Interest Rate Swaps Estimated Amount to be Reclassified into Earnings Next 12 Months (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016	Dec. 31, 2016	Dec. 26, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments, Loss Recognized in Other Comprehensive Income (Loss), Effective Portion					$ (1,822)
Derivative Instruments, Gain Recognized in Other Comprehensive Income (Loss), Effective Portion		$ 59	$ 412	$ 270
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Net Amount to be Transferred	$ 200
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 1,557	$ 1,557	$ (1,111)	$ 1,557	$ (1,111)	$ 1,392
Beginning Balance [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax						$ 1,392	$ 0