Fair Value Measurements - Recurring Fair Value Measurements Related to Liabilities (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 20, 2017	Dec. 21, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
TSR Performance Based Incentive Plan(1)	$ 452	$ 1,129
Derivative - Interest Rate Swap	93	91
Total liabilities at Fair Value	545	1,220
Performance Shares [Member] | 2015 Performance Based Incentive Plan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
TSR Performance Based Incentive Plan(1)		491
Performance Shares [Member] | 2016 Performance Based Incentive Plan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
TSR Performance Based Incentive Plan(1)	369	526
Performance Shares [Member] | 2017 Performance Based Incentive Plan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
TSR Performance Based Incentive Plan(1)	83	112
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
TSR Performance Based Incentive Plan(1)	0	0
Derivative - Interest Rate Swap	0	0
Total liabilities at Fair Value	0	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
TSR Performance Based Incentive Plan(1)	452	1,129
Derivative - Interest Rate Swap	93	91
Total liabilities at Fair Value	545	1,220
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
TSR Performance Based Incentive Plan(1)	0	0
Derivative - Interest Rate Swap	0	0
Total liabilities at Fair Value	$ 0	$ 0