Share-Based Compensation (Details) - Activity in share-based compensation plans	0 Months Ended	6 Months Ended
	Dec. 29, 2012	Jun. 15, 2013
Service Based Grants [Member]
Share-Based Compensation (Details) - Activity in share-based compensation plans [Line Items]
Outstanding Numbers	512,200	524,100
Outstanding, Weighted Average Remaining Restriction/ Vesting Period (Years)	36 days	36 days
Vested Numbers	475,400	474,800
Granted		12,800
Forfeited/cancelled
Restrictions lapsed/ units settled		(8,400)
Shares deferred upon vesting/settlement & dividend equivalents on deferred shares(1)		7,500
Performance Based Grants [Member]
Share-Based Compensation (Details) - Activity in share-based compensation plans [Line Items]
Outstanding Numbers	641,700	919,500
Outstanding, Weighted Average Remaining Restriction/ Vesting Period (Years)	328 days	1 year 73 days
Vested Numbers	303,100	294,600
Granted		297,800
Forfeited/cancelled		(11,500)
Restrictions lapsed/ units settled		(13,600)
Shares deferred upon vesting/settlement & dividend equivalents on deferred shares(1)		5,100