Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 27, 2017	Dec. 28, 2016	Dec. 30, 2015
Statement of Comprehensive Income [Abstract]
Minimum pension liability adjustment, tax expense (benefit)	$ (22)	$ 2,148	$ 1,425
Recognition of unrealized gain (loss) on hedged transactions, tax expense (benefit)	$ (559)	$ 353	$ (898)