rent	$ 0	$ 32
Maximum [Member]
Operating Leased Assets [Line Items]
Lessee Leasing Arrangements, Operating Leases, Renewal Term	20 years
Minimum [Member]
Operating Leased Assets [Line Items]
Lessee Leasing Arrangements, Operating Leases, Renewal Term	5 years