Stockholders' Equity - Accumulated Other Comprehensive Loss (Details) - USD ($)	6 Months Ended
	Jul. 01, 2018	Jun. 25, 2017	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (1,400,000)	$ (1,500,000)	$ (1,400,000)
Reclassifications from other comprehensive income	0	0
Cumulative translation adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	(1,000,000)	(900,000)
Post-retirement benefit reserve adjustment net of tax expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (400,000)	$ (600,000)