Shareholders' equity Stock-Based Compensation Related Amounts Recognized in the Consolidated Statements of Income (Loss) for Equity Awards (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 33,882	$ 33,437	$ 26,608
Income tax benefit	12,875	12,706	10,111
Share-based compensation expense, net of tax	21,007	20,731	16,497
Per diluted share impact (in dollars per share)	$ 0.09	$ 0.09	$ 0.07
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	17,754	18,105	14,362
Income tax benefit	9,500	7,000	5,400
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	14,850	12,331	7,991
Stock options and other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 1,278	$ 3,001	$ 4,255