Changes in Accumulated Other Comprehensive Loss (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Deferred pension and other post-retirement benefit costs, taxes	$ (57)	$ (69)	$ (99)
Amortization of Deferred benefit costs, tax	$ 11	$ 101	$ (43)