EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Numerator:
Net earnings attributable to controlling interest	$ 33,693	$ 27,819	$ 88,397	$ 80,429
Adjustment for earnings allocated to non-vested restricted common stock	656	463	1,633	1,281
Net earnings for calculating EPS	$ 33,037	$ 27,356	$ 86,764	$ 79,148
Denominator:
Weighted average shares outstanding (in shares)	20,474	20,402	20,481	20,360
Adjustment for non-vested restricted common stock (in shares)	(399)	(340)	(378)	(324)
Shares for calculating basic EPS (in shares)	20,075	20,062	20,103	20,036
Effect of dilutive stock options (in shares)	41	33	37	32
Shares for calculating diluted EPS (in shares)	20,116	20,095	20,140	20,068
Net earnings per share
Basic (USD per share)	$ 1.65	$ 1.36	$ 4.32	$ 3.95
Diluted (USD per share)	$ 1.64	$ 1.36	$ 4.31	$ 3.94
Antidilutive securities
Options to purchase shares excluded from computation of EPS (in shares)	0	0