Quarterly Data - Unaudited, in Thousands, except Per Share Data (Details 1) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 28, 2014 item	Sep. 28, 2014 item	Jun. 29, 2014 item	Mar. 30, 2014 item	Dec. 29, 2013 item	Sep. 29, 2013 item	Jun. 30, 2013 item	Mar. 31, 2013 item	Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012
Quarterly Data
Total revenues	$ 425,509	$ 390,399	$ 380,864	$ 401,377	$ 387,890	$ 346,342	$ 349,186	$ 355,604	$ 1,598,149	$ 1,439,022	$ 1,342,653
Operating income	33,443	25,186	26,999	32,002	28,482	21,448	26,948	29,625	117,630	106,503	99,807
Net income attributable to the Company	$ 21,181	$ 16,075	$ 16,748	$ 19,311	$ 18,805	$ 14,276	$ 17,150	$ 19,306	$ 73,315	$ 69,537	$ 61,660
Basic earnings per common share	$ 0.53	$ 0.39	$ 0.40	$ 0.46	$ 0.42	$ 0.33	$ 0.39	$ 0.43	$ 1.78	$ 1.58	$ 1.31
Diluted earnings per common share	$ 0.52	$ 0.39	$ 0.40	$ 0.45	$ 0.41	$ 0.32	$ 0.39	$ 0.42	$ 1.75	$ 1.55	$ 1.29
Dividends declared per common share (in dollars per share)	$ 0.14	$ 0.14	$ 0.125	$ 0.125	$ 0.125	$ 0.125			$ 0.53	$ 0.25
Number of weeks in quarter	13	13	13	13	13	13	13	13