Share-Based Payments Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified		12 Months Ended								12 Months Ended									12 Months Ended				12 Months Ended
	Dec. 29, 2012 Grant_Types Share-based_Compensation_Plans	Dec. 31, 2011 Class B common stock, non-voting		Dec. 25, 2010 Class B common stock, non-voting		Dec. 29, 2012 Class B common stock, non-voting		Dec. 26, 2009 Class B common stock, non-voting		Dec. 29, 2012 Stock options	Dec. 31, 2011 Stock options	Dec. 25, 2010 Stock options	Dec. 29, 2012 RSUs	Dec. 31, 2011 RSUs	Dec. 25, 2010 RSUs	Dec. 29, 2012 DSUs	Dec. 31, 2011 DSUs	Dec. 25, 2010 DSUs	Dec. 29, 2012 PUs	Dec. 31, 2011 PUs	Dec. 25, 2010 PUs	Dec. 29, 2012 PUs Class B common stock, non-voting	Dec. 31, 2011 SOSARs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-based compensation plans	3
Number of SBC plan grants, by type	2
Terms of SBC award										10	10 years												10 years
Annual vesting percentage										33.33%
Award vesting period										3 years	3 years		3 years						3 years				3 years
Granted (in shares)										300,000	700,000	700,000	400,000	300,000	300,000				700,000	600,000	700,000		0
Equity instruments other than options, nonvested, weighted average grant date fair value										$ 8.09	$ 9.60	$ 10.95	$ 42.04	$ 44.27	$ 43.61	$ 43.74	$ 43.53	$ 45.25	$ 10.90	$ 11.67
Performance units, payout value low end of range																			0
Performance units, payout value high end of range																			2
Common stock, issued shares		162,700,000	[1]	162,000,000	[1]	164,200,000	[1]	159,400,000	[1]													0
Stock options outstanding, intrinsic value																			$ 18.9	$ 22.9
Equity instruments other than options, compensation expense, mark-to-market		$ 0.1		$ 2.6

[1] During 2011, we repurchased Class B common shares which results in a lower number of outstanding shares compared to issued shares. See "Share Repurchase Program" below for further discussion. For all other classes, issued shares equal outstanding shares.